System, Method, And Apparatus For Regulating Pressure
Subject matter relating to pressure regulation is described. In one illustrative embodiment, an apparatus for regulating pressure may include a supply chamber, a control chamber, and a charging chamber. The supply chamber may have a supply port adapted for coupling to a supply lumen, and the control chamber may have a control port adapted for coupling to a feedback lumen. The charging chamber can be fluidly coupled to the supply chamber through a charging port. A regulator valve within the control chamber can operate to control fluid communication through the charging port based on a differential between pressure in the control chamber and a target pressure.
The present invention is a divisional of U.S. patent application Ser. No. 14/024,066, filed Sep. 11, 2013, which claims the benefit, under 35 USC § 119(e), of the filing of U.S. Provisional Patent Application Ser. No. 61/701,394, entitled “SYSTEM, METHOD, AND APPARATUS FOR REGULATING PRESSURE,” filed 14 Sep. 2012, which is incorporated herein by reference for all purposes
TECHNICAL FIELDThe subject matter described herein relates generally to regulating pressure. In more particular embodiments, the subject matter relates to regulating pressure for reduced-pressure therapy.
BACKGROUNDClinical studies and practice have shown that reducing pressure in proximity to a tissue site can augment and accelerate growth of new tissue at the tissue site. The applications of this phenomenon are numerous, but it has proven particularly advantageous for treating wounds. Regardless of the etiology of a wound, whether trauma, surgery, or another cause, proper care of the wound is important to the outcome. Treatment of wounds with reduced pressure is commonly referred to as “reduced-pressure therapy,” but may also be known by other names, including “negative pressure wound therapy” and “vacuum therapy,” for example. Reduced-pressure therapy may provide a number of benefits, including migration of epithelial and subcutaneous tissues, improved blood flow, and micro-deformation of tissue at a wound site. Together, these benefits can increase development of granulation tissue and reduce healing times.
While the clinical benefits of reduced-pressure therapy are widely known, the cost and complexity of reduced-pressure therapy can be a limiting factor in its application, and the development and operation of reduced-pressure systems, components, and processes continues to present significant challenges to manufacturers, healthcare providers, and patients.
SUMMARYIllustrative embodiments of systems, methods, and apparatuses for regulating pressure are described below. One such illustrative embodiment may be described as a reduced-pressure treatment system, which may include a dressing, a supply chamber, a control chamber, a charging chamber. The supply chamber can be fluidly coupled to the dressing through a supply lumen, and the control chamber can be fluidly coupled to the dressing through a feedback lumen. The charging chamber can be fluidly coupled to the supply chamber through a port. A regulator valve within the control chamber controls fluid communication through the port based on a differential between a control pressure in the control chamber and a therapy pressure.
Another illustrative embodiment relates to a method for regulating pressure, such as a therapeutic pressure. One such method may include placing a manifold in a sealed environment proximate to a tissue site, fluidly coupling the manifold to a supply chamber through a supply lumen, and fluidly coupling the manifold to a control chamber through a control lumen. The supply chamber may also be fluidly coupled to a charging chamber, and a charging pressure in the charging chamber can be reduced below a therapy pressure. Fluid communication between the supply chamber and the charging chamber can be regulated based on a differential between a control pressure in the control chamber and the therapy pressure. A regulated supply pressure from the supply chamber can be delivered to the manifold.
Yet another illustrative embodiment relates to an apparatus for regulating pressure. In one form, such an apparatus may include a supply chamber, a control chamber, and a charging chamber. The supply chamber may have a supply port adapted for coupling to a supply lumen, and the control chamber may have a control port adapted for coupling to a feedback lumen. The charging chamber can be fluidly coupled to the supply chamber through a charging port. A regulator valve within the control chamber can operate to control fluid communication through the charging port based on a differential between pressure in the control chamber and a target pressure.
Another illustrative embodiment of an apparatus for regulating pressure may include a lower housing having an end wall and a side wall. A first piston opposite the end wall of the lower housing may be engaged to the side wall of the lower housing to define a charging chamber within the lower housing. A partition in the first piston can separate a lower bowl from an upper bowl. A charging spring may be engaged to the first piston and the end wall of the lower housing. A charging port through the first piston can provide fluid communication between the charging chamber and a supply chamber defined by the partition and the lower bowl. An upper housing may have a floor and a side wall, wherein the side wall of the upper housing can be coupled to the side wall of the lower housing. A control chamber may be generally defined by the upper bowl and the floor of the upper housing. A second piston opposite the upper bowl may be engaged to the side wall of the lower housing, wherein the second piston can divide the control chamber into an ambient pressure region and a control pressure region. A valve body may extend through an aperture in the partition into the supply chamber, the valve body having a first end coupled to the second piston and a second end disposed adjacent to the charging port in the supply chamber. A regulator spring can engage the valve body between the charging port and the second piston. A multi-channel port can be exposed externally through the upper housing, and the multi-channel port can provide a supply port fluidly coupled to the supply chamber and a control port fluidly coupled to the control pressure region of the control chamber. The multi-channel port can be coupled with a multi-lumen tube.
Other features and advantages will become apparent with reference to the drawings and detailed description that follow.
New and useful systems, methods, and apparatuses associated with regulating pressure are set forth in the appended claims. Objectives, advantages, and a preferred mode of making and using the systems, methods, and apparatuses may be understood best by reference to the following detailed description in conjunction with the accompanying drawings. The description provides information that enables a person skilled in the art to make and use the claimed subject matter, but may omit certain details already well-known in the art. Moreover, descriptions of various alternatives using terms such as “or” do not necessarily require mutual exclusivity unless clearly required by the context. The claimed subject matter may also encompass alternative embodiments, variations, and equivalents not specifically described in detail. The following detailed description should therefore be taken as illustrative and not limiting.
The example embodiments may also be described herein in the context of a reduced-pressure therapy applications, but many of the features and advantages are readily applicable to other environments and industries. Spatial relationships between various elements or to the spatial orientation of various elements may be described as depicted in the attached drawings. In general, such relationships or orientations assume a frame of reference consistent with or relative to a patient in a position to receive reduced-pressure therapy. However, as should be recognized by those skilled in the art, this frame of reference is merely a descriptive expedient rather than a strict prescription.
In general, components of reduced-pressure therapy system 100 may be coupled directly or indirectly. For example, reduced-pressure source 104 may be directly coupled to regulator 106 and indirectly coupled to dressing 102 through regulator 106. Components may be fluidly coupled to each other to provide a path for transferring fluids (i.e., liquid and/or gas) between the components. In some embodiments, components may be fluidly coupled with a tube, for example. A “tube,” as used herein, broadly refers to a tube, pipe, hose, conduit, or other structure with one or more lumina adapted to convey fluids between two ends. Typically, a tube is an elongated, cylindrical structure with some flexibility, but the geometry and rigidity may vary. In some embodiments, components may additionally or alternatively be coupled by virtue of physical proximity, being integral to a single structure, or being formed from the same piece of material. Coupling may also include mechanical, thermal, electrical, or chemical coupling (such as a chemical bond) in some contexts.
In operation, pressure distribution manifold 110 may be placed within, over, on, or otherwise proximate to a tissue site. Drape 108 may be placed over pressure distribution manifold 110 and sealed to tissue proximate to the tissue site. The tissue proximate to the tissue site is often undamaged epidermis peripheral to the tissue site. Thus, dressing 102 can provide a sealed therapeutic environment proximate to a tissue site, substantially isolated from the external environment, and reduced-pressure source 104 can reduce the pressure in the sealed therapeutic environment. Reduced pressure applied uniformly through pressure distribution manifold 110 in the sealed therapeutic environment can induce macrostrain and microstrain in the tissue site, as well as remove exudates and other fluids from the tissue site, which can be collected in container 112 and disposed of properly.
The fluid mechanics of using a reduced-pressure source to reduce pressure in another component or location, such as within a sealed therapeutic environment, can be mathematically complex. However, the basic principles of fluid mechanics applicable to reduced-pressure therapy are generally well-known to those skilled in the art, and the process of reducing pressure may be described illustratively herein as “delivering,” “distributing,” or “generating” reduced pressure, for example.
In general, exudates and other fluids flow toward lower pressure along a fluid path. This orientation is generally presumed for purposes of describing various features and components of reduced-pressure therapy systems herein. Thus, the term “downstream” typically implies something in a fluid path relatively closer to a reduced-pressure source, and conversely, the term “upstream” implies something relatively further away from a reduced-pressure source. Similarly, it may be convenient to describe certain features in terms of fluid “inlet” or “outlet” in such a frame of reference. However, the fluid path may also be reversed in some applications, such as by substituting a positive-pressure source, and this descriptive convention should not be construed as a limiting convention.
The term “tissue site” in this context broadly refers to a wound or defect located on or within tissue, including but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. A wound may include chronic, acute, traumatic, subacute, and dehisced wounds, partial-thickness burns, ulcers (such as diabetic, pressure, or venous insufficiency ulcers), flaps, and grafts, for example. The term “tissue site” may also refer to areas of tissue that are not necessarily wounded or defective, but are instead areas in which it may be desired to add or promote the growth of additional tissue. For example, reduced pressure may be used in certain tissue areas to grow additional tissue that may be harvested and transplanted to another tissue location.
“Reduced pressure” generally refers to a pressure less than a local ambient pressure, such as the ambient pressure in a local environment external to a sealed therapeutic environment provided by dressing 102. In many cases, the local ambient pressure may also be the atmospheric pressure in a patient's vicinity. Alternatively, the pressure may be less than a hydrostatic pressure associated with tissue at the tissue site. Unless otherwise indicated, values of pressure stated herein are gauge pressures. Similarly, references to increases in reduced pressure typically refer to a decrease in absolute pressure, while decreases in reduced pressure typically refer to an increase in absolute pressure.
A reduced-pressure source, such as reduced-pressure source 104, may be a reservoir of air at a reduced pressure, or may be a manual or electrically-powered device that can reduced the pressure in a sealed volume, such as a vacuum pump, a suction pump, a wall suction port available at many healthcare facilities, or a micro-pump, for example. The reduced-pressure source may be housed within or used in conjunction with other components, such as sensors, processing units, alarm indicators, memory, databases, software, display devices, or user interfaces that further facilitate reduced-pressure therapy. While the amount and nature of reduced pressure applied to a tissue site may vary according to therapeutic requirements, the pressure typically ranges between −5 mm Hg (−667 Pa) and −500 mm Hg (−66.7 kPa). Common therapeutic ranges are between −75 mm Hg (−9.9 kPa) and −300 mm Hg (−39.9 kPa).
Pressure distribution manifold 110 can generally be adapted to contact a tissue site. Pressure distribution manifold 110 may be partially or fully in contact with the tissue site. If the tissue site is a wound, for example, pressure distribution manifold 110 may partially or completely fill the wound, or may be placed over the wound. Pressure distribution manifold 110 may take many forms, and may be many sizes, shapes, or thicknesses depending on a variety of factors, such as the type of treatment being implemented or the nature and size of a tissue site. For example, the size and shape of pressure distribution manifold 110 may be adapted to the contours of deep and irregular shaped tissue sites.
More generally, a manifold is a substance or structure adapted to distribute reduced pressure to or remove fluids from a tissue site, or both. In some embodiments, though, a manifold may also facilitate delivering fluids to a tissue site, if the fluid path is reversed or a secondary fluid path is provided, for example. A manifold may include flow channels or pathways that distribute fluids provided to and removed from a tissue site around the manifold. In one illustrative embodiment, the flow channels or pathways may be interconnected to improve distribution of fluids provided to or removed from a tissue site. For example, cellular foam, open-cell foam, porous tissue collections, and other porous material such as gauze or felted mat generally include structural elements arranged to form flow channels. Liquids, gels, and other foams may also include or be cured to include flow channels.
In one illustrative embodiment, pressure distribution manifold 110 may be a porous foam material having interconnected cells or pores adapted to uniformly (or quasi-uniformly) distribute reduced pressure to a tissue site. The foam material may be either hydrophobic or hydrophilic. In one non-limiting example, pressure distribution manifold 110 may be an open-cell, reticulated polyurethane foam such as GranuFoam® dressing available from Kinetic Concepts, Inc. of San Antonio, Tex.
In some embodiments, such as embodiments in which pressure distribution manifold 110 may be made from a hydrophilic material, pressure distribution manifold 110 may also wick fluid away from a tissue site while continuing to distribute reduced pressure to the tissue site. The wicking properties of pressure distribution manifold 110 may draw fluid away from a tissue site by capillary flow or other wicking mechanisms. An example of a hydrophilic foam is a polyvinyl alcohol, open-cell foam such as V.A.C. WhiteFoam® dressing available from Kinetic Concepts, Inc. of San Antonio, Tex. Other hydrophilic foams may include those made from polyether. Other foams that may exhibit hydrophilic characteristics include hydrophobic foams that have been treated or coated to provide hydrophilicity.
Pressure distribution manifold 110 may further promote granulation at a tissue site if pressure within a sealed therapeutic environment is reduced. For example, any or all of the surfaces of pressure distribution manifold 110 may have an uneven, coarse, or jagged profile that can induce microstrains and stresses at a tissue site if reduced pressure is applied through pressure distribution manifold 110.
In one example embodiment, pressure distribution manifold 110 may be constructed from bioresorbable materials. Suitable bioresorbable materials may include, without limitation, a polymeric blend of polylactic acid (PLA) and polyglycolic acid (PGA). The polymeric blend may also include without limitation polycarbonates, polyfumarates, and caprolactones. Pressure distribution manifold 110 may further serve as a scaffold for new cell-growth, or a scaffold material may be used in conjunction with pressure distribution manifold 110 to promote cell-growth. In general, a scaffold material may be a substance or structure used to enhance or promote the growth of cells or formation of tissue, such as a three-dimensional porous structure that provides a template for cell growth. Illustrative examples of scaffold materials include calcium phosphate, collagen, PLA/PGA, coral hydroxy apatites, carbonates, or processed allograft materials.
Drape 108 is an example of a sealing member. A sealing member may be constructed from a material that can provide a fluid seal between two environments or components, such as between a therapeutic environment and a local external environment. The sealing member may be, for example, an impermeable or semi-permeable, elastomeric material that can provide a seal adequate to maintain a reduced pressure at a tissue site for a given reduced-pressure source. For semi-permeable materials, the permeability generally should be low enough that a desired reduced pressure may be maintained. An attachment device may be used to attach a sealing member to an attachment surface, such as undamaged epidermis, a gasket, or another sealing member. The attachment device may take many forms. For example, an attachment device may be a medically-acceptable, pressure-sensitive adhesive that extends about a periphery, a portion, or an entire sealing member. Other example embodiments of an attachment device may include a double-sided tape, paste, hydrocolloid, hydrogel, silicone gel, organogel, or an acrylic adhesive.
Container 112 is representative of a container, canister, pouch, or other storage component that can be used to manage exudates and other fluids withdrawn from a tissue site. In many environments, a rigid container may be preferred or required for collecting, storing, and disposing of fluids. In other environments, fluids may be properly disposed of without rigid container storage, and a re-usable container could reduce waste and costs associated with reduced-pressure therapy.
In general, reduced-pressure therapy can be beneficial for wounds of all severity, but the cost and complexity of reduced-pressure therapy systems often limit the application of reduced-pressure therapy to large, highly-exudating wounds present on patients undergoing acute or chronic care, as well as other severe wounds that are not readily susceptible to healing without application of reduced pressure. For example, the complexity of conventional reduced-pressure therapy systems can limit the ability of a person with little or no specialized knowledge from administering reduced-pressure therapy. The size of many reduced-pressure therapy systems may also impair mobility. Many reduced-pressure therapy systems also require careful cleaning after each treatment, and may require electrical components or other powered devices to supply the reduced pressure for treatment. Although some reduced-pressure therapy systems deploy a purely mechanical method for reducing pressure, such systems have been unable to provide adequate control of the level of reduced pressure.
Reduced-pressure therapy system 100 may overcome these shortcomings and others by providing mechanical regulation of therapeutic pressure. In one example embodiment, reduced-pressure therapy system 100 may include a manually-actuated hand pump for reducing pressure. A valve can regulate pressure down to a mechanically pre-determined target pressure and supply this pressure to a sealed therapeutic environment proximate a tissue site via a supply lumen, and a feedback lumen can be fluidly connected to the valve within the pump. Pressure transmitted by the feedback lumen can control the action of the valve, which controls the pressure delivered to the tissue site. Thus, such an embodiment of reduced-pressure therapy system 100 can accurately control the pressure within the sealed therapeutic environment, including offsetting blockage that may occur in a dressing or storage system by further reducing the supplied pressure.
A supply port 212 may fluidly connect supply chamber 204 to a dressing, such as dressing 102 in
A regulator valve 220 can be operably associated with charging port 205 to regulate fluid communication between the charging chamber 202 and supply chamber 204. In some embodiments, regulator valve 220 may include a piston, a valve body, and an elastic member. A piston can be a flexible or movable barrier, for example, illustrated in
In some embodiments, housing 200 may be formed from two components. For example, housing 200 may be formed from a lower housing 200a and a upper housing 200b, as illustrated in
Charging chamber 202 may be generally defined by adjoining walls of housing 200, such as an end wall of housing 200, a side wall or walls of housing 200, and a partition within housing 200, such as chamber wall 207a. Supply chamber 204 may also be generally defined by adjoining walls within housing 200. For example, supply chamber 204 in
Regulator valve 220 in this example can be disposed partially within control chamber 206 and partially within supply chamber 204, with circumferential edges of piston 222 abutting or engaging the side wall or walls of control chamber 206. The interface between piston 222 and the walls of control chamber 206 may also provide a fluid seal, dividing control chamber 206 into a region of ambient pressure 228 and a region of control pressure 230. However, regulator valve 220 may also reciprocate within control chamber 206 while maintaining the fluid seal. For example, regulator valve 220 may additionally include flexible o-rings disposed between piston 222 and the side wall of control chamber 206, and the o-rings may be lubricated so that regulator valve 220 can reciprocate within control chamber 206.
In operation, pressure in supply chamber 204 can be distributed to a remote chamber, environment, or other location through supply port 212. For example, pressure in supply chamber 204 may be distributed to a controlled environment, such as a sealed therapeutic environment associated with reduced-pressure therapy system 100. Control pressure 230 in control chamber 206 can be equalized with the pressure in the remote location through control port 214. In reduced-pressure therapy applications, control pressure 230 should be less than ambient pressure 228, resulting in a pressure differential across regulator valve 220. To simplify further description, the force on regulator valve 220 resulting from the pressure differential on opposing sides of piston 222 may be referred to as a “differential force.” Regulator spring 226 also generally exerts a force on regulator valve 220. In expected operating ranges, the force of regulator spring 226 is directly proportional to the spring constant of regulator spring 226 and to a displacement X (i.e., displacement from a state of equilibrium) of the ends of regulator spring 226. Thus, if control pressure 230 is less than ambient pressure 228, the differential force on piston 222 tends to compress regulator spring 226 and, consequently, the force of regulator spring 226 opposes the differential force. The differential force and the force of regulator spring 226 can be combined to determine a net force acting on regulator valve 220. The net force can cause regulator valve 220 to move reciprocally within control chamber 206, such as along a central axis 231 aligned with charging port 205.
Regulator spring 226 may be selected, adjusted, modified, tuned, or otherwise calibrated so that control pressure 230 must drop below a threshold value (such as a target pressure) before the net force can move regulator valve 220 into a position that closes charging port 205. In some embodiments, for example, piston 222 may rotate within housing 200 to adjust the compression of regulator spring 226. In the embodiment illustrated in
Thus, charging chamber 202 may be charged and the pressure in the therapeutic environment may be controlled based on a differential between the therapy pressure and control pressure 230, by balancing the force of regulator spring 226 and the differential force (i.e., control pressure 230 on one side of piston 222 against ambient pressure 228 on an opposing side of piston 222). For reduced-pressure therapy applications, charging chamber 202 may be charged to a pressure lower than the therapy pressure. In one embodiment, for example, the desired therapy pressure may be about −125 mm Hg and pressure in charging chamber 202 may be reduced to a pressure of about −150 mm Hg.
If regulator valve 220 is calibrated to a particular therapy pressure and control pressure 230 is higher than the therapy pressure, the force of regulator spring 226 should exceed the differential force and the net force should actuate regulator valve 220, moving regulator valve 220 into an open position (see
Referring to
A check valve may be used to allow unidirectional flow out of vacuum chamber 310. For example, an o-ring may seal piston 302 against the side wall of cylinder 308 and a ball check valve in piston 302 may allow fluid to flow out of vacuum chamber 310 through a port in piston 302. In other embodiments, such as the embodiment illustrated in
Piston 302 can reciprocate within cylinder 308 between a compressed position (as illustrated in
In operation, port 314 may be fluidly coupled to a charging chamber, such as charging chamber 202. To reduce pressure in the charging chamber, piston 302 can be moved to the compressed position, which decreases the volume of vacuum chamber 310. Seal 312 allows fluid within vacuum chamber 310 to exit during the compression stroke. After moving piston 302 to the compressed position, piston spring 304 exerts a force on seal 312 that attempts to return piston 302 to the expanded position, which increases the volume of vacuum chamber 310. As the volume of vacuum chamber 310 increases, seal 312 prevents fluid from entering vacuum chamber 310, which reduces the pressure in vacuum chamber 310. The pressure between vacuum chamber 310 and the charging chamber can be equalized through port 314, which results in a pressure reduction in the charging chamber. After piston 302 has moved to an expanded position, piston 302 may be moved again to a compressed position to recharge the charging chamber.
Piston-driven pump 300 may be manually-actuated, or may be actuated by an electrical, hydraulic, or pneumatic actuator, for example. For all of the charging chambers described herein, pressure may be reduced by manual or electrically powered means. In some embodiments, for example, charging chamber 202 may initially be charged or re-charged to a selected reduced pressure by a reduced pressure pump or a vacuum pump driven by an electric motor. In another illustrative embodiment, a wall suction unit (such as are commonly available in hospitals and other medical facilities) may be used to reduce pressure in charging chamber 202 to a selected pressure.
Referring to
Referring more specifically to
Referring again to
A plurality of guides 563 can be disposed on piston 531, and in one embodiment, one of guides 563 may be disposed on each radial support 559. Guides 563 can align piston 531 relative to seal 535 and second barrel 519. Guides 563 can further serve to secure piston 531 to second barrel 519 by means of a friction fit.
In the illustrated embodiment, piston 531 further includes a lower bowl 567 defined by inner wall 551, a partition 569, and an inner floor 571. Piston 531 may also include an upper bowl 568, generally defined by inner wall 551 and partition 569, wherein lower bowl 567 and upper bowl 568 are disposed on opposing sides of partition 569. In one embodiment, inner floor 571 may be two-tiered or multi-tiered, but inner floor 571 may instead be single-tiered and/or substantially planar. Inner floor 571 may also be positioned such that a recess 573 is defined beneath inner floor 571 to receive an end of charging spring 543 (see
A well 583 may also be positioned in annulus 555 of piston 531, and a channel 587 can fluidly connect well 583 and lower bowl 567. Channel 587 can allow fluid communication between well 583 and lower bowl 567.
Referring still to
Skirt portion 595 of seal 535 extends axially from an edge of central portion 591. As illustrated in
As illustrated in more detail in
In one embodiment, both seal 535 and valve body 603 can be made from an elastomeric material, such as a medical grade silicone, for example. While many different materials may be used to construct, form, or otherwise create seal 535 and valve body 603, a flexible material can improve the sealing properties of skirt portion 595 with inner surface 605 and valve body 603 with valve seat 579.
Referring more specifically to
Referring again to
Referring more specifically to
Second housing portion 615 may include an end cap 639 integrally or otherwise connected to a guide 643. Together, end cap 639 and guide 643 may slidingly engage outer shell 619 of first housing portion 611 to create a substantially closed second barrel 519 (with the exception of various apertures and passages). While second barrel 519 may be constructed from fewer components, the existence of first housing portion 611 and second housing portion 615 can allow easier access within second barrel 519 and easier assembly of vacuum pump 402.
In certain example embodiments, a shaft 647 may extend from end cap 639 and can include an engagement end 649 opposite end cap 639. When second barrel 519 is assembled, shaft 647 may be substantially coaxial with a longitudinal axis of second barrel 519 and extend through aperture 631 in floor 627 of first housing portion 611. An elastic member such as spring 651 may be positioned within second barrel 519 such that one end of spring 651 bears upon floor 627 of first housing portion 611 and another end of spring 651 bears upon shaft 647 or another portion of second housing portion 615. Spring 651 can bias shaft 647 and other portions of second housing portion 615 toward a disengaged position (see position of shaft 647 in
When vacuum pump 402 is assembled as illustrated in
While charging port 575 is illustrated as being disposed within piston 531 in this example, charging port 575 could instead be routed through the wall of first barrel 515. Charging port 575 could be any conduit or passage suitable for allowing fluid communication between the chambers.
In operation, vacuum pump 402 can be used with other components of a reduced pressure treatment system similar to those of reduced pressure treatment system 100. Supply port 527 of vacuum pump 402 can be adapted to be connected to a delivery tube or other conduit, for example, which may be fluidly connected to a tissue site. Although a fluid container could be integrated into vacuum pump 402, in some embodiments, vacuum pump 402 may not be intended to collect wound exudates or other fluids within an internal chamber. In certain embodiments, vacuum pump 402 may either be used with low-exudating wounds, or an alternative collection system such as an external canister or absorptive dressing may be used to collect fluids.
Referring to
If the compressive force exerted upon second barrel 519 is removed, the biasing force exerted by charging spring 543 on piston 531 moves piston 531, seal 535, and second barrel 519 toward an expanded position. As this movement occurs, the volume of charging chamber 655 increases. Since skirt portion 595 of seal 535 allows only unidirectional flow, air and other gases are not permitted to enter charging chamber 655 past skirt portion 595. A reduction in pressure (i.e., a generation of reduced pressure) occurs within charging chamber 655 as the volume increases. The pressure reduction within charging chamber 655 is generally dependent on the size of charging chamber 655, range of motion of piston 531, properties of charging spring 543, and the integrity of seal 535. Thus, the pressure limits of charging chamber 655 may be controlled by adjusting these parameters. In some embodiments, for example, a range of motion of piston 531 may be calibrated at so that a complete stroke (i.e., compression and expansion) reduces pressure in charging chamber 655 below a prescribed therapy pressure. For example, if the prescribed therapy pressure is −125 mmHg, a range may be selected to reduce the pressure in charging chamber 655 to −150 mmHg.
In the example embodiment of vacuum pump 402, regulator valve 604 includes seal 535, valve body 603, and regulator spring 607. The operation of regulator valve 604 can be controlled by two forces acting primarily on seal 535. One of the forces is the result of a pressure differential between control pressure 662 and ambient pressure 663. The force resulting from the pressure differential may again be referred to as a “differential force.” Regulator spring 607 also generally exerts another force on regulator valve 604. In expected operating ranges, the force of regulator spring 607 is directly proportional to the spring constant of regulator spring 607 and displacement of the ends of regulator spring 607 from a state of equilibrium. The force exerted by regulator spring 607 is generally in direct opposition to the direction of displacement. Thus, the differential force tends to compress regulator spring 607 if control pressure 662 is less than ambient pressure 663, and the force of regulator spring 607 in a compressed position opposes the differential force. The differential force and the force of regulator spring 607 can be combined to determine a net force acting on regulator valve 604.
Regulator valve 604 can leverage the differential force and the force of regulator spring 607 to regulate a therapy pressure that can be delivered to supply port 527 and a dressing applied to a tissue site. In some embodiments, regulator spring 607 may be tuned based on a prescribed therapy. For example, a spring constant may be selected based on a prescribed therapy pressure, or the compression of regulator spring 607 may be adjusted based on the prescribed therapy pressure. In one illustrative embodiments for example, first barrel 515 and second barrel 519 may be threaded so that second barrel 519 can be rotated to change the compression of regulator spring 607. Since changing the compression of regulator spring 607 changes the force of regulator spring 607 acting on valve body 603, the pressure differential required to actuate regulator valve 607 can also be changed.
Thus, if regulator spring 607 is calibrated to a particular therapy pressure and control pressure 662 in control chamber 661 is higher than the therapy pressure, the force of regulator spring 607 should exceed the differential force and move regulator valve 604 into an open position (see
When vacuum pump 402 is initially connected to a delivery tube and tissue site for treatment, it may be necessary to compress second barrel 519 within first barrel 515 more than once. As each compression stroke is completed, air and other gases may be pulled from the delivery tube and the tissue site until the pressure within the tube and at the tissue site begins to approach the desired therapy pressure.
If second barrel 519 is compressed within first barrel 515, second housing portion 615 can move relative to first housing portion 611 so that shaft 647 exerts a force on valve body 603 that holds valve body 603 in the closed position to prevent positively pressurized gas (such as gas from charging chamber 655) from entering supply chamber 659. Since shaft 647 remains engaged during the entire charging stroke of vacuum pump 402, the air within charging chamber 655 can be vented past seal 535 and not into supply chamber 659.
While in some embodiments of vacuum pump 402, first barrel 515, second barrel 519, piston 531, seal 535, and other components may be cylindrical, the size and/or shape of the components may be varied. Additionally, the relative positions of valve seat 579 and valve body 603 may be reversed such that valve body 603 is positioned below valve seat 579.
It should be apparent from the foregoing that systems, methods, and apparatuses having significant advantages has been described. While shown in only a few forms, the systems, methods, and apparatuses illustrated are susceptible to various changes, modifications, and uses encompassed within the claims that follow.
Claims
1-13. (canceled)
14. A method of regulating therapeutic pressure, the method comprising:
- placing a manifold in a sealed environment proximate to a tissue site;
- fluidly coupling the manifold to a supply chamber through a supply lumen;
- fluidly coupling the manifold to a control chamber through a control lumen;
- fluidly coupling the supply chamber to a charging chamber;
- reducing a charging pressure in the charging chamber below a therapy pressure;
- regulating fluid communication between the supply chamber and the charging chamber based on a differential between a control pressure in the control chamber and the therapy pressure; and
- delivering a supply pressure from the supply chamber to the manifold.
15. The method of claim 14, wherein the supply lumen and the control lumen are disposed in a tube fluidly coupled to the manifold.
16. The method of claim 14, wherein regulating fluid communication between the supply chamber and the charging chamber comprises:
- opening a port between the supply chamber and the charging chamber if the control pressure exceeds the therapy pressure; and
- closing the port if the therapy pressure exceeds the control pressure.
17. The method of claim 14, wherein regulating fluid communication between the supply chamber and the charging chamber comprises:
- actuating a valve to open a port between the supply chamber and the charging chamber if the control pressure exceeds the therapy pressure; and
- actuating the valve to close the port if the therapy pressure exceeds the control pressure.
18. The method of claim 14, wherein:
- the therapy pressure is about −125 mm Hg; and
- the charging pressure is reduced to about −150 mm Hg.
19. The method of claim 14, wherein reducing the charging pressure comprises compressing and expanding the charging chamber.
20. The method of claim 14, wherein regulating fluid communication between the supply chamber and the charging chamber comprises:
- providing a seal between the control pressure and ambient pressure in the control chamber;
- coupling a valve body to the seal, the valve body movable with the seal and having an end adapted to engage a port between the supply chamber and the charging chamber;
- coupling an elastic member to the valve body to bias the seal against the ambient pressure; and
- calibrating the elastic member to the therapy pressure;
- whereby the elastic member actuates the valve body to open the port if the control pressure exceeds the therapy pressure, and actuates the valve body to close the port if the therapy pressure exceeds the control pressure.
21. The method of claim 20, wherein calibrating the elastic member comprises compressing the elastic member.
22. The method of claim 14, further comprising fluidly isolating the charging chamber and the supply chamber from ambient pressure.
23. An apparatus, comprising:
- a supply chamber having a supply port adapted for coupling to a supply lumen;
- a control chamber having a control port adapted for coupling to a feedback lumen;
- a charging chamber fluidly coupled to the supply chamber through a charging port; and
- a regulator valve within the control chamber and operable to move within the control chamber to control fluid communication through the charging port based on a differential between a control pressure in the control chamber and a target pressure.
24. The apparatus of claim 23, wherein the regulator valve comprises a piston and an elastic member adapted to bias the piston against ambient pressure in the control chamber.
25. The apparatus of claim 23, wherein:
- the control chamber is divided into a region of ambient pressure and a region of control pressure;
- the control port is fluidly coupled to the region of control pressure; and
- the regulator valve comprises a piston and an elastic member adapted to bias the piston against the ambient pressure.
26. The apparatus of claim 23, wherein:
- a piston divides ambient pressure from a region of control pressure in the control chamber;
- the control port is fluidly coupled to the region of control pressure; and
- an elastic member is disposed in the control chamber and engaged to the piston.
27. The apparatus of claim 23, wherein the regulator valve comprises:
- a piston;
- a valve body coupled to the piston, the valve body movable with the piston and having an end adapted to engage the charging port; and
- an elastic member coupled to the valve body to bias the piston against ambient pressure in the control chamber.
28. The apparatus of claim 23, wherein the regulator valve comprises:
- a piston;
- a valve body comprising a first end and a second end, wherein the first end is coupled to the piston, the valve body extends into the supply chamber, and the second end is adapted to engage the charging port; and
- an elastic member coupled to the valve body to bias the piston against ambient pressure in the control chamber.
29. The apparatus of claim 23, wherein the regulator valve comprises:
- a piston;
- a valve body comprising a first end and a second end, wherein the first end is coupled to the piston, the valve body extends into the supply chamber, and the second end is adapted to engage the charging port; and
- a coil spring coaxial with the valve body and engaged to the piston to bias the piston against ambient pressure in the control chamber.
30. The apparatus of claim 23, wherein the regulator valve comprises:
- a piston;
- a valve body comprising a first end and a second end, wherein the first end is coupled to the piston, the valve body extends into the supply chamber, and the second end is adapted to engage the charging port; and
- a coil spring coaxial with the valve body and engaged to the valve body to bias the piston against ambient pressure in the control chamber.
31. The apparatus of claim 23, wherein the regulator valve comprises:
- a piston;
- a valve body threaded to the piston, the valve body movable with the piston and having an end adapted to engage the charging port; and
- an elastic member coupled to the valve body to bias the piston against ambient pressure in the control chamber;
- wherein the elastic member may be calibrated to the target pressure by rotating the piston relative to the valve body.
32. The apparatus of claim 23, wherein:
- the charging chamber is fluidly isolated from the supply chamber except through the charging port;
- the charging chamber is fluidly isolated from ambient pressure;
- the supply chamber is fluidly isolated from ambient pressure; and
- the control chamber is fluidly isolated from the charging chamber and the supply chamber.
33. The apparatus of claim 23, wherein:
- the charging chamber comprises a piston opposing a closed end;
- an elastic member is operably engaged to the piston;
- the piston defines a wall of the supply chamber; and
- the charging port is a passage through the piston.
34. The apparatus of claim 23, wherein the control port and the supply port are adapted to engage a multi-lumen tube.
35. An apparatus, comprising:
- a lower housing having an end wall and a side wall;
- a first piston opposite the end wall of the lower housing and engaged to the side wall of the lower housing to define a charging chamber within the lower housing, wherein the first piston comprises a partition separating a lower bowl from an upper bowl;
- a charging spring engaged to the first piston and the end wall of the lower housing;
- a charging port through the first piston;
- a supply chamber defined by the partition and the lower bowl;
- an upper housing having a floor and a side wall, wherein the side wall of the upper housing is coupled to the side wall of the lower housing;
- a control chamber defined by the upper bowl and the floor of the upper housing;
- a second piston opposite the upper bowl and engaged to the side wall of the lower housing, wherein the second piston divides the control chamber into an ambient pressure region and a control pressure region;
- a valve body extending through an aperture in the partition into the supply chamber, the valve body having a first end coupled to the second piston and a second end disposed adjacent to the charging port;
- a regulator spring engaged to the valve body between the charging port and the second piston; and
- a multi-channel port exposed externally through the upper housing, the multi-channel port comprising a supply port fluidly coupled to the supply chamber and a control port fluidly coupled to the control pressure region of the control chamber;
- wherein the multi-channel port is adapted for coupling with a multi-lumen tube.
36. A vacuum pump, comprising:
- a first barrel comprising a closed end, an open end, and an adjoining side wall defining a cylinder;
- a piston slidingly received within the cylinder;
- a second barrel slidingly received within the open end of the first barrel;
- a charging chamber defined by a sealed portion of the cylinder between the piston and the closed end of the first barrel;
- a supply chamber within the piston;
- a control chamber between the piston and the second barrel;
- a seal slidingly received within the cylinder between the piston and the second barrel, wherein the seal divides the control chamber into a region of control pressure and a region of ambient pressure;
- a charging port disposed through the piston to allow fluid communication between the charging chamber and the supply chamber; and
- a regulator valve adapted to be actuated by a differential force on the seal to regulate fluid communication between the supply chamber and the control chamber through the charging port.
37. The vacuum pump of claim 36, wherein:
- the piston comprises a partition separating a lower bowl from an upper bowl;
- the supply chamber is defined by the partition and the lower bowl; and
- the control chamber is defined by the upper bowl and a floor of the second barrel.
Type: Application
Filed: Feb 22, 2019
Publication Date: Jun 20, 2019
Inventors: Richard Daniel John COULTHARD (Verwood), Christopher Brian LOCKE (Bournemouth)
Application Number: 16/283,223