US20090182307A1 - System and Method for Tension-Activated Fluid Control - Google Patents

Abstract

A medication infusion system may include a controller and a reservoir module including a reservoir containing medication to be delivered to an internal wound site via the controller. The controller may have a peristaltic pump driven by a motor to urge medication to flow toward the internal wound site, through a conduit. When the conduit is not tensioned via engagement with the pump, a valve blocks fluid flow to prevent unrestricted flow of medication. The valve may have a tapered plunger separated from an annular valve seat by a portion of the conduit that elongates under tension to enable withdrawal of the plunger from the valve seat. Alternatively, the valve may have features such as a spherical plunger between two annular valve seats, a rigid tubular member biased with respect to the conduit, or an opening in the conduit that moves axially or radially to enable fluid flow.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of Pending U.S. application Ser. No. 10/946,269, filed Sep. 21, 2004 and entitled SYSTEM AND METHOD FOR TENSION-ACTIVATED FLUID CONTROL, the disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
• 1. The Field of the Invention
• The present invention relates generally to the post-surgical treatment of closed wounds and specifically to methods and systems for infusion of a wound site to manage pain, swelling, bleeding and infection.
• 2. The Relevant Technology
• One of the most difficult aspects of enduring a major surgical procedure is coping with the post-operative pain and swelling. Commonly, opioid analgesics, sometimes referred to as narcotics, are administered post-operatively to counter the pain associated with wound healing and recovery. However, the use of systemic opioid analgesics, whether administered by oral, intramuscular, or intravenous methods, includes a host of possible undesirable side effects, including: respiratory depression, renal function depression, nausea, constipation, ataxia, confusion, sweating, and itching. The length of hospital stay for patients undergoing a major surgical procedure is, in part, determined by the need to monitor and control the side effects of systemically administered opioid analgesics.
• More recently, infusion pumps have been used to percutaneously deliver local anesthetics directly to the surgical wound. Thus, many of the undesirable side effects of systemic opioid analgesics are avoided. Furthermore, medication dosage is considerably less than systemic delivery since the medication is delivered directly to the affected site. However, contemporary percutaneous pain medication infusion pumps do not provide consistent relief of pain. Furthermore, many currently available medication infusion pumping arrangements are unable to adequately aspirate the affected site to reduce fluid build-up and swelling.
• Yet further, many medication infusion pumps lack adequate safety measures to ensure that the proper dosage of medication is delivered. Some medication infusion pumps have safety measures that are too complex, and therefore cannot be reliably implemented, or that add unduly to the cost of the medication pump. Accordingly, existing medication infusion pumps may not be as cost-effective, failsafe, or easy to use as may be desirable. For controllers utilizing peristaltic pump technology, there may exist a unique need to ensure that the conduit through which the fluid is driven is properly tensioned before fluid flow is permitted, so that only the desired amount of medication is able to flow through the conduit when the pump is operating. Additionally, it is necessary to prevent unregulated flow through the conduit before the conduit is tensioned about the peristaltic pump.
BRIEF DESCRIPTION OF THE DRAWINGS
• Various embodiments of the present invention will now be discussed with reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope.
• FIG. 1 is a schematic view of an integrated infusion and aspiration system applied to the knee of a patient.
• FIG. 2 is a perspective view of the integrated infusion and aspiration system ofFIG. 1, in a fully-assembled state.
• FIG. 3 is an enlarged, plan view of a portion of the infusion unit of the integrated infusion and aspiration system ofFIG. 1, with a portion of the infusion unit sectioned to illustrate a tension-activated valve.
• FIG. 4 is a perspective view of a portion of the reservoir module of the integrated infusion and aspiration system ofFIG. 1, with a portion of the tube cut away to illustrate the valve in the closed position.
• FIG. 5 is a perspective view of a portion of the integrated infusion and aspiration system ofFIG. 1, with a portion of the tube cut away to illustrate the valve in the open position.
• FIG. 6 is a partially-sectioned view of a valve of an infusion system according to one alternative embodiment of the invention.
• FIG. 7 is a partially-sectioned view of a valve of an infusion system according to another alternative embodiment of the invention.
• FIG. 8 is a partially-sectioned view of a valve of an infusion system according to another alternative embodiment of the invention.
• FIG. 9 is a partially-sectioned view of a valve of an infusion system according to yet another alternative embodiment of the invention.
• FIG. 10 is a partially-sectioned view of a valve of an infusion system according to still another alternative embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Referring toFIG. 1, a schematic view illustrates an integrated infusion andaspiration system10, orsystem10, according to one embodiment of the invention. Thesystem10 may be postoperatively used to provide pain relief medication directly to aninternal wound site12. InFIG. 1, theinternal wound site12 is a knee that has been surgically treated, for example, via a partial or total knee arthroplasty. However, the systems and methods of the present invention are not limited to postoperative use, and may be used to relieve pain before or after treatment of injury to any part of the body. In addition to providing pain relief medication to theinternal wound site12, thesystem10 aspirates internal fluids, such as spent medication and biological fluids, from theinternal wound site12.
• In the embodiment ofFIG. 1, thesystem10 includes an integrated infusion andaspiration unit14, hereinafter referred to as aninfusion unit14, that provides pressurized medication and provides a corresponding relative vacuum to receive fluids aspirated from theinternal wound site12. Additionally, thesystem10 includes aninfusion catheter16 through which medication is delivered to theinternal wound site12, and anaspiration catheter18 through which fluids are received in theinfusion unit14 from theinternal wound site12. As shown, a portion of theinfusion catheter16 may be nested within a corresponding portion of theaspiration catheter18 so that bothcatheters16,18 gain access to theinternal wound site12 through a single point-of-entry20.
• As illustrated, theinfusion catheter16 has aproximal end22 and adistal end24, with a plurality offlow orifices26 arrayed along thedistal end24 to provide infusion of medication along a relatively broad dispersal path within theinternal wound site12. Similarly, theaspiration catheter18 has aproximal end28 and adistal end30, with a plurality offlow orifices32 arranged along thedistal end30 to receive fluids from a relatively broad area of theinternal wound site12. Theproximal end22 of theinfusion catheter16 is generally nested within theproximal end28 of theaspiration catheter18 so that medication moves toward theinternal wound site12 through theinfusion catheter16, and fluids are removed from theinternal wound site12 through thedistal end30 of theaspiration catheter18, and then through the generally annular space between theproximal ends22,28 of thecatheters16,18.
• Referring toFIG. 2, a perspective view illustrates theinfusion unit14 of thesystem10 ofFIG. 1, without thecatheters16,18. Theinfusion unit14 has alongitudinal direction40, alateral direction42, and atransverse direction44, which are oriented as illustrated by the arrows inFIG. 2. Theinfusion unit14 has acontroller46 and areservoir module48. Thereservoir module48 contains medication to be provided to theinternal wound site12 and fluids aspirated from theinternal wound site12. Thecontroller46 provides the necessary pressure differentials to control infusion of medication to theinternal wound site12 and aspiration of fluids from theinternal wound site12. Theinfusion unit14 may also have a pair ofmounting brackets50 or other attachment devices that can be used to attach theinfusion unit14 to a mobile rack, hospital bed frame, or other piece of hospital equipment.
• Thecontroller46 has amain body52 that contains most of the internal components (not shown) of thecontroller46, and acap54 that can be removed to couple thecontroller46 to thereservoir module48 in a manner that will be shown and described in greater detail subsequently. Themain body52 has afirst portion56 and asecond portion58 that are attached together via relative motion in thelongitudinal direction40 to encase the internal components. Thecontroller46 has controls such asbuttons60 that can be used by medical personnel to control the operation of thecontroller46. Additionally, thecontroller46 may have adisplay62 that may show information such as infusion and aspiration history, the current operational mode of thecontroller46, and the like.
• Thereservoir module48 has areservoir retainer64 that serves to retain a first reservoir (not shown inFIG. 2) and asecond reservoir66. The first reservoir contains medication to be infused into theinternal wound site12 and thesecond reservoir66 receives fluid aspirated from theinternal wound site12. Thereservoir retainer64 has afirst portion68 and asecond portion70 that are attached together along thelongitudinal direction40 in a manner similar to that of the first andsecond portions56,58 of themain body52 of thecontroller46. Additionally, thereservoir module48 has aninfusion port72 shaped to be connected to theproximal end22 of theinfusion catheter16 and anaspiration port74 shaped to be connected to theproximal end28 of theaspiration catheter18. Afill port76 is shaped to be connected to a supply of medication to enable the first reservoir to be filled without removing it from thereservoir retainer64.
• Thecontroller46 and thereservoir module48 are coupled together in a manner that is simple and relatively failsafe, for example, through the use of mating surfaces (not shown) of thecontroller46 and thereservoir module48 that interlock via dovetail features or the like. Thecontroller46 may be coupled to any of multiple reservoir modules, not all of which need have the same configuration as thereservoir module48. For example, in alternative embodiments of the invention, a reservoir module may have only a single reservoir for infusion. Thecontroller46 may be connectable to such a reservoir module in a manner similar to that of thereservoir module48.
• When thecontroller46 and thereservoir module48 are coupled together, thecontroller46 limits flow of the medication from thereservoir module48. Thecontroller46 may utilize peristaltic pumping so that medication us unable to flow into theinfusion catheter16 in the absence of pumping action by thecontroller46. It is desirable to have a valve that prevents medication flow into theinfusion catheter16 in the event that thereservoir module48 is not properly coupled to the peristaltic pumping components (not shown inFIG. 2) of thecontroller46. Such a valve prevents the delivery of excess medication by ensuring that medication can flow only when the peristaltic pumping components are properly engaged to limit medication flow. One embodiment of such a valve will be shown and described in connection withFIGS. 3,4, and5, as follows.
• Referring toFIG. 3, a plan view illustrates the upper end of theinfusion unit14 with thecap54 withdrawn to reveal internal components. As shown, thereservoir module48 has a conduit, which may take the form of atube80, that extends in a generally circular pathway from a location in communication with thefill port76 to convey medication to theinfusion port72. In this application, the term “conduit” refers to a fluid conveying structure with any cross sectional shape. Accordingly, a “conduit” need not necessarily be a tube.
• Thecontroller46 has apump82, which may take the form of a peristaltic pump designed to compress a portion of thetube80 and to move the compressed portion along thetube80 to urge the medication to move through thetube80 in a highly controllable manner. Thepump82 may include a plurality of rotor pins84, only one of which is visible inFIG. 3. The rotor pins84 are retained by arotor carriage86 that rotates about an axis of rotation88 to move the rotor pins84 along a circular path. Therotor carriage86 may have a generally triangular E shape and may carry three rotor pins84. Therotor carriage86 is driven by a motor (not shown inFIG. 3) that provides rotational output about an axis of rotation.
• The rotor pins84 may take the form of small-diameter cylindrical rollers that are able to roll along the exterior of thetube80. Thetube80 may be “tightly routed,” or stretched tightly around the rotor pins84 such that thetube80 is pinched relatively tightly proximate each of the rotor pins84, so that, when thetube80 is properly engaged by thepump82, medication is generally unable to flow into theinfusion catheter16 in the absence of motion of the rotor pins84. Thecap54 is generally shaped to cover thetube80, the rotor pins84, and therotor carriage86 to prevent external objects from interfering with the operation of thepump82.
• The present invention envisions the use of a wide variety of different types of pumps. For example, peristaltic pumps need not involve stretching of a conduit about the rotor pins, but may instead be based upon compression of the conduit by the rotor pins against an opposing surface, such as a generally cylindrical interior wall. Indeed, a controller according to the present invention need not have a peristaltic pump, but may instead use a different type of pump such as a screw pump, a rotary vane pump, a rod-and-piston pump, or any other known type of pump. Indeed, the present invention may be useful in any situation in which it is desirable to prevent fluid flow in the absence of tension, regardless of whether a pump is present within the system.
• Thecontroller46 also has a constraining member in the form of anarcuate wall90 that abuts a portion of thetube80 to control the path of thetube80 around the rotor pins84. Thearcuate wall90 also causes thetube80 to assume a generally oval cross section proximate the arcuate wall to enhance the operation of ablockage sensor92. Theblockage sensor92 is designed to sense preferential distention of the portion of thetube80 proximate thearcuate wall90 to determine whether thetube80 or theinfusion catheter16 has been pinched or blocked. Accordingly, theblockage sensor92 includes a switch that either closes or opens a circuit in response to abnormal distention of thetube80. Closing or opening the circuit may trigger cessation of infusion and/or aspiration, production of an audible alarm tone, or the like.
• InFIG. 3, the switch of theblockage sensor92 takes the form of abutton94 that can be compressed to cause conductors within thebutton94 to either contact each other, thereby closing the circuit. Thebutton94 may extend upward from a circuit board (not shown) that controls the operation of thecontroller46 and lies generally coplanar with thedisplay62 illustrated inFIG. 2. Indeed, the circuit board may have a continuous expanse of substrate that extends from behind thedisplay62 into thebutton94.
• Thereservoir module48 may have a second constraining member, which takes the form of anarcuate wall96 adjoining thearcuate wall90 of thecontroller46. Thearcuate walls90,96 may provide a relatively continuous surface about which thetube80 bends at a relatively constant radius. Thearcuate walls90,96 operate to broaden the adjoining portion of thetube80 along thelongitudinal direction40, while constraining the adjoining portion along the lateral andtransverse directions42,44 to provide a constrainedportion98 of thetube80. The existence of the constrainedportion98 enhances operation of theblockage sensor92 by magnifying the distention of thetube80 measured by theblockage sensor92.
• As shown, thereservoir module48 also has a tension-activatedvalve100, orvalve100, that permits flow into thetube80 only when thetube80 is under tension. Thevalve100 lies at the junction of thetube80 with thefill port76, and prevents medication from flowing from thefill port76 into thetube80 when thetube80 is not under tension. Accordingly, thevalve100 is opened when thetube80 is routed tightly about the rotor pins84 as shown inFIG. 3, and is closed when thetube80 is not engaged by thepump82. When thetube80 is engaged by thepump82, thepump82 limits flow of medication through thetube80 medication is generally unable to flow past the rotor pins84 in the absence of rotor motion. When thetube80 is not engaged by thepump82, thevalve100 prevents flow. Accordingly, medication is not allowed to flow freely into theinfusion catheter16, regardless of whether thetube80 is engaged by thepump82.
• Thevalve100 may have a number of components, one of which is awall102 of thetube80 proximate the end of thetube80 adjoining thefill port76. Additionally, thevalve100 includes aplunger104 and avalve seat106. Theplunger104 generally engages thevalve seat106 to prevent flow, and is removed from thevalve seat106 to permit flow. Theplunger104 is retained within abore108 of thetube80. In this application, a “plunger” and a “valve seat” are any two structures that can be brought into contact with each other to impede fluid flow. In certain embodiments, such as thevalve100, the plunger may be moveable while the valve seat is stationary. In alternative embodiments, a movable valve seat may be used in addition to or in the alternative to a movable plunger.
• In the embodiment ofFIG. 3, thevalve seat106 is integrally formed with thefill port76. Thevalve seat106 has a generally tubular configuration. Accordingly, thevalve seat106 has anouter surface110 and aninner surface112. The end portion of thewall102 of thetube80 relatively tightly engages theouter surface110, and may also be bonded, ultrasonically welded, clamped, or otherwise attached to theouter surface110 to ensure that thewall102 is not disengaged from theouter surface110 during assembly or operation of theinfusion unit14. Medication is able to flow from thefill port76 into the adjacent end of thetube80 through theinner surface112. Additionally, theplunger104 is able to seat against theinner surface112 to prevent flow in the absence of tension in thetube80.
• As shown, theplunger104 has a sealingend120 and aretention end122. Theretention end122 keeps theplunger104 in place within thebore108 of thetube80, while the ° sealingend120 seats against theinner surface112 to keep medication from flowing past theplunger104 when thevalve100 is closed. Use of the phrase “sealing end” does not require that thevalve100 provide a perfect, fluid-tight seal; a perfect seal may not be necessary to avoid the delivery of unsafe quantities of medication to theinternal wound site12. However, a perfect seal may be desirable to prevent any undesired medication flow to theinternal wound site12.
• The sealingend120 has acontact surface124 that has a generally frusto-conical shape. Thecontact surface124 is able to contact theinner surface112 in such a manner that medication is substantially unable to move through the contacting portions of thecontact surface124 and theinner surface112. Theretention end122 is sized slightly larger than the uncompressed diameter of thebore108 so that theretention end122 is relatively tightly gripped by thewall102 of thetube100. Accordingly, theplunger104 does not move significantly along the axis of thetube80, despite the existence of oscillating levels of tension on thetube80 and pressure differentials across theplunger104 during operation of theinfusion unit14. Theretention end122 hassplines126 that permit fluid to flow past theretention end122 in a manner that will be shown and described in connection withFIGS. 4 and 5.
• Referring toFIG. 4, an enlarged, perspective view illustrates the top portion of thereservoir module48 of theinfusion unit14 ofFIGS. 1,2, and3, with thevalve100 in the closed configuration. As shown, theinfusion unit14 has been removed from thecontroller46. Thus, thetube80 is not engaged by the pump82 (not shown inFIG. 4). Accordingly, thetube80 is not under significant tension, and thevalve100 is closed.
• A portion of thetube80 has been cut away to illustrate theplunger104 and a small portion of thevalve seat106 of thevalve100. InFIG. 4, the sealingend120 is relatively E tightly seated in thevalve seat106. The portion of thewall102 of thetube80 between thesplines126 and the attachment of thetube80 to thevalve seat106 is resilient (like the remainder of the tube80), and is slightly stretched so as to urge the sealingportion120 of theplunger104 into engagement with thevalve seat106. There is no additional tension on thetube80 to counteract this resilient force, so thevalve100 remains in the closed configuration.
• As shown inFIG. 4, the splined shape of theretention end122 of theplunger104 defines a plurality ofpassageways128 that extend along thelateral direction42, between thesplines126. Thepassageways128 permit medication to flow past theretention end122 when thevalve100 is in the open position. In this application, a “splined shape” is a shape with a plurality of grooves and/or ridges distributed relatively about its perimeter.
• In order to deliver medication from thereservoir module48 to theinternal wound site12, thereservoir module48 needs to be coupled to thecontroller46. Attachment of thereservoir module48 to thecontroller46 is relatively simple, and may be performed by sliding mating dovetail features of thecontroller46 and thereservoir module48 into engagement with each other along thelongitudinal direction40. Thetube80 is then positioned in engagement with thepump82 to open the valve, as will be shown and described in greater detail in connection with the discussion ofFIG. 5.
• Referring toFIG. 5, an enlarged, perspective view illustrates the top portion of thereservoir module48 of theinfusion unit14 ofFIGS. 1,2, and3, with thevalve100 in the open configuration to permit medication to flow toward theinternal wound site12. As thetube80 is stretched relatively tightly about the rotor pins84, the rotor pins84 pinch thetube80 to impede fluid flow through thetube80. Medication is generally able to flow through thetube80 only to the extent that therotor carriage86 rotates to move the rotor pins84 along the curvature of thetube80. This tension on thetube80 remains while thetube80 is engaged by thepump82, regardless of whether thepump82 is operating.
• When thetube80 is stretched around the rotor pins84, the resulting tension in thetube80 opens thevalve100. More precisely, the portion of thetube80 between theretention end122 of theplunger104 and thevalve seat106 stretches in response to the tension in thetube80 caused by engagement of thepump82 and thetube80. The elongation of the portion of thetube80 between theretention end122 of theplunger104 and thevalve seat106 enables thecontact surface124 of the sealingend120 of theplunger104 to be withdrawn from contact with theinner surface112 of thevalve seat106. Withdrawal of thecontact surface124 from theinner surface112 opens thevalve100 by providing an annular gap between thecontact surface124 and theinner surface112. Medication is then able to enter thetube80 by flowing through the annular gap, and then flowing through thepassageways128 to pass through theretention end122.
• Thereafter, the relatively constant tension on thetube80 causes thevalve100 to remain open until thetube80 is disengaged from thepump82. Accordingly, medication flow through thetube80 is always either controlled by thepump82, or substantially blocked via closure of thevalve100, and theinfusion unit14 is unable to provide an unregulated flow of medication into theinfusion catheter16.
• In the alternative to the configuration illustrated inFIG. 5, thevalve100 may be positioned at the junction of thetube80 with theinfusion port72. In such a position, thevalve100 would not impede fluid flow into thetube80, but would instead block fluid flow from thetube80 to theinfusion port72 when thetube80 is not under tension. Thevalve100 itself may be configured substantially as shown inFIG. 5 and the preceding figures, and would open in response to tension in substantially the same manner set forth above.
• Notably, fluid flow into thetube80 is substantially independent of any pressure gradient that exists within the fluid. Such a pressure differential would have to be large enough to overcome the resilient force of the portion of thetube80 between theretention end122 of theplunger104 and thevalve seat106. The resilient force exerted by this portion of thetube80 is generally large enough to keep theplunger104 seated in thevalve seat106 until thetube80 is tensioned80, despite pressure rises that may be expected to occur within the fluid supply. Thus, thevalve100 does not operate as a check valve, and is not generally subject to accidental opening in response to a pressure rise in the fluid within thefill port76, as may occur when theunit14 is dropped or knocked, for example.
• The systems and methods of the present invention may be applied to a wide variety of applications in which it may be desirable to control fluid flow based on the tension in a member. Fluid flow may more precisely be controlled based on the tension in a conduit that conveys the fluid. Such a valve system is not limited to use in medication infusion systems, but is broadly applicable in a variety of fields such as hydraulics, consumer products, and manufacturing systems.
• Furthermore, a wide variety of configurations may be used in place of thevalve100 ofFIGS. 3-5 to provide tension-based fluid control. In some applications, it may be desirable to provide a valve that is closed, not opened, in response to tension in a conduit. For example, those of skill in the art will recognize that theplunger104 and/or thevalve seat106 may be repositioned and/or reconfigured to provide a valve (not shown) that is open in the absence of tension in thetube80, and closed when tension is applied to thetube80. Furthermore, in certain configurations, a stretchable conduit need not be present to cause the valve to operate. Some exemplary alternative embodiments will be shown and described in connection withFIGS. 6-10, as follows.
• Referring toFIG. 6, afill port176 and atube180 may be parts of an infusion E system like theinfusion system10 ofFIG. 1, and may thus be incorporated into an infusion unit such as theinfusion unit14. Thetube180 may be designed for engagement by a peristaltic pump like thepump82. Accordingly, avalve200 may be provided to control fluid flow from thefill port176 to thetube180 to serve a function similar to that of thevalve100. For clarity, thefill port176,tube180, andvalve200 are illustrated in isolation in the side elevation, section view ofFIG. 6.
• As shown, thetube180 has awall202, a portion of which is incorporated into thevalve200. Thevalve200 also includes aplunger204 and avalve seat206. Theplunger204 is integrally formed with thefill port176, and thevalve seat206 is integrally formed with thewall202, so that thevalve seat206 defines a stepped-down portion of abore208 of thetube180. Accordingly, thevalve seat206 has aninner surface212 defining a bore smaller than the remainder of thebore208 of thetube180.
• Theplunger204 has a sealingend220 designed to seat against thevalve seat206, and aretention end222 designed to retain thetube180. More precisely, the sealingend220 has acontact surface224 with a generally conical shape. Thecontact surface224 is positioned within thebore208 of thetube180, and is slidable into engagement with theinner surface212 of thevalve seat206 to block fluid flow through thevalve seat206. Theretention end222 has anouter surface226 that is generally cylindrical in shape. Theouter surface226 is sized slightly larger than the nominal diameter of thebore208 so that thetube180 must stretch radially to fit around theouter surface226. Thus, thetube180 grips theouter surface226. If desired, an adhesive, ultrasonic weld, clamp, or the like (not shown) may be applied to strengthen the attachment of thetube180 to theouter surface226.
• In addition to thecontact surface224, the sealingend220 has a plurality ofpassageways228, which may take the form of holes passing through thecontact surface224. Thepassageways228 pass through the portion of thecontact surface224 that lies outside thevalve seat206 when thecontact surface224 is pressed against thevalve seat206 so that, when thecontact surface224 is seated against thevalve seat206, fluid is unable to pass from thepassageways228 through thevalve seat206. Only threepassageways228 are illustrated in the section view ofFIG. 6 to provide a total of fourpassageways228, but any number of passageways may be used.
• In the configuration ofFIG. 6, thevalve200 is in the closed configuration. Accordingly, thecontact surface224 abuts the adjacent rim of theinner surface212 of thevalve seat206 along a generally annular sealing interface to prevent fluid from entering thetube180 from within thefill port176. When thetube180 is stretched around the rotor pins84, the resulting tension in thetube180 opens thevalve200.
• More precisely, the portion of thetube180 between thevalve seat206 and the outer surface of theplunger204 stretches in response to the tension in thetube180 caused by engagement of thepump82 and thetube180. The resulting elongation of thetube180 withdraws thevalve seat206 from contact with thecontact surface224 of the sealingend220 of theplunger204. Withdrawal of thevalve seat206 from thecontact surface224 opens thevalve200 by providing an annular gap between thecontact surface224 and theinner surface212. Medication is then able to enter thetube180 from thefill port176 by flowing through thepassageways228, then flowing through the annular gap to pass through thevalve seat206.
• Referring toFIG. 7, afill port276 and atube280 may be parts of an infusion system like theinfusion system10 ofFIG. 1, and may thus be incorporated into an infusion unit such as theinfusion unit14. Thetube280 may be designed for engagement by a peristaltic pump like thepump82. Accordingly, avalve300 may be provided to control fluid flow from thefill port276 to thetube280 to serve a function similar to that of thevalve100. For clarity, thefill port276,tube280, andvalve300 are illustrated in isolation in the side elevation, section view ofFIG. 7.
• As shown, thetube280 has awall302, a portion of which is incorporated into thevalve300. Thevalve300 also includes aplunger304 and afirst valve seat306. Theplunger304 is generally spherical and is sized to fit within abore308 of thetube280 with clearance so that theplunger304 is movable within thebore308. Thevalve300 also includes asecond valve seat310 positioned such that theplunger304 rests between the first and second valve seats306,310. Each of the valve seats306,310 is integrally formed with thebore308 of thetube280. Additionally, each of the first and second valve seats306,310 has aninner surface312,314, respectively. The valve seats306,310 provide stepped down portions of thebore280 so that each of theinner surfaces312,314 defines a bore smaller than the remainder of thebore308 of thetube280.
• Thefill port276 has anouter surface326 that is generally cylindrical in shape. Theouter surface326 is sized slightly larger than the nominal diameter of thebore308 so that thetube280 must stretch radially to fit around theouter surface326. Thus, thetube280 grips theouter surface326. If desired, an adhesive, ultrasonic weld, clamp, or the like (not shown) may be applied to strengthen the attachment of thetube280 to theouter surface326.
• In the configuration ofFIG. 7, thevalve300 is in the closed configuration. Accordingly, theplunger304 abuts the adjacent rims of theinner surfaces312,314 of the first and second valve seats306,310 along generally annular sealing interfaces to prevent fluid from passing through the valve seats312,314 to enter thetube280 from within thefill port276. The length of thetube280 between the valve seats312,314 is short enough that the valve seats312,1314 press against opposite sides of theplunger304 to keep theplunger304 centered within thebore308 and provide the seals. Theplunger304 abuts both of the valve seats306,310 to redundantly restrict fluid flow into thetube280. When thetube280 is stretched around the rotor pins84, the resulting tension in thetube280 opens thevalve300.
• More precisely, the portion of thetube280 between the first and second valve seats306,310 stretches in response to the tension in thetube280 caused by engagement of thepump82 and thetube280. The resulting elongation of thetube280 draws the valve seats306,310 apart to provide gaps between the valve seats306,310 and theplunger304. Medication is then able to enter thetube280 from thefill port276 by flowing through thefirst valve seat306, flowing around theplunger304, and then flowing through thesecond valve seat310. The motion of the fluid through thevalve300 may tend to keep theplunger304 generally centered within the space between the valve seats306,310 to maintain the gaps between the valve seats306,310 and theplunger304, thereby enabling the fluid to continue to flow efficiently through thevalve300.
• Referring toFIG. 8, afill port376 and atube380 may be parts of an infusion system like theinfusion system10 ofFIG. 1, and may thus be incorporated into an infusion unit such as theinfusion unit14. Thetube380 may be designed for engagement by a peristaltic pump like thepump82. Accordingly, avalve400 may be provided to control fluid flow from thefill port376 to thetube380 to serve a function similar to that of thevalve100. For clarity, thefill port376,tube380, andvalve400 are illustrated in isolation in the side elevation, section view ofFIG. 8.
• As shown, thetube380 has awall402, a portion of which is incorporated into thevalve400. Thevalve400 also includes aplunger404 and avalve seat406. Theplunger404 is a generally conical structure integrally formed with thefill port376 and oriented toward the tube1380. Thevalve seat406 is generally tubular in shape, and may be formed of a rigid plastic, metal, or the like. One end of thevalve seat406 is seated in abore408 of thetube380, as shown, so that thevalve seat406 essentially forms a rigid extension of thetube380. Thevalve400 also has a rigidtubular body410 that is integrally formed with thefill port376, and has a generally tubular shape concentric with thevalve seat406. One end of thevalve seat406 is slidable into the interior of the rigidtubular body410, and is biased toward theplunger404 by a resilient member, which may take the form of atension spring412.
• Thevalve seat406 has aninner surface414 that defines a relatively constricted bore in communication with thebore408 of thetube380. Further, thevalve seat406 has a firstouter surface416, a secondouter surface418, and aretention flange420. Theouter surfaces416,418 are both generally cylindrical in shape, and the firstouter surface416 is sized to slide into the bore of the rigidtubular body410. The secondouter surface418 is sized slightly larger than the nominal diameter of thebore408 so that thetube380 must stretch radially to fit around the secondouter surface418. Thus, thetube380 grips the secondouter surface418. If desired, an adhesive, ultrasonic weld, clamp, or the like (not shown) may be applied to strengthen the attachment of thetube380 to the secondouter surface418.
• Theretention flange420 serves to anchor one end of thetension spring412 against thevalve seat406. The adjacent end of thetension spring412 may be adhesive bonded, insert molded, or otherwise attached to theretention flange420. In the alternative, a portion of the adjacent end of thetension spring412 may extend behind theretention flange420.
• Theplunger404 has acontact surface424, which may be generally conical in shape. Thecontact surface424 is shaped to contact theinner surface414 of thevalve seat406 to prevent fluid from flowing into thevalve seat406 when thecontact surface424 abuts theinner surface414. Theplunger404 is centered between a plurality ofpassageways428 that enable fluid to enter the rigidtubular body410 by flowing around theplunger404. If thecontact surface424 of theplunger404 is not positioned to abut theinner surface414 of thevalve seat406, the fluid is able to flow from the rigidtubular body410 into thevalve seat406, and from thevalve seat406 into thetube380.
• As shown, the rigidtubular body410 has aninner surface430 and aretention flange432. Theinner surface430 is generally cylindrical and is sized to receive the firstouter surface416 of thevalve seat406 with clearance so that thevalve seat406 is able to slide into and out of the rigidtubular body410. However, theinner surface430 may be sized closely enough to the firstouter surface416 so that a seal is provided between theinner surface430 and the firstouter surface416 to keep fluid from leaking from thevalve400 by flowing between the firstouter surface416 and theinner surface430.
• Theretention flange432 anchors the end of thetension spring412 opposite to that anchored by theretention flange420 of thevalve seat406. The adjacent end of thetension spring412 may be adhesive bonded, insert molded, or otherwise attached to theretention flange420. Alternatively, the adjacent end of thetension spring412 may simply extend behind theretention flange432. In any case, theretention flanges420,432 cooperate to retain thetension spring412 in such a manner that thetension spring412 tends to draw thevalve seat406 into the rigidtubular body410. Thus, thetension spring412 presses thevalve seat406 against theplunger404 to block fluid flow into thevalve seat406.
• In the configuration ofFIG. 8, thevalve400 is in the closed configuration. Accordingly, theplunger404 abuts the adjacent rim of theinner surface414 of the valve seats406 along a generally annular sealing interface to prevent fluid from passing through thevalve seat406 to enter thetube380 from within thefill port376. When thetube380 is stretched around the rotor pins84, the resulting tension in thetube380 opens thevalve400.
• More precisely, tension on thetube380 tends to pull thevalve seat406 away from the rigidtubular body410. Relative motion between thevalve seat406 and the rigidtubular body410 is generally proportional to the tension in thetube380, and is limited by the counteracting tension provided by thetension spring412. As a result of relative motion between thevalve seat406 and the rigidtubular body410, thevalve seat406 is drawn away from theplunger404, and theinner surface414 of thevalve seat406 is withdrawn from contact with thecontact surface424 of theplunger404. A gap is provided between thevalve seat406 and theplunger404, and medication is thus able to enter thetube380 from thefill port376 by flowing through thepassageways428, into the rigidtubular body410, around theplunger404, and through thevalve seat406.
• Thevalve400 ofFIG. 8 is different from the embodiments described previously because it does not depend on elongation of thetube380 to open thevalve400. Rather, thetube380 can be substantially non-stretchable without impairing the operation of thevalve400 because relative motion between theplunger404 and thevalve seat406 is derived from elongation of thetension spring412. Thus, thevalve400 provides greater flexibility in the type oftube380 that can be used.
• Referring toFIG. 9, asupply tube476 and atube480 may be parts of an infusion system like theinfusion system10 ofFIG. 1, and may thus be incorporated into an infusion unit such as theinfusion unit14. Thesupply tube476 may be provided in place of a fill port such as thefill port76, or may be attached to such a fill port to operate in conjunction with it. Thetube480 may be designed for engagement by a peristaltic pump like thepump82. Accordingly, avalve500 may be provided to control fluid flow from thesupply tube476 to thetube480 to serve a function similar to that of thevalve100. For clarity, thesupply tube476,tube480, andvalve500 are illustrated in isolation in the side elevation, section view ofFIG. 9.
• As shown, thetube480 has awall502, a portion of which is incorporated into thevalve500. In the embodiment ofFIG. 9, thevalve500 is designed to operate independently of engagement of a rigid valve seat with a rigid plunger. Rather, axial motion of a portion of thetube480 is used to permit thevalve500 to open. This concept will be set forth in greater detail below.
• Thevalve500 has a blockingmember504 formed of a generally rigid material such as a plastic, and located partially within abore508 of thetube480. Anopening510 is formed in thetube480, in communication with a bore of thesupply tube476. As shown, thetube480 has aninner surface512 with a generally cylindrical shape with a diameter only slightly larger than the blockingmember504. The blockingmember504 and theinner surface512 are generally coaxial, with axes of symmetry (not shown) aligned with anaxis514 of thetube480.
• In the embodiment ofFIG. 9, the blockingmember504 has a sealingend520 that controls fluid flow into thetube480 and an anchoringend522 at which the blockingmember504 is attached to some other stationary structure. The sealingend520 has anouter surface524 and aterminal surface526. Theouter surface524 has a generally cylindrical shape that fits tightly enough within theinner surface512 of thetube480 that fluid is generally unable to flow between theinner surface512 and theouter surface524. However, there is sufficient clearance and/or surface smoothness between theouter surface524 and theinner surface512 to permit thetube480 to slide along theaxis514 with respect to the blockingmember504. Theinner surface512 may be adhesive bonded, ultrasonically welded, clamped, or otherwise attached to theouter surface524 proximate the anchoringend522.
• In the configuration ofFIG. 9, thevalve500 is in the closed configuration. Accordingly, theopening510 faces theouter surface524 of the blockingmember504 such that the blockingmember504 blocks fluid flow into thetube480 from thesupply tube476. When thetube480 is stretched around the rotor pins84, the resulting tension in thetube480 opens thevalve500.
• More precisely, the portion of thetube480 between the anchoringend522 and theopening510 stretches in response to the tension in thetube480 caused by engagement of thepump82 and thetube480. The resulting elongation of thetube480 draws theopening510 along theaxis514 until some or all of theopening510 has moved beyond theterminal surface526 of the sealingend520 of the blockingmember504. The blockingmember504 is then no longer positioned to fully impede fluid flow through theopening510. Consequently, medication is able to enter thetube480 from thesupply tube476 by flowing through theopening510, past theterminal surface526.
• As set forth above, the operation of thevalve500 is not dependent on engagement of a rigid plunger with a rigid valve seat. Rather, thevalve500 operates based on motion of theopening510 along theaxis514 of thetube480. Such motion occurs as a direct response to elongation of thetube480.
• Referring toFIG. 10, asupply tube576 and atube580 may be parts of an infusion system like theinfusion system10 ofFIG. 1, and may thus be incorporated into an infusion unit such as theinfusion unit14. Thesupply tube576 may be provided in place of a fill port such as thefill port76, or may be attached to such a fill port to operate in conjunction with it. Thetube580 may be designed for engagement by a peristaltic pump like thepump82. Accordingly, avalve600 may be provided to control fluid flow from thesupply tube576 to thetube580 to serve a function similar to that of thevalve100. For clarity, thesupply tube576,tube580, andvalve600 are illustrated in isolation in the side elevation, section view ofFIG. 10.
• As shown, thetube580 has awall602, a portion of which is incorporated into thevalve600. In the embodiment ofFIG. 10, thevalve600 is designed to operate independently of engagement of a rigid valve seat with a rigid plunger. Rather, diametral contraction of a wall of thetube580 in response to elongation is used to permit thevalve600 to open. This concept will be set forth in greater detail below.
• Thevalve600 has a blockingmember604 formed of a generally rigid material such as a plastic, and positioned to encase a portion of thetube580. Two ormore openings610 are formed in thetube580, in communication with thebore608 of thetube580. As shown, thetube580 has anouter surface612 with a generally cylindrical shape with a diameter only slightly smaller than the interior diameter of the blockingmember604. The blockingmember604 and theinner surface612 are generally coaxial, with axes of symmetry (not shown) aligned with anaxis614 of thetube580.
• In the embodiment ofFIG. 10, the blockingmember604 has a sealingend620 that controls fluid flow into thetube580 and an anchoringend622 at which the blockingmember604 is attached to some other stationary structure. The sealingend620 has aninner surface624 and asupply tube receiver626. Theinner surface624 has a generally cylindrical shape that fits tightly enough around theouter surface612 of thetube580 that fluid is generally unable to flow between theouter surface612 and theinner surface624 when thetube580 is untensioned. However, when thetube580 is under tension, diametral contraction of thetube580 may cause there to be sufficient clearance between theinner surface624 and theouter surface612 to permit fluid flow between theinner surface624 and theouter surface612.
• Theouter surface612 may be adhesive bonded, ultrasonically welded, clamped, or otherwise attached to theinner surface624 proximate the anchoringend622. The anchoringend622 has anub628 that is shaped to fit into thebore608 of thetube580. Thenub628 may fit tightly enough into thebore608 to prevent fluid flow between thenub628 and thebore608, thereby forming a seal that prevents fluid from escaping from thevalve600 via the anchoringend622. The interior of thetube580 may also be attached to thenub628 via an adhesive, clamp, ultrasonic weld, or the like (not shown).
• In the configuration ofFIG. 10, thevalve600 is in the closed configuration. Accordingly, theouter surface612 is pressed against theinner surface624 proximate theopenings610 so that fluid is unable to enter theopenings610 from thesupply tube576. When thetube580 is stretched around the rotor pins84, the resulting tension in thetube580 opens thevalve600.
• More precisely, thetube580 stretches in response to the tension in thetube580 caused by engagement of thepump82 and thetube580. The resulting elongation of thetube580 causes diametral contraction of thetube580, i.e., motion of thewall602 nearer theaxis614 of thetube580. Theopenings610 are also drawn toward theaxis614, and are therefore drawn away from theinner surface624 of the sealingend620 of the blockingmember604. Since theinner surface624 no longer blocks fluid flow from thesupply tube576 into theopenings610, medication is able to enter thetube80 from thesupply tube576 by flowing from thesupply tube576 along the space between theouter surface612 and theinner surface624, and then through theopenings610.
• Thetube580 may have a sealingmember630 with afirst end632 that extends outward from theouter surface612 and asecond end634 attached to the sealingend620 of the blockingmember604. The sealingmember630 retains fluids that flow past theopenings610 and escape from between theouter surface612 and theinner surface624 when thevalve600 is open. The sealingmember630 has a plurality ofridges636 that are relatively easily bendable to permit the first and second ends632,634 to move further from each other when thetube580 stretches, and to move closer to each other again when tension is removed from thetube580. The sealingmember630 effectively moves like a bellows to provide its sealing function regardless of the relative positions of the first and second ends632,634.
• As set forth above, the operation of thevalve600 is not dependent on engagement of a rigid plunger with a rigid valve seat. Rather, thevalve600 operates based on motion of theopenings610 toward theaxis614 of thetube580 as a result of diametral contraction of thetube580. Such diametral contraction occurs as a direct response to elongation of thetube580.
• The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. Thus the described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (50)

1. A system for percutaneous infusion of an internal wound site, the system comprising:

a conduit positioned to convey a first fluid toward the internal wound site;

a rotor positioned to impinge against the conduit to urge the first fluid to move through the conduit; and

a valve positioned to impede flow of the first fluid through the conduit in response to absence of impingement of the rotor against the conduit.

2. The system ofclaim 1, further comprising a first reservoir shaped to contain the first fluid, wherein the conduit is coupled to the first reservoir to receive the first fluid from the first reservoir.

3. The system ofclaim 2, further comprising a second reservoir in communication with the internal wound site to receive a second fluid aspirated from the internal wound site.

4. The system ofclaim 1, wherein the rotor is incorporated into a peristaltic pump comprising multiple rotor pins, wherein the conduit is routed tightly about the rotor pins such that tension in the conduit causes opposing sides of the tube to press against each other proximate each of the rotor pins to impede flow of the first fluid past the rotor pins.

5. The system ofclaim 4, wherein the peristaltic pump is driven by a motor having an axis of rotation about which the rotor pins rotate.

6. The system ofclaim 1, wherein the valve operates substantially independently of a pressure gradient across the valve.

7. The system ofclaim 1, wherein the valve comprises a valve seat and a plunger, wherein the plunger is movable with respect to the valve seat such that the plunger contacts the valve seat to impede flow of the first fluid through the conduit.

8. The system ofclaim 7, wherein the conduit comprises a tube within which the valve seat and the plunger are retained, wherein elongation of a portion of the tube between the plunger and the valve seat enables the plunger to move with respect to the valve seat.

9. The system ofclaim 8, wherein the valve seat has a generally annular shape, wherein the plunger has a sealing end and a retention end, the sealing end having a tapered shape insertable into the valve seat to substantially prevent flow of the first fluid through the valve seat, the retention end having a splined shape selected to permit passage of the first fluid between the retention end and a bore of the tube.

10. The system ofclaim 8, wherein the valve seat has a generally annular shape, wherein the plunger has a sealing end and a retention end, the sealing end having a tapered shape insertable into the valve seat to substantially prevent flow of the first fluid through the valve seat, the retention end having a plurality of passageways formed therein to permit passage of the first fluid through the retention end.

11. The system ofclaim 8, wherein the valve seat comprises a first valve seat having a generally annular shape, wherein the plunger comprises a generally spherical shape, wherein the plunger is positioned to be pressed into engagement with the first valve seat via motion of a second valve seat having a generally annular shape.

12. The system ofclaim 7, wherein the valve further comprises a rigid tubular body, wherein one of the plunger and valve seat is attached to the rigid tubular body and the other of the plunger and valve seat is attached to the conduit, wherein the rigid tubular body is resiliently coupled to the conduit to enable the plunger to move with respect to the valve seat.

13. The system ofclaim 1, wherein the conduit has an opening oriented generally radially with respect to an axis of the conduit, wherein the valve comprises a blocking member positioned to block flow of the first fluid through the opening, wherein the opening moves along an axis of the tube with respect to the blocking member in response to elongation of the conduit to permit flow of the first fluid through the opening.

14. The system ofclaim 1, wherein the conduit has an opening oriented generally radially with respect to an axis of the conduit, wherein the valve comprises a blocking member positioned to block flow of the first fluid through the opening, wherein the opening moves toward an axis of the tube in response to elongation of the conduit to permit flow of the first fluid through the opening.

15. A peristaltic pump comprising:

a conduit positioned to convey a first fluid;

a plurality of rotor pins about which the conduit is routed tightly routable such that tension in the conduit causes opposing sides of the conduit to press against each other proximate each of the rotor pins to impede flow of the first fluid past the rotor pins, wherein the rotor pins are rotatable about an axis of rotation to urge the first fluid to move through the conduit; and

a plunger positioned to impede flow of the first fluid through the conduit in response to absence of impingement of the rotor pins against the conduit.

16. The peristaltic pump ofclaim 15, wherein the plunger moves substantially independently of a pressure gradient across the valve.

17. The peristaltic pump ofclaim 15, wherein plunger is incorporated into a valve, the valve further comprising a valve seat, wherein the plunger is movable with respect to the valve seat such that the plunger contacts the valve seat to impede flow of the first fluid through the conduit.

18. The peristaltic pump ofclaim 17, wherein the conduit comprises a tube within which the valve seat and the plunger are retained, wherein elongation of a portion of the tube between the plunger and the valve seat enables the plunger to move with respect to the valve seat.

19. The peristaltic pump ofclaim 18, wherein the valve seat has a generally annular shape, wherein the plunger has a sealing end and a retention end, the sealing end having a tapered shape insertable into the valve seat to substantially prevent flow of the first fluid through the valve seat, the retention end having a splined shape selected to permit passage of the first fluid between the retention end and a bore of the tube.

20. The peristaltic pump ofclaim 18, wherein the valve seat has a generally annular shape, wherein the plunger has a sealing end and a retention end, the sealing end having a tapered shape insertable into the valve seat to substantially prevent flow of the first fluid through the valve seat, the retention end having a plurality of passageways formed therein to permit passage of the first fluid through the retention end.

21. The peristaltic pump ofclaim 18, wherein the valve seat comprises a first valve seat having a generally annular shape, wherein the plunger comprises a generally spherical shape, wherein the plunger is positioned to be pressed into engagement with the first valve seat via motion of a second valve seat having a generally annular shape.

22. The peristaltic pump ofclaim 17, wherein the valve further comprises a rigid tubular body, wherein one of the plunger and valve seat is attached to the rigid tubular body and the other of the plunger and valve seat is attached to the conduit, wherein the rigid tubular body is resiliently coupled to the conduit to enable the plunger to move with respect to the valve seat.

23. A valve comprising:

a conduit positioned to convey a first fluid;

a valve seat; and

a plunger resiliently urged to contact the valve seat;

wherein at least one of the valve seat and the plunger is coupled to the conduit to be movable in response to tension in the conduit to withdraw the plunger from the valve seat, thereby permitting flow of the first fluid through the valve.

24. The valve ofclaim 23, wherein the plunger moves substantially independently of a pressure gradient across the valve.

25. The valve ofclaim 23, wherein the conduit comprises a tube within which the valve seat and the plunger are retained, wherein elongation of a portion of the tube between the plunger and the valve seat enables the plunger to move with respect to the valve seat.

26. The valve ofclaim 25, wherein the valve seat has a generally annular shape, wherein the plunger has a sealing end and a retention end, the sealing end having a tapered shape insertable into the valve seat to substantially prevent flow of the first fluid through the valve seat, the retention end having a splined shape selected to permit passage of the first fluid between the retention end and a bore of the tube.

27. The valve ofclaim 25, wherein the valve seat has a generally annular shape, wherein the plunger has a sealing end and a retention end, the sealing end having a tapered shape insertable into the valve seat to substantially prevent flow of the first fluid through the valve seat, the retention end having a plurality of passageways formed therein to permit passage of the first fluid through the retention end.

28. The valve ofclaim 25, wherein the valve seat comprises a first valve seat having a generally annular shape, wherein the plunger comprises a generally spherical shape, wherein the plunger is positioned to be pressed into engagement with the first valve seat via motion of a second valve seat having a generally annular shape.

29. The valve ofclaim 23, further comprising a rigid tubular body, wherein one of the plunger and valve seat is attached to the rigid tubular body and the other of the plunger and valve seat is attached to the conduit, wherein the rigid tubular body is resiliently coupled to the conduit to enable the plunger to move with respect to the valve seat.

30. A method for percutaneously infusing an internal wound site through the use of a system comprising a peristaltic pump having a conduit and a rotor, the method comprising:

tightly routing the conduit about the rotor;

opening the valve in response to tight routing of the conduit about the rotor; and

moving the rotor along the conduit to urge a first fluid to move through the conduit, toward the internal wound site.

31. The method ofclaim 30, wherein the system further comprises a first reservoir shaped to contain the first fluid, wherein the conduit is coupled to the first reservoir to receive the first fluid from the first reservoir, wherein urging the first fluid to move through the conduit comprises drawing the first fluid from the first reservoir.

32. The method ofclaim 31, wherein the system further comprises a second reservoir in communication with the internal wound site, the method further comprising receiving a second fluid aspirated from the internal wound site into the second reservoir.

33. The method ofclaim 30, wherein the peristaltic pump comprises multiple rotor pins, wherein tightly routing the conduit about the rotor comprises tightly routing the conduit about the plurality of rotor pins such that tension in the conduit causes opposing sides of the tube to press against each other proximate each of the rotor pins to impede flow of the first fluid past the rotor pins.

34. The method ofclaim 33, wherein the peristaltic pump is driven by a motor having an axis of rotation, wherein moving the rotor along the conduit comprises rotating the rotor about the axis of rotation.

35. The method ofclaim 30, wherein opening the valve comprises opening the valve substantially independently of a pressure gradient across the valve.

36. The method ofclaim 30, wherein the valve comprises a valve seat and a plunger, wherein opening the valve comprises moving the plunger with respect to the valve seat such that the plunger is withdrawn from contact with the valve seat to permit flow of the first fluid through the conduit.

37. The method ofclaim 36, wherein the conduit comprises a tube within which the valve seat and the plunger are retained, wherein opening the valve comprises elongating of a portion of the tube between the plunger and the valve seat to enable the plunger to move with respect to the valve seat.

38. The method ofclaim 37, wherein the valve seat has a generally annular shape, wherein the plunger has a sealing end and a retention end, the sealing end having a tapered shape insertable into the valve seat, the retention end having a splined shape selected to permit passage of the first fluid between the retention end and a bore of the tube, wherein opening the valve comprises withdrawing the sealing end from the valve seat to permit flow of the first fluid through the valve seat.

39. The method ofclaim 37, wherein the valve seat has a generally annular shape, wherein the plunger has a sealing end and a retention end, the sealing end having a tapered shape insertable into the valve seat, the retention end having a plurality of passageways formed therein to permit passage of the first fluid through the retention end, wherein opening the valve comprises withdrawing the sealing end from the valve seat to permit flow of the first fluid through the valve seat.

40. The method ofclaim 37, wherein the valve seat comprises a first valve seat having a generally annular shape, wherein the plunger comprises a generally spherical shape, wherein opening the valve comprises withdrawing a second valve seat to permit withdrawal of the plunger from the first valve seat, wherein the second valve seat has a generally annular shape.

41. The method ofclaim 36, wherein the valve further comprises a rigid tubular body, wherein one of the plunger and valve seat is attached to the rigid tubular body and the other of the plunger and valve seat is attached to the conduit, wherein the rigid tubular body is resiliently coupled to the conduit, wherein opening the valve comprises moving the conduit axially with respect to the rigid tubular body to withdraw the plunger from the valve seat.

42. The method ofclaim 30, wherein the conduit has an opening oriented generally radially with respect to an axis of the conduit, wherein the valve comprises a blocking member positioned to block flow of the first fluid through the opening, wherein opening the valve comprises moving the opening along an axis of the tube with respect to the blocking member in response to elongation of the conduit to permit flow of the first fluid through the opening.

43. The method ofclaim 30, wherein the conduit has an opening oriented generally radially with respect to an axis of the conduit, wherein the valve comprises a blocking member positioned to block flow of the first fluid through the opening, wherein opening the valve comprises moving the opening toward an axis of the tube in response to elongation of the conduit to permit flow of the first fluid through the opening.

44. A method for permitting fluid flow through a conduit through the use of a valve comprising a plunger and a valve seat, the method comprising:

exerting tension on the conduit; and

moving at least one of the plunger and the valve seat in response to the tension to withdraw the plunger from the valve seat, thereby permitting flow of the first fluid through the valve.

45. The method ofclaim 44, wherein moving at least one of the plunger and the valve seat comprises moving at least one of the plunger and the valve seat substantially independently of a pressure gradient across the valve.

46. The method ofclaim 44, wherein the conduit comprises a tube within which the valve seat and the plunger are retained, wherein moving at least one of the plunger and the valve seat comprises elongating of a portion of the tube between the plunger and the valve seat to enable the plunger to move with respect to the valve seat.

47. The method ofclaim 46, wherein the valve seat has a generally annular shape, wherein the plunger has a sealing end and a retention end, the sealing end having a tapered shape insertable into the valve seat, the retention end having a splined shape selected to permit passage of the first fluid between the retention end and a bore of the tube, wherein moving at least one of the plunger and the valve seat comprises withdrawing the sealing end from the valve seat to permit flow of the first fluid through the valve seat.

48. The method ofclaim 46, wherein the valve seat has a generally annular shape, wherein the plunger has a sealing end and a retention end, the sealing end having a tapered shape insertable into the valve seat, the retention end having a plurality of passageways formed therein to permit passage of the first fluid through the retention end, wherein moving at least one of the plunger and the valve seat comprises withdrawing the sealing end from the valve seat to permit flow of the first fluid through the valve seat.

49. The method ofclaim 46, wherein the valve seat comprises a first valve seat having a generally annular shape, wherein the plunger comprises a generally spherical shape, wherein moving at least one of the plunger and the valve seat comprises withdrawing a second valve seat to permit withdrawal of the plunger from the first valve seat, wherein the second valve seat has a generally annular shape.

50. The method ofclaim 44, wherein the valve further comprises a rigid tubular body, wherein one of the plunger and valve seat is attached to the rigid tubular body and the other of the plunger and valve seat is attached to the conduit, wherein the rigid tubular body is resiliently coupled to the conduit, wherein moving at least one of the plunger and the valve seat comprises moving the conduit axially with respect to the rigid tubular body to withdraw the plunger from the valve seat.

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