US20070142729A1

Movatterモバイル変換

Info

Publication number: US20070142729A1
Application number: US11/637,546
Authority: US
Inventors: Ulrich Pfeiffer; Reinhold Knoll; Daniel Moulas
Original assignee: UP Management and Co Med Systems KG GmbH
Current assignee: Edwards Lifesciences IPRM AG
Priority date: 2005-12-15
Filing date: 2006-12-12
Publication date: 2007-06-21
Also published as: EP1800598B1; US20120330168A1; JP5062727B2; DE102005063412A1; EP1800598A1; DE102005063411A1; BRPI0605347A; DE102005063410A1; US8858451B2; JP2007167645A

Abstract

An injection system for injecting an injectate fluid into a blood vessel of the patient and for carrying out a blood pressure measurement of a patient. The injection system includes a catheter tube having a first end for penetrating the blood vessel of the patient, and a pressure sensor which is arranged close to a second end of the catheter tube and can sense a pressure of a liquid in the catheter tube as an indication of the blood pressure of the patient.

Description

This claims priority toGerman application DE 10 2005 060 079.4, filed Dec. 15, 2005, the entire disclosure of which is incorporated by reference herein.
The present invention relates to blood vessel catheter located proximate to a patient's body for measuring blood pressure, drawing blood samples or injecting fluids into a blood vessel of the patient. The present invention further relates to a system for drawing blood samples or injecting fluids into the blood vessel of the patient and for carrying out a blood pressure measurement of a patient.

BACKGROUND

Measurement systems for measuring blood pressure of a patient's body are well known in clinical appliances. They usually comprise a rinsing fluid reservoir which is connected using a fluid flow tube to a catheter tube, which in use penetrates a patient's body such that the rinsing fluid is supplied as a continuous rinsing fluid stream. Along the rinsing channel one or more valves can be arranged to manually stop the rinsing of the fluid into the patient's body.

The continuous measurement of a blood pressure of a patient is important to monitor the condition of ill patients. It is common that the measurement of the blood pressure is carried out using a single use pressure sensor and a rinsing system both mounted on an organizer plate. This organizer plate with the sensors is well accessible on heart level for the operator. The pressure sensor on this organizer plate is then connected to the patient via a long tube which is filled with liquid. Thus, the pressure signal is hydraulically transmitted via the transfer tube. Typically there is a 3 way stop cock between patient and pressure sensor for drawing blood samples or injecting fluids.

The disadvantage of this system is that the pressure signal is falsified by the transfer characteristic of the long transfer tube system due to damping or resonance as a result of the length of the transfer tube.

As another possibility for measuring the blood pressure the use of a tip manometer is known. The tip manometer is located at the tip of the catheter tube such that in use the manometer is located inside the patient's body. Although such an arrangement provides a very good signal transmission it is very expensive and a larger diameter of the catheter tube is needed. Furthermore, controlling and adjusting the zero point pressure of the tip manometer is no longer possible after the catheter tube is placed inside the patient's body.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a blood vessel catheter and a fluid transfer system which avoids the drawbacks of the prior art and allows for an accurate and continuous measurement of the blood pressure of the patient.

The present invention provides a blood vessel catheter and a fluid transfer system.

According to a first aspect of the present invention, a blood vessel catheter is provided for locating in close proximity to a patient's body and for injecting an injectate fluid into a blood vessel of the patient or drawing blood samples from the patient. The blood vessel catheter includes a catheter tube having a first end for penetrating the blood vessel of the patient and a pressure sensor which is arranged at a second end of the catheter tube outside of the patient, wherein the pressure sensor is adapted to sense a pressure of the liquid in the catheter tube as an indication of the blood pressure of a patient.

The catheter has an advantage that the pressure sensor for sensing the blood pressure of the patient is located close to the blood vessel of the patient such that a damping or a resonance of the detected pressure is reduced or eliminated. Furthermore, the pressure sensor is located outside of the patient's body such that a zeroing of the pressure sensor can be carried out even if the catheter is in use.

Preferably, the pressure sensor is further adapted to supply an electric pressure signal, wherein an electric interface is provided to releasably couple the pressure sensor to a reusable measurement unit. Thereby, the catheter is provided as a disposable item which can be further coupled to a disposable fluid transfer unit.

According to another embodiment of the present invention, a valve, especially a control valve, is provided which is arranged between the end of the catheter tube and the pressure sensor wherein the valve is adapted to be operated depending on a valve activation signal. A valve control interface may be provided to couple the valve with a remote valve control element.

Advantageously, the valve includes a squeezable tube portion having an adaptable lumen wherein the squeezable tube is provided in such a way to adapt the size of the lumen depending on a pneumatic or hydraulic valve activation signal.

According to a further embodiment, the valve may be coupled to the electric interface for receiving an electric valve activation signal.

Preferably, a connector is provided for coupling the catheter tube to a unit for rinsing, injection or drawing blood samples. This allows for the catheter to be provided as a disposable item which can be releasably coupled to a fluid transfer unit. Unlike the previous art this connector is close to the patient and preferably arranged upstream to the pressure sensor

The present invention may further provide a shut-off valve arranged upstream to the pressure sensor which is adapted to be manually operated for controlling a liquid flow through the catheter tube. This allows an instant manual control of the fluid flow into the patient's body. For this valve also a 3 way stop cock could be used. This can allow convenient application of a guide wire to the catheter e.g. for a Seldinger catheter placement technique.

According to another aspect of the present invention a fluid transfer system is provided for rinsing the catheter or injecting an injectate fluid into a blood vessel of the patient or drawing blood samples from the patient and for carrying out a blood pressure measurement on a patient. The fluid transfer system includes a catheter tube having a first end for penetrating the blood vessel of a patient and a pressure sensor which is arranged close to a second end of the catheter tube, wherein the pressure sensor is adapted to sense a pressure of liquid in the catheter tube as an indication of the blood pressure of the patient.

The fluid transfer system according to present invention allows a continuous measurement of a blood pressure of a patient while the blood pressure is sensed close to the patient's body. A damping or a resonance of the pressure signal thus advantageously can be avoided.

According to an embodiment of the present invention, a measurement unit is provided which is electrically coupled to the pressure sensor for determining a pressure value.

Preferably, a control valve is arranged between the end of the catheter tube and the pressure sensor, wherein the control valve is adapted to be operated depending on a valve activation signal. Furthermore, the fluid transfer system includes a remote valve control element for providing the valve activation signal. The valve permits remote control of the fluid flow through the catheter tube.

Advantageously, a pneumatic signal activation line is provided to couple the valve to the valve control element wherein the remote valve control element provides a pneumatic or hydraulic valve activation signal.

Furthermore, it may be provided that the control valve includes a squeezable tube portion having a flexible lumen wherein the squeezable tube is provided in such a way to adapt the flexible lumen depending on the pneumatic or hydraulic valve activation signal.

According to a preferred embodiment of the present invention the fluid transfer system includes a reservoir for a rinsing medium, a fluid flow means coupled to the catheter tube, and a stop cock which is adapted to couple the reservoir to the catheter tube in a rinsing position.

Furthermore, the stop cock may be adapted to couple a reference pressure to the fluid flow means in a nulling position.

Moreover, the stop cock may be coupled to the valve control element in such a way that in the nulling position the valve is closed.

Preferably, the stop cock is adapted to cut off the fluid flow in the fluid flow means in a sampling position.

A fluid transfer system can be provided with a flow control unit having an upstream end which is coupled to a stop cock and a downstream end. The flow control unit includes a rinsing capillary for providing a predetermined flow of liquid through the fluid flow means, a first check valve adapted to open if a pressure difference between the upstream end and the downstream end of the flow control unit exceeds a predetermined first pressure value, and a second check valve adapted to open if a pressure difference between the downstream end and the upstream end of the flow control unit exceeds a predetermined second pressure value. Preferably the check valves are arranged in order that all fluid paths are reached by the rinsing streams through the capillary or the downstream check valve. In case the pressure sensor could not withstand the pressure generated during manual injection, the smallest cross section of the fluid path in the flow control unit is chosen smaller than the smallest cross section downstream the pressure sensor. This will reduce the pressure acting at the sensor position. Alternatively other pressure limiting means could be applied.

According to a preferred embodiment, a syringe is provided which is connected to the fluid flow means between the stop cock and the flow control unit for supply a bolus into the fluid flow means, e.g. for flush rinsing. Similar to state of the art blood sampling systems which are applied before the pressure sensor, blood samples could be drawn through the pressure sensor e.g. by:

Positioning the stopcock in sampling position.
Pulling the piston out of the syringe thereby removing rinsing fluid from the downstream fluid system.
Applying a needleless vacuum blood collection system to a blood sampling port, thereby drawing blood from the patient.
Removing the needleless vacuum blood collection system.
Pushing back the piston to the syringe, thereby refilling the rinsing fluid and cleaning the system.
Positioning the stopcock in rinsing position.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention are now described in more detail with respect to the accompanying drawings in which:

FIG. 1 is a schematic view of one embodiment of a fluid transfer system according to the present invention;

FIG. 2 is a more detailed schematic view of a fluid transfer system according to the present invention;

FIG. 3a-dshow a cross-sectional view of a flow control unit arranged in the fluid flow path of the fluid transfer system according to a preferred embodiment; and

FIG. 3e-fshow a cross-sectional view of a flow control unit arranged in the fluid flow path of the fluid transfer system according to a another preferred embodiment; and

FIGS. 4aand4bshow a cross sectional view of another embodiment of a flow control unit for use in the fluid transfer system according to the present invention in a first and a second operational condition.

FIG. 5 is a schematic view of another embodiment of the fluid transfer system according to the present invention;

FIG. 6 is a schematic view of another embodiment of the fluid transfer system according to the present invention;

FIG. 7 is a more detailed schematic view of another fluid transfer system according to the present invention;

FIG. 8aand8bare a cross-sectional view from two sides of a catheter as shown inFIG. 7; and

FIG. 9 is a more detailed view of the interface as shown inFIG. 7.

DETAILED DESCRIPTION

FIG. 1 shows a schematic view of a fluid transfer system for supplying an injected fluid into a patient's body. The fluid transfer system includes a bloodvessel catheter unit1, afluid transfer unit2, anoperational unit3, and areservoir4 for supplying a rinsing fluid. The bloodvessel catheter unit1 and thefluid transfer unit2 may be coupled by afirst interface15 and the blood vessel catheter unit and theoperational unit3 are coupled by asecond interface19. Furthermore, thefluid transfer unit2 may include athird interface29 for coupling with thereservoir4.

The bloodvessel catheter unit1 includes acatheter tube11 having a tip end for penetrating a blood vessel of the patient's body. At another end of the catheter tube11 acontrol valve12 is arranged to cut off the flow of the injected fluid through thecatheter tube11 depending on an activation signal. The activation signal can be applied as a pneumatic, hydraulic or electrical signal. In the illustrated embodiment the activation signal is supplied to the control valve by means of a pneumaticvalve activation line19 which is coupled by means of thesecond interface19 with avalve control element31. Thevalve control element31 can be designed as a bellow to provide a pressure for controlling the control valve.

Thecatheter tube11 can be provided with atemperature sensor10. Temperaturesensor signal lines16 are coupled to thesecond interface19. Theoperational unit3 which may be coupled to thesecond interface19 is designed for measuring the temperature. Thetemperature sensor10 is preferably located at a portion of thecatheter tube11, e.g. the tip, which is located inside the patient's body while in use.

Upstream to the control valve12 apressure sensor13 is coupled to the lumen of the fluid channel within thecatheter unit1. Thepressure sensor13 supplies an electrical pressure signal via electricalpressure signal lines17 to thesecond interface19 such that the electric pressure signal can be received by theoperational unit3 for detection. Thepressure sensor13 determines the pressure of the liquid within the lumen of the fluid channel as an indication of the blood pressure of the patient. Usually, the pressure of the liquid in the fluid channel substantially corresponds to the blood pressure of the patient. Thus, thesecond interface19 includes ports for connecting thetemperature signal lines16, thepressure signal lines17 as well as the pneumaticvalve activation line18.

The bloodvessel catheter unit1 may further comprise a cut-offvalve14 for manually cutting off the fluid stream through thecatheter tube11.

Upstream to the cut-offvalve14, thefirst interface15 is located which is provided as aconnector15. Theconnector15 serves for a releasably coupling thefluid transfer unit2 to the bloodvessel catheter unit1 such that the rinsing fluid can flow from thefluid transfer unit2 to thecatheter unit1. By providing thesecond interface19 and theconnector15, the bloodvessel catheter unit1 can be completely released from theoperational unit3 and thefluid transfer unit2. This allows that thecatheter unit1 and thefluid transfer unit2 can be designed as a disposable item while theoperational unit3 may e.g. be designed for repeated use.

Thefluid transfer unit2 includes a fluid flow means orsection24 on which from upstream to downstream astop cock28, asyringe27, ablood sample port26, and aflow control unit20 are arranged. On the upstream end of the fluid flow means24 as the third interface areservoir connector port29 is provided which serves for applying thereservoir4 including the rinsing fluid to be supplied to the patient.

Thestop cock28 can be placed into three positions:

In a first rinsing position thereservoir4 is connected to the fluid flow means24 such that the injectate fluid flows via the fluid flow means and theconnector15 to the bloodvessel catheter unit1 to supply the injectate fluid to the patient.

In a nulling position thestop cock28 applies on the fluid in the fluid flow means24 a predetermined pressure reference, preferably an atmospheric pressure of an outer environment. Via the fluid flow means24 the predetermined pressure reference is applied to thecatheter unit1. Therein, the predetermined pressure reference is used to calibrate thepressure sensor13.

In a sampling position thestop cock28 is closed to cut off the fluid flow means24 from thereservoir4 as well as from the pressure reference. This position may be used to draw a blood sample via theblood sample port26. Thesyringe27 could be used to remove the rinsing fluid from thecatheter unit1 and thefluid transfer unit2 and release it back after the blood sample is drawn. In the sampling position also for flush rinsing a bolus can be applied to the patient using thesyringe27.

To apply the pressure reference onto thepressure sensor13 of thecatheter unit1 it is necessary that thecontrol valve12 is closed such that no fluid can flow through thecatheter tube11. This is achieved by applying the activation signal on the pneumaticvalve activation line18. Furthermore, a calibration signal can be generated by thestop cock28 which is applied to theoperation unit3 such that a calibration measurement of the pressure in thecatheter unit1 can be initiated automatically.

Theflow control unit20 is designed to permanently allow a rinsing fluid flow though a capillary21 which has a predetermined flow rate e.g. of 3 ml/h. To allow that the rinsing fluid could be removed and blood samples could be taken via theconnector15 theflow control unit20 has to provide a bypass which is formed by afirst check valve23. Thefirst check valve23 opens if a pressure between a downstream end, e.g. at theconnector15, and an upstream end excites a predetermined first threshold pressure. This threshold is chosen at a low negative value e.g. 10 mmHg in order not to damage blood cells. The pressure difference can for example be achieved by thesyringe27 or by connecting asyringe26 to theblood sample port26 and by applying an underpressure onto the fluid flow means24. Theflow control unit20 includes asecond check valve22 which opens if at least a second threshold pressure is applied from upstream to downstream for example if a bolus is injected into the fluid flow means24 which shall be dispensed to the patient. This threshold is chosen at a positive value greater than the pressure usually applied to thefluid reservoir4 e.g. 500 mmHg.

InFIG. 2 a more detailed view of the fluid transfer system is illustrated. With regard to the bloodvessel catheter unit1 it is shown that thecatheter unit1 is integrally formed as theinterface19, theconnector15 and the pneumaticvalve activation line18 which are releasably connectable to thefluid transfer unit2 and theoperation unit3.

In the detailed view, it can be seen that thecontrol valve12 of thecatheter unit1 is designed as a squeeze valve which can be controlled by means of a pneumatic activation signal that is applied onto aflexible tube32. An increasing pressure within the pneumaticsignal activation line18 results in that the lumen of theflexible tube32 is reduced and finally cut off such that amain flow path33 within thecontrol valve12 is closed. By releasing the overpressure within the pneumaticsignal activation line18 the blood pressure of the patient within themain flow path33 results in that theflexible tube32 opens such that the rinsing fluid is able to flow again through thecatheter tube11 into the patients body. In a preferred embodiment of the present invention, a low or even negative pressure gradient is applied to the pneumaticsignal activation line18 in order to force theflexible tube32 to be extended and forced at the inner wall of themain flow path33. Thus, it is ensured that the flexible tube is not even partly blocking the way of the main flow path and thus thecontrol valve12 is fully opened again.

Generally, thecontrol valve12 can be remote controlled via the pneumaticsignal activation line18 and may be coupled to thestop cock28 such that the overpressure is applied to thecontrol valve12 if thestop cock28 is positioned in the nulling position.

In one embodiment, thestop cock28 may comprise a pivotable inner member which provides a cutting off of the fluid flow connection between thereservoir4 and the fluid flow means24 and a connection between the fluid flow means24 and the pressure reference depending on the position of the inner member. The pivotable inner member is provided with alever34 which activates thevalve control element31 in form of the bellow such that the bellow is squeezed and an overpressure in the pneumaticsignal activation line18 is obtained. In other positions thelever34 releases thebellow31 such that the pressure within the pneumatic signal line relieves resulting in the control valve opening again.

According to other embodiments thecontrol valve12 can be electrically or mechanically activated and deactivated in a remote manner.

In the nulling position thecontrol valve12 is closed and the fluid flow means24 is opened to the pressure reference such that thepressure sensor13 can be calibrated even if thecatheter tube11 penetrates the blood vessel of the patient. Furthermore, the close coupling of thepressure sensor13 with thecatheter tube11 allows for a continuous measuring of the blood pressure while the damping and resonance effects are reduced.

Thesecond interface19 is adapted to be coupled to theoperational unit3 via an appropriate plug such that anelectronic monitoring unit35 can continuously monitor the blood temperature and the blood pressure of the patient.

InFIGS. 3atod, a preferred embodiment of theflow control unit20 is shown. Theflow control unit20 includes ahousing50 in which a rinsing capillary51 included in acapillary body59 is arranged which provides a small flow path from anupstream port52 to adownstream port53 of theflow control unit20. The flow path has a small lumen adapted to maintain a constant predetermined rinsing flow rate of e.g. 3 ml/h. The first check valve23 (FIG. 2) includes a first flexible member54 a first end of which is fixedly attached at asupport element55. A second end of the firstflexible member54 abuts astop area56 of thecapillary body59 if no additional pressure is applied. If an increased pressure between the upstream and the

downstream port

52,53 of theflow control unit20 is applied the overpressure also acts on the firstflexible member54 which opens if a first threshold pressure is exceeded.

The firstflexible member54 is usually closed and may be provided having an “umbrella behavior”, i.e. if the first threshold pressure is exceeded the firstflexible member54 flaps such that the second end of the firstflexible member54 is instantly removed from thestop area56 and a fluid channel is established between the upstream and the

downstream port

52,53 of theflow control unit20. The lumen of the established fluid channel has a size which allows a flow rate which is essentially larger than the rinsing flow rate through the capillary51.

downstream port

52,53 of theflow control unit20 is applied. If a positive pressure difference between thedownstream port53 and theupstream port52 is applied the secondflexible member58 may flap. The secondflexible member58 is adapted that it flaps if a pressure between thedownstream port53 and theupstream port52 excites a second threshold pressure. Thus, one exemplary embodiment of aflow control unit20 having the aforementioned functionality can be realized.

InFIG. 3bto3dthe mechanism is illustrated for these three basic situations. InFIG. 3bflow through the capillary21 takes place whereas a threshold pressure is not exceeded.

InFIG. 3cthe situation is illustrated where the first threshold pressure is exceeded and the firstflexible member54 flaps such that the second end of the firstflexible member54 is instantly removed from thestop area56. This is the situation when a pressure difference exists where the higher pressure is applied from thedownstream port53.

The other situation is illustrated inFIG. 3d. Herein, a pressure from the upstream port is applied which causes a pressure difference between the upstream port and the downstream port in favor of the upstream port which exceeds the threshold. Thus, the secondflexible member58 flaps to give way whereas the firstflexible member54 is pressed against the wall.

InFIGS. 3eand3f, two situations for another embodiment of theflow control unit20 are illustrated. In this embodiment,flexible member55 in form of a ring is provided in the circumference of thehousing50. Thisflexible member55 is adapted to close the lumen between thedownstream port53 and theupstream port52. This is accomplished byflexible member55 being pressed against the outer wall of the member withcapillary21. Thus, in the situation ofFIG. 3eflow between theupstream port52 and thedownstream port53 is only possible via thecapillary21. In order to ensure that theflexible member55 closes the lumen, a pressure is applied onto a medium throughinlet57. By means of this pressure applied, theflexible member55 is pressed against the member comprising the capillary21.

InFIG. 3fa second situation is shown as inFIG. 3ewhereas now negative pressure is applied to theinlet57. Thus, theflexible member55 is deflated and thereby gives path for flow between theupstream port52 and thedownstream port53. The actuation of theflexible member55 to give free this path can be controlled remotely by applying the respective negative pressure. Thus, in both cases of flow fromupstream port52 todownstream port53 or flow fromdownstream port53 toupstream port52 theflexible member55 can be switched from the situation inFIG. 3e(closed) to the situation inFIG. 3f(open). The opening activation signal could be derived from the nulling and sampling position ofstop cock28.

InFIGS. 4aand4b, another embodiment of the flow control unit is illustrated. The flow control unit includes ahousing70 having anupstream port72 and adownstream port73. Inside the housing70 a rinsingcapillary75 is arranged in acapillary body74 to provide a rinsing flow channel which is permanently opened. Neighboured to the capillary body74 a first flow path orchannel76 is arranged which leads to afirst check valve77 having firstflexible members78 which are adapted to flap if the pressure between theupstream port72 and thedownstream port73 exceeds a first threshold pressure.FIG. 4ashows a condition wherein the first threshold pressure is exceeded by the applied pressure such that the firstflexible members78 are flapped such that a fluid channel between thefirst flow path76 and thedownstream port73 is established.

Furthermore, asecond flow path71 is provided which leads from thedownstream port73 to a second check valve79 which includes secondflexible members80 one and of which in a closed condition abut thestop area81 which is integrally formed with thehousing70. If a pressure difference between theupstream port72 and thedownstream port73 exceeds a predetermined second threshold pressure the secondflexible members80 flap such that the free ends of the secondflexible members80 are removed from thestop area81 such that a flow channel between thesecond flow path71 and theupstream port72 is established. This condition is shown inFIG. 4b.

The first and second flexible members are preferably arranged such that they snap if a pressure to which they are subjected exceeds a threshold pressure. The snapping of a valve is also known as an umbrella effect.

The first and second

flexible members

78,80 are preferably included in anintegral element81 which is formed as a flexible part and can be introduced in thehousing70. Theintegral element81 may comprise anengagement member83 which engages in arecess84 of thehousing70 when inserted.

As a result, a pressure measuring system with an improved signal transfer behavior and a simple handling is provided.

The present invention includes a disposable catheter I withintegrated pressure sensor13 connected to a remote disposable unit2 (fluid transfer unit) and a remote reusable unit3 (operational or measurement unit). Since the catheter is usually accessible for maintenance only with difficulty, the necessary operations after placing the catheter like rinsing, drawing blood samples and zeroing the pressure sensor are remotely operated. Preferred this is achieved by a preferably pneumatically operatedcontrol valve12 and/or pressure

dependent check valves

22,23. For measuring and adjusting the zero point pressure a remotely controlledvalve12 is arranged before thepressure sensor13. This is preferably a pneumatically activated stop cock or a squeeze valve. For practical reasons a hand operated shut-offvalve14 can be attached after thepressure sensor13.

Thepressure sensor13 and the

valves

12,14 and theconnector15, are preferably arranged in a single rigid housing at the end of thecatheter tube11 and located outside of the patient. For catheter placement thepressure sensor13 and all firmly

connected valves

12,14 preferably possess a straight free passage, by which a guide wire can be introduced through thecatheter lumen11. Frequently also ablood temperature sensor10 is needed. Therefore, preferably a thermistor is located at the tip of the catheter I and is in thermal contact to the streaming blood of the patient. The thermistor wires (temperature sensor signal lines)16 are placed in the same catheter tube however in a separate lumen. Preferably thethermistor wires16, the pressure transducer wires (electrical pressure signal lines)17 and the pneumaticvalve activation line18 are connected by an interface, preferably asingle plug19 which is integrated in the mentioned rigid housing.

Usually, such catheters need a constant small flow (3 ml/h) of a rinsing solution. In order that thisrinsing system2 does not damp the pressure signal, preferably immediately after the catheter connection15 a capillary21 is attached. Because at the same connection also blood samples could be taken or flush rinsing could be performed, the capillary21 could be bypassed dependent on the differential pressure by

check valves

22,23. Checkvalve22 opens if the pressure in the rinsing system is 500 mmHg above the blood pressure in thecatheter1. Checkvalve23 opens if the pressure in the rinsing system is 10 mmHg below than blood pressure in thecatheter1. The capillary21 and the

check valves

22,23 are preferably arranged in asingle housing20 and the functions are preferably performed in a single part. In a further embodiment, aflexible tube24 of appropriate length extends from thehousing20 to ablood sample port26, asyringe27 and a hand operatedstop cock28. All of them are preferably located on a bedbox at a convenient place for the operator. Thestop cock28 is preferably at the level of the heart.

Thestop cock28 is preferably adapted to be placed in three positions: Rinsing position—by connectingfluid reservoir4 tocatheter1. Nulling position—by connecting atmosphere tocatheter1. Sampling position—by closing all ports. Forcingstop cock28 in nulling position preferably also mechanically activates a bellow30 which activates thevalve12 simultaneously via apneumatic signal line32.

Preferably, theinterface plug19 is connected to the sensor electronic33 by electric signal lines25. As usual thefluid reservoir4 is held at 300 mmHg using a wristband.

InFIG. 5 another schematic view of one embodiment of an injection system according to the present invention is shown. This view is similar to the design as shown and described inFIG. 1. In the embodiment ofFIG. 5, however, apressure sensor13 is provided that is connected to atube32 filled with liquid or gel. Thistube32 has at its end areservoir37. The other end is connected via thesecond interface19 to the bloodvessel catheter unit1. Especially, thetube32 is connected to atube36 within the bloodvessel catheter unit1. Thus, the pressure of the liquid column intube32 acts on the pressure sensor viatube36. As a result, the pressure sensor is acted upon the pressure difference of the pressure within the catheter, i.e. the patient, and the pressure within the column oftube32.Tube32 and thereservoir37 are arranged such that the reservoir is on the same height as the heart of the patient. Thus, the pressure difference measured by the pressure sensor is the pressure within the catheter, i.e. the patient, corrected by the offset caused by the location of the pressure sensor away from the heart. Thus, the pressure at the pressure sensor is the pressure as present in the patient in the heart region. In pressure sensors of the prior art, this offset has to be calculated and the read out of the pressure sensor has to be corrected mathematically to give the value of the pressure in the heart region. As an advantage of the present arrangement, this pressure sensor does not have to be calibrated and set to atmospheric pressure since it already shows the correct difference, i.e. the result which is usually calculated via the absolute pressure and correction data taking into account the distance of the catheter to the heart.

InFIG. 6, a schematic view of another embodiment of the injection system according to the present invention is shown. This assembly is the system as described inFIG. 5 additionally providing a remote control and actuation device40 to operate theflow control unit20.

This arrangement is preferably used when using aflow control unit20 as shown inFIGS. 3eand3f. The opening activation signal could be derived from the nulling and sampling position ofstop cock28 which is operating a bellow40. Thus, it is possible to remotely control theflow control unit20 and to open the fast flush lumen or to close it. This is accomplished similar as the activation of thevalve control element31 inFIG. 1.

InFIG. 7, a more detailed schematic view of another fluid transfer system according to the present invention is shown. This arrangement is applicable with the system as shown inFIG. 5.

Apressure sensor13 is arranged next to acatheter1 having a lumen to which thepressure sensor13 is connected. Further, aninterface19 comprising two connectors19.1 and19.2 being connectable to each other is provided. Thepressure sensor13 is connected to the connector19.1 vialine36. The connector19.2 is connected to themeasurement unit3 vialine32.Line32 includes a line filled with liquid building a liquid column, and is connected to themeasurement unit3 via a pressure channel111 with a hydrophobic membrane115, and a connector117 such as an electrical monitor circuit plug. As a result, the pressure of the liquid column withinline32 acts upon the pressure sensor via theinterface19 andline36.

The catheter is further connected to a rinsing andblood sample system2 by aline24, theblood sample system2 having asyringe27 and ablood sample port26. Betweencatheter1 and the rinsing and blood sample system2 aflow control unit20 is provided. Thisflow control unit20 includes a capillary21 (seeFIG. 1) thus allowing a rinsing of fluid from thefluid reservoir4 intocatheter1. Further, theflow control unit20 allows for fast flush and blood sampling as described above, especially with respect to theflow control units20 as described inFIGS. 3ato3f.

When working, themeasurement unit3 will be situated at the same height as the heart of the patient. Thus, the fluid column withinline32 will act upon the pressure sensor from the one side and the pressure within the lumen ofcatheter1 will act upon thepressure sensor13 from the other side. Thepressure sensor13 will then read out the difference of the two pressures, i.e. the pressure at the heart region of the patient as corrected by the pressure applied inline32.

InFIGS. 8aand8b, cross-sectional views from two sides of thecatheter1 as shown inFIG. 7 are illustrated.

Thecatheter1 includes ahousing95 with acatheter tube92 arranged at the distal end of thehousing95 comprising aninner lumen93. Thecatheter tube92 is connected to the housing via abend protection96. At the proximal end of the housing, aluer access124 is provided.

In the housing95 apressure sensor13 is arranged next to a pressure channel99 (which is filled with liquid) extending from theinner lumen93. Thepressure sensor13 is connected to thepressure channel99 via atransmission membrane100, preferably made of gel. On the other side, the pressure sensor is connected to apressure channel101. Thepressure channel101 is attached to astrain relief105. Within thestrain relief105, other circuits like thepressure channel101, aconnection cable102 and electrical circuits106 are integrated. Thepressure channel101 is filled with a pressure transmitting material, for instance gel or water emulsions. Within thehousing95

further sensors

107 like a temperature sensor is integrated.

With such an arrangement, thepressure sensor13 is subjected to a pressure difference between the pressure in thepressure channel99 and the pressure frompressure channel101 acting upon thepressure sensor13.

Further, the pressure sensor is kept out of the way of the inner lumen. Thus, a guide wire to be inserted into the inner lumen can not be brought into contact with the pressure sensor and damage the pressure sensor. It is advantageous to choose the angle of thepressure channel99 within the housing in such a way that thehousing95 additionally protects thecatheter tube92 from damages by bending. Further, thehousing95 provides for an advantage distance between theluer access124 from the skin of the patient. Preferably, thehousing95 includes abase plate91 that can be placed on the skin of the patient. In combination with abend protection96 which itself is preferably bendable, a good protection for thecatheter tube92 is provided.

InFIG. 8ba view ontocatheter1 is illustrated. At the distal end of thecatheter tube92, a conical formedtip94 is provided. The housing further includes suture eyes97.1 and97.2 for fastening the housing to the skin of the patient.

InFIG. 9 a more detailed view of theinterface19 as shown inFIG. 7 is illustrated.

Theinterface19 includes two connectors19.1 and19.2. The connector19.1 is connected to the bloodvessel catheter unit1 whereas the connector19.2 is connected to themeasurement unit3. Aconnection cable102 coming from thecatheter unit1 includes different circuits and apressure channel101 coming from thepressure sensor13 as indicated inFIG. 8a. The interface connector19.1 is made as a plug matching to the counter part interface connector19.2. Thepressure channel101 forms apuncture spike104 within the first interface connector19.1. This puncture spike is preferably made of a thin, bendable tube out of Nitinol. At the other side, apuncture membrane114 is provided. This puncture membrane closes awater column110 towards the second interface connector19.2. This puncture membrane can be made of elastic material, for instance silicon discs, already comprising a puncture which is long enough to prevent water to flow through the long puncture within the elastic material. Thus, no water from thewater column110 can flow out. In the upper part of the second connector19.2, theelectrical circuits109 are provided around thewater column110 within themonitor cable108.

When the two connectors19.1 and19.2 are put together, the electrical circuits of the connectors19.1 and19.2 will be plugged together. Further, thepuncture spike14 will penetrate thepuncture membrane114 thus giving way between the fluid medium, preferably gel, of thepressure channel101 and thewater column110. Since within thepuncture membrane114 there was already provided a puncture, the puncture membrane is not inflicted. Thus, when separating the two connectors19.1 and19.2 from each other again, thepuncture membrane114 will again close thewater column110.

The other end of thewater column110 is either open or protected by a hydrophobe membrane115 (FIG. 7) which is permeable to air and not permeable to water to avoid loss of water. This other end of thewater column110 is situated at the height of the heart. Thus, the pressure sensor will output the correct difference of pressure with respect to the location of the heart. Preferably, the inner diameter of thewater columns110 is chosen so small that the water is additionally hindered to flow out because of these dimensions. The other end of the water column can be fixed at the height of the heart by integrating thewater column110 within themonitor cable108 or an electrical monitor circuit plug which is connectable to a so called monitor-bed-box. On the front plate or panel of this monitor-bed-box, further system members like blood sampling ports, etc. can be mounted. Preferably, the other open end of thewater column110 end into a clamping piece on themonitor cable108 between the electrical circuits and can be fixed at a suitable location at the height of the heart. Further, additional clamping pieces can be provided on themonitor cable108 to allow fasten a rinsing conduit.

To theluer access124 of the housing95 a capillary valve or a flow control unit, for instance according toFIGS. 3atof, with a rinsing conduit or capillary can be connected. Thus, a continuous rinsing ofcatheter1 is achieved and at the same time a decoupling of the rinsing conduit that is tampering with the accuracy of the measuring signals and the blood sample units from the pressure channel is achieved.