US20080058697A1 - Heat exchange systems, devices and methods - Google Patents

Abstract

Embodiments of the present invention relate generally to heat-exchanger systems that can be used to heat or cool a fluid such as blood. Pod pumps that provide low shear and low turbulence may be used in such systems, particularly for systems that pump blood. A certain heat-exchanger system used to heat blood or other fluids may be used to provide whole-body hyperthermic treatments or regional hyperthermic chemotherapy treatments. A disposable unit may be used to separate the fluid path from the fluid control systems. The disposable unit typically includes a heat-exchanger component that is received by a corresponding heat exchanger in a base unit. Fluid pumped through the heat-exchanger component is heated by the heat exchanger.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application claims priority from the following United States Provisional Patent Applications, all of which are hereby incorporated herein by reference in their entireties:
• U.S. Provisional Patent Application No. 60/792,073 entitled Extracorporeal Thermal Therapy Systems and Methods filed on Apr. 14, 2006;
• U.S. Provisional Patent Application No. 60/835,490 entitled Extracorporeal Thermal Therapy Systems and Methods filed on Aug. 4, 2006;
• U.S. Provisional Patent Application No. 60/904,024 entitled Hemodialysis System and Methods filed on Feb. 27, 2007; and
• U.S. Provisional Patent Application No. 60/921,314 entitled Sensor Apparatus filed on Apr. 2, 2007.
• This application is also related to the following United States patent applications, all of which are being filed on even date herewith and are hereby incorporated herein by reference in their entireties:
• U.S. patent application entitled LIQUID PUMPING SYSTEM, DEVICE AND METHOD (Attorney Docket No. 1062/E78); and
• U.S. patent application entitled THERMAL AND CONDUCTIVITY SENSING SYSTEMS, DEVICES, AND METHODS (Attorney Docket No. 1062/E79).
• This application is also related to U.S. patent application Ser. No. 10/697,450 entitled BEZEL ASSEMBLY FOR PNEUMATIC CONTROL filed on Oct. 30, 2003 and published as Publication No. US 2005/0095154 (Attorney Docket No. 1062/D75) and related PCT Application No. PCT/US2004/035952 entitled BEZEL ASSEMBLY FOR PNEUMATIC CONTROL filed on Oct. 29, 2004 and published as Publication No. WO 2005/044435 (Attorney Docket No. 1062/D71 WO), both of which are hereby incorporated herein by reference in their entireties.
TECHNICAL FIELD
• The present invention relates heat exchange systems
BACKGROUND ART
• It is known in the prior art that altering the body temperature of a patient by means of extracorporeal heating can treat a variety of diseases, such as Hepatitis C and possibly some types of cancer, HIV/AIDS, rheumatoid arthritis and psoriasis. In order to heat the blood in a reasonable amount of time, high flow rates are necessary from the patient's body to a heater and back to the patient.
• Centrifugal pumps have been used in prior art systems in order to achieve relatively large flow rates of blood to and from the patient's body. Although the centrifugal pumps can achieve the necessary high flow rates, the centrifugal pumps create relatively large shear forces on the blood resulting in an undesirable amount of hemolysis. Heated blood is even more prone to hemolysis.
• Because of the large flow rates of blood to and from the patient, a leak in the system could quickly result in the death of the patient.
• The prior art systems also typically involve bulky equipment and are relatively clumsy, resulting in time lags when switching the system from one patient to the next, and increasing the risk of the system being improperly set up.
SUMMARY OF THE INVENTION
• In accordance with one aspect of the invention there is provided a method for heating or cooling a fluid, the method comprising:
• providing at least one reciprocating positive-displacement pump, each pump having:
• • a curved rigid chamber wall;
  • a flexible membrane attached to the rigid chamber wall, so that the flexible membrane and rigid chamber wall define a pumping chamber;
  • an inlet for directing fluid through the rigid chamber wall into the pumping chamber in at least one of (a) a direction that is substantially tangential to the rigid chamber wall and (b) a direction that provides low-shear flow into the pumping chamber; and
  • an outlet for directing fluid through the rigid chamber wall out of the pumping chamber in at least one of (a) a direction that is substantially tangential to the rigid chamber wall and (b) a direction that provides low-shear flow out of the pumping chamber;
• providing a heat exchanger; and
• pumping the fluid from a source using the at least one reciprocating positive-displacement pump so as to cause the fluid to pass through the heat exchanger.
• In accordance with another aspect of the invention there is provided a disposable unit for use in a heat exchanger system, the disposable unit comprising:
• at least one reciprocating positive-displacement pump, each pump having
• • a curved rigid chamber wall;
  • a flexible membrane attached to the rigid chamber wall, so that the flexible membrane and rigid chamber wall define a pumping chamber;
  • an inlet for directing fluid through the rigid chamber wall into the pumping chamber in at least one of (a) a direction that is substantially tangential to the rigid chamber wall and (b) a direction that provides low-shear flow into the pumping chamber; and
  • an outlet for directing fluid through the rigid chamber wall out of the pumping chamber in at least one of (a) a direction that is substantially tangential to the rigid chamber wall and (b) a direction that provides low-shear flow out of the pumping chamber; and
• a heat-exchanger component, in fluid communication with the at least one pump and adapted to be received by a heat exchanger.
• In accordance with another aspect of the invention there is provided a heat-exchanger system comprising:
• a heat exchanger for receiving a heat-exchanger component of a disposable unit;
• a pneumatic actuation system for operating at least one pump of the disposable unit for pumping fluid through the heat-exchanger component; and
• a controller for controlling the pneumatic actuation system.
• In some embodiments, the disposable unit may be considered to be part of the heat-exchanger system.
• In accordance with another aspect of the invention there is provided a method of moving blood between a patient-access device and a heat exchanger for heating the blood, the method comprising:
• providing a reciprocating positive-displacement pump;
• providing a flow line having a first portion between the patient-access device and the pump and having a second portion between the pump and the heat exchanger;
• providing for each of the first and second portions of the flow line a valve for permitting flow in only one direction of the flow line; and
• actuating the pump to cause the flow of blood between the patient-access device and the heat exchanger.
• In accordance with another aspect of the invention there is provided a system for extracorporeal thermal therapy, the system comprising:
• a heat exchanger for heating the blood;
• a reciprocating positive-displacement pump for moving blood between a patient-access device and the heat exchanger, the pump having an inlet line and an outlet line;
• a first valve, located in the inlet line, for preventing flow of blood out of the pump; and
• a second valve, located in the outlet line, for preventing flow of blood into the pump.
• In accordance with another aspect of the invention there is provided a heat exchanger for heating extracorporeal blood for hyperthermia treatment, the heat exchanger comprising a pump according to one of above claims, and further including a heat-exchange flow path having an inlet for unheated blood an outlet for heated blood;
• an electricity-to-heat converter that turns electrical power into heat for absorption by the blood;
• a first temperature sensor located at the inlet for measuring the temperature of the blood entering the heat exchanger;
• a second temperature sensor located at the outlet for measuring the temperature of the blood exiting the heat exchanger;
• a metering system that measures the flow rate of blood passing through the heat exchanger; and
• a controller in communication with the converter, the first and second temperature sensors, and the metering system, the controller receiving information regarding the amount of power being used by the converter, receiving temperature information from the first and second temperature sensors, receiving flow-rate information from the metering system, analyzing the received information in order to determine whether a fault condition exists, and generating a signal if a fault condition is detected.
• In accordance with another aspect of the invention there is provided a heat exchanger for heating extracorporeal blood for hyperthermia treatment, the heat exchanger comprising:
• an inlet for unheated blood;
• an outlet for heated blood;
• a flow path from the inlet to the outlet;
• a set of heating elements overlapping the flow path, including at least first and second heating elements, the second heating element being located adjacent the flow path near the outlet, and the first heating element being located adjacent the flow path at a point upstream of the second heating element;
• a first temperature sensor located adjacent the flow path upstream of the first heating element;
• a second temperature sensor located adjacent the flow path between the first and second heating elements; and
• a controller for receiving temperature information from the first and second temperature sensors and for generating a signal if a temperature difference being measured by the first and second sensors exceeds a limit.
• In accordance with another aspect of the invention there is provided a heat exchanger for heating extracorporeal blood for hyperthermia treatment, the heat exchanger comprising:
• an inlet for unheated blood;
• an outlet for heated blood;
• a flow path from the inlet to the outlet;
• a set of heating elements overlapping the flow path, including at least first, second and third heating elements, the third heating element being located adjacent the flow path near the outlet, the second heating element being located adjacent the flow path at a point prior to the third heating element, and the first heating element being located adjacent the flow path at a point prior to the second heating element;
• a first temperature sensor located adjacent the flow path between the first and second heating elements;
• a second temperature sensor located adjacent the flow path between the second and third heating elements; and
• a controller for receiving temperature information from the first and second temperature sensors and for generating a signal if a temperature difference being measured by the first and second sensors exceeds a limit.
• In accordance with another aspect of the invention there is provided a heat exchanger for heating extracorporeal blood for hyperthermia treatment, the heat exchanger comprising:
• an inlet for unheated blood;
• an outlet for heated blood;
• an electricity-to-heat converter that turns electrical power into heat for absorption by the blood;
• a first temperature sensor located at the inlet for measuring the temperature of the blood entering the heat exchanger;
• a second temperature sensor located at the outlet for measuring the temperature of the blood exiting the heat exchanger;
• a metering system that measures the flow rate of blood passing through the heat exchanger; and
• a controller in communication with the converter, the first and second temperature sensors, and the metering system, the controller receiving information regarding the amount of power being used by the converter, receiving temperature information from the first and second temperature sensors, receiving flow-rate information from the metering system, analyzing the received information in order to determine whether a fault condition exists, and generating a signal if a fault condition is detected.
• In accordance with another aspect of the invention there is provided a heat exchanger for heating extracorporeal blood for hyperthermia treatment, the heat exchanger comprising:
• an inlet for unheated blood;
• an outlet for heated blood;
• an electricity-to-heat converter that turns electrical power into heat for absorption by the blood;
• a disposable unit containing a flow path of the blood from the inlet to the outlet, the disposable unit being made primarily of a thermoplastic material;
• an electrical-conductivity sensor for measuring the resistance between the blood in the flow path a thermowell and the converter; and
• a controller in communication with the electrical-conductivity sensor and generating a signal if the measured resistance does not satisfy a safety parameter.
• In accordance with another aspect of the invention there is provided a heat exchanger for heating extracorporeal blood for hyperthermia treatment, the heat exchanger comprising:
• a disposable unit having
• • an inlet for unheated blood,
  • an outlet for heated blood, and
  • a flow path of the blood from the inlet to the outlet; and
• a base unit having
• a heater for heating blood in the flow path, the heater including a first thermally conductive plate for conducting heat to a first side of the disposable unit, and a second thermally conductive plate for conducting heat to a second side of the disposable unit opposite the first plate, the first and second plates being adapted to squeeze together, upon actuation by a controller, in order to urge blood out of the disposable.
• In accordance with another aspect of the invention there is provided a method of locating temperature probes for monitoring a patient's temperature, the method comprising:
• taking temperature readings from a first temperature probe to be located at a first location in the patient's body;
• taking temperature readings from a second temperature probe to be located at a second location in the patient's body;
• comparing the temperature readings from the first and second probes;
• positioning the first and second temperature probes in the patient's body;
• determining if the temperature reading from the first or second location is above a pre-set limit; and
• generating a placement signal, if the temperature reading from the first probe is within a pre-set range from the temperature reading from the second probe, and if the reading from the first or second location is above a pre-set limit.
• In accordance with another aspect of the invention there is provided a method of providing a hyperthermic treatment to a patient, the method comprising:
• providing a heat-exchanger system for heating blood from the patient and pumping heated blood to the patient;
• connecting a first temperature probe from the patient to the heat-exchanger system, the heat-exchanger system controlling the blood heating and pumping based on temperature information received from the first temperature probe and displaying the temperature information received from the first temperature probe to an operator;
• monitoring patient temperature by the operator using an independent second temperature probe; and
• • terminating the treatment if either of the temperature probes conveys an unacceptable temperature reading.
• In some embodiments of the invention there is provided a pump-pod geometry that reduces shear on the fluid being pumped and, when used to pump blood (especially heated blood), reduces hemolysis.
• In one embodiment of the invention, a reciprocating positive-displacement pump is provided with a hemispherical rigid chamber wall; a flexible membrane attached to the rigid chamber wall, so that the flexible membrane and rigid chamber wall define a pumping chamber; an inlet for directing flow through the rigid chamber wall into the pumping chamber in a direction that provides low-shear flow into the pumping chamber; and an outlet for directing flow through the rigid chamber wall out of the pumping chamber in a direction that provides low-shear flow out of the pumping chamber.
• In one embodiment of the invention, a reciprocating positive-displacement pump is provided comprising a rigid hemispherical chamber wall; a flexible membrane attached to the rigid chamber wall, so that the flexible membrane and rigid chamber wall define a pumping chamber; an inlet for directing flow through the rigid chamber wall into the pumping chamber in a direction that is substantially tangential to the rigid chamber wall; and an outlet for directing flow through the rigid chamber wall out of the pumping chamber in a direction that is substantially tangential to the rigid chamber wall. In some embodiments, the reciprocating positive-displacement pump also includes a rigid limit structure for limiting movement of the membrane and limiting the maximum volume of the pumping chamber, the flexible membrane and the rigid limit structure defining an actuation chamber. The rigid limit structure may be adapted to limit movement of the flexible membrane such that, when the pumping chamber is at maximum volume, the rigid chamber and the flexible membrane (which will be urged against the rigid limit structure) define the pumping chamber as a spherical volume. The rigid limit structure may be a hemispherical limit wall that, together with the flexible membrane, defines a spherical actuation chamber when the pumping chamber is at minimum volume.
• In certain embodiments, the reciprocating positive-displacement pump is provided with a pneumatic actuation system that intermittently provides either a positive or a negative pressure to the actuation chamber. The pneumatic actuation system in some embodiments include a reservoir containing a gas at either a positive or a negative pressure, and a valving mechanism for controlling the flow of gas between the actuation chamber and the gas reservoir. The reciprocating positive-displacement pump may be provided with an actuation-chamber pressure transducer for measuring the pressure of the actuation chamber, and a controller that receives pressure information from the actuation-chamber pressure transducer and controls the valving mechanism. In certain embodiments, a reservoir pressure transducer for measuring the pressure of the pressure of gas in the reservoir is provided, and the controller receives pressure information from the reservoir pressure transducer. The controller in some embodiments compares the pressure information from the actuation-chamber and reservoir pressure transducers to determine whether either of the pressure transducers is malfunctioning.
• In certain embodiments, the pneumatic actuation system alternately provides positive and negative pressure to the actuation chamber. In one arrangement, the pneumatic actuation system includes a positive-pressure gas reservoir, a negative-pressure gas reservoir, and a valving mechanism for controlling the flow of gas between the actuation chamber and each of the gas reservoirs. In such embodiments, an actuation-chamber pressure transducer is also provided for measuring the pressure of the actuation chamber, and a controller that receives pressure information from the actuation-chamber pressure transducer and controls the valving mechanism. In addition, such embodiments may include a positive-pressure-reservoir pressure transducer for measuring the pressure of the positive-pressure gas reservoir, and a negative-pressure-reservoir pressure transducer for measuring the pressure of the negative-pressure gas reservoir. The controller receives pressure information from these transducers and analyzes the pressure information to determine whether any of the pressure transducers are malfunctioning. The controller also controls the pressure of the reservoir or reservoirs to ensure it does not exceed a pre-set limit.
• In certain embodiments, the controller causes dithering of the valving mechanism and determines when a stroke ends from pressure information from the actuation-chamber pressure transducer. In further embodiments, the controller controls the valving mechanism to cause the flexible membrane to reach either the rigid chamber wall or the rigid limit structure at each of a stroke's beginning and end. In this embodiment, the controller can determine the amount of flow through the pump based on a number of strokes. In addition, the controller may integrate pressure information from the actuation-chamber pressure transducer over time during a stroke (or otherwise determines the work done during a stroke) as a way of detecting an aberrant flow condition.
• In some embodiments of the invention, the reciprocating positive-displacement pump includes an inlet valve for preventing flow out of the pump and an outlet valve for preventing flow into the pump. In some embodiments, these valves are simply passive check valves, and in other embodiments, these valves are active valves that are controlled to cause fluid to flow in the desired direction. In certain embodiments, the pump is adapted for pumping a liquid, and in further embodiments, the pump is adapted for pumping a biological liquid, such as blood. As noted above, some embodiments of the inventions are well adapted for pumping heated blood.
• In certain embodiments, the pumps are paired—or otherwise ganged—together so that an inlet line leads to both pumps' inlets and wherein an outlet line leads from both pumps' outlets. In such embodiments, the pumps may be operated out of phase such that when one pump's pumping chamber is substantially full the other pump's pumping chamber is substantially empty.
• Embodiments of the invention also provide methods for heating blood extracorporeally. One method includes the steps of providing a reciprocating positive-displacement pump; providing a flow line having a first portion between the patient-access device and the pump and having a second portion between the pump and a heat exchanger; providing for each of the first and second portions of the flow line a valve for permitting flow in only one direction of the flow line; and actuating the pump to cause the flow of blood between the patient-access device and the heat exchanger. The pump may be provided with a flexible membrane as a reciprocating member. A pneumatic actuation system may be provided for alternately providing positive and negative pressure to the membrane. A pump having one of the various structures described herein may be used in such methods.
• Certain methods for heating blood extracorporeally include the steps of providing a reciprocating positive-displacement pump having a curved rigid chamber wall, a flexible membrane attached to the rigid chamber wall so that the flexible membrane and rigid chamber wall define a pumping chamber, an inlet for directing flow through the rigid chamber wall into the pumping chamber in a direction that is substantially tangential to the rigid chamber wall, and an outlet for directing flow through the rigid chamber wall out of the pumping chamber in a direction that is substantially tangential to the rigid chamber wall; providing a heater; providing blood from a source; and pumping the blood using the reciprocating positive-displacement pump so as to cause the blood to flow through the heater and be heated. The reciprocating positive-displacement pump is, in certain embodiments, provided with the structural features discussed herein.
• Certain embodiments of these methods include the step of monitoring the patient's temperature. Monitoring the patient's temperature may include the steps of taking a temperature reading from a first location in the patient's body; taking a temperature reading from a second location in the patient's body; comparing the temperature readings from the first and second locations; generating a first alarm signal indicating faulty temperature readings, if the temperature reading at the first location is not within a pre-set range from the temperature reading at the second location; determining if the temperature reading from the first location is above a pre-set upper limit; and generating a second alarm signal indicating an overheated condition, if a reading is above the pre-set upper limit.
• The methods described herein may use a disposable unit for use in a system for heating blood extracorporeally. Such disposable units may include a reciprocating positive-displacement pump having a curved rigid chamber wall, a flexible membrane attached to the rigid chamber wall so that the flexible membrane and rigid chamber wall define a pumping chamber, an inlet for directing flow through the rigid chamber wall into the pumping chamber in a direction that is substantially tangential to the rigid chamber wall, and an outlet for directing flow through the rigid chamber wall out of the pumping chamber in a direction that is substantially tangential to the rigid chamber wall; and a heat-exchanger component, in fluid communication with the pump, and adapted to be received by a heater. The heat-exchanger component may include a flexible bag that defines a flow path therethrough. The reciprocating positive-displacement pump may have a structure as described herein.
• The disposable unit preferably attaches, in an easily removable manner, to a base unit, which preferably includes means for attaching to a pneumatic actuation system that intermittently provides either a positive or a negative pressure to the pump's actuation chamber, and preferably includes the controller for controlling the pneumatic actuation system. The controller preferably controls the system so as to perform methods described herein. The base unit is preferably capable of receiving and holding disposable units having pod pumps with different stroke volumes
• In one embodiment of a system for extracorporeal thermal therapy, a heat exchanger is provided for heating the blood; a reciprocating positive-displacement pump is provided for moving blood between a patient-access device (e.g., a cannula, needle or shunt) and the heat exchanger, the pump having an inlet line and an outlet line; a first valve, located in the inlet line, is provided for preventing flow of blood out of the pump; and a second valve, located in the outlet line, is provided for preventing flow of blood into the pump. The pump may have a structure as described herein.
• In a particular embodiment, the reciprocating positive-displacement pump uses a flexible membrane made from a material that reduces hard snapping of the membrane as the membrane reciprocates. The central portion may include bumps that space the central portion away from the rigid chamber wall when the membrane is in a minimum-pumping-chamber-volume position. Such bumps prevent liquid from being trapped between the membrane and the wall.
• The controller, in a particular embodiment, receives temperature information from a first temperature sensor located at the inlet for measuring the temperature of the blood entering the heat exchanger and from a second temperature sensor located at the outlet for measuring the temperature of the blood exiting the heat exchanger, while also receiving flow-rate information from a metering system that measures the flow rate of blood passing through the heat exchanger. These temperature sensors may be located in a base unit of the system, while thermally conductive thermowells in the disposable unit provide thermal communication between the flow path and the base unit's sensors. The controller is also in communication with an electricity-to-heat converter and receives information regarding the amount of power being used by the converter. The controller, in this embodiment, analyzes the received information from the temperature probes, the metering system and the converter in order to determine whether a fault condition exists, and generates a signal if a fault condition is detected.
• The controller may also receive temperature information from temperature sensors mounted near heating elements adjacent the heat exchanger's heating plates, wherein electrical current causes the heating elements to heat the heating plates, which in turn heat the blood passing through the heat exchanger. A set of heating elements may overlap the flow path through the heat exchanger. The set of heating elements includes at least first and second heating elements, the second heating element being located adjacent the flow path near the outlet, and the first heating element being located adjacent the flow path at a point upstream of the second heating element. A first temperature sensor is located adjacent the flow path upstream of the first heating element, and a second temperature sensor is located adjacent the flow path between the first and second heating elements. In this embodiment, the controller receives temperature information from the first and second temperature sensors, and generates a signal if a temperature difference being measured by the first and second sensors exceeds a limit. Of course, the heat exchanger may use additional heating elements beyond the two referred to here. The flow path may course through a substantially planar disposable unit. This disposable unit, as noted above, may be a flexible bag.
• A first heating plate, which in one embodiment is simply a thermally conductive plate, may be located between the heating elements and the disposable unit. A second heating plate may be located adjacent the disposable unit opposite the first heating plate, and a second set of heating elements may be located on a side of the second plate opposite the disposable unit and overlapping the flow path, including at least fourth, fifth and sixth heating elements, the sixth heating element being located adjacent the flow path near the outlet, the fifth heating element being located adjacent the flow path at a point prior to the sixth heating element, and the fourth heating element being located adjacent the flow path at a point prior to the fifth heating element. In this embodiment, a third temperature sensor may be located adjacent the flow path between the fourth and fifth heating elements, and a fourth temperature sensor is located adjacent the flow path between the fifth and sixth heating elements. The controller also receives temperature information from the third and fourth temperature sensors and generates a signal if a temperature difference being measured by the third and fourth sensors exceeds a limit. In one embodiment, the first and second plates may be adapted to squeeze together, upon actuation by the controller, in order to urge blood out of the disposable.
• In a certain embodiment, the thermowells referred to previously may also be electrically conductive and be used to detect leaks or air in the system. The disposable unit adapted to be received by the heat exchanger and containing a flow path of the blood may be made primarily of a thermoplastic material. The thermowells located at each of the inlet and outlet are preferably metal to improve thermal and electrical conductivity between the first temperature sensor and the blood in the inlet and between the second temperature sensor and the blood in the outlet. The heating plates each typically include an electrical-conductivity sensor for measuring the resistance between a thermowell and a plate. The controller is in communication with the electrical-conductivity sensor and generates a signal if the measured resistance is too low (indicating a leak in the disposable unit) and/or too high (indicating air in the disposable unit).
• In a certain embodiment, a valving system is provided. The valving system includes a valve cassette and a control cassette. The valve cassette contains a plurality of valves, each valve including a valving chamber and an actuation chamber, each valve being actuatable by a control fluid in the actuation chamber. The control cassette has a plurality of fluid-interface ports for providing fluid communication with a control fluid from a base unit. A plurality of tubes extends between the valve cassette and the control cassette. Each tube provides fluid communication between a fluid-interface port and at least one actuation chamber, such that the base unit can actuate a valve by pressurizing control fluid in a fluid interface port.
• These aspects of the invention are not meant to be exclusive or comprehensive and other features, aspects, and advantages of the present invention are possible and will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description, the appended claims, and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• The foregoing features of the invention will be more readily understood by reference to the following detailed description, taken with reference to the accompanying drawings, wherein:
• FIG. 1 is a perspective view of an extracorporeal-blood-heating system having a base unit with a disposable unit according to one embodiment of the invention;
• FIG. 2 is a perspective view of components of the disposable unit shown inFIG. 1;
• FIG. 3 is a perspective view of a pump pod of the disposable unit shown inFIG. 2;
• FIG. 4 is a schematic showing a pressure actuation system that may be used to actuate the pump pod shown inFIG. 3;
• FIGS. 5A and 5B are respectively upper and lower perspective views of an alternative embodiment of a pump pod arrangement;
• FIG. 6 is a schematic of an embodiment of the extracorporeal blood heating system;
• FIGS. 7 and 8 are graphs showing how pressure measurements can be used detect the end of a stroke, in one embodiment;
• FIGS. 9 and 10 show how the pressure-measurement signals are filtered by the system's controller;
• FIG. 11 is a graph showing pressure readings in each of the pump pods in the disposable unit, and the results of filtering these readings;
• FIG. 12 is a graph showing how pressure measurements are used to determine average pressure;
• FIG. 13A is a perspective view of the components from the system ofFIG. 1 used for transferring heating to the blood;
• FIG. 13B is a perspective, back-side cross-sectional view of the manifold ofFIGS. 2 and 49, in accordance with an exemplary embodiment of the present invention;
• FIG. 13C shows a thermowell that may be used in the manifold ofFIGS. 2, 49, and13B in the heat-exchanger figure ofFIG. 1, in accordance with an exemplary embodiment of the present invention;
• FIG. 14 is an exploded view showing the basic components of a heat exchanger in an alternative embodiment;
• FIGS. 15, 16 and17 show respectively top perspective, end perspective and top plan views of the disposable unit's heat-exchanger bag used in the heat exchanger shown inFIG. 14;
• FIG. 18 shows a preferred placement of temperature transducers in a heat exchanger;
• FIG. 19 is a flow chart showing a method for checking a patient's temperature;
• FIG. 20 is a sectional view of a pod-pump that may be incorporated into embodiments of fluid-control cassettes;
• FIG. 21 is a sectional view of a valve that may be incorporated into embodiments of fluid-control cassettes;
• FIGS. 22A and 22B shows a pump cassette incorporating two pump pods of the type shown inFIG. 20 and a number of valves of the type shown inFIG. 21 along with various fluid paths and other components, in accordance with an exemplary embodiment of the present invention;
• FIG. 23 is a schematic representation of dual-housing cassette arrangement according to one embodiment;
• FIG. 24 is a schematic view of a whole-body hyperthermic treatment system in accordance with an exemplary embodiment of the present invention;
• FIG. 25 shows the base unit ofFIG. 1, in accordance with an exemplary embodiment of the present invention;
• FIG. 26 shows a close-up view of the manifold interface ofFIG. 25, in accordance with an exemplary embodiment of the present invention;
• FIG. 27 shows an exemplary user interface screen in accordance with an exemplary embodiment of the present invention;
• FIG. 28 is a graph showing how pressures applied to a pod pump may be controlled in order to facilitate end-of-stroke detection, in accordance with an exemplary embodiment of the present invention;
• FIG. 29 is a schematic representation of circulatory fluid flow in the pump pod shown inFIG. 3, in accordance with an exemplary embodiment of the present invention;
• FIGS. 30A and 30B are top and section views of a modular pod pump;
• FIGS. 31A and 31B are top and section views of a pod pump with separate inlet and outlet ports,FIG. 31A showing a section line to indicate the view inFIG. 31B;
• FIGS. 32A and 32B are top and section views of a pod pump with an insert in the actuation chamber;
• FIGS. 33A and 33B are top and section views of a pod pump with a laminated construction;
• FIGS. 34A and 34B are top and section views of a pod pump with a laminated construction;
• FIG. 35A is an exploded pictorial view of a pod pump with a multi part housing; FIGS.35B-E are pictorial views of various embodiments of diaphragms;
• FIGS. 36A and 36B are side and end views of an assembled pod pump with a multi part housing;
• FIG. 36C is a close up view of a port on a pod pump with a multi part housing;
• FIG. 37 is an exploded pictorial view of a multi part pod pump housing;
• FIGS. 38A and 38B are top and section views of a pod pump assembly with integral valves;
• FIG. 39 is an exploded pictorial view of a pod pump assembly;
• FIG. 40A is a pictorial view of two parts of a multi part pod pump housing;
• FIG. 40B is a pictorial closeup view of aligning features on parts of a multi part pump housing;
• FIG. 41A is a pictorial section view of a pod pump assembly with some portions removed;
• FIG. 41B is a close up pictorial view of aligning and joining features on a pod pump housing;
• FIG. 42A is a pictorial view of a pod pump;
• FIG. 42B is a sectional view of the pod pump shown inFIG. 42A;
• FIG. 42C is a pictorial view of a pod pump;
• FIG. 42D is a sectional view of the pod pump shown inFIG. 42C;
• FIGS. 43A-43C are exploded and section views of one embodiment of a pod pump cassette;
• FIGS. 44A-44B are pictorial views of one embodiment of a pod pump cassette;
• FIG. 45 shows a representation of a regional hyperthermic chemotherapy treatment system in accordance with an exemplary embodiment of the present invention;
• FIGS. 46A and 46B respectively show upper and lower perspective views of a flexible membrane having a configuration of raised bumps, such as may be used in pump pods such as the in the pump pod ofFIG. 4, in accordance with an exemplary embodiment of the present invention;
• FIG. 47A shows some of the interior components of the base unit ofFIGS. 1 and 25, in accordance with an exemplary embodiment of the present invention;
• FIG. 47B shows a rear perspective view of the base unit ofFIGS. 1 and 25 showing patient interfaces, in accordance with an exemplary embodiment of the present invention;
• FIG. 48 shows an exemplary disposable unit in accordance with an exemplary embodiment of the present invention;
• FIGS. 49A and 49B respectively show a perspective back-side view and a perspective bottom view of the manifold fromFIG. 2, in accordance with an exemplary embodiment of the present invention;
• FIGS. 50A and 50B are embodiments of the sensing apparatus where the thermal well is a continuous part of the fluid line;
• FIGS. 51A and 51B are embodiments of the sensing apparatus where the thermal well is a separate part from the fluid line;
• FIGS. 52A and 52B are embodiments of the sensing apparatus showing various lengths and widths of the thermal well;
• FIG. 53 is a pictorial view of a thermal well according to one embodiment of the sensing apparatus;
• FIG. 54 is a cross sectional view of an exemplary embodiment of the thermal well;
• FIGS. 55A and 55B show section views of embodiments of thermal wells having variable wall thickness;
• FIGS. 56A-56S are sectional views of various embodiments of the thermal well embedded in a fluid line;
• FIG. 57 is a section side view of one embodiment of the sensing probe;
• FIG. 58 is an exploded view of the embodiment shown inFIG. 8;
• FIG. 59 is a sectional view of an alternate embodiment of the tip of the sensing probe;
• FIG. 60A is an alternate embodiment of the sensing probe;
• FIG. 60B is an alternate embodiment of the sensing probe;
• FIG. 61 is a side view of an alternate embodiment of the sensing probe;
• FIG. 62A is a section view of a sensing probe coupled to a thermal well;
• FIG. 62B is an alternate embodiment of the sensing probe shown inFIG. 13A;
• FIG. 63A is a section view of a sensing probe as shown inFIG. 8 coupled to a thermal well;
• FIG. 63B is an alternate embodiment of the sensing probe shown inFIG. 14A;
• FIG. 64 is a sectional view of one exemplary embodiment of the sensor apparatus;
• FIG. 65 shows an alternate embodiment of a sensing probe coupled to a thermal well;
• FIG. 66 is a section view of one embodiment of a sensing probe coupled to a thermal well and suspended by a spring;
• FIG. 67 is a section view of one embodiment of a sensing probe in a housing;
• FIG. 68 is a section view of one embodiment of a sensing probe in a housing;
• FIG. 69 is a section view of one embodiment of a sensing probe in a housing;
• FIG. 70 is a side view of a fluid line including two sensors;
• FIG. 71 is a section view of a fluid line with a sensor apparatus;
• FIG. 72 shows one way in which the various components of the disposable unit ofFIG. 2 can be interconnected;
• FIGS. 73A-73B are graphical representations of occlusion detection in accordance with an exemplary embodiment of the present invention;
• FIGS. 74A-74C show plots for volume flow, pod volumes, and total hold up flow for two pump pods operating in a zero degree phase relationship, a 180 degree phase relationship, and a 90 degree phase relationship, respectively, in accordance with exemplary embodiments of the present invention
• FIG. 75 shows a radiator for use with a length of tubing, in accordance with an exemplary embodiment of the present invention;
• FIG. 76 shows a length of flexible tubing install in the radiator ofFIG. 75 in accordance with an exemplary embodiment of the present invention;
• FIG. 77 shows a heat exchanger plate having guides for receiving the radiator ofFIG. 75, in accordance with an exemplary embodiment of the present invention;
• FIG. 78 shows a heat exchanger plate having a cylindrical wall for receiving the radiator ofFIG. 75, in accordance with an exemplary embodiment of the present invention;
• FIG. 79 shows a heat exchanger plate having an integral radiator of the type shown inFIG. 75, in accordance with an exemplary embodiment of the present invention;
• FIG. 80 shows an enclosed radiator having fluid inlet and outlet ports, in accordance with an alternate embodiment of the present invention;
• FIG. 81 shows a variation of the disposable unit ofFIG. 48 including a patient connection circuit having a sterile protective covering, in accordance with an exemplary embodiment of the present invention;
• FIG. 82 shows a representation of the patient connection circuit fromFIG. 81 with a portion of tubing exposed through the sterile protective covering, in accordance with an exemplary embodiment of the present invention; and
• FIG. 83 shows a variation of the disposable unit ofFIG. 81 including an additional fluid delivery line, in accordance with an exemplary embodiment of the present invention;
• FIG. 84 shows a fluid circuit that may be used for providing regional hyperthermic chemotherapy treatment, in accordance with an exemplary embodiment of the present invention;
• FIG. 85 shows another fluid circuit including a balancing chamber that may be used for providing regional hyperthermic chemotherapy treatment, in accordance with an exemplary embodiment of the present invention;
• FIG. 86 shows another fluid circuit including a balancing chamber and a second pump that may be used for providing regional hyperthermic chemotherapy treatment, in accordance with an exemplary embodiment of the present invention; and
• FIG. 87 shows a fluid circuit including a drain valve that may be used for providing regional hyperthermic chemotherapy treatment, in accordance with an exemplary embodiment of the present invention.
• It should be noted that the foregoing figures and the elements depicted therein are not necessarily drawn to consistent scale or to any scale. Unless the context otherwise suggests, like elements are indicated by like numerals.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
• Definitions. As used in this description and the accompanying claims, the following terms shall have the meanings indicated, unless the context otherwise requires:
• “Spheroid” means any three-dimensional shape that generally corresponds to a oval rotated about one of its principal axes, major or minor, and includes three-dimensional egg shapes, oblate and prolate spheroids, spheres, and substantially equivalent shapes.
• “Hemispheroid” means any three-dimensional shape that generally corresponds to approximately half a spheroid.
• “Spherical” means generally spherical.
• “Hemispherical” means generally hemispherical.
• “Dithering” a valve means rapidly opening and closing the valve.
• “Pneumatic” means using air or other gas to move a flexible membrane or other member.
• “Substantially tangential” means at an angle less than 75° to a tangent, or in the case of a flat wall, at an angle of less than 75° to the wall.
• “Fluid” shall mean a substance, a liquid for example, that is capable of being pumped through a flow line. Blood is a specific example of a fluid.
• “Impedance” shall mean the opposition to the flow of fluid.
• A “patient” includes a person or animal from whom, or to whom, fluid is pumped, whether as part of a medical treatment or otherwise.
• “Subject media” is any material, including any fluid, solid, liquid or gas, that is in contact with either a sensing probe or a thermal well.
• Various aspects of the present invention are described below with reference to various exemplary embodiments. It should be noted that headings are included for convenience and do not limit the present invention in any way.
1. Exemplary Reciprocating Positive-Displacement Pumps
• Embodiments of the present invention relate generally to certain types of reciprocating positive-displacement pumps (which may be referred to hereinafter as “pods,” “pump pods,” or “pod pumps”) used to pump fluids, such as a biological fluid (e.g., blood or peritoneal fluid), a therapeutic fluid (e.g., a medication solution), or a surfactant fluid. Certain embodiments are configured specifically to impart low shear forces and low turbulence on the fluid as the fluid is pumped from an inlet to an outlet. Such embodiments may be particularly useful in pumping fluids that may be damaged by such shear forces (e.g., blood, and particularly heated blood, which is prone to hemolysis) or turbulence (e.g., surfectants or other fluids that may foam or otherwise be damaged or become unstable in the presence of turbulence).
• Generally speaking, the pod pump is a modular pump apparatus. The pod pump can be connected to any subject fluid (i.e., liquid, gas or variations thereof) source, which includes but is not limited to a path, line or fluid container, in order to provide movement of said subject fluid. In some embodiments, multiple pod pumps are used, however, in other embodiments, one pod pump is used. The pod pump can additionally be connected to at least one actuation source, which in some embodiments, is at least one air chamber. In some embodiments, the pod pump is modularly connected to any device or machine. However, in other embodiments, the pod pump is part of a device, machine or container that is attached to another device, machine or container. Although the pod pump is modular, the pod pump may also be part of another modular structure that interacts with any machine, device, container or otherwise.
• In one embodiment, the pod pump includes a housing having a diaphragm or movable impermeable membrane attached to the interior of the housing. The diaphragm creates two chambers. One chamber does not come into contact with subject fluid; this chamber is referred to as the actuation chamber. The second chamber comes into contact with the subject fluid. This chamber is referred to as the pump or pumping chamber.
• The pod pump, in some embodiments, includes an inlet fluid path and an outlet fluid path. Thus, in these embodiments, a subject fluid is pumped into the pump chamber, then out of the pump chamber. In some embodiments, valving mechanisms are used to ensure that the fluid moves in the intended direction. In other embodiments, the inlet fluid path and the outlet fluid path are one in the same.
• The actuation of the diaphragm is provided for by a change in pressure. This change in pressure can be created through use of positive and negative air pressures. In one embodiment, a pneumatic mechanism is used to fill the actuation chamber with air (creating a positive pressure) and then to suck the air out of the actuation chamber (creating a negative pressure). In some embodiments, the air flows through a port in the actuation chamber. The port can be, but is not limited to, an opening or aperture in the actuation chamber. In other embodiments, any fluid (i.e., liquid, gas or variations thereof) can be used as an actuation fluid.
• For purposes of this description, exemplary embodiments are shown and described. However, other embodiments are contemplated, thus, the description provided are meant to bring an understanding of the pod pump embodiments, other variations will be apparent.
1.1. Exemplary Pump Pod Configurations
• FIG. 3 shows a reciprocating positive-displacement pump25 in accordance with an exemplary embodiment of the present invention. In this embodiment, the reciprocating positive-displacement pump25 is essentially a self-contained unit (which may be referred to hereinafter as a “pod”) that may be used as a component of a larger pumping system. The reciprocating positive-displacement pump25 includes a “top” portion (also referred to as the “pumping chamber wall”)31 and a “bottom” portion (also referred to as the “actuation chamber wall”)32 that are coupled together atpod wall30, for example, by ultrasonic welding or other technique. It should be noted that the terms “top” and “bottom” are relative and are used here for convenience with reference to the orientation shown inFIG. 3. Each of theportions31 and32 has a rigid interior surface that is preferably (although not necessarily) hemispherical, such that the pod has an interior cavity that is preferably (although not necessarily) spherical.
• In the embodiment shown inFIG. 3, theactuation chamber wall32 is a unitary structure while the pumpingchamber wall31 is formed from two halves that are coupled together alongperimeter2052, for example, by ultrasonic welding or other technique (which facilitates assembly of the integral valves, discussed below).FIG. 37 shows an exploded view of the three pump pod wall sections in accordance with an exemplary embodiment of the present invention.FIG. 38A shows a top view of the assembled three-piece pump pod.FIG. 38B shows a side cross-sectional view of the assembled three-piece pump pod.FIG. 39 shows an exploded view of the pump pod components.FIGS. 37-39 are discussed in greater detail below. Of course, the present invention is in no way limited to the way in which thepumping chamber wall31 and theactuation chamber wall32 are constructed or assembled, although ultrasonic welding of the pumpingchamber wall31 and theactuation chamber wall32 is considered a preferred embodiment.
• Within the reciprocating positive-displacement pump25, a flexible membrane33 (also referred to as the “pump diaphragm”) is mounted where the pumping-chamber wall31 and the actuation-chamber wall32 meet (i.e., at the pod wall30). Thepump diaphragm33 effectively divides that interior cavity into a variable-volume pumping chamber (defined by the rigid interior surface of the pumpingchamber wall31 and a top surface of the membrane33) and a complementary variable-volume actuation chamber (defined by the rigid interior surface of theactuation chamber wall32 and a bottom side of the membrane33). Thetop portion31 includes afluid inlet34 and afluid outlet37, both of which are in fluid communication with the pumping chamber. Thebottom portion32 includes apneumatic interface38 in fluid communication with the actuation chamber. As discussed in greater detail below, themembrane33 can be urged to move back and forth within the cavity by alternately applying negative and positive pneumatic pressure at thepneumatic interface38. As themembrane33 reciprocates back and forth in the embodiment shown inFIG. 3, the sum of the volumes of the pumping and actuation chambers remains constant.
• During typical fluid pumping operations, the application of negative pneumatic pressure to thepneumatic interface38 tends to withdraw themembrane33 toward theactuation chamber wall32 so as to expand the pumping chamber and draw fluid into the pumping chamber through theinlet34, while the application of positive pneumatic pressure tends to push themembrane33 toward the pumpingchamber wall31 so as to collapse the pumping chamber and expel fluid in the pumping chamber through theoutlet37. During such pumping operations, the interior surfaces of the pumpingchamber wall31 and theactuation chamber wall32 limit movement of themembrane33 as it reciprocates back and forth. In the embodiment shown inFIG. 3, the interior surfaces of the pumpingchamber wall31 and theactuation chamber wall32 are rigid, smooth, and hemispherical. In lieu of a rigid actuation-chamber wall32, an alternative rigid limit structure—for example, a portion of a bezel used for providing pneumatic pressure and/or a set of ribs—may be used to limit the movement of the membrane as the pumping chamber approaches maximum value. Bezels and rib structures are described generally in U.S. patent application Ser. No. 10/697,450 entitled BEZEL ASSEMBLY FOR PNEUMATIC CONTROL filed on Oct. 30, 2003 and published as Publication No.US 2005/0095154 (Attorney Docket No. 1062/D75) and related PCT Application No. PCT/US2004/035952 entitled BEZEL ASSEMBLY FOR PNEUMATIC CONTROL filed on Oct. 29, 2004 and published as Publication No. WO 2005/044435 (Attorney Docket No. 1062/D71 WO), both of which are hereby incorporated herein by reference in their entireties. Thus, the rigid limit structure—such as the rigidactuation chamber wall32, a bezel, or a set of ribs—defines the shape of themembrane33 when the pumping chamber is at its maximum value. In a preferred embodiment, the membrane33 (when urged against the rigid limit structure) and the rigid interior surface of the pumpingchamber wall31 define a spherical pumping-chamber volume when the pumping chamber volume is at a maximum.
• Thus, in the embodiment shown inFIG. 3, movement of themembrane33 is limited by the pumping-chamber wall31 and the actuation-chamber wall32. As long as the positive and negative pressurizations provided through thepneumatic port38 are strong enough, themembrane33 will move from a position limited by the actuation-chamber wall32 to a position limited by the pumping-chamber wall31. When the membrane is forced against the actuation-chamber wall32, the membrane and the pumping-chamber wall31 define the maximum volume of the pumping chamber. When the membrane is forced against the pumping-chamber wall31, the pumping chamber is at its minimum volume.
• In a preferred embodiment, the pumping-chamber wall31 and the actuation-chamber wall32 both have a hemispheroid shape so that the pumping chamber will have a spheroid shape when it is at its maximum volume. More preferably, the pumping-chamber wall31 and the actuation-chamber wall32 both have a hemispherical shape so that the pumping chamber will have a spherical shape when it is at its maximum volume. By using a pumping chamber that attains a spheroid shape—and particularly a spherical shape—at maximum volume, circulating flow may be attained throughout the pumping chamber. Such shapes accordingly tend to avoid stagnant pockets of fluid in the pumping chamber. As discussed further below, the orientations of theinlet34 andoutlet37—with each being substantially tangential to the interior surface of the pumpingchamber wall31—also tend to improve circulation of fluid through the pumping chamber and reduce the likelihood of stagnant pockets of fluid forming. Additionally, compared to other volumetric shapes, the spherical shape (and spheroid shapes in general) tends to create less shear and turbulence as the fluid circulates into, through, and out of the pumping chamber.
1.2. Exemplary Inlet/Outlet Valves
• Generally speaking, reciprocating positive-displacement pumps of the types just described may include, or may be used in conjunction with, various valves to control fluid flow through the pump. Thus, for example, the reciprocating positive-displacement pump may include, or be used in conjunction with, an inlet valve and/or an outlet valve. The valves may be passive or active. In the exemplary embodiment shown inFIG. 3, the reciprocating positive-displacement pump25 includes a passive one-wayinlet check valve35 and a passive one-wayoutlet check valve36. Theinlet check valve35 allows fluid to be drawn into the pumping chamber through theinlet34 but substantially prevents backflow through theinlet34. Theoutlet check valve36 allows fluid to be pumped out of the pumping chamber through theoutlet37 but substantially prevents backflow through theoutlet37.
• Thus, in an exemplary embodiment using the reciprocating positive-displacement pump25, themembrane33 is urged back and forth by positive and negative pressurizations of a gas provided through thepneumatic port38, which connects the actuation chamber to a pressure-actuation system. The resulting reciprocating action of themembrane33 pulls liquid into the pumping chamber from the inlet34 (theoutlet check valve36 prevents liquid from being sucked back into the pumping chamber from the outlet37) and then pushes the liquid out of pumping chamber through the outlet37 (theinlet check valve35 prevents liquid being forced back into the inlet34).
• In alternative embodiments, active valves may be used in lieu of thepassive check valves35 and36. The active valves may be actuated by a controller in such a manner as to direct flow in a desired direction. Such an arrangement would generally permit the controller to cause flow in either direction through thepump pod25. In a typical system, the flow would normally be in a first direction, e.g., from the inlet to the outlet. At certain other times, the flow may be directed in the opposite direction, e.g., from the outlet to the inlet. Such reversal of flow may be employed, for example, during priming of the pump, to check for an aberrant line condition (e.g., a line occlusion, blockage, disconnect, or leak), or to clear an aberrant line condition (e.g., to try to dislodge a blockage).
1.3. Exemplary Pump Inlet/Outlet Orientations
• In the embodiment shown inFIG. 3, theinlet34 and theoutlet37 are oriented so as to direct fluid into and out of the pumping chamber at angles that are substantially tangential to the interior surface of the pumpingchamber wall31. Thus, the fluid flow through theinlet34 into the pumping chamber avoids being perpendicular to themembrane33, even as the membrane approaches a position where the pumping chamber is at its minimum volume. This orientation of theinlet34 and theoutlet37 tends to reduce the shear forces on the liquid being pumped, particularly when compared to centrifugal pumps, which generally apply a great deal of stress on the fluid being pumped.
• The orientation of theinlet34 andoutlet37 with respect to each other also tends to reduce shear flow and turbulence. When the pumping chamber reaches its maximum volume, the fluid continues circulating through the pumping chamber even as fluid stops flowing through theinlet34. The direction of this circulating flow is a result of the direction of theinlet34 and the internal flow geometry. Generally speaking, after a very short pause, themembrane33 will be actuated to start moving to reduce the volume of the pumping chamber and fluid will start flowing through theoutlet37. When the fluid enters the pumping chamber, it moves in a rotating current and stays rotating until exiting the pumping chamber. The exiting fluid peels off from the outer layer of the rotating current in the same direction in which it was rotating. The spherical shape of the pump pods is particularly advantageous to achieve the desired flow circulation. The orientation of theoutlet37 with respect to circulating flow within the pumping chamber at the moment of maximum pumping chamber volume is such that flow does not have to change direction sharply when it begins to be urged through theoutlet37. By avoiding sharp changes in flow direction, shear and turbulence is reduced. Thus, the orientation of theinlet34 andoutlet37 with respect to each other and the internal flow geometry reduces shear and turbulence on the liquid being pumped. For example, inFIG. 3, there is only a small change in direction in a path extending from theinlet34 directly to theoutlet37, but other arrangements will also reduce sharp changes in direction as the pump pod transitions from a fill stroke to an expel stroke.
• Thus, when the fluid being pumped is whole blood, centrifugal pumps (which apply a great deal of stress on the red blood cells) can cause a large amount of hemolysis and therefore can reduce a patient's hematocrit to the detriment of the patient, whereas pump pods of the types described above (which apply low shear forces and turbulence) tend to produce substantially lower hemolysis. Similarly, when the fluid being pumped is a surfactant or other fluid prone to foaming, the reduced shear forces and reduced turbulence of the pod pumps tends to reduce foaming.
• FIG. 29 is a schematic representation of circulatory fluid flow in thepump pod25 shown inFIG. 3, in accordance with an exemplary embodiment of the present invention. As fluid enters the pumping chamber through the inlet, the orientation of the inlet directs fluid tangentially to the inside surface of the pumping chamber wall so as to create a circulatory flow. As fluid approaches the outlet, the fluid is already flowing substantially in the direction of the outlet so that the fluid is not required to make any drastic changes in direction when being pumped from the outlet. The fluid therefore tends to peel off of the circulatory flow in a laminar fashion to provide reduced shear forces on the fluid.
• Generally speaking, for low shear and/or low turbulence applications, it is desirable for the inlet and outlet to be configured so as to avoid sharp or abrupt changes of fluid direction. It is also generally desirable for the inlet and outlet (and the pump chamber itself) to be free of flash or burrs. The inlet and/or outlet may include rounded edges to help smooth out fluid flow.
1.4. Alternative Pump Configurations
• FIG. 20 is a sectional view of analternative pump pod2025 such as may be incorporated into a larger fluid-control cassette, in accordance with an alternative embodiment of the present invention. In this embodiment, the pump pod is formed from three rigid pieces, namely a “top”plate2091, amiddle plate2092, and a “bottom” plate2093 (it should be noted that the terms “top” and “bottom” are relative and are used here for convenience with reference to the orientation shown inFIG. 20). The top andbottom plates2091 and2093 may be flat on both sides, while themiddle plate2092 is provided with channels, indentations and holes to define the various fluid paths, chambers, and ports. To form thepump pod2025, the top andbottom plates2091 and2093 may include generally hemispheroid portions that together define a hemispheroid chamber.
• Amembrane2109 separates the central cavity of the pump pod into a chamber (the pumping chamber) that receives the fluid to be pumped and another chamber (the actuation chamber) for receiving the control gas that pneumatically actuates the pump. Aninlet2094 allows fluid to enter the pumping chamber, and anoutlet2095 allows fluid to exit the pumping chamber. Theinlet2094 and theoutlet2095 may be formed betweenmiddle plate2092 and thebottom plate2093. Pneumatic pressure is provided through apneumatic port2106 to either force, with positive gas pressure, themembrane2109 against one wall of pump pod's cavity to minimize the pumping chamber's volume (as shown inFIG. 20), or to draw, with negative gas pressure, the membrane towards the other wall of the pump pod's cavity to maximize the pumping chamber's volume.
• Themembrane2109 is provided with a thickenedrim2088, which is held tightly in agroove2089 in themiddle plate2092. Thus, themembrane2109 can be placed in and held by thegroove2089 before thetop plate2091 is ultrasonically welded to themiddle plate2092, so the membrane will not interfere with the ultrasonic welding of the two plates together, and so that the membrane does not depend on the two plates being ultrasonically welded together in just the right way to be held in place. Thus, this pump pod should be able to be manufactured easily without relying on ultrasonic welding to be done to very tight tolerances.
• One ormore pump pods2025 may be incorporated into a single cassette, which may also include one ormore valves2000.FIG. 21 is a sectional view of a pneumatically controlledvalve2000 that may be used in embodiments of the above-mentioned cassette. Amembrane2090, along with themiddle plate2092, defines avalving chamber2097. Pneumatic pressure is provided through apneumatic port2096 to either force, with positive gas pressure, themembrane2090 against avalve seat2099 to close the valve, or to draw, with negative gas pressure, the membrane away from the valve seat to open the valve. Acontrol gas chamber2098 is defined by themembrane2090, thetop plate2091, and themiddle plate2092. Themiddle plate2092 has an indentation formed on it, into which themembrane2090 is placed so as to form thecontrol gas chamber2098 on one side of the membrane and thevalving chamber2097 on the other side.
• Thepneumatic port2096 is defined by a channel formed on the “top” surface of themiddle plate2092, along with thetop plate2091. By providing fluid communication between several valving chambers in a cassette, valves can be ganged together so that all the valves ganged together can be opened or closed at the same time by a single source of pneumatic pressure. Channels formed on the “bottom” surface of themiddle plate2092, along with the bottom plate, define thevalve inlet2094 and thevalve outlet2095. Holes formed through themiddle plate2092 provide communication between theinlet2094 and the valving chamber2097 (through the valve seat2099) and between the valving chamber and theoutlet2095.
• Themembrane2090 is provided with a thickenedrim2088, which fits tightly in agroove2089 in themiddle plate2092. Thus, themembrane2090 can be placed in and held by thegroove2088 before thetop plate2091 is ultrasonically welded to themiddle plate2092, so the membrane will not interfere with the ultrasonic welding of the two plates together, and so that the membrane does not depend on the two plates being ultrasonically welded together in just the right way to be held in place. Thus, this valve should be easy to manufacture without relying on ultrasonic welding to be done to very tight tolerances. As shown inFIG. 21, thetop plate2091 may include additional material extending intocontrol gas chamber2098 so as to prevent themembrane2090 from being urged too much in a direction away from thegroove2089, so as to prevent the membrane's thickenedrim2088 from popping out of thegroove2089.
• Referring now toFIGS. 30A and 30B, one embodiment of thepod pump3000 is shown. In this embodiment, thepod pump3000 includes a housing. Referring now toFIG. 30B, the housing includes twoportions3002,3004. Theportions3002,3004 are joined and retain adiaphragm3006. Referring toFIG. 30A, as shown in this embodiment, thehousing portions3002,3004 are joined by screws. However, in alternate embodiments, any fasteners or fastening method can be used, which include, but are not limited to: snap together tabs, ultrasonic welding, laser welding or other assembly means known in the art.
• Although as shown in the embodiments inFIGS. 30A and 30B, the housing is formed by twoportions3002,3004, in other embodiments (some described below) the housing is formed from more than two portions. In still other embodiments, the housing is a single portion.
• In various embodiments, the size of the housing may vary. The size may vary depending on the volume of subject fluid intended to be pumped by each stroke of the pod pump. Another factor that may influence the size is the desired aspect ratio of the pod pump.
• Also, in various embodiments, the shape of the housing chamber may vary. Thus, althoughFIGS. 30A and 30B, as well as many of the additional figures in this description describe and show substantially spherical pod pump housing, the pod pump housing is by no means limited to a spherical shape. Referring now toFIGS. 42A and 42B, analternate pod pump4200 shape is shown. Thus, although only two shapes are shown herein, in alternate embodiments, the pod pump housing can be any shape desired.
• Referring now toFIGS. 42A and 42B, an alternate embodiment of the pod pump is shown. Although in this embodiment, the pod pump is oval shaped, in still other embodiments, the pod pump can be any shape desired. Many of the embodiments of the pod pumps will include a pump chamber, an actuation chamber, a diaphragm (or movable member), at least one actuation port and at least one inlet/outlet port. In some embodiments, the pod pump includes an inlet and an outlet port. Various embodiments are described herein and features described with respect to one embodiment should be understood to be available for any embodiment, thus the embodiment features can be mixed and matched, and any embodiment can include one or more of the features described herein.
• Referring again toFIGS. 30A and 30B the pod pump shown in this embodiment, is substantially spherical. As shown in this embodiment, the pump housing (which includes the pump chamber and the actuation chamber) is substantially spherical; however, the lip or facade around the pump housing is not entirely spherical. Thus, the exterior of the housing can be any shape, and in some embodiments, the exterior of the housing is a different shape from the pump housing. However, in some embodiments, the exterior housing is the same shape or substantially the same shape as the pump housing.
• Thehousing portions3002,3004, when joined, form a hollow chamber. In embodiments where the housing is a single portion, the interior of the housing is a hollow chamber. Where adiaphragm3006 is connected or attached to the interior of the housing, thediaphragm3006 divides the interior of the housing into two chambers, anactuation chamber3010 and apump chamber3012. In some embodiments, the interior of the housing is divided into equal volume chambers, however, in other embodiments, the chambers are varying volume chambers.
• Thediaphragm3006 may be made of any flexible material having a desired durability and compatibility with the subject fluid. Thediaphragm3006 can be made from any material that may flex in response to liquid or gas pressure or vacuum applied to theactuation chamber3010. The diaphragm material may also be chosen for particular bio-compatibility, temperature compatibility or compatibility with various subject fluids that may be pumped by thediaphragm3006 or introduced to the chambers to facilitate movement of thediaphragm3006. In the exemplary embodiment, thediaphragm3006 is made from high elongation silicone. However, in other embodiments, thediaphragm3006 is made from any elastomer or rubber, including, but not limited to, silicone, urethane, nitrite, EPDM or any other rubber or elastomer.
• The shape of thediaphragm3006 is dependent on multiple variables. These variables include, but are not limited to: the shape of the chamber; the size of the chamber; the subject fluid characteristics; the volume of subject fluid pumped per stroke; and the means or mode of attachment of thediaphragm3006 to the housing. The size of thediaphragm3006 is dependent on multiple variables. These variables include, but are not limited to: the shape of the chamber; the size of the chamber; the subject fluid characteristics; the volume of subject fluid pumped per stroke; and the means or mode of attachment of thediaphragm3006 to the housing. Thus, depending on these or other variables, the shape and size of thediaphragm3006 may vary in various embodiments. Thediaphragm3006 can have any thickness. However, in some embodiments, the range of thickness is between 0.002 inches to 0.125 inches. Depending on the material used for the diaphragm, the desired thickness may vary. In one embodiment, high elongation silicone is used in a thickness ranging from 0.015 inches to 0.050 inches.
• In the exemplary embodiment, thediaphragm3006 is pre-formed to include a substantially dome-shape in at least part of the area of thediaphragm3006. One embodiment of the dome-shapeddiaphragm3006 is shown inFIG. 35A as3514. Again, the dimensions of the dome may vary based on some or more of the variables described above. However, in other embodiments, thediaphragm3006 may not include a pre-formed dome shape.
• In the exemplary embodiment, thediaphragm3006 dome is formed using compression molding. However, in other embodiments, the dome may be formed by using injection molding.
• In alternate embodiments, thediaphragm3006 is substantially flat until actuated. In other embodiments, the dome size, width or height may vary.
• In various embodiments, thediaphragm3006 may be held in place by various means and methods. In one embodiment, thediaphragm3006 is clamped between the portions of the housing, and in some of these embodiments, the rim of the housing may include features to grab thediaphragm3006. In others of this embodiment, thediaphragm3006 is clamped to the housing using at least one bolt or another device. In another embodiment, thediaphragm3006 is over-molded with a piece of plastic and then the plastic is welded or otherwise attached to the housing. In another embodiment, thediaphragm3006 is bonded to a mid-body portion (not shown, described below with respect toFIGS. 33A-34B) and the actuation housing portion. Although some embodiments for attachment of thediaphragm3006 to the housing are described, any method or means for attaching thediaphragm3006 to the housing can be used. Thediaphragm3006, in one alternate embodiment, is attached directly to one portion of the housing at the attachment points3018.
• In the embodiment shown inFIG. 30B, thediaphragm3006 is held in place in the interior of the housing atattachment points3018 using one of the above described embodiments or another method for attachment. The attachment points3018 are areas where thediaphragm3006 is held between the twoportions3002,3004 of the housing at the two portions'3002,3004 meeting point. In some embodiments, thediaphragm3006 is thicker at the attachment points3018 than in other areas of thediaphragm3006. In some embodiments, this thicker area is a gasket, in some embodiments an O-ring, ring or any other shaped gasket. Referring now toFIG. 35A, an embodiment of thediaphragm3514 is shown with agasket3520. In these embodiments, thegasket3520 is the point that connects to the housing.
• In some embodiments of thegasket3520, thegasket3520 is contiguous with thediaphragm3514. However, in other embodiments, thegasket3520 is a separate part of thediaphragm3514. In some embodiments, thegasket3520 is made from the same material as thediaphragm3514. However, in other embodiments, thegasket3520 is made of a material different from thediaphragm3514. In some embodiments, thegasket3520 is formed by over-molding a ring around thediaphragm3514. Thegasket3520 can be any shape ring or seal desired so as to complement the pod pump housing embodiment. In some embodiments, thegasket3520 is a compression type gasket.
• The interior of the housing includes at least one port for subject fluid (pump port) and at least one port for actuation fluid (actuation port). Referring toFIG. 30B, theactuation port3008 and pumpport3014 are shown. Although the embodiment shown inFIG. 30B includes onepump port3014 and oneactuation port3008, in other embodiments (some of which are described below) the pod pump includes more than one pump port and/or more than one actuation port.
• Still referring toFIG. 30B, the location of thepump port3014 and theactuation port3008 may also vary in the different embodiments. In the embodiment shown, thepump port3014 and theactuation port3008 are located on one side of thepod pump3000. In other embodiments, some which are shown and described herein, the pump port and the actuation port may be in various locations on the pod pump, sometimes the same side, sometimes different side, and in embodiments having more than one pump port and/or more than one actuation port, the locations of all of these ports can vary. In most embodiments, however, the actuation port (or, in some embodiments, at least one actuation port)3008 is in fluid communication with theactuation chamber3010 and the pump port (or, in some embodiments, at least one actuation port)3014 is in fluid communication with thepump chamber3012.
• Theactuation port3008 communicates liquid or gas pressure with a liquid or gas source to add or remove liquid or gas from theactuation chamber3010. Upon addition or removal of liquid or gas from theactuation chamber3010 thediaphragm3006 flexes to increase or decrease the volume of thepumping chamber3012. The action of thediaphragm3006 flexing causes the movement of the subject fluid either into or out of apump port3014. In the embodiments shown inFIG. 30B, both theactuation port3008 and pumpingport3014 are aligned for attachment to or removal from other equipment. However, as discussed above, the ports may be oriented in any manner desired.
• Still referring toFIG. 30B, in the embodiment shown, O-rings3020 are located at theactuation port3008 and pumpingport3014. However, in other embodiments, other means for connecting thepod pump3000 to other equipment such as barbed connectors, quick connects, glue, clamps and other fastening means may be used. Referring toFIG. 30A, in one embodiment,flex tabs3016 are provided to facilitate the fastening of thepod pump3000 to other equipment, however, in alternate embodiments, additional or alternative locating and fastening features or means may be used. In still other embodiments, fastening features may not be present on thepod pump3000.
• Movement of thediaphragm3006 causes the volume of thepump chamber3012 and the volume of theactuation chamber3010 to change. When the volume of theactuation chamber3010 decreases, the volume of thepump chamber3012 increases. This in turn creates a negative pressure in thepump chamber3012. The negative pressure causes the subject fluid to enter thepump chamber3012.
• When a positive pressure is present in theactuation chamber3010, either through air or liquid entering theactuation chamber3010 through one ormore actuation ports3008, the volume of thepump chamber3012 decreases, creating a positive pressure in thepump chamber3012. The positive pressure urges the subject fluid out of thepump chamber3012 through one ormore pump ports3014. Although onepump port3014 is shown, in other embodiments, more than one pump port is included. In some of these embodiments, one pump port is an inlet port and one pump port is an outlet port. The location, position and configurations of the pump ports vary and in may vary accordingly to a particular intended purpose.
• Referring now toFIGS. 31A and 31B, another embodiment of thepod pump3100 is shown. In this embodiment, the housing includes twoportions3102,3104. Referring now toFIG. 31B, adiaphragm3106 is connected to the interior chamber of the housing at points3116. In this embodiment, thediaphragm3106 is connected to the housing at a position where the twoportions3102,3104 meet. This sandwiches thediaphragm3106 holding thediaphragm3106.
• Thediaphragm3106 divides the interior of thepod pump3100 housing into two chambers; anactuation chamber3108 and apump chamber3110. In this embodiment thepump chamber3110 includes with twopump ports3114, either of which may be an inlet or outlet port when the pump is actuated. Referring again to bothFIGS. 31A and 31B, thepod pump3100 includesbarbed connectors3112, which may be used for the attachment of tubing to thepump ports3114 andactuation port3118. The duty of each port is determined by the configuration of other equipment the port is attached to. In this embodimentbarbed connectors3112 are provided for the attachment of tubing but other attachment methods are possible.
• Referring now toFIGS. 32A and 32B, an alternate embodiment of thepod pump3000 similar to the pod pump shown inFIGS. 30A and 30B is shown. However, in this embodiment, anadditional component3202 is included in theactuating chamber3108. In some embodiments, anadditional component3202 can also be included in thepump chamber3110, and in other embodiments, anadditional component3202 can be included in just the pump chamber. Theadditional component3202 may serve to limit the motion of thediaphragm3006, dampen the diaphragm's3006 travel, filter air or gas entering or leaving theactuation chamber3108 or dampen sound or vibration in thepod pump3000. In some embodiments, e.g., where thepod pump3000 is used in a fluid management system, anadditional component3202 may be present in both chambers to quicken the time for equalizing temperature within the chambers. In some of these embodiments, the additional component(s)3202 may include a mesh plastic, a woven type material, a copper wool, a foam material, or other material, and may create a greater surface area to equilibrate air or other gas. In some embodiments, the additional component(s)3202 may be part of a fluid management system (FMS) and may be used to perform certain fluid management system measurements, such as, for example, measuring the volume of subject fluid pumped through the pump chamber during a stroke of thediaphragm3006 or detecting air in the pumping chamber, e.g., using techniques described in U.S. Pat. Nos. 4,808,161; 4,826,482; 4,976,162; 5,088,515; and 5,350,357, which are hereby incorporated herein by reference in their entireties. Theadditional component3202 may completely or partially cover the actuation chamber port or may be completely free of the actuation chamber port.
• In the preceding figures, various embodiments, characteristics and features of the pod pump are described and shown. The various characteristics can be “mixed-and-matched”, i.e., any one characteristic can be added to any embodiment of the pod pump. The configurations shown are for example only, and the location of the ports, number of ports, attachment means, size of the housing, sizes of the chamber, etc., may vary in the different embodiments. The figures and embodiments described below additionally include various embodiments, characteristics and features, all of which also can be “mixed-and-matched” with any of the characteristics and features described in any of the embodiments in this description.
• Referring toFIGS. 33A and 33B, an alternate embodiment of apod pump3300 is shown with apump chamber cover3302, anactuation chamber cover3304 and amid plate portion3306. In this embodiment themid plate3306 and theactuation chamber cover3304 retain thediaphragm3308 and one or moresecondary diaphragms3310 or3312. The secondary diaphragms may act passively or may be actuated by gas, liquid or mechanical forces to serve as active valves to control the flow of fluid through the pump chamber coverfluid path3314. In this embodiment of thepod pump3300, afluid path3314 is formed in thepump chamber cover3302 such that fluid may flow through theflow path3314 regardless of the position of thediaphragm3308. In this embodiment as in other embodiments thepump chamber cover3302,actuation chamber cover3304 andmid plate3306, in one embodiment, are made of plastic but in other embodiments, may be made from other materials including but not limited to metal or glass. In this embodiment thepump chamber cover3302,actuation chamber cover3304 andmid plate3306 may be joined by laser welding or may be joined by various other methods as deemed appropriate for the chosen component materials and the desired pod pump use. Other joining possibilities include but are not limited to snap together tabs, press fit, snap fit, solvent bonding, heat welding, electromagnetic welding, resistance welding, RF welding, screws, bolts, ultrasonic welding, adhesive, clamping by components that neighbor the pump when in use or other joining methods commonly used in the art.
• Referring now toFIGS. 34A and 34B one embodiment of apod pump3400 is shown. In this embodiment inlet and outlet ports are located at opposite ends of thepump chamber3406 and are interchangeable depending on the configuration of the pump or its intended use. Thediaphragm3408 is shown nearly fully extended into thepump chamber3406. In this embodiment the inlet andoutlet ports3402 and3404 may be partially or fully obscured by thediaphragm3408 when fully actuated by fluid pressure in theactuation chamber3410. Blocking of the inlet or outlet ports may serve to limit or switch the flow of subject fluid through thepump chamber3406 as may be desired in certain applications. In this embodiment the pumping side of thediaphragm3408, i.e., the side of thediaphragm3408 that contacts the subject fluid, is smooth, which may provide different flow characteristics with some subject fluids or provide different contact between thediaphragm3408 and pumpchamber3406 when reduction of flow through the inlet oroutlet ports3402 and3404 is desired when the diaphragm is fully extended into thepump chamber3406.
• In some embodiments, the diaphragm has a variable cross-sectional thickness, as shown inFIG. 34B. Thinner, thicker or variable thickness diaphragms may be used to accommodate the strength, flexural and other properties of the chosen diaphragm materials. Thinner, thicker or variable diaphragm wall thickness may also be used to manage the diaphragm thereby encouraging it to flex more easily in some areas than in other areas, thereby aiding in the management of pumping action and flow of subject fluid in thepump chamber3406. This embodiment thediaphragm3408 is shown having its thickest cross-sectional area closest to its center. However in other embodiments having adiaphragm3408 with a varying cross-sectional, the thickest and thinnest areas may be in any location on thediaphragm3408. Thus, for example, the thinner cross-section may be located near the center and the thicker cross-sections located closer to the perimeter of thediaphragm3408. Still other configurations are possible. Referring to FIGS.35B-E, one embodiment of a diaphragm is shown having various surface embodiments, these include smooth (FIG. 35), rings (FIG. 35E), ribs (FIG. 35D), dimples or dots (FIG. 35C) of variable thickness and or geometry located at various locations on the actuation and or pumping side of thediaphragm3408. In one embodiment of the diaphragm, the diaphragm has a tangential slope in at least one section, but in other embodiments, the diaphragm is completely smooth or substantially smooth.
• Referring now toFIG. 35A a pictorial exploded view of an exemplary embodiment of apod pump3500 is shown. This figure shows one embodiment of the ports, however, an exemplary embodiment is described below with respect toFIG. 37. In this embodiment the housing is made of three sections. Two of theportions3502,3504 may be joined to form a pump chamber3506 (portions3502,3504 referred to as “pump chamber portions”) and the third portion3508 (referred to as the actuation chamber portion) includes anactuation chamber3512 and anactuation port3510 to communicate fluid pressure to theactuation chamber3512. Thepump chamber portions3502,3504 may be joined together to form a pump chamber assembly. This assembly may then be joined with theactuation chamber portion3508 to form the housing.
• Thediaphragm3514 is connected to the interior of the housing. In the exemplary embodiment, thediaphragm3514 is sandwiched between thepump chamber3506 and theactuation chamber3512. Thediaphragm3514 segregates theactuation chamber3512 from thepump chamber3506.
• In this exemplary embodiment, where thepump chamber3506 is composed of twoportions3502,3504, where the portions are molded, this design may allow for minimum flash or burrs. Thus, in this embodiment, the pump chamber will not have flash in the fluid path thus, presents a gentle pumping environment. This embodiment may be advantageous for use with those subject fluids vulnerable to shearing, and/or where delicate subject fluids are pumped, thus flash or burrs should be avoided.
• In the exemplary embodiment shown inFIG. 35A, thepump3500 is shown having twoports3518,3516. For ease of description, theseports3518,3516 are called “inlet” and “outlet” ports. However, eitherport3518,3516 can serve as an inlet port, likewise, either port can serve as an outlet port. The pump inlet andoutlet ports3516,3518 connect to thepump chamber3506 atedges3520 and3522. In one embodiment, theedges3520,3522 are left sharp and are subject to flash when they are molded with retractable cores. However, in the exemplary embodiment, the pump may be manufactured without retractable cores and therefore may have radii on theedges3520,3522 thereby eliminating flash or burrs from the flow path that may damage delicate or sensitive subject fluids.
• Still referring toFIG. 35A, as shown in this exemplary embodiment, thepod pump3500 includes threehousing portions3502,3504,3508 and adiaphragm3514. Twohousing portions3502,3504 form apump chamber3506 portion as well as twoports3516,3518. Athird portion3508 forms theactuation chamber3512. Thediaphragm3514 is attached between thepump chamber3506 andactuation chamber3512 by sandwiching thediaphragm lip3520, which in one embodiment, is an integral O-ring, however, in other embodiments, can be any other shaped gasket, between therims3524 of the housing portions. In the embodiment shown inFIG. 35A, thediaphragm3514 includes tangent edges. The tangent edges are present where the shape of thediaphragm3514 is not a continuous dome, thus, in one section; the diaphragm is conical shaped as indicated by the tangent edges. Although tangent edges are depicted in this embodiment, in alternate embodiments, the diaphragm can include various surfaces, which may include, but are not limited to one or more of the following: dimples, rings, ridges, ribs, smooth, or another variable surface.
• As discussed above, thepump chamber3506 and theports3516,3518 are formed by twohousing portions3502,3504. Theseportions3502,3504 fit together as described below with respect toFIGS. 36A-36C.
• Referring now toFIGS. 36A and 36B, assembled side and end views of thepump3500 ofFIG. 35 are shown. Here thepump chamber portions3502 and3504 and theactuation chamber portion3508 have been joined to conceal thediaphragm3514, not shown. The components of the pod pump housing may be joined by various methods including but not limited to snap together tabs, press fit, snap fit, solvent bonding, heat welding, electromagnetic welding, resistance welding, RF welding, screws, bolts, ultrasonic welding, adhesive, clamping by components that neighbor the pump when in use or other joining methods commonly used in the art.
• In the exemplary embodiment as shown inFIGS. 35A-41B, thepod pump3500 housing includes three portions having features, some specific for the portions to be ultrasonically welded. The design of these three portions includes features that allows for the portions to be joined by ultrasonic welding, but the resultant pod pump is can pump delicate subject fluids with minimal, if any, resultant damage to the subject fluid following ultrasonic welding. A description of the three portions of the housing and the features for assembly is below. Although these embodiments are described with respect to ultrasonic welding, it should be understood that these embodiments alternatively may be laser welded or joined using snap together tabs, press fit, snap fit, solvent bonding, heat welding, electromagnetic welding, resistance welding, RF welding, screws, bolts, adhesive, clamping by components that neighbor the pump when in use or other joining methods commonly used in the art.
• Referring now toFIG. 36C an enlarged view of one port is shown. This can be either the inlet or outlet port as shown inFIG. 35A. In this embodiment the inlet and outlet ports are interchangeable and both have similar interior and exterior geometry. However, their locations may vary.
• In this embodiment, portions of thehousing3502,3504 are joined to form aport3604. In this embodiment thepump chamber portions3502,3504 are depicted as being joined by ultrasonic welds at theenergy director3602. However, in alternate embodiments, other joining methods, as described above, can be used. Thezone3606 wherehousing portions3502,3504 are joined is at least partially isolated from the fluid path of theport3604 by anarea3608. Thearea3608 is formed after joining thehousing portions3502,3504 together. Thearea3608, in one embodiment, increases resistance to flow, thus, thearea3608 creates a path of more resistance than the main flow through the chamber. Thus, thearea3608 is a flow inhibiting area. Thus, the flow of fluid to thezone3606 where the housing portions meet is decreased. Thisflow inhibiting area3608 can be any size desired, however, in the embodiment shown, theflow inhibiting area3608 is created where the distance between the two portions may range from 0.001 inch-0.005 inch and in some embodiments a range of 0.015 inch-0.020 inch. However, thearea3608 can be any size desired and may vary depending on a number of variables including but not limited to: fluid volume, chamber volume and pumping rate. In many embodiments, the distance between the twoportions3502,3504 creating thearea3608 is a fraction of the size or volume of the main flow path. In other embodiments, thearea3608 is any size or volume desired to present desired resistance to the flow of fluid to thearea3606.
• In alternate embodiments, and in some of these embodiments, depending on the overall volume of the pod pump, thearea3608 may have a larger or smaller range. Theflow inhibiting area3608 provides a means where if fluid does flow across theflow inhibiting area3608 it will experience much greater resistance than fluid flowing through the larger area of theport3604. By virtue of less fluid flowing in theflow inhibiting area3608 and reaching thezone3606 where the housing components are joined, less fluid will tend to contact any burrs, flash, surface irregularities or impurities that may be present inarea3606 where the housing components are joined. This isolation from flash, burrs, surface irregularities or other effects of various joining methods may provide for more gentle and safer transport of delicate of sensitive subject fluids as may be desired for certain applications.
• Roundededges3612 on thepump housing portions3502,3504 provide, amongst other things, a delicate environment for the subject fluid, liquid or gas flowing through thepump3500. Although theflow inhibiting area3608 and roundededges3612 are shown in specific locations inFIG. 36C, these features can be present in any area of the pump desired.
• Referring now toFIG. 37 an exemplary embodiment of the pod pump is shown. In this figure, the ports are shown havingvalves3712 within. Again, as shown in this figure, the pod pump housing has threeportions3702,3704,3706.Portion3702 includes theactuation chamber3704 andalignment features3706 for assembly with the other twopump housing portions3704,3706. In this embodiment thepump housing portions3704,3706 include areas where one way valves may be installed3712. Thehousing portions3702,3704,3706 may be joined by ultrasonic welding, laser welding, snap together features, screws, bolts, adhesive or other joining methods commonly used in the art.
• Thediaphragm3714 is shown with ribs in this embodiment. However, in alternate embodiments, thediaphragm3714 may include one or more of the variable surfaces as described above, or alternatively, may be a smooth surface. Although each of the various figures herein show one embodiment of the diaphragm, any embodiment of the diaphragm may be used in conjunction with any embodiment of the pod pump.
• Referring now toFIGS. 38A and 38B, an alternate embodiment of thepod pump3800 is shown. In various embodiments, thepod pump3800 is connected to a system, container or otherwise, where fluid is pumped from and/or into. In some embodiments, the fluid is pumped to/from a system, container or otherwise via a line or tubing. In one embodiment, the fluid is pumped through flexible tubing. In any case, in these embodiments, the line or tubing is connected to the inlet andoutlet ports3814 of the pod pump. However, in alternate embodiments, the fluid can be pumped through a molded fluid line, or the ports can be directly connected to the fluid source, or where the fluid is being pumped.
• Still referring toFIGS. 38A and 38B, the housing is a multi portion design, similar to the design shown inFIG. 37, including a two portionpump chamber housing3704,3706. However, in this embodiment,barbed hose connectors3802 are shown for the connection of flexible tubing (not shown). Other means of connection to a system may be used in other embodiments. These means include, but are not limited to, quick connects, press fit or gluing of tubing directly into the inlet or outlet ports or other means and methods commonly used in the art.
• Referring now toFIG. 38B a section view of the embodiment shown inFIG. 38A is shown. In thisembodiment valves3816 are installed in the interior of theport3814 portion of the housing portions (as shown as3806,3804 inFIG. 38A). Thevalves3816 control the flow of subject fluid in and out of thepump chamber3818 as thediaphragm3808 is actuated by variations in liquid or gas pressure in theactuation chamber3810. As shown in this embodiment, thevalves3816 are duck bill valves, however, in other embodiments, thevalves3816 can be any passive or active valves, including but not limited to, ball check valves, flapper valves, volcano valves, umbrella valves, a poppet, a controlled valve or other types of valves used in the art. In this embodiment thefluid path3812 is located near the top of thepump chamber3818 and has a portion not inhibited by thediaphragm3808 even when the diaphragm is fully extended into thepump chamber3806 by liquid or gas pressure applied to theactuating chamber3810 via theactuation port3820.
• As shown in this embodiment, thediaphragm3808 includes rings, however, as described above, thediaphragm3808 can include dimples, rings, and/or ribs, or any other variation on the surface, or, in some embodiments, no variation on the surface. The varying embodiments of the diaphragm can be used in any of the embodiments of the pod pumps.
• Referring now toFIG. 39, an exploded pictorial view of one embodiment of apod pump3900 is shown.Valves3902, in some embodiments, may be installed in the inlet and oroutlet ports3904 of thepump housing portions3906 and3916. Thevalves3902 may any passive or active valve, including but not limited to, duck bill valves, ball check valves, flapper valves, volcano valves, umbrella valves, a poppet, a controlled valve or other types of valves used in the art to control the flow of fluid. Adiaphragm3908 is attached between the pumpchamber housing portions3906 and3916 and theactuation housing portion3910. Thediaphragm3908 is made of any sufficiently flexible and durable material that it may flex in response to fluid pressure or vacuum applied to theactuation chamber3910. Thediaphragm3908 material may also be chosen for particular bio-compatible, temperature compatibility or compatibility with various gases or liquids that may be introduced to the pump or actuation chambers.
• Thediaphragm3908 may have a ring ofthick material3912 near its outer diameter to be located or fastened in mating features of the podpump housing components3906,3916 and3910. The moveable portion of thediaphragm3908 includes two surfaces, for purposes of description; these will be referred to an exterior surface and an interior surface. The exterior surface is the pump chamber surface and the interior surface is the actuation chamber surface. Either surface of the movable portion of the diaphragm may be of uniform or variable thickness, and both surfaces do not have to be the same. Various embodiments of the surface are shown in FIGS.35B-E. Either or both surfaces may be smooth or include one or more features including but not limited to dimples, dots, rings, ribs, grooves or bars that stand above or below surrounding surfaces. In this embodiment, an arrangement ofdots3914 are shown on the exterior surface of the diaphragm.
• The surface features, or lack thereof, may serve a number of various functions. One of these may be to provide space for fluid to pass through the pump chamber. Another may be to aid in the diaphragm sealing against the pump chamber housing for applications where it is desirable to prevent the flow of fluid through the pump chamber when the diaphragm is pressed against the pump chamber housing by liquid or gas pressure in the actuation chamber. Some diaphragm surfaces may provide one or more of these features, or provide another function or feature.
• Geometry on the exterior or interior surface of the diaphragm may also serve to cushion the movement of the diaphragm at either end of the diaphragm stroke. When geometry on the diaphragm contacts the pump or actuation chamber walls those features will stop moving but the diaphragm material between the features may continue to move to allow the fluid that is being pumped to be gently accelerated or decelerated as it enters or leaves the pump chamber.
• Referring now toFIG. 40A, a pictorial view ofportions3906 and3916 of the multi portion pump shown inFIG. 39 is shown. For illustration purposes only, thepump housing portions3906 and3916 are shown oriented base to base to illustrate the relationship of the alignment and joining features that may be used in the pump portion of a multi-part pod pump housing. Theportions3906 and3916 align and join together in two locations in this exemplary embodiment. However, in other embodiments, these features may vary, and the location of the joining of the two portions may vary. For purposes of description, one of the alignment and joining features will be described with respect toFIG. 40B, however, it should be understood, that although one is described, the details can apply to both.
• Referring now toFIG. 40B, a close up pictorial view of one area ofFIG. 40A is shown.Pump housing portion3916 has analignment feature4002 that may align with acomplimentary alignment groove4004 onhousing portion3906. In this embodiment the aligningfeature4002 includes anenergy director4006 so thehousing portions3906 and3916 may be joined by ultrasonic welding. In this embodiment the energy director is located in line with arelieved area4008 in the base of thepump housing3916. Therelieved area4008 may accommodate the outer ring of a diaphragm (not shown), in embodiments where the diaphragm includes an outer ring.
• Therelieved area4008 is continued inpump housing portion3906 but is only visible as theedge4010. In this embodiment where ultrasonic welding is used, flash from theenergy director4006 may attempt to flow beyond theedge4010 upon assembly. By virtue of theenergy director4006 being in line with the outer ring of the diaphragm (not shown) any flash will be adjacent the outer ring of the diaphragm which flexes to seal despite the presence of flash on the diaphragm outer ring sealing surface. When alternate joining methods such as, but not limited to, laser welding, adhesives, screws or other fasteners are used, theenergy director4006 may be excluded and the geometry of the alignment features4002 and4004 may vary form the embodiment shown. In the embodiment an additional aligningfeature4012 andenergy director4014 are present to orient thepump housing components3906 and3916 such that they are joined down to their base where they will be joined to an actuation housing (not shown) as shown in earlier and subsequent figures.
• Referring now toFIG. 41A, a pictorial view of a partially assembledpod pump4100 is shown. For illustration purposes, only one portion of thepump housing3916, a portion of a possible embodiment of adiaphragm4102 and a portion of anactuator housing4104 are shown.
• Referring now toFIG. 41B, a close up pictorial view of one area ofFIG. 41A is shown. In this embodiment of theactuator housing4104, twoenergy directors4106 and4108 are shown for joining by ultrasonic welding although other joining methods are possible. In thisembodiment energy director4108 is in line withenergy director4014 onpump housing portion3916. Aligning the energy directors as shown in this embodiment ensures that flash from one weld is consumed by the other ultrasonic weld thereby creating a reliable seal between all three housing portions, one housing portion is excluded from this figure for clarity.
• Still referring toFIGS. 41A and 41B, the alignment ofenergy director4006 with the outer portion of thediaphragm4102 is shown. Aligningenergy director4006 with thediaphragm4102 in this way allows any flash resulting from an ultrasonic weld in the area ofenergy director4006 to be sealed by the flexible material of thediaphragm4102. The pod pump housing can be made from any material including any plastic, metal, wood or a combination thereof. In one exemplary embodiment, the pod pump housing is made from medical grade polycarbonate. In another exemplary embodiment, the pod pump housing is made from polysulfone. As described in more detail in the description, the compatibility of the materials selected to the subject fluid may be one factor in some embodiments.
• Referring now toFIGS. 42A-42D, an alternate shape embodiment of thepod pump4200 is shown. The shape embodiments shown herein are meant for illustration and description purposes only. In alternate embodiments, it should be understood that the pod pump can be any shape desired.
• The pod pump housing can be manufactured using any one of a number of methods of manufacturing, including but not limited to injection molding, compression molding, casting, thermoforming or machining. In some embodiments, for example, where the housing is machined, the housing can be fused together using mechanical fasteners or heat fused.
• The wall thickness of the pod pump housing may vary between embodiments. A myriad of variables may contribute to wall thickness selection. These include, but are not limited to, the housing material used, pressure at which the fluid will be pumped; size of the chambers; overall size of the pod pump, strength needed in response to the materials using, durability, assembly method, the device in which the pod pump may be working in conjunction with, cost and manufacturing time. In some embodiments, the pod pump wall thickness is variable.
• The wall thickness, in the various embodiments, can range from 0.005 to any thickness. The term “any thickness” is used because in some embodiments, the pod pump can be integrated into a device or machine. Thus, the wall of the pod pump may be the same thickness as the overall machine. Thus, in some cases, the wall thickness is quite large. In the exemplary embodiment described herein, the wall thickness ranges from 0.04 inch to 0.1 inch. In another embodiment, the wall thickness ranges from 0.06 inch to 0.08 inch.
• The material selection and method of manufacture of the various embodiments of the pod pump may depend on a number of variables. Some include durability, cost, pressure from the fluid, performance, and many others. In some embodiments, the pod pump housing and diaphragm is intended to last months or years. In other embodiments, the pod pump is intended to be a one-use disposable. In still other embodiments, the pod pump is intended to last any number of hours, days, weeks or years. In some embodiments, even where the pod pump is a one-use disposable, the pod pump is designed to pump for a much longer period of time, for example, days, weeks, months or years.
• In one embodiment of the disposable, the housing is made from a thin film made of a material which includes, but is not limited to PETE, PETG, and PET. In these embodiments, the housing may be thermoformed, for example, vacuum or pressure formed, and the diaphragm is formed from a thin plastic film that can be heat sealed to the housing. In some embodiments, the housing is a multi-layer film. This embodiment is conducive to bonding the housing to another component.
• The pod pump can be incorporated and/or integrated into another device, machine, container, or other, or act in conjunction with another device, machine, container or other. In some embodiments, a single pod pump is used. However, in other embodiments, two or more pod pumps are used. In some embodiments, the pod pump is incorporated into a device which is then integrated or attached to a machine, device, container or other. One example of this embodiment is a cassette having integrated pod pumps, fluid paths, fluid ports, actuation ports and actuation fluid paths. Two embodiments of a cassette are described with respect toFIGS. 43A-43C and44A-44B. Many additional embodiments will be understood. For purposes of description, an exemplary embodiment and an alternate embodiment will be described. However, these are only exemplary and other embodiments, with greater or less than two pod pumps, using different valves, various flow paths and incorporating additional containers or other devices, are understood.
• Referring now to FIGS.43A-43C,one embodiment of apod pump cassette4300 is shown. Referring now toFIG. 43A, this embodiment of the pod pump cassette includes two pod pumps4310. The pod pumps4310 can be any pod pump embodiment, but in this exemplary embodiment, the pod pumps4310 are similar to the pod pump shown inFIGS. 33A-33B. Thecassette4300 includes three plates, anactuation plate4320, amid plate4330 and apump chamber plate4340.
• Theactuation plate4320 includes, for eachpod pump4310, a pod pumpactuation chamber housing4312 portion and twovalves actuation housing4314 portions. Thevalve actuation housing4314 includes avalve actuation port4316. In addition to pod pumps, thecassette4300, in some embodiments, may contain additional ports and/or containers for various fluids to be pumped to and from.
• Themid plate4330 includes, for each pod pump, apump diaphragm4332 and twovalve diaphragms4334. In the embodiment shown, the valves are volcano or active valves actuated by adiaphragm4334 which is actuated by a fluid, which in this embodiment is pneumatic air. Also shown on this embodiment of thecassette4300 are additional diaphragms in themid plate4330. These are for embodiments that may contain additional container for various fluids to be pumped to and from.
• Referring now to thepump plate4340, eachpod pump4310 includes apump chamber housing4342 which includes anintegral fluid path4344. Thepump chamber housing4342 is in fluid connection with anexterior fluid path4346. In this exemplary embodiment, the threeplates4320,4330,4340 are laser welded together. However, in other embodiments, various modes of attachment, some of which are described above, may be used.
• Referring now toFIG. 43B, a cross sectional view of thecassette4300 is shown. The volcano valves are shown including thevalve diaphragms4334, thevalves actuation housing4314 portions and theexterior fluid line4346. The valves are actuated by pneumatic air throughactuation ports4318.
• Referring now toFIG. 43C, in some embodiments, anair filter4350 and anadditional fluid line4352 may be included in the cassette.
• An alternate embodiment of the cassette is shown inFIGS. 44A and 44B. Referring now toFIG. 44A, thecassette4400 includes greater than three portions. The portions include amid plate4410 with multiple covers4412-4416 laser welded onto the mid plate. These multiple covers4412-4416 are used rather than the pump plate shown inFIG. 43A as4340. Referring now toFIG. 44B, themid plate4410 again is shown. However, in this embodiment, multiple covers4442-4444 are used rather than an single actuation plate as shown inFIG. 43A as4320. As shown inFIGS. 44A-44C, this is one embodiment, however, in other embodiments, the number of multiple covers may vary.
1.5. Exemplary Embodiments Incorporating Multiple Pump Pods
• It should also be noted that pumping systems may employ multiple pump pods for pumping fluid. Pump pods may be employed individually, in which case the pump pods may be individually controlled, or pump pods may be interconnected in various ways, such as, for example, interconnecting the inlets of multiple pump pods in order to draw fluid from a common source, interconnecting the outlets of multiple pump pods in order to pump fluid to a common destination, and/or interconnecting the pneumatic ports of multiple pump pods in order to control the pump pods through a common pneumatic interface. In various embodiments, multiple pump pods may be operated out-of-phase (i.e., one pumping chamber is emptying while the other is filling) in order to provide a substantially continuous flow, in-phase in order to provide a pulsatile flow, or in other ways. For in-phase operation, a single pneumatic interface may be provided for multiple pump pods so that the base station can operate the pump pods simultaneously. Similarly, a single pneumatic interface may be provided for multiple valves so that the base station can operate the valves simultaneously.
• In the embodiments shown inFIGS. 2 and 48, two individual self-containedpump pods25aand25bof the type shown inFIG. 3 are included in a disposable system. In this embodiment, each of thepump pods25aand25bhas its ownpneumatic port38, so thepump pods25aand25bcan be controlled separately.
• In the embodiment shown inFIGS. 5A and 5B, twopump pods25aand25bare incorporated intolarger assembly2004 such that the inlets of twopump pods25aand25bare connected to acommon inlet line54 and the outlets of both pumppods25aand25bare connected to acommon outlet line57.FIG. 5B shows thepneumatic ports38 of thepump pods25aand25b.Theinlets34 andoutlets37 of thepump pods25aand25bare arranged to direct the flows into and out of the pumping chambers at angles that are substantially tangential with the rigid pumping-chamber walls31 of each pump pod, in order to—as discussed above—reduce shear force and turbulence on the fluid and to improve circulation through the pumping chambers. In this embodiment, thepump pods25aand25bhavepurge ports55, which allow air to be purged from the system, for example, during priming. Also in this embodiment, thecommon inlet line54 is fitted with a number of luer ports2001 (e.g., to permit attachment of additional fluid sources, such as medical solutions, chemical solutions, dilutants, etc.) and is also fitted with a thermocouple2002 (e.g., to allow for monitoring the temperature of the fluid entering thepump pods25aand25b). Also in this embodiment, theassembly2004 includes two flow-throughports2003 having tube connections on the top side (shown inFIG. 5A) and o-ring connections on the bottom side (shown inFIG. 5B). The flow-throughports2003 can be used to facilitate installation or use of theassembly2004 with a base station, for example, by allowing all pneumatic and fluidic connections to be made from the bottom of theassembly2004, in which case theinlet line54 may be pre-connected via tubing to one of the flow-throughports2003 and theoutlet line57 may be pre-connected via tubing to the other flow-throughport2003.
• In the embodiment shown inFIGS. 22A and 22B, twopump pods2025aand2025bof the type shown inFIG. 20 and a number ofvalves2000a-2000dof the type shown inFIG. 21 are incorporated in apump cassette2015 along with various fluid paths and other components. Thepump cassette2015 includes acommon inlet2005 in fluid communication withpump pod2025aviafluid paths2007 and2009 and withpump pod2025bviafluid paths2008 and2010. Thepump cassette2015 also includes acommon outlet2006 in fluid communication withpump pod2025aviafluid paths2011 and2013 and withpump pod2025bviafluid paths2012 and2014. Thus,pump pods2025aand2025bdraw fluid from thecommon inlet2005 and pump fluid to thecommon outlet2006. That being said,valve2000ais used to control fluid flow at the intersection offluid paths2008 and2010 (i.e., at the inlet to pumppod2025b);valve2000bis used to control fluid flow at the intersection offluid paths2007 and2009 (i.e., at the inlet to pumppod2025a);valve2000cis used to control fluid flow at the intersection offluid paths2011 and2013 (i.e., at the outlet ofpump pod2025a); andvalve2000dis used to control fluid flow at the intersection offluid paths2012 and2014 (i.e., at the outlet ofpump pod2025b). Each of thepump pods2025aand2025bhas its ownpneumatic interface2106aand2106b,respectively. Also, each of thevalves2000a-2000dhas its ownpneumatic interface2096a-2096d,respectively. Thus, each of pump pods and each of the valves can be independently controlled by a base station.
• FIG. 23 is a schematic representation of dual-housing arrangement2016 according to another embodiment of the invention. This arrangement may be advantageously used with disposable cassettes that include many pneumatically actuated pumps and/or valves. If the number of pneumatically actuated pumps and/or valves in a cassette is large enough, the cassette containing these pumps and valves can become so large—and the pressures involved can become so great—that it may become difficult to properly seal and position all of the pumps and valves. This difficulty may be alleviated by using two different housings. The valves and pumps (such as pump pods2042) are placed in amain housing2041, from which connectingtubes2045 lead frompneumatic ports2044. Themain housing2041 also has inlet andoutlet tubes2043, which allow liquid to flow into and out of the main housing. The connectingtubes2045 provide pneumatic communication between valves and pumps in themain housing2041 and a smaller, secondary tube-support housing2046, which is provided with apneumatic interface2047 for each of the tubes. The proper positioning and sealing of all thepneumatic interfaces2047 against receptacles in the base unit can be accomplished more easily with the smaller tube-support housing2046 than it would be if the pneumatic actuation was applied to the larger main housing directly.
1.6. Alternative Chamber Configurations and Stroke Sizes
• It should be noted that pump pods of the types described above can be configured with different chamber configurations and/or different stroke sizes. Thus, for example, pump pods having different pump volumes may be provided. Furthermore, pump pods having different pump volumes may be provided with a standardized pneumatic port configuration (and perhaps standardized actuation chamber wall configuration) so that pump pods having different volumes may be easily swapped into and out of a common pumping system or apparatus (e.g., a base unit) having a corresponding standardized pneumatic port interface. For example, the base unit may be able to receive lower-volume pump pods for pediatric use and receive higher-volume pump pods for adult use. The pneumatic ports are preferably adapted to be quickly and easily connected to—and disconnected from—the pneumatic actuation system of the base unit. In certain embodiments, the pump pods may be considered to be disposable and may be provided individually or as part of a larger disposable system.
• Thus, for example, in the embodiments shown inFIGS. 2 and 48, disposable systems (specifically for use in a heat-exchange system, as discussed more fully below) include two self-containedpump pods25aand25b.Different versions of such disposable systems having pump pods of different pump volumes could be provided for different applications (e.g., one version with smaller pump volumes for children, another version with larger pump volumes for adults). Similarly, in the embodiment shown inFIGS. 5A and 5B, different versions of theassembly2004 having pump pods of different pump volumes could be provided, and in the embodiment shown inFIGS. 22A and 22B, different versions of thecassette2015 having pump pods of different pump volumes could be provided. Similarly, in the embodiment shown inFIG. 23, different versions of themain housing2041 having pump pods of different pump volumes could be provided for use with a common secondary tube-support housing2046.
• It should be noted that the pumping chamber wall may be molded, formed, produced, or otherwise configured with various features facilitate intake, circulation, and/or delivery of the fluid. For example, the inside wall of the pumping chamber may include certain features or materials to help induce circulatory flow, induce smooth/laminar flow, reduce boundary layer effects, or even produce turbulence (e.g., to facilitate mixing of materials or prevent coagulation within the pumping chamber).
1.7. Exemplary Diaphragm Configurations
• In certain embodiments, the pump pod diaphragm may be provided with small raised bumps, grooves, or other structures, particularly on the side of the membrane facing the pumping chamber.FIGS. 46A and 46B show anexemplary membrane33 having raisedbumps39, in accordance with an exemplary embodiment of the present invention. Such raisedbumps39 or other raised structures prevent pockets of fluid from being caught away from the inlet and outlet, specifically by keeping the membrane spaced away from the rigid pumping chamber wall even when the pumping chamber volume is at a minimum. This spacing keeps flow passages open for blood to flow from the periphery of the pumping chamber to the outlets. In the exemplary embodiment shown inFIGS. 46A and 46B, thebumps39 are located on a portion of the membrane spaced away from the edge of the membrane such that the membrane lacks bumps in the area near the edge of the membrane. Generally speaking, such a configuration allows the portion of the membrane around the edge to contact the pumping chamber wall, which tends to force fluid from the edge toward the outlet.
• In addition to, or in lieu of, bumps or other raised structures on the membrane, the pump chamber wall may include spacers or conduits to allow for fluid flow as the pumping chamber approaches and reaches its minimum volume.
• The membrane may be made from any of a wide variety of flexible materials, but is preferably made of a high-elongation silicone or similar material in order to maintain smooth pumping of the membrane and to reduce the tendency of membrane to “snap hard” into its minimum-pumping-chamber-volume position. By reducing hard snapping, sharp localized spikes of force on the fluid are reduced. Such hard snapping could cause disruptions in the fluid rotation in the chamber and could result in excessive shear forces and turbulence, which, the case of blood pumping, could cause hemolysis, and in the case of surfactant pumping, could result in foaming. Alternatively, the membrane may be made of a variety of thermoplastic elastomers or rubbers. Also, the membrane may be provided with dimples or grooves to make the membrane more flexible.
• It should be noted that the membrane may be molded, formed, produced, or otherwise configured so as to bias reciprocation of the membrane in a predetermined pattern or manner. For example, the membrane may be formed with portions of having different thickness or stiffness so that certain portions move more freely than others (e.g., a portion of the membrane proximate to the pump inlet may be configured to be more flexible than a portion of the membrane proximate to the pump outlet so that the inlet side of membrane retreats more quickly during the draw stroke and collapses more quickly during the delivery stroke, which could facilitate filling and emptying of the pumping chamber in some embodiments).
2. Exemplary Pump Control Systems2.1. Pressure Actuation System
• FIG. 4 is a schematic showing an embodiment of apressure actuation system40 that may be used to actuate a pump pod, such as thepump pod25 shown inFIG. 3, in accordance with an exemplary embodiment of the present invention. Thepressure actuation system40 is capable of intermittently or alternately providing positive and negative pressurizations to the gas in theactuation chamber42 of thepump pod25. Thepump pod25—including theflexible membrane33, theinlet34, theoutlet37, thepneumatic port38, the pumpingchamber41, theactuation chamber42, and possibly including aninlet check valve35 and anoutlet check valve36 or other valves—may be part of a larger disposable system. Thepneumatic actuation system40—including an actuation-chamber pressure transducer44, a positive-supply valve47, a negative-supply valve48, a positive-pressure gas reservoir51, a negative-pressure gas reservoir52, a positive-pressure-reservoir pressure transducer45, a negative-pressure-reservoir pressure transducer46, as well as anelectronic controller49 including a user interface console (such as a touch-panel screen)—may be part of a base unit.
• The positive-pressure reservoir51 provides to theactuation chamber42 the positive pressurization of a control gas to urge themembrane33 towards a position where the pumpingchamber41 is at its minimum volume (i.e., the position where the membrane is against the rigid pumping-chamber wall31). The negative-pressure reservoir52 provides to theactuation chamber42 the negative pressurization of the control gas to urge themembrane33 in the opposite direction, towards a position where the pumpingchamber41 is at its maximum volume (i.e., the position where the membrane is against the rigid actuation-chamber wall32).
• A valving mechanism is used to control fluid communication between each of thesereservoirs51,52 and theactuation chamber42. InFIG. 4, a separate valve is used for each of the reservoirs; a positive-supply valve47 controls fluid communication between the positive-pressure reservoir51 and theactuation chamber42, and a negative-supply valve48 controls fluid communication between the negative-pressure reservoir52 and theactuation chamber42. These twovalves47,48 are controlled by thecontroller49. Alternatively, a single three-way valve may be used in lieu of the twoseparate valves47,48. Thevalves47,48 may be binary on-off valves or variable-restriction valves.
• Thecontroller49 also receives pressure information from the three pressure transducers shown inFIG. 4: an actuation-chamber pressure transducer44, a positive-pressure-reservoir pressure transducer45, and a negative-pressure-reservoir pressure transducer46. As their names suggest, these transducers respectively measure the pressure in theactuation chamber42, the positive-pressure reservoir51, and the negative-pressure reservoir52. The actuation-chamber-pressure transducer is located in the base unit but is in fluid communication with theactuation chamber42 through the pump pod'spneumatic port38. Thecontroller49 monitors the pressure in the tworeservoirs51,52 to ensure they are properly pressurized (either positively or negatively). In one exemplary embodiment, the positive-pressure reservoir51 may be maintained at around 750 mmHG, while the negative-pressure reservoir52 may be maintained at around −450 mmHG.
• A compressor-type pump or pumps (not shown) may be used to maintain the desired pressures in thesereservoirs51,52. For example, two independent compressors may be used to respectively service thereservoirs51,52. Pressure in thereservoirs51,52 may be managed using a simple bang-bang control technique in which the compressor servicing the positive-pressure reservoir51 is turned on if the pressure in thereservoir51 falls below a predetermined threshold and the compressor servicing the negative-pressure reservoir52 is turned on if the pressure in thereservoir52 is above a predetermined threshold. The amount of hysteresis may be the same for both reservoirs or may be different. Tighter control of the pressure in the reservoirs can be achieved by reducing the size of the hysteresis band, although this will generally result in higher cycling frequencies of the compressors. If very tight control of the reservoir pressures is required or otherwise desirable for a particular application, the bang-bang technique could be replaced with a PID control technique and could use PWM signals on the compressors.
• The pressure provided by the positive-pressure reservoir51 is preferably strong enough—under normal conditions—to urge themembrane33 all the way against the rigid pumping-chamber wall31. Similarly, the negative pressure (i.e., the vacuum) provided by the negative-pressure reservoir52 is preferably strong enough—under normal conditions—to urge the membrane all the way against the actuation-chamber wall32. In a further preferred embodiment, however, these positive and negative pressures provided by thereservoirs51,52 are within safe enough limits that even with either the positive-supply valve47 or the negative-supply valve48 open all the way, the positive or negative pressure applied against themembrane33 is not so strong as to damage the pump pod or create unsafe fluid pressures (e.g., that may harm a patient receiving pumped blood or other fluid).
• It will be appreciated that other types of actuation systems may be used to move the membrane back and forth instead of the two-reservoir pneumatic actuation system shown inFIG. 4, although a two-reservoir pneumatic actuation system is generally preferred. For example, alternative pneumatic actuation systems may include either a single positive-pressure reservoir or a single negative-pressure reservoir along with a single supply valve and a single tank pressure sensor, particularly in combination with a resilient diaphragm. Such pneumatic actuation systems may intermittently provide either a positive gas pressure or a negative gas pressure to the actuation chamber of the pump pod. In embodiments having a single positive-pressure reservoir, the pump may be operated by intermittently providing positive gas pressure to the actuation chamber, causing the diaphragm to move toward the pumping chamber wall and expel the contents of the pumping chamber, and releasing the gas pressure, causing the diaphragm to return to its relaxed position and draw fluid into the pumping chamber. In embodiments having a single negative-pressure reservoir, the pump may be operated by intermittently providing negative gas pressure to the actuation chamber, causing the diaphragm to move toward the actuation chamber wall and draw fluid into the pumping chamber, and releasing the gas pressure, causing the diaphragm to return to its relaxed position and expel fluid from the pumping chamber.
2.2. Alternative Embodiments Using Active Inlet/Outlet Valves
• As discussed above, active valves may be used instead of passive check valves at the pump pod inlet and output. Active valves would allow for greater control and flexibility (generally at the expense of added complexity and cost). Among other things, active valves would allow for reversal of fluid flow, which could be used, for example, to facilitate priming, air purging, and/or detection and mitigation of certain conditions (e.g., occlusion, blockage, leakage, line disconnect). With regard to detection of a line disconnect, a reversal of flow may cause air to be drawn into the pumping chamber through the outlet if the outlet line is disconnected. Such air flow could be detected using any of a variety of techniques, including the amount of work needed to move the pump diaphragm. If the line is safely connected, some amount of work would normally be necessary to reverse flow and draw fluid in through the outlet, whereas if the return line has been disconnected, much less work would generally be necessary to reverse flow, since the pump would be drawing air into the return line. If upon reversing flow, the controller detects an aberrant flow condition, the controller would preferably cause the system to stop pumping blood from the patient.
• During normal pump operations, the active valves generally would be operated as follows. During a fill stroke, when fluid is drawn into the pumping chamber, thecontroller49 would typically open the inlet valve and close the outlet valve so as to allow fluid to enter the pumping chamber through the inlet but prevent fluid from being drawn back in from the outlet. During a delivery stroke when fluid is pumped out of the pumping chamber (e.g., after the pumping chamber is full or at other appropriate times), thecontroller49 would generally close the inlet valve and open the outlet valve so as to allow fluid to be pumped out of the outlet but prevent fluid from being pumped back through the inlet. Between strokes, thecontroller49 may cause both the inlet valve and the outlet valve to be closed for some time interval.
• It should be noted that for embodiments in which pneumatically actuated inlet and outlet valves (e.g., binary on-off valves either integral to the pump pod or external to the pump pod) are used in place of passive inlet and outlet check valves, such valves may be coupled to the positive and/ornegative pressure reservoirs51,52 through appropriate supply valves actuated by thecontroller49.
• The use of active inlet and outlet valves can facilitate detection of air in the pumping chamber. For example, following a full draw stroke to bring the pumping chamber to its maximum volume, positive pressure can be applied to the actuation chamber and the rate at which the pressure in the actuation chamber (or the pumping chamber) increases can be monitored. If the pumping chamber is full of air, then the pressure should increase more gradually, as the air in the pumping chamber will allow the diaphragm to move more readily. If, however, the pumping chamber is full of liquid, then the pressure should increase more rapidly because the pump diaphragm will be held more firmly by the uncompressible liquid.
2.3. Pump Operation
• During normal pumping operations, thecontroller49 typically monitors the pressure information from the actuation-chamber-pressure transducer44 and, based on this information, controls the valving mechanism (valves47,48) to urge themembrane33 all the way to its minimum-pumping-chamber-volume position and then after this position is reached to pull themembrane33 all the way back to its maximum-pumping-chamber-volume position. In this embodiment, volume may be measured by counting full strokes of fluid delivery (e.g., volume=number of full strokes x pumping chamber volume).
• In typical embodiments of the invention, the controller may be able to detect the end of a stroke, i.e., when the membrane reaches one of the rigid pumping-chamber or actuation-chamber walls. Referring toFIG. 4, an expel stroke is started by opening positive-supply valve47, thereby resulting in positive pressure being exerted against themembrane33. Preferably, the positive-supply valve47 is cycled on and off (dithered) to create a ripple in the actuation chamber's pressure as long as themembrane33 is moving. When themembrane33 reaches the pumping-chamber wall31 the pressure ripple stops. Thecontroller49, receiving pressure information from actuation-chamber-pressure transducer44, monitors this pressure ripple and detects the end of stroke when this pressure ripple stops.
• When thecontroller49 detects the end of the expel stroke, the controller closes positive-supply valve47 and dithers the negative-supply valve48, thereby causing a vacuum to be applied to themembrane33. The same process followed in the expel stroke is repeated for the fill stroke. The controller determines the time to complete each stroke and uses that information to calculate flow rate. The flow rate information is then used to set the commands for pressure and valving for the next stroke.
• Thecontroller49 sets the flow rate using a timed sequence of alternately applying positive pressure and vacuum to themembrane33. A positive pressure will be applied for a determined time interval to achieve a desired delivery (i.e., expelling) flow rate. When this time interval has expired, a vacuum is applied to achieve a fill flow rate. This control of time intervals can be an open-loop system without feedback on flow rate; thus, there can be delays between the end of one stroke and the start of another. Such an open-loop time-based system may be used when closed-loop systems based on flow-rate will not operate properly, such as during priming when there is a mixture of liquid and air in the pump pods.
• As mentioned above, a stroke is preferably effected by delivering a sequence of pressure pulses (forming a pressure ripple) to themembrane33. The speed of a stroke can be adjusted by changing how frequently a supply valve is opened and/or by changing how long it is opened each time it is opened. A pressure pulse involves opening the valve between the actuation chamber and the reservoir for a fixed time and then closing it for the rest of the pulse period. The total length of a pressure pulse is 1/(pulse pumping frequency). In one embodiment, the pulse pumping frequency increases from 2 Hz to 16 Hz as the controller's pumping command increases from 0 to 100%. The minimum frequency of 2 Hz is intended to ensure a minimum flow rate is met when there is water in the system. A maximum frequency of 16 Hz is intended to correspond to the minimum time required for the valve to be at a 50% duty cycle. The pumping algorithm preferably divides a stroke into two periods, the initial pumping period and the end-of-stroke period. During the initial pumping period, the valve open time of the pressure pulse is preferably 166 ms (100% duty cycle at 16 Hz). Thus, with a maximum command from the controller, the valve to the reservoir is always open. The number of pressure pulses in the initial period is increased from one to ten as the pumping command increase from zero to 100%.
• After the initial pumping period, there is a transition to the end-of-stroke pumping period. In this respect, software filters are preferably used to determine when a stroke ends, with at least five pressure pulses used in the end-of-stroke period for the end-of-stroke filters to initialize. The end-of-stroke period ends when the end of stroke is detected. During the end-of-stroke period, the valve open time of the pressure pulse is preferably 83.3 ms (50% duty cycle at 16 Hz).FIGS. 7 and 8 show the pressure pulses during the initial and end-of-stroke periods.FIG. 7 shows pressure pulses for a low-flow command by the controller, andFIG. 8 shows a pressure pulse for a large-flow command by the controller. Note that the on time for a pulse is much longer for higher commands.
• The pressure pulses generate a ripple in the measured pressure in the actuation chamber while the membrane is moving. By filtering and isolating this pressure ripple, the end-of-stroke algorithm can detect when the diaphragm has reached the chamber wall and stopped moving. This end-of-stroke information may be used for flow calculations and for sequencing the pump pods for fill and expel strokes.
• In the first stage of filtering, the pressure signal for each pump pod is passed through a band-pass filter. This filter is used to isolate the pulse-pumping frequency. As discussed above, the pulse-pumping frequency preferably increases from 2 Hz to 16 Hz as the pumping command increases from 0% to 100%.FIG. 9 shows the output of the band-pass filter.
• The absolute value of this filtered signal is then passed through a second-order low-pass filter with a damping ratio of one. The corner frequency of this filter is varied based on the pulse pumping frequency.FIG. 10 shows the output of this low-pass filter. The output from the low-pass filter is divided by the absolute value of the supply pressure to normalize the ripple value. This final value of the pressure ripple is then used to detect the end of stroke. Once in the end-of-stroke period, this ripple characteristically drops down to zero when the diaphragm is stopped by the chamber wall.
• FIG. 11 is a graph showing pressure measurements in the actuation chambers of each of the pump pods in the disposable unit, and also showing the results of the filtering described above. It should be noted that the unfiltered pressure readings show that the two pump pods are out of phase, with one pump pod expelling liquid while the other is filling with liquid. As can be seen in the plots of filtered readings, these filtered readings drop to zero at the end of each stroke.
• At the end of the stroke, the flow rate is calculated for a given pump pod and flow direction by dividing the chamber volume by the time for the stroke to complete. Once the expel stroke has ended, the variables for the stroke are reset, and this process repeats for the fill stroke.
• The pressure ripple causes pressure readings to vary significantly for the duration of the stroke. Thus, an average pressure is calculated and logged. As shown inFIG. 12, the average pressure is preferably computed by integrating pressure between the fifth and tenth pulse. In this embodiment, the fifth and tenth pulses are chosen as the start and end of the average to ignore effects of the pressure when initiating the stroke and when the diaphragm hits the chamber wall.
• To check whether any of the pressure transducers (the actuation-chamber-pressure transducer44, the positive-reservoir-pressure transducer45 or the negative-reservoir-pressure transducer46) may be malfunctioning, the controller preferably compares pressure readings at the end of a stroke. Referring toFIG. 4, at the end of an expel stroke, while the positive-supply valve47 is open, the pressure reading of the actuation-chamber-pressure transducer44 is compared to the reading of the positive-reservoir-pressure transducer45. Since at the end of the expel stroke the pressure readings from these two transducers should be the same, any difference in pressure readings from these two transducers indicates a malfunction in one of the two transducers. Similarly, at the end of a fill stroke, while the negative-supply valve48 is open, thecontroller49 preferably compares the pressure reading of the actuation-chamber-pressure transducer44 to the reading of the negative-reservoir-pressure transducer46. If the controller detects a significant change in these pressure readings, the controller generates an alarm signal indicating a malfunction in one of the transducers.
• The controller can also detect aberrant flow conditions by integrating the pressure readings over time to obtain a measure of the work done in moving the liquid. If the amount of work done goes up or down, the controller preferably generates an alarm signal indicating that something has gone wrong in the line, such as an occlusion, a leak, or a disconnect. The ability to detect a disconnect or a leak may be important, particularly when pumping blood or other life-critical fluids, because of the relatively large flow rates of fluids being pumped. In one embodiment, by integrating the pressure readings and determining the work function, the controller can detect a line disconnect within approximately three seconds.
• This calculation can also take into account the head height between the pod pumps and the patient, although this height may be assumed to be constant during a thermal-therapy procedure. This calculation can be represented as
  K_fluidpath×m_pod=∫_stroke(P_pod−P_{height—diff})dt
  where
• • K_fluidpathis the resistance in the fluid path,
  • m_podis the mass of fluid contained in the pod,
  • P_podis the pressure in the pump pod, and
  • P_{height—diff}is the pressure due to head height between the pod and the patient.
    Since both K_fluidpathand m_podshould be constant during a thermal therapy procedure, any variation in the integrated pressure should indicate a change in resistance in the fluid and/or a change in the amount of mass displaced during a stroke, and thus indicate an aberrant flow condition, such as an occlusion or a disconnect.
• In one embodiment, the head height is not monitored during the procedure. The head height is calculated based on the first few pumps of the pod. Those first few pumps set the standard for the head height calculation, based on the following calculation
  P_pod=K_fluidpathm′+P_{height—diff}
  where m′ is the mass flow rate.
• In particular, since normally the flow rate is low in the first few strokes of the pod, m′ may be assumed to be zero and the pressure in the pod equal to the head pressure; P_pod=P_{height—diff}. Based on this calculation, the head height is presumed to be constant.
• In one embodiment, the controller looks for a change in the integrated pressure between consecutive strokes or a change (with a smaller tolerance) over three strokes of the low-pass filtered value of the integrated pressure. If either of these changes is excessive, an error is declared and pumping is stopped until a medical technician intervenes. This detection algorithm is not run during priming due to the large variations in the integrated pressure signal that occur when there is a mixture of air and liquid in the pods.
• Another method of detecting occlusions at low flow rates may be run in tandem with the pod-pressure-integration method. In this method, the controller looks for multiple consecutive short strokes of the exact same length. If such strokes are detected, the pod pump is probably not completing strokes due to an occlusion or a pneumatic problem. In one embodiment, if more than six short strokes occur on a given pod pump, an error signal is generated. During priming, this detection method is not used because fast, short strokes are common when the chambers are filled with air.
• If the end of a stroke does not occur within a predetermined number of pressure pulses (e.g., 100 pressure pulses as discussed above in connection withFIGS. 7-12), the controller preferably generates an error signal. Excessive time to complete a stroke may indicate a pneumatic leak. Such a check can be run during priming as well as during the procedure.
2.4. Fluid Flow Management
• Generally speaking, a single pump pod operates in a pulsatile fashion, first drawing in fluid and then pumping out fluid. Pulsatile operation may be necessary, desirable, or inherent in certain applications (e.g., extracorporeal blood treatment in which blood is drawn from a patient and returned to the patient through a single needle is inherently pulsatile, since blood generally cannot be drawn from the patient and pumped back into the patient at the same time through the single needle).
• In a dual pump configuration, the two pump pods may be operated from a zero degree phase relationship (i.e., both pumping chambers act in the same direction) to a 180 degree phase relationship (i.e., the pumping chambers act in opposite directions). A zero degree phase relationship can be used to produce a substantially pulsatile fluid flow, similar to a single pump pod. A 180 degree phase relationship can be used to produce a substantially continuous fluid flow both toward the pumps and from the pumps. A 90 degree phase relationship can be used to produce a substantially sinusoidal fluid flow.FIGS. 74A-74C show plots for volume flow, pod volumes, and total hold up flow for a zero degree phase relationship, a 180 degree phase relationship, and a 90 degree phase relationship, respectively.
• In some applications, it may be necessary or desirable to provide substantially continuous fluid flow to the pump pod(s) and/or from the pump pod(s). As discussed above, substantially continuous fluid flow may be provided using two pump pods operating with a 180 degree phase relationship. For one or more pump pods operating in a pulsatile mode (e.g., a single pump pod or two pump pods operating in a zero degree phase relationship), one way to produce a more continuous fluid flow output is to fill the pump pod(s) as quickly as possible and then pump out the fluid over an extended period of time (e.g., the desired deliver time could be set to be a total desired stroke time minus the time that the fill stroke took).
• Even when operating two pump pods in a 180 degree phase relationship, it is possible for there to be discontinuous fluid flow under some conditions, particularly when the input impedance is significantly different than the output impedance. For example, in extracorporeal blood treatment applications, input impedance may be higher than output impedance due to such things as needle size (e.g., the needle used to draw blood from the patient may be smaller than the needle used to return blood to the patient), blood viscosity (e.g., the patient may have very viscous blood that is thinned as part of the treatment), or poor patient access (e.g., poor patient circulation may limit the rate at which blood can be drawn). Such impedance differences can result in different pump pod fill and delivery times, particularly if the system cannot be balanced by applying more pressure to one pump pod than the other pump pod (in theory, it should be possible to ensure a precise 180 degree phase relationship if there were no limit on the amount of pneumatic pressure that could be applied to the pump pods, but there are typically both physical limits—the maximum pressures in the two reservoirs—and practical limits to the amount of pressure that can be applied). Therefore, in some situations, the stroke of one pump pod might finish before the corresponding stroke of the other pump pod, in which case it may be necessary to delay the former pump pod while the latter pump pod completes its stroke, resulting in a pause in the fluid flow produced by the former pump pod. One possible solution is to limit the flow rate to the slowest of the fill and deliver strokes. Although this would result in slower blood delivery flow rates, the flow rate would still be known and would be continuous.
2.5. Alternative Embodiment Using Variable-Restriction Pneumatic Valves
• As noted above, the positive-supply valve47 and the negative-supply valve48 in thepneumatic actuation system40 ofFIG. 4 may be variable-restriction valves, as opposed to binary on-off valves. By using variable valves, the pressure applied to theactuation chamber42 and themembrane33 can be more easily controlled to be just a fraction of the pressure inreservoirs51,52, instead of applying the full reservoir pressure to the membrane. This facilitates use of the same reservoir or set of reservoirs for pump pods having different operating parameters, such as pump volume, pump stroke size, or pump actuation pressure. Of course, the reservoir pressure generally needs to be greater than the desired pressures to be applied to various pump pod's membranes, but one pump pod may be operated at, say, half of the reservoir pressure, and another pump pod may be actuated with the same reservoir but at, say, a quarter of the reservoir pressure. Thus, even though different pump pods may be designed to operate at different pressures, these pump pods may all share the same reservoir or set of reservoirs but still be actuated at different pressures, through the use of variable valves. The pressures used in a pump pod may be changed to address conditions that may arise or change during pumping. For example, if flow through the system's tubing becomes constricted because the tubes get twisted, one or both of the positive or negative pressures used in the pump pod may be increased in order to compensate for the increased restriction.
• FIG. 28 is a graph showing how pressures applied to a pod pump may be controlled using variable valves. The vertical axis represents pressure with P_R+ and P_R− representing respectively the pressures in the positive and negative reservoirs (items51 and52 inFIG. 4), and P_C+ and P_C− representing respectively the positive and negative control pressures acting on the pump pod's membrane. As can be seen inFIG. 28, from time T₀to about time T₁, a positive pressure is applied to the actuation chamber (so as to force fluid out of the pumping chamber). By repeatedly reducing and increasing the flow restriction caused by the positive variable valve (item47 inFIG. 4), the pressure being applied to the actuation chamber can be held at about the desired positive control pressure, P_C+. The pressure varies, in a sinusoidal manner, around the desired control pressure. An actuation-chamber pressure transducer (item44 inFIG. 4) in communication with the actuation chamber measures the pressure in the actuation chamber and passes the pressure-measurement information to the controller (item49 inFIG. 4), which in turn controls the variable valve so as to cause the actuation chamber's pressure to vary around the desired control pressure, P_C+. If there are no fault conditions, the membrane is pushed against a rigid wall of the pumping chamber, thereby ending the stroke. The controller determines that the end of stroke has been reached when the pressure measured in the actuation chamber no longer drops off even though the restriction created by the variable valve is reduced. InFIG. 28, the end of the expelling stroke occurs around time T₁. When the end of stroke is sensed, the controller causes the variable valve to close completely so that the actuation chamber's pressure does not increase much beyond the desired control pressure, P_C+.
• After the positive variable valve is closed, the negative variable valve (item48 inFIG. 4) is partially opened to allow the negative pressure reservoir to draw gas from the actuation chamber, and thus draw fluid into the pumping chamber. As can be seen inFIG. 28, from a time shortly after T₁to about time T₂, a negative pressure is applied to the actuation chamber). As with the expelling (positive pressure), stroke described above, repeatedly reducing and increasing the flow restriction caused by the negative variable valve can cause the pressure being applied to the actuation chamber can be held at about the desired negative control pressure, P_C− (which is weaker than the pressure in the negative pressure reservoir). The pressure varies, in a sinusoidal manner, around the desired control pressure. The actuation-chamber pressure transducer passes pressure-measurement information to the controller, which in turn controls the variable valve so as to cause the actuation chamber's pressure to vary around the desired control pressure, P_C−. If there are no fault conditions, the membrane is pulled against a rigid wall of the actuation chamber, thereby ending the draw (negative pressure) stroke. As described above, the controller determines that the end of stroke has been reached when the partial vacuum measured in the actuation chamber no longer drops off even though the restriction created by the variable valve is reduced. InFIG. 28, the end of the draw stroke occurs around time T₂. When the end of stroke is sensed, the controller causes the variable valve to close completely so that the actuation chamber's vacuum does not increase much beyond the desired negative control pressure, P_C−. Once the draw stroke has ended, the positive variable valve can be partially opened to begin a new expelling stroke with positive pressure.
• Thus, two variable-orifice valves may be used to throttle the flow from the positive-pressure source and into the negative-pressure. The pressure in the actuation chamber is monitored and a controller uses this pressure measurement to determine the appropriate commands to both valves to achieve the desired pressure in the actuation chamber. Two advantages of this arrangement are that the filling and delivering pressure may be precisely controlled to achieve a desired flow rate while respecting pressure limits, and that the pressure may be varied with a small sinusoidal signature command. This signature may be monitored to determine when the pump reaches the end of a stroke.
• Another advantage of using variable valves in this way, instead of binary valves, is that by only partially opening and closing the variable valves the valves are subject to less wear and tear. The repeated “banging” of binary valves all the way opened and all the way closed can reduce the life of the valve.
• If the end of stroke is detected and the integrated value of the correlation function is very small, this may be an indication that the stroke occluded and did not complete properly. It may be possible to distinguish upstream occlusions from downstream occlusions by looking at whether the occlusion occurred on a fill or a delivery stroke (this may be difficult for occlusions that occur close to the end of a stroke when the diaphragm is near the chamber wall).FIGS. 73A-73B depict occlusion detection (lines2703 and2704 represent when occlusion is detected) in accordance with an exemplary embodiment of the present invention.
• Under normal operation, the integrated value of the correlation function increases as the stroke progresses. If this value remains small or does not increase, then the stroke is either very short (as in the case of a very low impedance flow or an occlusion) or the actual pressure may not be tracking the desired sinusoidal pressure, e.g., due to a bad valve or pressure signals. Lack of correlation can be detected and used for error handling in these cases.
• Under normal circumstances when the flow controller is running, the control loop preferably adjusts the pressure for any changes in flow rate. If the impedance in the circuit increases dramatically and the pressure limits are saturated before the flow has a chance to reach the target rate, the flow controller generally will not be capable of adjusting the pressures higher to reach the desired flow rate. These situations may arise if a line is partially occluded (e.g., a blockage, such as a blood clot in a blood pumping embodiment) has formed in the circuit. Pressure saturation when the flow has not reached the target flow rate can be detected and used in error handling.
• If there are problems with the valves or the pneumatics, such as a leaking fluid valve or a noisy pressure signal, ripple may continue on the stroke indefinitely and the end of stroke algorithm may not see enough of a change in the pressure ripple to detect end of stroke. For this reason a safety check is preferably added to detect if the time to complete a stroke is excessive. This information can be used for error handling.
2.6. Exemplary Applications for Pump Pods
• Reciprocating positive-displacement pumps and related control systems of the types described above may be used in a wide variety of fluid pumping applications, and are particularly well-suited for (although not limited to) use in applications that involve artificial or extracorporeal blood pumping such as, for example, hyperthermic or hypothermic blood treatments, hemodialysis and other blood processing and filtering treatments (e.g., plasmapheresis and apheresis), cardiac bypass and other assisted blood circulation treatments (e.g., ventricular assist), cardioplegia (as part of cardiac bypass or otherwise), lung bypass or artificial lung and other applications involving extracorporeal blood oxygenation, and chemotherapy and other drug treatments (e.g., regional hyperthermic chemotherapy), to name but a few. For example, in certain embodiments, reciprocating positive-displacement pumps and related control systems of the types described above may be used in a heat-exchanger system that can be used to heat or cool a fluid such as blood. Exemplary heat-exchanger systems are described below.
3. Exemplary Heat-Exchanger Systems
• Embodiments of the present invention relate generally to heat-exchanger systems that can be used to heat or cool a fluid such as blood. A blood heating system may be particularly useful for whole-body hyperthermic treatments (e.g., to raise the body temperature to combat hypothermia or to combat certain diseases, such as Hepatitis C and possibly some types of cancer, HIV/AIDS, rheumatoid arthritis and psoriasis) or for regional hyperthermic chemotherapy treatments. Exemplary heat-exchanger systems are described below, one in the context of the pumping and heating of blood as part of whole-body hyperthermic treatment, and the other in the context of regional hyperthermic chemotherapy treatment. Of course, it should be noted that such a heat-exchanger systems may be used in other applications for heating and/or cooling fluid. Furthermore, while the exemplary heat-exchanger systems described below incorporate pump pods of the types described above, it should be noted that embodiments are not limited to the use of pump pods. Other types of pumps may be usable in various alternative embodiments.
3.1. Whole-Body Hyperthermic Treatment
• As discussed above, a blood heating system may be used for whole-body hyperthermic treatments (e.g., to raise the body temperature to combat hypothermia or to combat Hepatitis C by raising the core body temperature to a sufficient level so as to purge the virus from infected liver cells). Generally speaking, whole-body hyperthermic treatment for Hepatitis C involves raising the core body temperature to approximately 41.6 degrees Celsius (107 degrees Farenheit) for an extended period of time. A typical treatment might last three to four hours, including a 30-60 minute warm-up period, 80-120 minute plateau period, and 30-45 minute cool-down period. Core body temperature, and therefore fluid temperature generated by the heat-exchanger system, must be controlled carefully to maintain the patient at the target core temperature with little variation—if the core temperature is too low, then the treatment may not be effective; if the core temperature gets too high, then the patient can be harmed.
• FIG. 24 is a schematic view of a whole-body hyperthermic treatment system in accordance with an exemplary embodiment of the present invention. Blood leaves the patient via the 14F left femoral venous cannulae. Within the heat-exchanger system10, the blood is pumped by two pump pods through a heat exchanger for heat exchange. A control system monitors various parameters (e.g., blood temperature entering and exiting the heater/cooler as well as patient core temperature) and adjusts operation of the pump pods and the heater/cooler accordingly. following the heat exchanger, the blood passes through a particulate and air filter and returns to the patient via the 12F right femoral venous cannulae. During this procedure, the patient is typically supine, intubated, anesthetized, and monitored by a doctor or other professional.
3.1.1. Exemplary Heat Exchanger Systems
• FIG. 1 shows a heat-exchanger system10 in accordance with an exemplary embodiment of the present invention. The heat-exchanger system10 includes abase unit11 and adisposable unit16. As described further below, thedisposable unit16 is installed into thebase unit11 such that a heat-exchanger bag (e.g., a heat-exchanger bag21 as shown inFIGS. 2 and 48) of thedisposable unit16 rests within a heat exchanger portion of thebase unit11. As blood from a patient circulates through thedisposable unit16, and specifically through the heat-exchanger bag21, the blood is heated by the heat exchanger and is returned to the patient. During such circulation, the blood remains within thedisposable unit16 and generally does not come into contact with components of thebase unit11. Thedisposable unit16 is considered to be “disposable” in that it is generally discarded after a patient treatment, whereas thebase unit11 can be re-used repeatedly by simply installing a newdisposable unit16. In fact, thebase unit11 may include mechanisms to prevent re-use of a disposable unit (e.g., using a bar code, RFID tag, or other identifier associated with the disposable unit).
3.1.2. Exemplary Base Unit
• FIG. 25 shows thebase unit11 in accordance with an exemplary embodiment of the present invention.FIG. 47A shows some of the interior components of thebase unit11 in accordance with an exemplary embodiment of the present invention, whileFIG. 47B shows a rear perspective view of thebase unit11. Thebase unit11 includes, among other things, aheat exchanger2541, apneumatic actuation system40, a disposables interface2500 (also referred to as a manifold interface), a patient interface, a controller, auser interface console13, and aventilation system2701. Thepneumatic actuation system40 may be generally of the type shown inFIG. 4, but with separate pneumatic interfaces, valves, and sensors for each of two pump pods. The disposables interface may include two sensors that provide both thermal and electrical connectivity to a disposable unit to allow for monitoring blood temperature both upstream and downstream of the heat exchanger and also to allow for monitoring other parameters, as discussed below. The patient interface may include one ormore temperature inputs2702 for receiving temperature information (specifically patient temperature information) from one or more temperature probes. The user interface console allows the user to control and monitor operation of the system. In an exemplary embodiment, the controller controls operation of the heat exchanger and the pump pods based on, among other things, blood temperature information received from the disposables interface, pressure information received from the pneumatic actuation system, patient temperature information received from the patient interface, and user inputs received from the user interface console.
3.1.3. Exemplary Disposable Unit Configurations
• As mentioned above, a disposable unit for a heat-exchanger system typically includes a heat-exchanger bag through which blood flows while passing through the heat exchanger. The heat-exchanger bag may include one or more fluid paths. In one exemplary embodiment described below, a heat-exchanger bag includes a single fluid path connecting two fluid inlets to a common fluid outlet. In another exemplary embodiment described below, a heat-exchanger bag includes a single fluid path having a single inlet and a single outlet. Heat-exchanger bags are typically made of a flexible plastic material, although the heat-exchanger bag may be made from other materials and may include a metallic material or other material to improve thermal conductivity.
• FIG. 2 shows relevant components of adisposable unit16, in accordance with an exemplary embodiment of the present invention. Thedisposable unit16 includes, among other things, a heat-exchanger bag21 (also referred to as a “flow-path bag”) with a manifold130 and apanel2017 holding (or configured to hold) twopump pods25aand25band a filter/air trap29. Thedisposable unit16 preferably also includes a handle (not shown here, but shown inFIG. 48) that is used to mechanically interconnect the above-referenced components into a cohesive unit that can be readily installed into thebase unit11, which preferably includes a manifold interface (described below) for receiving the manifold130 and providing pneumatic connections for operating thepumps25a,25b.Thebag21 includes afluid path150 through which fluid can be pumped. In this embodiment, the manifold130 is integrated with the heat-exchanger bag21 and is configured with appropriate tubing connections and supports that are used to interconnect the heat-exchanger bag21 with the twopump pods25aand25b.
• In the embodiment shown inFIG. 2, the manifold130 includes two flow-path inlets23aand23b(also referred to as “heat-exchanger bag inlets”) in fluid communication with one end of thefluid path150 and a flow-path outlet27 (also referred to as a “heat-exchanger bag outlet”) in fluid communication with the other end of thefluid path150. The blood is preferably pumped from the patient and through the heat-exchanger bag21, in this embodiment by a pair of self-containedpump pods25a,25b(referred to individually as a pump pod25), which are preferably reciprocating positive-displacement pumps of the types described herein. In this embodiment, the manifold130 includespneumatic passageways138a,138bto facilitate establishment of pneumatic connections respectively to thepump pods25a,25b(typically using tubing). It should be noted that embodiments are not limited to the use of two pump pods or, for that matter, to the use of pump pods. The manifold130 is described more fully below.
• In this embodiment, eachpump pod25 includes aninlet34 and an outlet37 (i.e., pumppod25ahas aninlet34aand anoutlet37a,whilepump pod25bhas aninlet34band anoutlet37b). The various components may be interconnected in at least two configurations. In a first configuration shown inFIGS. 48 and 72, thepump pods25a,25bmay be coupled upstream of the heat-exchanger bag21 such that thepump inlets34a,34bare coupled to receive blood directly from the patient (e.g., through a “Y” connector2024), thepump outlets37a,37bare connected respectively to the heat-exchanger-bag inlets23a,23bbytubes2026a,2026b,and the filter/air trap29 is connected to the heat-exchanger-bag outlet27 bytube2027. In this way, thepump pods25a,25bare operable to urge blood through the heat-exchanger bag21, from which the blood exits through the flow-path outlet27 and then passes through the filter/air trap29 before returning to the patient. In a second configuration (not shown), thepump pods25a,25bmay be coupled downstream of the heat-exchanger bag21 such that blood from the patient enters the heat-exchanger-bag inlets23a,23b(e.g., through a “Y” connector, not shown), thepump inlets34a,34bare coupled to the flow-path outlet27 (e.g., through a “Y” connector, not shown), and thepump outlets37a,37bare coupled (e.g., through a “Y” connector, not shown) to return blood to the patient via the filter/air trap29. In this way, thepump pods25a,25bdraw blood through the heat-exchanger bag21 and pump the blood through the filter/air trap29 to the patient. It should be noted, in an alternate embodiment, the heat-exchanger bag21 could include separate outlets, which could facilitate its coupling with the pump pods in some situations. In the embodiments shown inFIGS. 2 and 48, the filter/air trap29 is preferably provided with a purge port to allow air to escape from the filter.FIG. 48 shows a datakey slot2542 in which a data key can be placed, for example, during manufacturing.
• FIG. 81 shows a variation of thedisposable unit16 ofFIG. 48 including apatient connection circuit2060 having a sterileprotective covering2062, in accordance with an exemplary embodiment of the present invention. Specifically, a configuration oftubing2061 is connected between the pump pod inlets and the filter outlet to form a complete circuit. In this embodiment, thetubing2061 includes an air purge/sample port2019 and a blood monitoring interface optionally includingshunt sensor connections2020 and/or disposable H/S cuvette2022. In order to effectuate connections to the patient, the surgeon or other technician typically cuts through thetubing2061 at or about the distal portion of the tubing (in this embodiment, the U-shaped portion toward which the arrow forreference numeral2060 points, which may be referred to as the “circus maximus”) in order to create two tube ends. The surgeon or technician can then connect appropriate needles to the two tube end for insertion into the patient.
• In this embodiment, the distal portion is sterilized and covered with a thin plasticprotective material2062 in order to maintain sterility. Prior to cutting through thetubing2061, a portion of thetubing2061 in the sterile field is exposed, for example, by pulling on theprotective material2062 in opposite directions until it separates.FIG. 82 shows a representation of the patient connection circuit fromFIG. 81 with a portion oftubing2061 exposed through the sterileprotective covering2062, in accordance with an exemplary embodiment of the present invention. Once the section oftubing2061 has been exposed, a cut can be made atlocation2063.
• FIG. 83 shows a variation of the disposable unit ofFIG. 81 including an additionalfluid delivery line2065, in accordance with an exemplary embodiment of the present invention. Thefluid delivery line2065 is in fluid communication with the pump pod inlets to that fluid from the fluid delivery line2065 (e.g., IV fluids) can be incorporated into the patient blood and circulated through the heat exchanger and into the patient. In this embodiment, thefluid delivery line2065 is configured with a connector2064 (e.g., a needle for introduction into an IV bag) in order to facilitate connection with a fluid source.
• FIGS. 15, 16 and17 show respectively top perspective, end perspective, and top plan views of an alternative heat-exchanger bag121 in accordance with another embodiment of the present invention. In this embodiment, thebag121 has asingle inlet123, asingle outlet127, and aflow path150 extending between theinlet121 and theoutlet123. Theinlet123 and theoutlet127 of thisbag121 are spaced away from each other, whereas in thebag21 ofFIGS. 2 and 48, theinlet23a,23bandoutlet27 are adjacent each other. Having the inlet and outlet adjacent each other (like the bags shown inFIGS. 2 and 48) generally makes the disposable unit less bulky to handle. Thebag121 may be formed from two sheets of plastic or other appropriate material that are welded at the seams to produce theflow path150.
• It should be noted that alternative embodiments may employ other pump pod configurations as part of thedisposable unit16. For example, various alternative embodiments could employ thepump pod assembly2004 shown inFIGS. 5A and 5B, thepump cassette2015 shown inFIGS. 22A and 22B, or the dual-housing arrangement2016 shown inFIG. 23. With regard to pumppod assembly2004, thecommon inlet54 may be coupled to receive blood from the patient and thecommon outlet57 may be coupled to provide blood to the heat-exchanger bag21, or thecommon inlet54 may be coupled to receive heated blood from the heat-exchanger bag21 and thecommon outlet57 may be coupled to provide blood to the filter/air trap29. Similarly, with regard to pumpcassette2015, thecommon inlet2005 may be coupled to receive blood from the patient and thecommon outlet2006 may be coupled to provide blood to the heat-exchanger bag21, or thecommon inlet2005 may be coupled to receive heated blood from the heat-exchanger bag21 and thecommon outlet2006 may be coupled to provide blood to the filter/air trap29.
• It should be noted that various components of thedisposable unit16 may be provided separately and/or in various assemblies and sub-assemblies, and therefore the word “unit” is not intended to require that the disposables be provided as a complete system or kit. Thus, for example, the pump pods (or pump pod assemblies/cassettes) could be provided separately from the rest of thedisposable unit16. Among other things, providing the pump pods separately could allow pump pods of different volumes to be easily integrated, without requiring separate versions of the main disposable unit for different pump volumes. Furthermore, thedisposable unit16 could be provided with some tubing connections already in place, e.g., with thepump outlets37a,37balready coupled to the heat-exchanger-bag inlets23a,23band/or with thepump inlets34a,34balready coupled to a “Y” connector and/or with the flow-path outlet27 already coupled to the filter/air trap29.
• In typical embodiments, thesame controller49 preferably controls both pump pods (items25aand25bofFIGS. 2 and 48) of thedisposable unit16, and preferably (although not necessarily) causes the two pump pods to pump out of phase (i.e., one pumping chamber is emptying while the other is filling) during normal blood-pumping operation in order to provide for more continuous flow to/from the patient and through the heater. Some ways in which thecontroller49 may monitor and control the pumps, heaters, and other components are discussed above as well as further below.
3.1.4. Exemplary Heat Exchanger Components
• FIG. 13A shows greater detail of theheat exchanger2541 shown inFIG. 25. In this embodiment, anupper heating plate12 is mounted in adoor18 located at the top of the base unit. Alower heating plate14 is located in thebase unit11 under thedoor18. The heat-exchanger bag21, which is part of thedisposable unit16, is placed on top of thelower heating plate14, such that when thedoor18 is closed, thebag21 rests between the twoheating plates12,14. This arrangement generally permits more heat to be transferred to the blood more quickly than a single-plate arrangement would, although alternative embodiments may use a single plate either above or below the heat-exchanger bag21 and/or may use other types of heating elements. Thedoor18 and/or theupper plate12 may include pneumatic sealing tracks to evacuate air from the heat exchanger or produce a better coupling between theupper plate12 and the bag21 (e.g., by producing a vacuum that pulls the upper surface of thebag21 into contact with theupper plate12.
• Each of theheating plates12,14 may include a single heating element or multiple heating elements. The heating elements are typically (although not necessarily) electric heating elements.FIG. 14 shows an exploded view of one exemplary heating element configuration in which theupper heating plate12 includes asingle heater element141 and aplaten142 and thelower heating plate14 includes asingle heater element143 and aplaten144.FIG. 18 shows an alternative heating element configuration in each of theheating plates12,14 includes sevenheating elements182,183,184,185. In practice, electricity passing through the heating elements heats the heating elements, which in turn heat the platens, which in turn conduct heat to the blood passing through the heat-exchanger bag. It should be noted that heating elements can be used without platens, although the platens tend to provide a more even distribution of heat. In the embodiment shown inFIG. 18, if one or even several of the heating elements fails, the heat exchanger should still be able to perform at least some blood heating, since the platens generally can still be heated with fewer than all the heating elements working and still impart heat to the blood passing through the heat-exchanger bag.
• In order to improve thermal coupling between theheating plates12,14 and the heat-exchanger bag, thedoor18 may produce a substantially air-tight seal when closed. Furthermore, air may be evacuated from around the heat-exchanger bag to achieve better thermal coupling between the bag and the plates. In this regard, a compressor (not shown) that may be used to produce the positive and/or negative pressures for thereservoirs51,52 may be used to evacuate air from around the heat-exchanger bag. Coolingfins131 or other elements may be provided to draw away excess heat.
• The temperature inside the heat exchanger may be monitored to ensure that the blood does not get so heated as to cause damage to the blood. In the embodiment shown inFIG. 18, each heating plate is provided with twotemperature sensors180,181 located near theoutlet27 at points near where the blood should be at its hottest. Since theinlet23 is near the outlet27 (in this figure), the blood flowing through the outlet may be a little cooler than further upstream, because the cooler blood flowing into the inlet can cool the warmer blood passing through the outlet nearby. Three of theheating elements182,183,184 are located towards the end of the flow path in the heat-exchanger bag21. Eachtemperature sensor180,181 may be located between heating elements and near theoutlet27, and thetemperature sensors180,181 are preferably spaced some distance apart with at least one heating element located between them (in this embodiment, heating element183). Thus, as shown inFIG. 18, onesensor181 is located between the last twoheating elements183,184 that the flow path crosses before the blood exits theoutlet27. Theother sensor180 is located upstream of both of these twoheating elements183,184 and between twoheating elements182,183. If the twotemperature sensors180,181 are working properly and if the heat exchanger is working properly, the two temperature sensors should have readings within a certain number of degrees of each other (although they would not typically have the exact same temperature reading). The controller preferably receives temperature information from the twotemperature sensors180,181 and may generate an alarm, discontinue operation, reduce power to the heating elements, and/or take other action if either (or both) of the temperature sensors indicates an unsafe temperature or if the difference in temperature readings measured by the two sensors exceeds a predetermined limit. The maximum temperature of the plates should not be allowed to exceed the maximum allowable blood temperature, because otherwise, if the flow of blood were to stop or slow, the blood could be over-heated.
• In certain embodiments, one or both of theheating plates12,14 may be translatable in a vertical direction when the door is closed, e.g., to facilitate evacuation of air from the heat-exchanger bag21 during priming or to squeeze residual blood out of the heat-exchanger bag21 and back into the patient at the end of the blood-heating procedure. The plates may additionally or alternatively be tiltable so that the bag may be tilted, e.g., in order to assist in removing air bubbles from the bag during priming or to assist with returning blood to the patient. Such vertical translation and/or tilting could be performed manually or could be performed automatically, for example, under control of thecontroller49.
• Thus, at the end of the blood-heating procedure, the membranes in thepump pods25a,25bmay be urged against the pumping-chamber wall so as to minimize the volume of the pumping chambers and expel as much blood as possible back toward the patient. Furthermore, in embodiments that include vertically translatable and/or tiltable plates, the heat-exchanger bag21 may be squeezed and/or tilted to direct as much blood as possible back toward the patient.
3.1.5. Exemplary Manifold and Manifold Interface
• FIGS. 49A and 49B respectively show a perspective back-side view and a perspective bottom view of the manifold130 fromFIG. 2, in accordance with an exemplary embodiment of the present invention.FIG. 49A shows bag inlet andoutlet connectors2053,2054 for connection at the inlet and outlet openings of thefluid channel150 of thebag21. Thebag inlet connector2053 is in fluid communication with theinlets23a,23b,while thebag outlet connector2054 is in fluid communication with theoutlet27. Thethermowells133aand133bare shown in the outlet fluid path and the inlet fluid path, respectively. Thepneumatic interfaces139a,139bthat are used to provide pneumatic pressure from thebase unit11 to thepneumatic ports138a,138bare shown.
• FIG. 13B shows a perspective back-side cross-sectional view of themanifold130 ofFIGS. 2, 49A, and49B, in accordance with an exemplary embodiment of the present invention. In this embodiment, the manifold130 includes aninlet thermowell133alocated in abag inlet23aand anoutlet thermowell133blocated in abag outlet27. Thethermowells133a,133binterface with corresponding probes in a manifold interface of the base unit11 (discussed below) when thedisposable unit16 is installed in thebase unit11.FIG. 13C shows a close-up view of an exemplary thermowell.
• Thethermowells133a,133bprovide for both thermal and electrical interconnections between thebase unit11 and thedisposable unit16. Among other things, such thermal and electrical interconnections allow thecontroller49 to monitor blood temperature as the blood enters and exits the heat-exchanger bag21 and also allow thecontroller49 to take other measurements (e.g., to detect the presence of blood or air in the heat-exchanger bag21 and to perform leak detection) as discussed below. In this embodiment, each of thethermowells133a,133bis coupled so as to have a portion residing directly in the fluid path (i.e., in contact with the blood) so as to permit better transmission of blood temperature from thedisposable unit16 to thebase unit11. In lieu of, or in addition to, the thermowells, thedisposable unit16 may include other temperature probes/sensors and interfaces by which thecontroller49 can monitor blood temperature as the blood enters and exits the heat-exchanger bag21.
• While the exemplary embodiment shown inFIGS. 13B, 49A, and49B include thermal wells for transmitting thermal information to thebase unit11 and optionally for use in conductivity sensing, it should be noted that other types of sensor components may be additionally or alternatively used. For example, rather than using a thermal well, a sensor component that sends temperature measurements or signals to thebase unit11 may be used. Various types and configurations of sensors are described below.
• Additionally, the manifold130 includes various tube supports to holds tubes extending from the pumps (items25a,25binFIG. 2) and the heat-exchanger bag (item21 inFIG. 13A). These tubes include the tubes leading from the outlets (items37a,37binFIG. 2) of the pumps into theinlets23a,23bof the heat-exchanger bag. Theoutlet27 of the heat-exchanger bag is also held by the tube support. In a preferred embodiment, thetube support130 also holds tubes leading to the pneumatic ports (item38 ofFIG. 3) of the pumps and provides the interface between pumps' pneumatic ports and base unit's pneumatic actuation system (item40 ofFIG. 4). The tubes from the pneumatic ports pass into thepneumatic passageways138a,138bin thetube support130; thepneumatic passageways138a,138bare respectively in fluid communication with thepneumatic interfaces139a,139b.Thepneumatic interfaces139a,139bconnect to receptacles in the base unit, and the receptacles in turn provide fluid communication with pneumatic actuation systems for each of the pumps. This arrangement allows the disposable unit's interface to the base unit to be manufactured more easily and eases the installation of the disposable unit in the base unit. Instead of manufacturing the pumps so that the pneumatic ports are properly positioned with respect to each other for installation into the base unit, the morecompact tube support130 holds thepneumatic interfaces139a,139bin the proper position; the smaller size and simpler structure of thetube support130 makes it easier to manufacture thepneumatic interfaces139a,139bwith the desired tolerances for installation into thebase unit11. Thedisposable unit16 may also include a data key or other feature for interfacing with thebase unit11 in order to provide relevant information to the base unit11 (e.g., disposable unit serial number and prior usage information) and/or store information provided by the base unit11 (e.g., usage information).
• A similar arrangement may be used with disposable cassettes that include pneumatically actuated pumps and/or valves. As discussed above, if the number of pneumatically actuated pumps and/or valves in a cassette is large enough, the cassette containing these pumps and valves can become so large—and the pressures involved can become so great—that it may become difficult to properly seal and position all of the pumps and valves. This difficulty may be alleviated by placing the valves and pumps in a main cassette, from which connecting tubes lead from pneumatic ports, so that pneumatic communication is provided between valves and pumps in the main cassette and a smaller, secondary tube-support cassette, which is provided with a pneumatic interface for each of the tubes, as shown inFIG. 23. In this way, the proper positioning and sealing of all the pneumatic interfaces can be accomplished more easily with the smaller tube-support cassette than it would be if the pneumatic actuation needed to be applied to the larger main cassette directly. Additionally, or alternatively, valves in the main cassette may be ganged to together in some embodiments, so that several valves may be actuated simultaneously through a single pneumatic interface on the tube-support cassette and through a single connecting tube between the pneumatic interface and the valves.
• FIG. 26 shows a close-up view of themanifold interface2500 shown inFIG. 25. Themanifold interface2500 includes, among other things, probes61,62 andpneumatic ports2539a,2539b.With reference again toFIG. 13B, it can be seen that the manifold130 can be installed in themanifold interface2500 such that theprobes61,62 interface respectively with thethermowells133a,133band thepneumatic ports2539a,2539binterface respectively with thepneumatic interfaces139a,139b.Themanifold interface2500 also includes adata key interface2540 for interfacing with a corresponding data key in the disposable unit. The datakey interface2540 preferably provides a bi-directional communication interface through which thecontroller49 can read information from the disposable unit (e.g., serial/model number, expiration date, and prior usage information) and write information to the disposable unit (e.g., usage information). In an exemplary embodiment, thecontroller49 may prevent the start of a treatment if the data key is not present or if the disposable unit is unusable, for example, because it includes an unacceptable serial/model number, is past a pre-configured expiration date, or has already been used. Thecontroller49 may terminate a treatment if the data key is removed. In lieu of adata key interface2540, thebase unit11 ormanifold interface2500 may include other types of interfaces for reading information from the disposable unit and/or writing information to the disposable unit (e.g., RFID, bar code reader, smart key interface).
• It should be noted that one or more pumps (e.g., pump pods) may be integral with a manifold such as the manifold130 and placed in a base unit as a single cartridge. The assembly could include pneumatic connections from the pneumatic ports (which are connected to the base unit) directly to the pump actuation chambers so that no external tubing would be needed to make the pneumatic connections to the pump pods. The assembly could additionally or alternatively include fluidic connections (e.g., from the pump outlets to the interface with the heat-exchanger bag) so that no external tubing would be needed between the pump outlets and the manifold or bag.
3.1.6. Exemplary Blood Heating Schematic
• FIG. 6 is a schematic of thedisposable unit16 connections in accordance with an exemplary embodiment of the present invention. After thedisposable unit16 is primed, aninlet catheter67 and anoutlet catheter68 are inserted into a vein or veins of a patient. Several patient-temperature probes66 are disposed in or on the patient; theseprobes66 provide patient-temperature information to the controller in order to monitor possible overheating of the patient.
• The action of thepump pods25a,25b—which are acted on by the base unit's pneumatic actuation system (under control of the controller49) through pneumatic ports38-raws the blood from theinlet catheter67 into the disposable unit's tubing. The pump pods' inlet andoutlet check valves35,36 ensure that the blood travels in the correct direction through the disposable unit's tubing (i.e., in a clockwise direction in the schematic shown inFIG. 6). After exiting thepump pods25a,25b,the blood is pumped to the heat-exchanger bag21, which is preferably installed between two heating plates in the base unit. Before the blood enters the heating area, the temperature is measured via a bag-inlet temperature sensor61, which communicates inlet temperature information to thecontroller49. After being heated, the blood's temperature is again measured via a bag-outlet temperature sensor62, which also provides temperature information to thecontroller49. The heated blood then flows through the air trap/filter29 and then to the patient through thereturn catheter68.
• The controller preferably uses a closed-loop control scheme based on, among other things, patient temperature information (e.g., received through the patient interface2704), blood temperature information (e.g., received via the thermal wells in the manifold130 and the corresponding sensors in the manifold interface2500), and pump status information (e.g., reservoir pressure, actuation chamber pressure, end-of-stroke detection, volumetric measurements, air detection, occlusion detection, leak detection) to attain/maintain patient body temperature and ensure that blood is not overheated locally (e.g., even if the patient body temperature is at a safe level, it may be possible for the blood to overheat in the heat-exchanger component, for example, if the heat exchanger malfunctions or blood is not pumped at a sufficient rate). Furthermore, the controller typically receives multiple patient temperature inputs. The controller may adjust the heat exchanger and/or pump operation dynamically based on patient temperature information and blood temperature information.
• The bag-inlet temperature sensor61 and the bag-outlet temperature sensor62 may be mounted permanently in thebase unit11 adjacent where the inlet and outlet of the bags are located. In order to improve thermal conductivity between the blood flowing within the bag and the temperature sensors located outside of the bag—and thereby improve the accuracy of the temperature readings—the bag may be provided with metal thermowells which extend into the flowpath of the blood at the bag's inlet and outlet. When the bag is placed between the heating plates, the thermowells can accommodate and receive thetemperature sensors61,62 extending from thebase unit11. As discussed below, the metal thermowells can also be used as electrical conductors and thus be used to detect leaks or air in thebag21.
• In the system shown inFIG. 6, aprime line2021 may be provided to supply a priming fluid (e.g., water) to the pod pumps. An air purge/sample port2019 may also be provided to facilitate air purging and also to allow for sampling of the blood being returned to the patient. A blood monitoring interface may also be provided, for example, including shunt sensor connections (mating luer locks)2020 and disposable H/S cuvette2022 for a CDI™ BloodParameter Monitoring System 500 blood gas monitor sold by Terumo Cardiovascular Systems, Corp.
• In various alternative embodiments, thecontroller49 may detect abnormal conditions in the system based on several factors including: (i) the difference in the bag-inlet and bag-outlet temperatures measured respectively by the bag-inlet and bag-outlet sensors61,62, (ii) the volumetric flow rate of blood through thedisposable unit16, and (iii) the power being provided to the base unit's heating plates. If each thepump pod25a,25bexpels the same, known volume of blood during each expel stroke, the volumetric flow rate can be measured by simply measuring the rate of expel strokes, and multiplying that rate by volume expelled per stroke. (The flow rate can be determined in this way as long as full pump strokes are being performed. As discussed above, the controller in a preferred embodiment monitors whether full strokes are being performed by dithering the valving mechanism and analyzing the pressure information from the actuation-chamber-pressure transducers.) The product of three factors—the measured flow rate, the measured increase in blood temperature, and the specific heat of the blood—should be proportional to the power going into the heating plates. If this proportion varies significantly during a procedure, the controller preferably generates an alarm signal, which may be used to cause an indication to a medical technician monitoring the procedure or which may be used directly to stop the procedure.
• Preferably, the controller generates two estimates based on a given set of temperature and flow-rate measurements, with one estimate based on all the uncertainties biased one way and the other estimate based on all the uncertainties biased the other way. The electrical power being consumed by the heating plates should always be below one estimate and above the other estimate; if the power measurement falls outside of this range, the controller will preferably generate the alarm signal.
• It should be noted that the system may include other types of sensors and systems. For example, the system could provide anticoagulant to the patient, particularly to allow for extended treatments. The system could provide additional fluid to the patient, and may include a hydration sensor to detect dehydration of the patient, particularly due to the hyperthermic treatment. The system could also include a hemolysis sensor to monitor for excessive amounts of hemolysis. Some of this sensing may involve conductivity sensing using the thermal wells/sensors or other mechanisms.
3.1.7. Leak and Air Detection
• In certain embodiments, detection of leaks in the heat-exchanger bag21 may be accomplished by measuring the electrical conductivity between one or both of thethermowells133a,133band one or both of the upper andlower heating plates12,14. As discussed above, thebase unit11 includessensors61,62 that interface with thethermowells133a,133bfor providing electrical connectivity between thebase unit11 and thedisposable unit16. Thebase unit11 typically also includes electrical probes connected to each of theheating plates12,14, which should also be electrically conductive. If there is a leak, the electrical conductivity between the thermowells and the heating plates should increase substantially (because the fluid passing through the leak is generally a much better conductor of electricity than the bag material). Normally, the resistance between the electrical probe contacting the thermowell and each of the electrical probes on the heating plates should be quite high, because the plastic material from which the bag is made is a relatively good insulator. However, if there is a leak, the liquid (e.g., the blood) passing through the leak in the bag provides a very good conductor of electricity, so the resistance drops significantly when there is a leak. Thus, the controller, which is in communication with these electrical probes, measures the conductivity between the probes and generates an alarm signal when the conductivity increases by a certain amount.
• Similarly, the metal thermowells can also be used to detect air in the flow path in the bag. If there is air in the bag, the resistance between the thermowells and the plates will increase, because air is a poor conductor of electricity. Thus, if the controller detects a decrease in the electrical conductivity between the plates and the thermowells, and if the decrease is more than a certain amount, the controller will preferably generate an error signal and will preferably cause the procedure to stop.
• Additionally or alternatively, the system could include other types of sensors to detect leaks, e.g., a carbon dioxide sensor for detecting blood leakage. A carbon dioxide sensor would typically be placed in an appropriate location, such as proximate to the fluidic paths through which blood passes, perhaps within a partially or fully enclosed space (e.g., within the heat exchanger with the door closed). The carbon dioxide detector could be included in the base unit or otherwise in communication with the base unit controller.
3.1.8. Patient Temperature Monitoring
• In a blood-heating procedure, the temperature of the patient must be closely monitored in order to prevent the patient from overheating beyond a safe limit. In certain embodiments, at least two separate temperature probes are located in the patient, e.g., one in the abdomen—either in the bladder or the rectum, in contact with the bladder wall or the rectal wall—and the other through the nasal passage, in contact with back wall of the nasal passage (patient temperature can be monitored using a single probe or more than two probes and can be monitored from other locations or methods, e.g., by monitoring air expired by the patient). If both sensors are properly positioned, the temperature readings of the two probes should be within a certain range. If the temperature readings from the two probes differ from each other too much, the controller may generate an alarm signal and/or abort the procedure. During the preparation for the blood-heating procedure, as the probes are being inserted into the patient, the readings of the two probes may be compared with each other and also compared normal patient temperature readings; when the two probes fall within a pre-set range of each other and within a range of normal patient temperature readings, the medical personnel positioning the probes will be able to tell when they have properly positioned the probes.
• During the blood-heating procedure, the method shown inFIG. 19 is preferably followed in order to ensure that the patient does not get dangerously overheated. Instep90, temperature readings from the abdominal and nasal probes are taken. In step91, the readings are compared with each other; if the readings fall outside of a pre-set range, an alarm signal is generated indicating a fault in the temperature readings. In step92, the controller monitors the temperature readings from one of the two probes and compares those readings to a pre-set upper limit; if a reading is above this pre-set upper limit, an alarm signal is generated indicating the patient is getting too overheated.
• As discussed above, the controller of the heat-exchanger system may monitor patient body temperature using at least two temperature probes. In actuality, the controller really only needs temperature readings from a single temperature probe; the second temperature probe essentially provides a control against which readings from the first temperature probe can be compared. In certain embodiments, then, a single temperature probe may be used to provide patient temperature readings to the controller. In such embodiments, an operator could independently monitor a second temperature probe and manually abort the procedure if the two temperature readings do not match sufficiently.
3.1.9. User Interface
• FIG. 27 shows an exemplary user interface screen in accordance with an exemplary embodiment of the present invention. The right-hand side of the screen includes various therapy controls including (from top to bottom) indicators for the various therapy phases (i.e., system idle, pre-check, prime, warm-up, plateau, cool-down, and end-therapy) for displaying the current phase of treatment (in this example, “warm-up” is highlighted, indicating that the therapy is currently in the warm-up phase), a phase progress indicator for showing, e.g., the time remaining or time elapsed in the current phase, and four control buttons through which the operator can control the therapy (e.g., pause treatment, stop treatment, start or re-start treatment, and step to the next phase). It should be noted that these four control buttons prevent an operator from stepping backward to a previous stage. The left-hand side of the screen allows the operator to tab through screens providing patient information, status information, temperature graphs, flow graphs, and logs.
3.1.10 Alternative Heat-Exchanger Embodiments
• In the embodiments described above, fluid is heated or cooled by running the fluid through a heat-exchanger bag that is placed between two plates of a heat exchanger. Of course, the present invention is in no way limited to the use of a heat-exchanger bag or plates. In alternative embodiments, heat-exchanger bags may be used with other types of heat exchangers (e.g., a heat-exchanger bag could be rolled up and placed in a tubular chamber or could be placed in other types of heat exchangers, such as an oven, refrigerator, water bath, or radiator). Additionally or alternatively, other types of fluid conduits (e.g., a length of tubing and/or a radiator) may be used with one or more plates. The heat exchanger may include heating and/or cooling capabilities. In fact, the heat-exchanger could include both heating and cooling capabilities so that the heat-exchanger system could be used for both heating and cooling applications, either as part of the same treatment (e.g., so that blood could be heated for hyperthermic treatment and quickly returned to normal temperature following treatment) or as part of separate treatments (e.g., the base unit could be used to provide hyperthermic treatment to one patient and later to provide hypothermic treatment to another patient).
• In one particular alternative embodiment, the disposable unit includes, or is configured to use, a length of tubing as the heat-exchanger component. The length of tubing is preferably thin-walled lay-flat tubing, although other types of tubing may be used. The tubing is placed in the radiator, which may be part of the disposable (e.g., the radiator may be attached to the manifold so that the entire unit can be placed in a base unit), part of the base unit (e.g., the radiator may be integral or attached to one of the heat-exchanger plates), or a separate component that may be disposable or reusable. In any case, the radiator preferably includes a channel for receiving the length of tubing.
• FIG. 75 shows aradiator8000 in accordance with an exemplary embodiment of the present invention. Theradiator8000 has a contiguous channel from afirst opening8001 to asecond opening8002. The channel is configured to receive a length of tubing8006 (e.g., thin-walled lay-flat tubing) such that one end of the tubing will protrude from theopening8001 and the other end of the tubing will protrude from theopening8002, as shown inFIG. 76. The tubing may be placed in the radiator by the user (particularly if the radiator is part of the base unit or is a separate, reusable component) or may be provided already installed in the radiator (particularly if the radiator is part of the disposable unit). The radiator is generally made of a thermally conductive material, such as a thermally conductive plastic or metal. In an exemplary embodiment, theradiator8000 may be approximately six inches in diameter and approximately two inches in height.
• In this embodiment, the channel includes inner and outer concentric loops (8003 and8004, respectively) that are connected via aserpentine section8005. Among other things, this configuration allows both of theopenings8001,8002 to be accessible along the outer edge of the radiator. Assuming the opening8001 (leading to the inner loop8003) represents the fluid inlet point and the opening8002 (leading to the outer loop8004) represents the fluid outlet point, then the fluid will flow through the tubing in theinner loop8003 in a clockwise direction and will flow through the tubing in theouter loop8004 in a counter-clockwise direction (using the orientation shown inFIG. 76). Theserpentine section8005 connects the two loops and reverses the flow direction. It should be noted that the inner andouter loops8003,8004 and theserpentine section8005 are configured to avoid sharp or abrupt fluid direction changes and therefore avoid imparting excessive shear forces or turbulence on the fluid. It should also be noted that the arrangement of tubing (and particularly lay-flat tubing, which expands when carrying pressurized fluid) and radiator should provide for efficient heat exchange because of the close coupling of the tubing with the radiator and because of the large surface areas involved.
• As discussed above, theradiator8000 could be provided as part of the disposable unit or as a separate component, and in such cases theradiator8000 would generally be placed into an appropriately configured heat exchanger of the base unit. For example, theradiator8000 could be placed between two plates of a heat exchanger (similar to the way the heat-exchanger bag is placed between two plates in various embodiments described above), in which case the heat exchanger may be configured to accommodate theradiator8000, such as, for example, by having the two plates farther apart and/or using a special door hinge to allow the upper plate to lie flat against the top of the radiator. The bottom plate could include guides (e.g., guides8007 as shown inFIG. 77 in both top view and front view) or a cylindrical wall (e.g.,cylindrical wall8008 as shown inFIG. 78 in both top view and front view) to facilitate placement of the radiator into the heat exchanger. Also as discussed above, the radiator could be part of the base unit. For example, theradiator8000 could be integral to thebottom plate14, as shown inFIG. 79.
• Alternatively, certain types of radiators may be used without separate tubing, such that fluid is carried directly in the channel of the radiator. Such radiators would typically be disposable, although they could be reusable, for example, after being rinsed and disinfected.FIG. 80 shows anenclosed radiator8009, similar to theradiator8000 described above, and including twoports8010,8011 for accommodating fluid connections such as tubing connections to a manifold or directly to one or more pumps. As with theradiator8000 described above, theradiator8009 could be part of the base unit, part of the disposable unit, or a separate component.
• It should be noted that these embodiments are exemplary and are not intended to represent all of the types of heat-exchanger components that can be used in heat-exchanger systems of the types described herein.
3.2. Regional Hyperthermic Chemotherapy Treatment
• FIG. 45 shows a representation of a regional hyperthermicchemotherapy treatment system2600 in accordance with an exemplary embodiment of the present invention. Thesystem2600 is essentially a smaller version of a heat-exchanger system of the types described above in that it includes abase unit2611 and adisposable unit2601. Similar to the systems described above, thebase unit2611 includes a heat exchanger, a pneumatic control system, a controller, and a built-inuser interface screen2606. The disposable2601 (e.g., a cassette) includes twopump pods2625aand2625b,asingle inlet2602, asingle outlet2603, and a drug delivery interface2604 (in this example, a syringe interface, although other types of interfaces, such as a luer port or a spike, may be included in alternative embodiments).
• An exemplary embodiment of thesystem2600 is designed to circulate approximately 1-2 liters per minute with added medication delivery, and also provide for draining. Thesystem2600 may be used for regional or localized therapies, such as, for example, filling a body cavity (e.g., upon removal of a tumor) with a chemotherapy solution at elevated temperature for some period of time, and then draining the cavity. Thesystem2600 may also be used to locally circulate bodily fluid (e.g., blood) with added medication, e.g., tourniquet a section of the body (e.g., a single lung) and circulate fluid.
• In a typical application, thepump inlet2602 may be in fluid communication with a fluid source (typically a separate reservoir, although fluid could be drawn directly from the patient), and thepump outlet2603 may be in fluid communication with the patient for delivering fluid from the fluid source to the patient. A fluid source reservoir or a separate receptacle may coupled so as to receive fluid drained from the patient. Thus, for example, a reservoir may be used to provide source fluid and a separate receptacle may be used to receive the drained fluid or the same reservoir (which could be the patient) may be used both to provide the source fluid and receive the drained fluid. The pump can be any fluid pump, including but not limited to, a pod pump of the types described herein, or any other type of diaphragm or other fluid pump. As fluid is pumped to the patient, medications or other fluids (e.g., one or more chemotherapy drugs) may be introduced into the fluid through thedrug delivery interface2604, for example, using an automatic syringe or any other automated or manual drug delivery device.
• During such pumping, the temperature of the fluid is controlled and is maintained at a predetermined temperature (e.g., about 37° C., or body temperature) during the entire process. The temperature control can be accomplished by use of a temperature sensor in conjunction with a heater. In certain embodiments, the temperatures sensor may be any of the types described herein. The temperature sensor can be located anywhere in the fluid path, and in the preferred embodiment, is anywhere in the fluid path outside of the patient. The fluid may be heated using any method including, but not limited to, induction heating or surface heating. The fluid may be heated in the reservoir or somewhere else along the fluid path.
• In one exemplary embodiment, the patient inlet may be located in the patient's peritoneum. The fluid and drug may be pumped into the patient until either a threshold fluid pressure has been reached or until a threshold fluid volume has been pumped into the patient, signifying completion of a fill stage. The fluid is typically allowed to remain in the patient for a certain amount of time, after which it is typically drained from the patient (e.g., by actuating a variable impedance on the patient outlet side). Fill/drain cycles may be repeated a predetermined number of times based on the patient's therapy needs.
• In another exemplary embodiment, a portion of the patient (e.g., a patient's limb) may be isolated, e.g., using a tourniquet or pressure cuff. Bodily fluid (e.g., blood) mixed with medication or other fluid may be circulated through the isolated area in a manner similar to that described above. The fluid temperature may be maintained using an in-line heater.
• FIG. 84 shows a fluid circuit that may be used for providing regional hyperthermic chemotherapy treatment, in accordance with an exemplary embodiment of the present invention. A reservoir holds fluid to be delivered to the patient. In this example, the fluid is pumped through a heater and into the patient. In alternative embodiments, the fluid may be heated in the reservoir and the in-line heater may be omitted. In some embodiments, the fluid in the reservoir may include medication, while in other embodiments, fluid may be added via the pump or by other means (e.g., a separate inlet into the fluid path. Fluid from the patient may be drained back to the reservoir or to some other receptacle (or simply discarded). The volume of fluid pumped and/or drained may be monitored in the reservoir, e.g., using a capacitive level probe or other sensor.
• FIG. 85 shows another fluid circuit including a balancing chamber that may be used for providing regional hyperthermic chemotherapy treatment, in accordance with an exemplary embodiment of the present invention. In this example, fluid is heated in the reservoir, and the volume of fluid in the reservoir is monitored using a capacitive level probe. Fluid is typically pumped to the patient through the top balancing chamber by appropriate control the valves, although fluid may be pumped directly to the patient (i.e., bypassing the balancing chamber) by appropriate control of the valves. Fluid drained from the patient flows through the bottom balancing chamber back to the reservoir. The balancing chambers help to maintain a constant volume of fluid into and out of the patient.
• FIG. 86 shows another fluid circuit including a balancing chamber and a second pump that may be used for providing regional hyperthermic chemotherapy treatment, in accordance with an exemplary embodiment of the present invention. In this example, the second pump is used to pump fluid from the top balancing chamber to the patient, which also helps to drain fluid from the patient to the bottom balancing chamber. As in previous embodiments, the fluid may be heated in the reservoir or in the fluid path.
• FIG. 87 shows a fluid circuit including a drain valve that may be used for providing regional hyperthermic chemotherapy treatment, in accordance with an exemplary embodiment of the present invention. In this example, the drain valve may be controlled to control the amount of fluid entering and leaving the patient. For example, with the valve closed, fluid may be pumped into the patient, e.g., to fill up a cavity of the patient. The drain valve may be partially or fully opened to drain the fluid from the patient or to allow for fluid circulation through the patient.
4. Thermal/Conductivity Sensors
• Various embodiments of thermal and/or conductivity sensors are described. Such thermal/conductivity sensors can be used in a wide variety of applications and are by no means limited to thermal/conductivity measurements of fluids or to thermal/conductivity measurements in the context of heat-exchanger systems.
4.1. Thermal Wells
• In one exemplary embodiment, a thermal well is used to accommodate a temperature sensing probe. The thermal well comes into direct contact with a subject media (e.g., a liquid such as blood) and the sensing probe does not. Based on heat transfer dictated in large part by the thermodynamic properties of the thermal well and sensing probe construction, the sensing probe can determine the properties of the subject media without coming into direct contact with the subject media. The accuracy and efficiency of the sensor apparatus arrangement depends on many factors including, but not limited to: construction material and geometry of both the probe and the thermal well.
• Referring now toFIGS. 50A and 50B, two embodiments of the sensor apparatus which includes thethermal well5100 and thesensing probe5102, are shown in relation to afluid line5108. In these embodiments, thethermal well5100 is integrated into thefluid line5108. However, in other embodiment, some described below, thethermal well5100 is not completely integrated into thefluid line5108, i.e., thethermal well5100 can be made from different materials as compared with thefluid line5108. In alternate embodiments, thethermal well5100 is not integrated into any fluid line but can be integrated into anything or nothing at all. For example, in some embodiments, thethermal well5100 can be integrated into a container, chamber, machine, protective sleeve, fluid pump, pump cassette, disposable unit, manifold, or other assembly, sub-assembly, or component. For purposes of the description, an exemplary embodiment is described for illustrative purposes. The exemplary embodiment includes the embodiment where thethermal well5100 is in a fluid line. However, the sensor apparatus and the thermal well can be used outside of a fluid line.
• Referring now toFIG. 50A, a side view showing athermal well5100 formed in afluid line5108 which provides thespace5104 for subject media to flow through, and asensing probe5102 is shown. Data from the sensing probe is transmitted using at least onelead5106. An end view ofFIG. 50A is shown inFIG. 50B.
• In this embodiment, thethermal well5100 is one piece with thefluid line5108. The total area of thethermal well5100 can vary. By varying the geometry of thethermal well5100, the variables, including, but not limited to, the thermal conductivity characteristic of thethermal well5100 and thus, the heat transfer between thethermal well5100 and thesensing probe5102 will vary. As described in more detail below, the material construction of thethermal well5100 is another variable in the sensor apparatus. In some embodiments, thefluid line5108 is made from a material having a desired thermal conductivity. This material may vary depending on the purpose. The material can be anything including, but not limited to, any plastic, ceramic, metals or alloys of metals or combinations thereof.
• Referring now toFIGS. 51A and 51B, in these embodiments, thefluid line5108 and thethermal well5100 are separate parts. In some embodiments, thefluid line5108 and thethermal well5100 are made form different materials.
• FIGS. 50A-50B andFIGS. 51A-51B show relatively simple embodiments of the sensor apparatus. Thus, for these embodiments, the sensing apparatus includes athermal well5100 and asensing probe5102 where the thermal well either is integrated as one continuous part with thefluid line5108 or is a separate part from thefluid line5108. However, many embodiments of the sensor apparatus are contemplated. Much of the various embodiments include variations on the materials and the geometries of thethermal well5100 and/or thesensing probe5102. These variations are dictated by multiple variables related to the intended use for the sensor apparatus. Thus, the subject media and the constraints of the desired sensor, for example, the accuracy, time for results and the fluid flow and subject media characteristics are but a sampling of the various constraints that dictate the embodiment used. In most instances, each of the variables will affect at least one part of the embodiment of the sensor apparatus.
• Thus, multiple variables affect the various embodiments of the sensor apparatus, these variables include but are not limited to: 1) geometry of the thermal well; 2) material composition of the thermal well; 3) material composition of the sensing probe; 4) desired flow rate of the subject media; 5) length and width of the thermal well; 6) desired accuracy of the sensing probe; 7) wall thicknesses; 8) length and width of the sensing probe; 9) cost of manufacture; 10) subject media composition and characteristics including tolerance for turbulence; 11) geometry of sensing probe; and 12) desired speed of readings.
• In the foregoing, various embodiments of the sensor apparatus are described. The description is intended to provide information on the affect the variables have on the sensor apparatus embodiment design. However, these are but exemplary embodiments. Many additional embodiments are contemplated and can be easily designed based on the intended use of the sensor apparatus. Thus, by changing one or more of the above mentioned partial list of variables, the embodiment of the sensor apparatus may vary. Referring now toFIGS. 52A and 52B, two embodiments of thethermal well5100 are shown as different parts from thefluid line5108. These embodiments show two geometries of thethermal well5100. InFIG. 52A, the geometry includes a longerthermal well5100. InFIG. 52B, the thermal well5100 geometry is shorter. The length and width of the thermal well5100 produce varying properties and accuracies of the thermal conductivity between thethermal well5100 and thesensing probe5102. Depending on the use of the sensor apparatus, the thermal well5100 geometry is one variable.
• Referring now toFIG. 52A, the longer thermal well5100 generally provides a greater isolation between the subject media temperature in thefluid line5104 and the ambient temperature. Although the longer thermal well5100 geometry shown inFIG. 52A may be more accurate, the embodiment shown inFIG. 52B may be accurate enough for the purpose at hand. Thus, the length and width of thethermal well5100 can be any length and width having the desired or tolerable accuracy characteristics. It should be understood that two extremes of length are shown in these embodiments; however, any length is contemplated. The description herein is meant to explain some of the effects of the variables.
• Still referring toFIGS. 52A and 52B, the longer thermal well5100 shown inFIG. 52A may impact the fluid flow of the subject media in thefluid line5108 to a greater degree than the embodiment shown inFIG. 52B. It should be understood that the length of thethermal well5100 may also impact the turbulence of the fluid flow. Thus, the length and width of thethermal well5100 may be changed to have greater or lesser impact on the fluid flow and turbulence of the fluid, while mitigating the other variables.
• The shape of thethermal well5100 is also a variable. Any shape desired is contemplated. However, the shape of thethermal well5100, as with the other variables, is determined in part based on the intended use of the sensor apparatus. For purposes of description, an exemplary embodiment is described herein. However, the shape in the exemplary embodiment is not meant to be limiting.
• Referring nowFIG. 53 for purposes of description, thethermal well5100 has been divided into 3 zones. Thetop zone5402 communicates with the sensing probe (not shown); themiddle zone5404 provides the desired length of thethermal well5100. As described above, the length may dictate the level of protrusion into the fluid path. The length is dictated in part by the desired performance characteristics as discussed above. Themiddle zone5404 also isolates thetop zone5402 from the ambient. Themiddle zone5404 may also serve to locate, fasten or seal the thermal well5100 into the fluid line (shown as5108 inFIGS. 50A-50B).
• Thebottom zone5406, which in some embodiments may not be necessary (seeFIG. 56K) thus, in these embodiments, themiddle zone5404 and thebottom zone5406 may be a single zone. However, in the exemplary embodiment, thebottom zone5406 is shaped to aid in press fitting the thermal well into an area in the fluid line and may locate and/or fasten the thermal well5100 into thefluid line5108. In other embodiments,zone5406 may be formed to facilitate various joining methods (seeFIGS. 56A-56J,56L-56S) Referring now toFIG. 54 a cross section of the exemplary embodiment of thethermal well5100 is shown. The dimensions of the exemplary embodiment of the thermal well5100 include a length A of approximately 0.113 inches (with a range from 0-0.379 inches), a radius B of approximately 0.066 inches and a wall thickness C ranging from approximately 0.003-0.009 inches. These dimensions are given for purposes of an exemplary embodiment only. Depending on the variables and the intended use of the sensing apparatus, the thermal well5100 dimensions may vary, and the various embodiments are not necessarily proportional.
• In some embodiments, the wall thickness can be variable, i.e., the wall thickness varies in different locations of the thermal well. Although these embodiments are shown with variable thicknesses in various locations, this is for description purposes only. Various embodiments of the thermal well may incorporate varying wall thickness in response to variables, these varying wall thicknesses can be “mixed and matched” depending on the desired properties of the sensing apparatus. Thus, for example, in some embodiments, athinner zone5404 may be used withthinner zone5406 and vice-versa. Or, any other combination of “thinner” and “thicker” may be used. Also, the terms used to describe the wall thicknesses are relative. Any thickness desired is contemplated. The figures shown are therefore for descriptive purposes and represent two embodiments where many more are contemplated.
• Referring now toFIGS. 55A and 55B,zone5402 can be thicker or thinner as desired. Thethinner zone5402, amongst other variables, generally provides for a faster sensing time while a thicker zone may be useful for harsh environments or where sensor damping is desired.Zone5404 may be thicker, amongst other variables, for greater strength or thinner for, amongst other variables, greater isolation from ambient.Zone5406 can be thinner or thicker depending on the fastening method used.
• Thethermal well5100, in practice, can be embedded into afluid line5108, as a separate part from thefluid line5108. This is shown and described above with respect toFIGS. 51A-51B. Various embodiments may be used for embedding the thermal well5100 into thefluid line5108. Although the preferred embodiments are described here, any method or process for embedding athermal well5100 into afluid line5108 can be used. Referring now toFIGS. 56A-56S, various configurations for embedding the thermal well5100 into thefluid line5108 are shown. For these embodiments, thethermal well5100 can be made from any materials, including but not limited to, plastic, metal, ceramic or a combination thereof. The material may depend in some part on the compatibility with the intended subject media. Thefluid line5108, in these embodiments, may be made from plastic, metal, or any other material that is compatible with the subject media.
• Referring first toFIG. 56A, thethermal well5100 is shown press fit into thefluid line5108 using the zone5404 (shown inFIG. 53). InFIG. 56B, thethermal well5100 is shown press fit into thefluid line5108 using thezone5406. Referring now toFIG. 56C, thethermal well5100 is shown retained in thefluid line5108 withflexible tabs5704, an O-ring is also provided. Referring now toFIG. 56D, thethermal well5100 is shown inserted into thefluid line5108 with an O-ring5702. Thethermal well5100 is also shown as an alternate embodiment, where the thermal well5100zone5406 includes an O-ring groove. The O-ring groove can be cut, formed, spun, cast or injection molded into the thermal well, or formed into the thermal well5100 by any other method.FIG. 56E shows a similar embodiment to that shown inFIG. 56D, however, the O-ring groove is formed inzone5406 rather than cut, molded or cast as shown inFIG. 56D. Referring now toFIG. 56F, thethermal well5100 is shown press fit into thefluid line5108,zone5406 includes flexibility allowing the edge ofzone5406 to deform the material of thefluid line5108. Referring now toFIG. 56G, thethermal well5100 includescuts5706 on thezone5406 providing flexibility of thezone5406 for assembly with thefluid line5108. An O-ring5702 is also provided. Although two cuts are shown, a greater number or less cuts are used in alternate embodiments.
• Referring now toFIG. 56H, the embodiment shown inFIG. 56F is shown with the addition of an O-ring5702. Referring toFIG. 561, thethermal well5100 is shown insert molded in thefluid line5108.Zone5406 is formed to facilitate or enable assembly by insert molding.
• FIG. 56J shows an embodiment where thethermal well5100 is heat staked5708 to retain the thermal well5100 in thefluid line5108. In some embodiments ofFIG. 56J, an O-ring5710 is also included. In this embodiment, the O-ring5710 has a rectangular cross section. However, in alternate embodiments, the O-ring may have a round or X-shaped cross section. Likewise, in the various embodiments described herein having an O-ring, the O-ring in those embodiments can have a round, rectangular or X-shaped cross section, or any cross sectional shape desired.
• Referring now toFIG. 56K, thethermal well5100 is retained in thefluid line5108 by adhesive5712. The adhesive can be any adhesive, but in one embodiment, the adhesive is a UV curing adhesive. In alternate embodiments, the adhesive may be any adhesive that is compatible with the subject media. In this embodiment, thethermal well5100 is shown without azone5406.
• Referring now toFIG. 56L,thermal well5100 is shown ultrasonically welded in thefluid line5108. Thezone5406 is fabricated to enable joining by ultrasonic welding. Referring now toFIG. 56M, athermal well5100 is shown insert molded in thefluid line5108.Zone5406 is a flange for the plastic in thefluid line5108 to flow around. In the embodiment shown, the flange is flat, however, in other embodiments; the flange may be bell shaped or otherwise.
• Referring now toFIG. 56N, thethermal well5100 is shown retained in thefluid line5108 by a retainingplate5714 and afastener5716. O-ring5702 is also shown. Referring now toFIGS. 560-56P, an end view is shown of athermal well5100 that is retained in afluid line5108 by a retaining ring5718 (FIG. 560) or in an alternate embodiment, a clip5720 (FIG. 56P). O-ring5702 is also shown. Referring now toFIG. 56Q, the embodiment ofFIG. 56C is shown with an alternate embodiment of thethermal well5100. In this embodiment of the thermal well5100 the referred to aszone5404 inFIG. 53 includes a taper that may allow for easier alignment with a sensing probe, better isolation ofzone5402 from the ambient and better flow characteristics in the fluid path. Thethermal well5100 is shown retained in thefluid line5108 usingflexible tabs5704. An O-ring is also provided.
• FIG. 56R shows the embodiment ofFIG. 56J with an alternate embodiment of thethermal well5100. The thermal well5100 shown in this embodiment has a taper inzone5404 that may allow for easier alignment with a sensing probe, may allow better isolation ofzone5402 from the ambient and may allow better flow characteristics in the fluid path.Zone5402 provides a hemispherical contact for effective thermal coupling with a thermal probe. Thethermal well5100 is heat staked5708 to retain the thermal well5100 in thefluid line5108. In some embodiments ofFIG. 56R, an O-ring5710 is also included. In this embodiment, the O-ring5710 has a rectangular cross section. However, in alternate embodiments, the O-ring can have a round or X-shaped cross section.
• Referring now toFIG. 56S, the embodiment ofFIG. 56H is shown with an alternate embodiment of thethermal well5100.FIG. 56S is shown with the addition of an O-ring5702. In this embodiment of the thermal well5100 zone5404 (as shown inFIG. 53) has convolutions that may allow better isolation ofzone5402 from the ambient. While several geometries have been shown forzone5404, many others could be shown to achieve desired performance characteristics.
4.2. Sensing Probes
• Referring now toFIG. 57, a sectional view of an exemplary embodiment of thesensing probe5800 is shown. Thehousing5804 is a hollow structure that attaches to thetip5802. The tip is made of a highly thermally conductive material. Thehousing5804, in the exemplary embodiment, is made from a thermally insulative material. In some embodiments, the housing is made of a thermally and electrically insulative material. In the exemplary embodiment, thehousing5804 is made of plastic which is a thermally insulative and electrically insulative material. Thetip5802 either contacts the subject media directly, or else is mated with a thermal well.
• In the exemplary embodiment, thetip5802 is attached to thehousing5804 using a urethane resin or another thermal insulator in between (area5807) thetip5802 and thehousing5804. Urethane resin additionally adds structural support. In alternate embodiments, other fabrication and joining methods can be used to join thetip5802 to thehousing5804.
• Thetip5802 of thesensing probe5800 is made of a thermally conductive material. The better thermally conductive materials, for example, copper, silver and steel, can be used, however, depending on the desired use for the sensing probe and the subject media; the materials may be selected to be durable and compatible for the intended use. Additionally, factors such as cost and ease of manufacture may dictate a different material selection. In one exemplary embodiment, thetip5802 is made from copper. In other embodiments, the material can be an alloy of copper or silver, or either solid or an alloy of any thermally conductive material or element, including but not limited to metals and ceramics. However, in the exemplary embodiments, thetip5802 is made from metal.
• In the exemplary embodiment, thetip5802 is shaped to couple thermally with a thermal well as described in the exemplary embodiment of the thermal well above. In the exemplary embodiment as well as in other embodiments, thetip5802 may be shaped to insulate thethermal sensor5808 from the ambient. In the exemplary embodiment, thetip5802 is made from metal.
• In alternate embodiments a non-electrically conductive material is used for the tip. These embodiments may be preferred for use where it is necessary to electrically insulate the thermal well from the probe. In another alternate embodiment, thetip5802 may be made from any thermally conductive ceramic.
• In the exemplary embodiment, thethermal sensor5808 is located in the housing and is attached to the interior of thetip5802 with a thermallyconductive epoxy5812. In the exemplary embodiment, the epoxy used is THERMALBOND, however, in other embodiments; any thermal grade epoxy can be used. However, in alternate embodiments, a thermal grease may be used. In alternate embodiments, an epoxy or grease is not used.
• Thethermal sensor5808, in the exemplary embodiment, is a thermistor. The thermistor generally is a highly accurate embodiment. However in alternate embodiments, thethermal sensor5808 can be a thermocouple or any other temperature sensing device. The choice ofthermal sensor5808 may again relate to the intended use of the sensing apparatus.
• Leads5814 from thethermal sensor5808 exit the back of thehousing5804. These leads5814 attach to other equipment used for calculations. In the exemplary embodiment, athird lead5816 from thetip5802 is also included. Thisthird lead5816 is attached to the tip on atab5818. Thethird lead5816 is attached to thetip5802 because in this embodiment, thetip5802 is metal and the housing is plastic. In alternate embodiments, thehousing5804 is metal, thus thethird lead5816 may be attached to thehousing5804. Thus, thetip5802, in the exemplary embodiment, includes atab5818 for attachment to a lead. However, in alternate embodiments, and perhaps depending on the intended use of the sensing apparatus, thethird lead5816 may not be included. Also, in alternate embodiments where a third lead is not desired, thetip5802 may not include thetab5818. Referring now toFIG. 58, an exploded view of thesensing probe5800 is shown.
• Referring now toFIG. 59 an alternate embodiment of the exemplary embodiment is shown. In this embodiment, thetip6002 of the sensing probe is shown. Thetip6002 includes azone6004 that will contact either a subject media to be tested or a thermal well. Azone6006 attaches to the sensor probe housing (not shown). Aninterior area6008 accommodates the thermal sensor (not shown). In this embodiment, thetip6002 is made from stainless steel. However, in other embodiments, thetip6002 can be made from any thermally conductive material, including but not limited to: metals (including copper, silver, steel and stainless steel), ceramics or plastics.
• In the exemplary embodiment,zone6006 includes atab6010. A third lead (as described with respect toFIG. 57, 5816) attaches from thetab6010. Referring next toFIGS. 60A and 60B, thesensing probe6000 is shown including thetip6002 and thehousing6012. In one embodiment, thehousing6012 is made from any thermally insulative material, including but not limited to, plastic. In one embodiment, thehousing6012 is press fit to thetip6002, glued or attached by any other method. In one embodiment, thethermal sensor6014 is thermally coupled to thetip6002 with thermal grade epoxy or, in alternate embodiments,thermal grease6022. Two leads6016 from thethermal sensor6014 extend to the distal end of the housing. In some embodiments, athird lead6018 is attached to thetip6002 from thetab6010. As discussed above, in some embodiments where the third lead is not desired, thetip6002 does not include atab6010.
• Referring now toFIG. 60B, an alternate embodiment of thesensing probe6000 is shown. In this embodiment, thehousing6012 is a plastic molded overzone6006 of thetip6002 and theleads6016, and in some embodiments, athird lead6018.
• Referring now toFIG. 61, a full side view of one embodiment of thesensing probe6000 shown inFIGS. 59-60B is shown. Thesensing probe6000 includes ahousing6012, atip6002 and theleads6016,6018.Flange6020 is shown. In some embodiment,flange6020 is used to mount and/or attachment to equipment.
• Referring now toFIG. 62A, thesensing probe6000 shown inFIGS. 59-61, is shown coupled to athermal well5100 which is fastened into afluid line5108. In the embodiment as shown, twoleads6016 are shown at the distal end of thesensing probe6000. And, in some embodiments, athird lead6018 is also incorporated into thesensing probe6000.FIG. 62B shows an alternate embodiment where thesensing probe6000 includes twoleads6016 but does not include thethird lead6018.
• Referring now to bothFIGS. 62A and 62B, thetip6002 of thesensing probe6000 is in direct contact with thethermal well5100. Referring back toFIG. 53 and still referring toFIG. 62A and 62B thethermal well5100 includes azone5402. Thethermal well5100 is hollow, and the inner part ofzone5402 is formed such that it will be in mating contact with thesensing probe tip6002. As shown in this embodiment, thethermal well5100 is designed to have a mating geometry with thesensing probe6000. Thus, the geometry of thethermal well5100 may depend on the geometry of thetip6002 of thesensing probe6000 and vice-versa. In some embodiments, it may be desirable that thesensing probe6000 does not have a tight fit or a perfect mate with thethermal well5100.
• Referring now toFIG. 63A, one embodiment of the sensing probe5800 (as shown inFIG. 57) is shown coupled to athermal well5100 which is fastened into afluid line5108. In the embodiment as shown, twoleads5814 are shown at the distal end of thesensing probe5800. In some embodiments, athird lead5816 is also incorporated into thesensing probe5800.FIG. 63B shows an alternate embodiment where thesensing probe5800 includes twoleads5814 but does not include thethird lead5816.
• Referring now to bothFIGS. 63A and 63B, thetip5802 of thesensing probe5800 is in direct contact with thethermal well5100. Referring back toFIG. 53 and still referring toFIGS. 63A and 63B, thethermal well5100 includes azone5402. Thethermal well5100 is hollow, and the inner part ofzone5402 is formed such that it will be in mating contact with thesensing probe tip5802. As shown in this embodiment, thethermal well5100 is designed to have a mating geometry with thesensing probe5800. Thus, the geometry of thethermal well5100 depends on the geometry of thetip5802 of thesensing probe5800 and vice-versa.
4.3. Sensor Apparatus
• For purposes of description of the sensor apparatus, the sensor apparatus is described with respect to exemplary embodiments. The exemplary embodiments are shown inFIGS. 62A, 62B, andFIG. 64, with alternate exemplary embodiments in63A and63B. In alternate embodiments of the sensor apparatus, the sensing probe can be used outside of the thermal well. However, the sensor apparatus has already been described herein alone. Thus, the description that follows describes one embodiment of the exemplary embodiment of the sensor apparatus which includes, for this purpose, a sensing probe and a thermal well.
• Referring now toFIG. 64, in an exemplary embodiment, thesensing probe6000 shown inFIG. 62A and thethermal well5100 are shown coupled and outside of a fluid line. As described above, thethermal well5100 can be in a fluid line, a protective sleeve, any disposable, machine, chamber, cassette or container. However, for purposes of this description of the exemplary embodiment, thethermal well5100 is taken to be anywhere where it is used to determine thermal and/or conductive properties (FIG. 62A) of a subject media.
• A subject media is in contact with the outside ofzone5402 of thethermal well5100. Thermal energy is transferred from the subject media to thethermal well5100 and further transferred to thetip6002 of thesensing probe6000. Thermal energy is then conducted to thethermal sensor6014. Thethermal sensor6014 communicates vialeads6016 with equipment that can determine the temperature of the subject media based on feedback of thethermal sensor6014. In embodiments where conductivity sensing is also desired,lead6018 communicates with equipment that can determine the conductivity of the subject media. With respect to determining the conductivity of the subject media, in addition to thelead6018, a second electrical lead/contact (not shown) would also be used. The second lead could be a second sensor apparatus as shown inFIG. 64, or, alternatively, a second probe that is not necessarily the same as the sensor apparatus shown inFIG. 64, but rather, any probe or apparatus capable of sensing capacitance of the subject media, including, an electrical contact.
• Heat transfer from thetip6002 to thethermal sensor6014 may be improved by the use of a thermal epoxy orthermal grease6022.
• Referring now toFIGS. 63A and 63B, in the alternate exemplary embodiment, whilst thesensing probe5800 is coupled to thethermal well5100, thetip5802, having the geometry shown, forms anair gap6402 between theinner zones5404 and5406 of thethermal well5100 and thetip5802. Theair gap6402 provides an insulative barrier so that only the top of the sensing tip of5802 is in communication with thetop zone5402 of thethermal well5100.
• Thesensing probe5800 and thermal well5100 are shown coupled and outside of a fluid line. As described above, thethermal well5100 can be in a fluid line, a protective sleeve, disposable unit, machine, non-disposable unit, chamber, cassette or container. However, for purposes of this description of the exemplary embodiment, thethermal well5100 is taken to be anywhere where it is used to determine thermal and/or conductive properties (FIG. 63A) of a subject media.
• A subject media is in contact with the outside ofzone5402 of thethermal well5100. Thermal energy is transferred from the subject media to thethermal well5100 and further transferred to thetip5802 of thesensing probe5800. Thermal energy is then conducted to thethermal sensor5808. Thethermal sensor5808 communicates vialeads5814 with equipment that can determine the temperature of the subject media based on feedback of thethermal sensor5808. In embodiments where conductivity sensing is also desired,lead5816 communicates with equipment that can determine the conductivity of the subject media. With respect to determining the conductivity of the subject media, in addition to thelead5816, a second electrical lead (not shown) would also be used. The second lead could be a second sensor apparatus as shown inFIG. 63A, or, alternatively, a second probe that is not necessarily the same as the sensor apparatus shown inFIG. 63A, but rather, any probe or apparatus capable of sensing capacitance of the subject media, including, an electrical contact.
• Heat transfer from thetip5802 to thethermal sensor5808 can be improved by the use of a thermal epoxy orthermal grease5812.
• Referring now toFIG. 65, an alternate embodiment showing asensing probe6602 coupled to athermal well5100 is shown. For purposes of this description, any embodiment of thesensing probe6602 and any embodiment of thethermal well5100 can be used. In this embodiment, to increase the thermal coupling between the tip of thesensing probe6602 and thethermal well5100,thermal grease6604 is present at the interface of the tip of thesensing probe6602 and theinner zone5402 of thethermal well5100. In one embodiment, the amount ofthermal grease6604 is a volume sufficient to only be present inzone5402. However, in alternate embodiments, larger or smaller volumes of thermal grease can be used.
4.4. Sensor Apparatus Systems
• Referring now toFIG. 66, a sensor apparatus system is shown. In the system, the sensor apparatus is shown in a device containing afluid line5108. The sensor apparatus includes thesensing probe6000 and thethermal well5100. In this embodiment, thethermal well5100 andfluid line5108 is a disposable portion and thesensing probe6000 is a reusable portion. Also in the reusable portion is aspring6700. Thespring6700 andsensing probe6000 are located in ahousing6708. Thehousing6708 can be in any machine, container, device or otherwise. Thespring6700 can be a conical, a coil spring, wave spring, or urethane spring.
• In this embodiment, thethermal well5100 and thesensing probe6000 may include alignment features6702,6704 that aid in thethermal well5100 andsensing probe6000 being aligned. The correct orientation of thethermal well5100 and thesensing probe6000 may aid in the mating of thethermal well5100 and thesensing probe6000 to occur. The configuration of thespace6706 provides thesensing probe6000 with space for lateral movement. This allows thesensing probe6000 to, if necessary; move laterally in order to align with the thermal well5100 for mating.
• Thesensing probe6000 is suspended by aspring6700 supported by theflange6020. Thespring6700 allow vertical movement of thesensing probe6000 when the thermal well5100 mates with thesensing probe6000. Thespring6700 aids in establishing full contact of thesensing probe6000 and thethermal well5100. Thefluid line5108 can be in any machine, container, device or otherwise. Thefluid line5108 contains afluid path5104. A subject media flows through thefluid path5104 and thethermal well5100, located in thefluid line5108 such that thethermal well5100 has ample contact with thefluid path5104 and can sense the temperature properties and, in some embodiments, the conductive properties of the subject media. The location of the thermal well5100 in thefluid path5104, as described in more detail above, may be related to the desired accuracy, the subject media and other considerations.
• Thespring6700 andsensing probe6000 assembly, together with thespace6706 in thehousing6708 may aid in alignment for the mating of thesensing probe6000 and thethermal well5100. The mating provides the thermal contact so that thethermal well5100 and thesensing probe6000 are thermally coupled.
• Awire6710 is shown. The wire contains the leads. In some embodiments, there are two leads. Some of these embodiments are temperature sensing. In other embodiments, the wire contains three or more leads. Some of these embodiments are for temperature and conductivity sensing.
• Referring now toFIG. 67, an alternate embodiment of the system shown inFIG. 66 is shown. In this embodiment, thesensing probe6000 is suspended by acoil spring6800. A retainingplate6802 captures thecoil spring6800 to retain thespring6800 andsensing probe6000. In one embodiment, the retainingplate6802 is attached to thehousing6708 using screws. However, in alternate embodiments, the retainingplate6802 is attached to thehousing6708 using any fastening method including but not limited to: adhesive, flexible tabs, press fit, and ultrasonic welding. Aligningfeatures6806 on thehousing6708 aid in alignment of thesensing probe6000 to a thermal well (not shown). Lateral movement of thesensing probe6000 is provided for by clearance inareas6808 in thehousing6708. Awire6710 is shown. The wire contains the leads. In some embodiments, there are two leads. Some of these embodiments are temperature sensing. In other embodiments, the wire contains three or more leads. Some of these embodiments are for temperature and conductivity sensing.
• Referring now toFIG. 68, asensing probe6000 is shown in ahousing6708. In these embodiments, an alternate embodiment of a spring, aflexible member6900, is integrated with thesensing probe6000 to allow vertical movement of thesensing probe6000 within thehousing6708. A retainingplate6902 captures theflexible member6900 to retain theflexible member6900 andsensing probe6000. In one embodiment, the retainingplate6902 is attached to thehousing6708 using screws. However, in alternate embodiments, the retainingplate6902 is attached to thehousing6708 using any fastening method including but not limited to: adhesive, flexible tabs, press fit, and ultrasonic welding. Lateral movement of thesensing probe6000 is provided for by clearance inareas6908 in thehousing6708. Awire6710 is shown. The wire contains the leads. In some embodiments, there are two leads. Some of these embodiments are temperature sensing. In other embodiments, the wire contains three or more leads. Some of these embodiments are for temperature and conductivity sensing.
• Referring now toFIG. 69, an alternate embodiment of asensing probe6000 in ahousing7002 is shown. In this embodiment,flexible member7000 is attached or part of thehousing7002, provides for vertical movement of thesensing probe6000. In this embodiment, theopenings7004,7006 inhousing7002 are sized such that thesensing probe6000 experiences limited lateral movement.Flexible member7000 acts on theflange7008 on thesensing probe6000. Awire6710 is shown. The wire contains the leads. In some embodiments, there are two leads. Some of these embodiments are temperature sensing. In other embodiments, the wire contains three or more leads. Some of these embodiments are for temperature and conductivity sensing.
• The flange, as shown and described with respect toFIGS. 61, 66,69, can be located in any area desired on thesensing probe6000. In other embodiments, the sensing probe may be aligned and positioned by other housing configurations. Thus, the embodiments of the housing shown herein are only some embodiments of housings in which the sensor apparatus can be used. The sensor apparatus generally depends on being located amply with respect to the subject media. The configurations that accomplish this can vary depending on the subject media and the intended use of the sensing apparatus. Further, in some embodiments where the thermal well is not used, but rather, the sensing probe is used only, the housing configurations may vary as well.
• The sensing apparatus, in some embodiments, is used to sense conductivity. In some embodiments, this is in addition to temperature sensing. In those embodiments where both temperature and conductivity sensing is desired, the sensing probe typically includes at least three leads, where two of these leads may be used for temperature sensing and the third used for conductivity sensing.
• Referring now toFIG. 70, for conductivity sensing, at least twosensors7102,7104 are located in an area containing the subject media. In the embodiment shown, the area containing the subject media is afluid path5104 inside afluid line5108. Theconductivity sensors7102,7104 can be one of the various embodiments of sensing probes as described above, or one of the embodiments of the sensor apparatus embodiments (including the thermal well) as described above. However, in other embodiments, only one of the sensors is one of the embodiments of the sensor apparatus or one of the embodiments of the sensing probe, and the second sensor is any electrical sensor known in the art. Thus, in the systems described herein, conductivity and temperature can be sensed through using either one of the sensor apparatus or one of the sensor probes as described herein and a second capacitance sensor, or one of the sensor apparatus or one of the sensor probes as described herein and an electrical sensor.
• Referring now toFIG. 71, an alternate embodiment of a sensor apparatus including asensing probe7200 and athermal well5100 is shown in afluid line5108. In this embodiment, thesensing probe7200 is constructed of a metal housing. Thethermal well5100 is also constructed of metal. Thethermal well5100 and thesensing probe7200 can be made from the same metal or a different metal. The metal, in the preferred embodiment, is a conductive metal, which may include stainless steel, steel, copper and silver. Alead7202 is attached to thesensing probe7200 housing for conductivity sensing. The thermal sensing leads7204 are attached to a thermal sensor located inside thesensing probe7200 housing. In this embodiment, therefore, the third lead7202 (or the lead for conductivity sensing) can be attached anywhere on thesensing probe7200 because thesensing probe7200 is constructed of metal. In the previously described embodiments, where the sensing probe housing was constructed of plastic, and the sensing tip constructed of metal, the third lead for conductivity sensing was attached to the sensing tip.
• A known volume of subject media may be used to determine conductivity. Thus, two sensors may be used and the volume of fluid between the two sensors can be determined. Conductivity sensing is done with the two electrical contacts (as described above), where one or both can be the sensor apparatus. The volume of subject media between the two contacts is known.
• Conductivity sensing is done by determining the conductivity from each of the sensors and then determining the difference. If the difference is above a predetermined threshold, indicating an abnormal difference in conductivity between the first and second sensor (the designations “first” and “second” being arbitrary), then it can be inferred that air may be trapped in the subject media and a bubble detection alarm may be generated to indicate a bubble. Thus, if there is a large decrease in conductivity (and likewise, a large increase in resistance) between the first and second sensor, air could be trapped and bubble presence may be detected.
• Leaks in a machine, system, device or container may be determined using the conductivity sensing. Where a sensing apparatus is in a machine, device or system, and that sensing apparatus senses conductivity, in one embodiment, a lead from the sensor apparatus (or electrical contacts) to an analyzer or computer machine may be present. In some embodiments, the analyzer that analyzes the electrical signals between the contacts is connected to the metal of the machine, device, system or container. If the analyzer senses an electrical signal from the machine, then a fluid leak may be inferred.
• For the various embodiments described herein, a fluid line can be made of any material including metal and plastic. In most embodiments, the fluid line is compatible with the subject media and has the desired characteristics depending on the configuration of the thermal well in the fluid line. The fluid line can be part of a disposable unit that attaches to the sensor apparatus. In some of these embodiments, the fluid line includes the thermal well. The subject media is located inside the fluid line and the sensing probe provides sensing data regarding the subject media once the sensing probe and thermal well are amply mated.
• The fluid line can be a chamber, a hose, a fluid path or other space or conduit for holding a volume of subject media. In some embodiments, the fluid line is a designed to hold fluid having a flow rate. In other embodiments, the space is designed to hold mostly stagnant media or media held in the conduit even if the media has flow.
• In some embodiments, the sensor apparatus may be used based on a need to separate the subject media from the sensing probe. However, in other embodiments, the sensing probe is used for temperature and/or conductivity sensing directly with subject media.
• In some embodiments, the thermal well may be part of a disposable portion of a device, machine, system or container. Thus, the thermal well may be in direct contact with subject media and may be the only component that is contaminated by same. In these embodiments, the sensing probe may be part of a machine, device, system or container, and be disposable or non-disposable.
5. Conclusion
• Various types and configurations of pump pods, heat-exchanger systems, and thermal/conductivity sensors are described above. It should be noted that a wide variety of embodiments can be produced from various combinations of components. For example, certain heat-exchanger systems may be configured without pump pods or thermal/conductivity sensors, may be configured with pump pods but not thermal/conductivity sensors, or may be configured with thermal/conductivity sensors but not pump pods. Pump pods can be used in a wide variety of applications and are by no means limited to use in heat-exchanger systems or for pumping of bodily fluids or medical fluids. Thermal/conductivity sensors can be used in a wide variety of applications and are by no means limited to thermal/conductivity measurements of fluids or to thermal/conductivity measurements in the context of heat-exchanger systems.
• Various embodiments are described above with reference to pneumatic actuation systems, specifically for operating pod pumps. It should be noted, however, that pod pumps can be operated using other types of control fluids, such as, for example, hydraulic fluids, in which case the actuation system would typically include an appropriate control fluid delivery system for delivering control fluid under positive and/or negative pressures. Thus, for example, a heat-exchanger system could include a hydraulic actuation system rather than a pneumatic actuation system, in which case pressurized hydraulic fluid could be stored in one or more reservoirs or be provided using other pressurizing means (e.g., a hydraulic fluid pump).
• Although the above discussion discloses various exemplary embodiments of the invention, it should be apparent that those skilled in the art can make various modifications that will achieve some of the advantages of the invention without departing from the true scope of the invention.

Claims (59)

1. A method for heating or cooling a fluid, the method comprising:

providing at least one reciprocating positive-displacement pump, each pump having:

a curved rigid chamber wall;

a flexible membrane attached to the rigid chamber wall, so that the flexible membrane and rigid chamber wall define a pumping chamber;

an inlet for directing fluid through the rigid chamber wall into the pumping chamber in at least one of (a) a direction that is substantially tangential to the rigid chamber wall and (b) a direction that provides low-shear flow into the pumping chamber; and

an outlet for directing fluid through the rigid chamber wall out of the pumping chamber in at least one of (a) a direction that is substantially tangential to the rigid chamber wall and (b) a direction that provides low-shear flow out of the pumping chamber;

providing a heat exchanger; and

pumping the fluid from at least one source using the at least one reciprocating positive-displacement pump so as to cause the fluid to pass through the heat exchanger.

2. A method according toclaim 1, wherein each pump is provided with a rigid chamber wall that is hemispheroid.

3. A method according toclaim 1, wherein each pump is provided with a rigid limit structure for limiting movement of the membrane and limiting the maximum volume of the pumping chamber the flexible membrane and the rigid limit structure defining an actuation chamber.

4. A method according toclaim 3, wherein each pump is provided with a rigid chamber wall that is hemispheroid and a rigid limit structure that is hemispheroid such that the pumping chamber is spheroid when the membrane is urged against the rigid limit structure, and the actuation chamber is spheroid when the membrane is urged against the rigid chamber wall.

5. A method according toclaim 1, wherein providing the at least one reciprocating positive-displacement pump comprising:

providing a pair of reciprocating, positive-displacement pumps as in any of the preceding claims.

6. A method according toclaim 5, wherein pumping the fluid comprising:

operating the pair of pumps out of phase so as to produce a substantially continuous fluid flow.

7. A method according toclaim 5 wherein, pumping the fluid comprising:

providing a disposable unit including a heat-exchanger component;

placing the heat-exchanger component in proximity with the heat exchanger; and

pumping the fluid through the heat-exchanger component so as to heat or cool the fluid in the heat-exchanger component.

8. A method according toclaim 7, wherein the heat-exchanger component includes at least one of a heat-exchanger bag, a length of tubing, and a radiator.

9. A method according toclaim 1, wherein the source is a patient and wherein the fluid is a bodily fluid.

10. A method according toclaim 1, further comprising:

pumping the heated fluid to a patient.

11. A method according toclaim 10, further comprising:

monitoring the patient's temperature; and

controlling operation of at least one of (a) the at least one pump and (b) the heat exchanger in order to attain a predetermined patient temperature.

12. (canceled)

13. A method according toclaim 3, further comprising:

providing a pneumatic actuation system for intermittently providing either a positive or a negative pressure to the actuation chamber of each pump.

14. A method according toclaim 13, wherein the pneumatic actuation system is provided with:

a reservoir containing a gas at either a positive or a negative pressure, and

a valving mechanism for controlling the flow of gas between the gas reservoir and the actuation chamber of each pump.

15. A method according toclaim 14, wherein the pneumatic actuation system is further provided with at least one actuation-chamber pressure transducer for measuring the pressure of the actuation chamber of each plump, and a controller that receives pressure information from the at least one actuation-chamber pressure transducer and controls the valving mechanism.

16. A method according toclaim 15, wherein the pneumatic actuation system is further provided with a reservoir pressure transducer for measuring the pressure of the gas in the reservoir, and wherein the controller receives pressure information from the reservoir pressure transducer.

17. A method according toclaim 16, wherein the controller compares the pressure information from the actuation-chamber and reservoir pressure transducers to determine whether any of the pressure transducers is malfunctioning.

18. A method according, toclaim 3, further comprising:

providing a pneumatic actuation system for alternately providing positive and negative pressure to the actuation chamber of each pump.

19. A method according toclaim 18, wherein the pneumatic actuation system is provided with:

a positive-pressure gas reservoir;

a negative-pressure gas reservoir; and

a valving mechanism for controlling the flow of gas between the gas reservoirs and the actuation chamber of each pump.

20. A method according toclaim 19, wherein the pneumatic actuation system is further provided with:

at least one actuation-chamber pressure transducer for measuring the pressure of the actuation chamber of each pump, and

a controller that receives pressure information from the at least one actuation-chamber pressure transducer and controls the valving mechanism.

21-23. (canceled)

24. A method according toclaim 20, wherein the controller controls the valving mechanism to cause the flexible membrane of each pump to reach either the rigid chamber wall or the rigid limit structure at each of stroke's beginning and end, and

wherein the controller determines the amount of flow through each pump based on a number of strokes.

25. A method according toclaim 24, wherein the controller integrates pressure information an actuation-chamber pressure transducer over time during a stroke to detect an aberrant flow condition.

26. A method according toclaim 1, wherein the inlet of each pump is provided with an inlet valve for preventing flow out of the pumping chamber through the inlet and the outlet of each pump is provided with an outlet valve for preventing flow into the pumping chamber through the outlet.

27. A method according toclaim 26, wherein the inlet valve and the outlet valve are passive check valves.

28. A method according toclaim 26, wherein the inlet valve and the outlet valve are actively controlled valves, and wherein pumping the fluid comprises operating the valves.

29. A disposable unit for use in a heat exchanger system, the disposable unit comprising:

at least one reciprocating positive-displacement pump, each pump having

a curved rigid chamber wall;

a flexible membrane attached to the rigid chamber wall, so that the flexible membrane and rigid chamber wall define a pumping chamber;

an inlet for directing fluid through the rigid chamber wall into the pumping chamber in at least one of (a) a direction that is substantially tangential to the rigid chamber wall and (b) a direction that provides low-shear flow into the pumping chamber; and

an outlet for directing fluid through the rigid chamber wall out of the pumping chamber in at least one of (a) a direction that is substantially tangential to the rigid chamber wall and (b) a direction that provides low-shear flow out of the pumping chamber; and

a heat-exchanger component, in fluid communication with the at least one pump and adapted to be received by a heat exchanger.

30. A disposable unit according toclaim 29, wherein the heat-exchanger component includes at least one of a heat-exchanger bag, a length of tubing, and a radiator.

31. A disposable unit according toclaim 29, wherein each pump includes a rigid chamber wall that is hemispheroid.

32. A disposable unit according toclaim 29, wherein each pump includes a rigid limit structure for limiting movement of the membrane and limiting the maximum volume of the pumping chamber, the flexible membrane and the rigid limit structure defining an actuation chamber.

33-35. (canceled)

36. A disposable unit according toclaim 29, wherein the inlet of each pump includes an inlet valve for preventing flow out of the pumping chamber through the inlet and the outlet of each pump includes an outlet valve for preventing flow into the pumping chamber through the outlet.

37. A disposable unit according toclaim 36, wherein the inlet valve and the outlet valve are passive check valves.

38. A disposable unit according toclaim 36, wherein the inlet valve and the outlet valve are actively controlled valves.

39. A disposable unit according toclaim 29, wherein the heat-exchanger component includes an inlet in fluid communication with the outlet of the at least one pump for pumping fluid into the heat-exchanger component for heating or cooling.

40. (canceled)

41. A disposable unit according toclaim 29, further comprising

a filter in fluid communication with an outlet of the heat-exchanger component for filtering heated or cooled fluid flowing out of the heat-exchanger component.

42. A disposable unit according toclaim 29, further comprising:

a manifold including:

at least one inlet port for providing fluidic connection to an inlet of the heat-exchanger component, and

an outlet port for providing fluidic connection to an outlet of the heat-exchanger component.

43-45. (canceled)

46. A disposable unit according toclaim 42, wherein the manifold further includes at least one sensor component, each sensor component disposed in a port and capable of transmitting thermal information regarding fluid passing through the port.

47. (canceled)

48. A disposable unit according toclaim 46, wherein each sensor component includes a thermal well.

49-56. (canceled)

57. A heat-exchanger system comprising:

a heat exchanger for receiving a heat-exchanger component of a disposable unit;

a pneumatic actuation system for operating at least one reciprocating positive-displacement pump of the disposable unit for pumping fluid through the heat-exchanger component, each pump including a pumping chamber defined by a curved rigid chamber wall and a flexible membrane attached to the rigid chamber wail an further including an actuation chamber defined at least in part by the flexible membrane, the actuation chamber in fluid communication with the pneumatic actuation system; and

a controller for controlling the pneumatic actuation system and the heat exchanger.

58-59. (canceled)

60. A heat exchanger system according toclaim 57, wherein the controller is adapted to compare the temperature readings from the first and second locations; generate a first alarm signal indicating faulty temperature readings, if the temperature reading at the first location is not within a pre-set range from the temperature reading at the second location; determine if the temperature reading from the first or second location is above or below a pre-set temperature range; and if a reading is above or below the pre-set temperature range, generate a second alarm signal indicating the temperature is above or below the pre-set temperature range.

61-85. (canceled)

86. A radiator for use in a heat-exchanger system, the radiator comprising:

a body including a thermally conductive material; and

a channel disposed in the body for receiving a length of tubing.

87. A radiator according toclaim 86, wherein the channel comprises:

an inner loop;

an outer loop; and

a serpentine portion connecting the inner and outer loops, such that fluid flowing through portions of tubing disposed in the inner and outer loops of the channel flow in opposite directions.

88. A method of moving blood between a patient-access device and a heat exchanger for heating the blood the method comprising:

providing a reciprocating positive-displacement pump;

providing a flow line having a first portion between the patient-access device and the pump and having a second portion between the pump and the heat exchanger;

providing for each of the first and second portions of the flow line a valve for permitting flow in only one direction of the flow line; and

actuating the pump to cause the flow of blood between the patient-access device and the heat exchanger.

89. A method according toclaim 88, wherein the pump is provided with a flexible membrane as a reciprocating member.

90. A method according toclaim 89, wherein the pump is provided with a pneumatic actuation system for alternately providing positive and negative pressure to the membrane.

91-92. (canceled)

93. A system for extracorporeal thermal therapy, the system comprising:

a heat exchanger for heating the blood,

a reciprocating positive-displacement pump for moving blood between a patient-access device and the heat exchanger, the pump having an inlet line and an outlet line;

a first valve, located in the inlet line, for preventing flow of blood out of the pump; and

a second valve, located in the outlet line, for preventing flow of blood into the pump.

94-95. (canceled)

96. A heat exchanger for heating extracorporeal blood, the heat exchanger comprising a pump, the heat exchanger comprising:

a heat-exchange flow path having an inlet and an outlet;

an electricity-to-heat converter that turns electrical power into heat for absorption by the blood;

a first temperature sensor located at the inlet for measuring the temperature of the blood entering the heat exchanger;

a second temperature sensor located at the outlet for measuring the temperature of the blood exiting the heat exchanger;

a metering system that determines at least one of the volume or flow rate of blood passing through the heat exchanger; and

a controller in communication with the converter, the first and second temperature sensors, and the metering system, the controller receiving information regarding at least one of: the amount of power being used by the converter, temperature information from the first and second temperature sensors, flow-rate information from the metering system, and volume information from the metering system, the controller analyzing the received information in order to determine whether a fault condition exists, and generating a signal if a fault condition is detected.

97. A heat exchanger for heating extracorporeal blood for hyperthermia treatment, the heat exchanger comprising:

an inlet for unheated blood;

an outlet for heated blood;

a flow path from the inlet to the outlet;

a set of heating elements overlapping the flow path, including at least first and second heating elements the second heating element being located adjacent the flow path near the outlet, and the first heating element being located adjacent the flow path at a point upstream of the second heating element;

a first temperature sensor located adjacent the flow path upstream of the first heating element;

a second temperature sensor located adjacent the flow path between the first and second heating elements; and

a controller for receiving temperature information from the first and second temperature sensors and for generating a signal if a temperature difference being measured by the first and second sensors exceeds a limit.

98-121. (canceled)

122. A method of heating a patient's blood, the method comprising;

providing a heat-exchanger system for heating blood from the patient and pumping heated blood to the patient;

connecting a first temperature probe from the patient to the heat-exchanger system, the heat-exchanger system controlling the blood heating and pumping based on temperature information received from the first temperature probe and displaying the temperature information received from the first temperature probe to an operator;

monitoring patient temperature by the operator using an independent second temperature probe, and

terminating the treatment if either of the temperature probes conveys an unacceptable temperature reading.

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