Patent ID: 12251295

DESCRIPTION OF EXAMPLE EMBODIMENTS

The following description of example embodiments provides information that enables a person skilled in the art to make and use the subject matter set forth in the appended claims, but it may omit certain details already well-known in the art. The following detailed description is, therefore, to be taken as illustrative and not limiting.

FIG.1is a block diagram of an example embodiment of a therapy system100that can provide negative-pressure therapy with instillation of topical treatment solutions to a tissue site in accordance with this specification.

The term “tissue site” in this context broadly refers to a wound, defect, or other treatment target located on or within tissue, including but not limited to, a surface wound, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. The term “tissue site” may also refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it may be desirable to add or promote the growth of additional tissue. For example, negative pressure may be applied to a tissue site to grow additional tissue that may be harvested and transplanted. A surface wound, as used herein, is a wound on a body that is exposed to the external environment, such as an injury or damage to the epidermis, dermis, and/or subcutaneous layers. Surface wounds may include ulcers or closed incisions, for example. A surface wound, as used herein, does not include wounds within an intra-abdominal cavity. 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 therapy system100may include a source or supply of negative pressure, such as a negative-pressure source105, and one or more distribution components. A distribution component is preferably detachable and may be disposable, reusable, or recyclable. A dressing, such as a dressing110, and a fluid container, such as a container115, are examples of distribution components that may be associated with some examples of the therapy system100. As illustrated in the example ofFIG.1, the dressing110may comprise or consist essentially of a tissue interface120, a cover125, or both in some embodiments.

A fluid conductor is another illustrative example of a distribution component. A “fluid conductor,” in this context, broadly includes a tube, pipe, hose, conduit, or other structure with one or more lumina or open pathways adapted to convey a fluid between two ends. Typically, a tube is an elongated, cylindrical structure with some flexibility, but the geometry and rigidity may vary. Moreover, some fluid conductors may be molded into or otherwise integrally combined with other components. Distribution components may also include or comprise interfaces or fluid ports to facilitate coupling and de-coupling other components. In some embodiments, for example, a dressing interface may facilitate coupling a fluid conductor to the dressing110. For example, such a dressing interface may be a SENSAT.R.A.C.™ Pad available from Kinetic Concepts, Inc. of San Antonio, Texas.

The therapy system100may also include a regulator or controller, such as a controller130. Additionally, the therapy system100may include sensors to measure operating parameters and provide feedback signals to the controller130indicative of the operating parameters. As illustrated inFIG.1, for example, the therapy system100may include a first sensor135and a second sensor140coupled to the controller130.

The therapy system100may also include a source of instillation solution. For example, a solution source145may be fluidly coupled to the dressing110, as illustrated in the example embodiment ofFIG.1. The solution source145may be fluidly coupled to a positive-pressure source, such as a positive-pressure source150, a negative-pressure source such as the negative-pressure source105, or both in some embodiments. A regulator, such as an instillation regulator155, may also be fluidly coupled to the solution source145and the dressing110to ensure proper dosage of instillation solution (e.g. saline) to a tissue site. For example, the instillation regulator155may comprise a piston that can be pneumatically actuated by the negative-pressure source105to draw instillation solution from the solution source during a negative-pressure interval and to instill the solution to a dressing during a venting interval. Additionally or alternatively, the controller130may be coupled to the negative-pressure source105, the positive-pressure source150, or both, to control dosage of instillation solution to a tissue site. In some embodiments, the instillation regulator155may also be fluidly coupled to the negative-pressure source105through the dressing110, as illustrated in the example ofFIG.1.

Some components of the therapy system100may 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 therapy. For example, in some embodiments, the negative-pressure source105may be combined with the controller130, the solution source145, and other components into a therapy unit.

In general, components of the therapy system100may be coupled directly or indirectly. For example, the negative-pressure source105may be directly coupled to the container115and may be indirectly coupled to the dressing110through the container115. Coupling may include fluid, mechanical, thermal, electrical, or chemical coupling (such as a chemical bond), or some combination of coupling in some contexts. For example, the negative-pressure source105may be electrically coupled to the controller130and may be fluidly coupled to one or more distribution components to provide a fluid path to a tissue site. In some embodiments, components may also be coupled by virtue of physical proximity, being integral to a single structure, or being formed from the same piece of material.

A negative-pressure supply, such as the negative-pressure source105, may be a reservoir of air at a negative pressure or may be a manual or electrically-powered device, such as a vacuum pump, a suction pump, a wall suction port available at many healthcare facilities, or a micro-pump, for example. “Negative 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. In many cases, the local ambient pressure may also be the atmospheric pressure at which a tissue site is located. 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. References to increases in negative pressure typically refer to a decrease in absolute pressure, while decreases in negative pressure typically refer to an increase in absolute pressure. While the amount and nature of negative pressure provided by the negative-pressure source105may vary according to therapeutic requirements, the pressure is generally a low vacuum, also commonly referred to as a rough vacuum, between −5 mm Hg (−667 Pa) and −500 mm Hg (−66.7 kPa). Common therapeutic ranges are between −50 mm Hg (−6.7 kPa) and −300 mm Hg (−39.9 kPa).

The container115is representative of a container, canister, pouch, or other storage component, which 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 negative-pressure therapy.

A controller, such as the controller130, may be a microprocessor or computer programmed to operate one or more components of the therapy system100, such as the negative-pressure source105. In some embodiments, for example, the controller130may be a microcontroller, which generally comprises an integrated circuit containing a processor core and a memory programmed to directly or indirectly control one or more operating parameters of the therapy system100. Operating parameters may include the power applied to the negative-pressure source105, the pressure generated by the negative-pressure source105, or the pressure distributed to the tissue interface120, for example. The controller130is also preferably configured to receive one or more input signals, such as a feedback signal, and programmed to modify one or more operating parameters based on the input signals.

Sensors, such as the first sensor135and the second sensor140, are generally known in the art as any apparatus operable to detect or measure a physical phenomenon or property, and generally provide a signal indicative of the phenomenon or property that is detected or measured. For example, the first sensor135and the second sensor140may be configured to measure one or more operating parameters of the therapy system100. In some embodiments, the first sensor135may be a transducer configured to measure pressure in a pneumatic pathway and convert the measurement to a signal indicative of the pressure measured. In some embodiments, for example, the first sensor135may be a piezo-resistive strain gauge. The second sensor140may optionally measure operating parameters of the negative-pressure source105, such as a voltage or current, in some embodiments. Preferably, the signals from the first sensor135and the second sensor140are suitable as an input signal to the controller130, but some signal conditioning may be appropriate in some embodiments. For example, the signal may need to be filtered or amplified before it can be processed by the controller130. Typically, the signal is an electrical signal, but may be represented in other forms, such as an optical signal.

The tissue interface120can be generally adapted to partially or fully contact a tissue site. The tissue interface120may take many forms, and may have 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 the tissue interface120may be adapted to the contours of deep and irregular shaped tissue sites. Any or all of the surfaces of the tissue interface120may have an uneven, coarse, or jagged profile.

In some embodiments, the tissue interface120may comprise or consist essentially of a manifold. A manifold in this context may comprise or consist essentially of a means for collecting or distributing fluid across the tissue interface120under pressure. For example, a manifold may be adapted to receive negative pressure from a source and distribute negative pressure through multiple apertures across the tissue interface120, which may have the effect of collecting fluid from across a tissue site and drawing the fluid toward the source. In some embodiments, the fluid path may be reversed or a secondary fluid path may be provided to facilitate delivering fluid, such as fluid from a source of instillation solution, across a tissue site.

In some embodiments, the cover125may provide a bacterial barrier and protection from physical trauma. The cover125may also be constructed from a material that can reduce evaporative losses and provide a fluid seal between two components or two environments, such as between a therapeutic environment and a local external environment. The cover125may comprise or consist of, for example, an elastomeric film or membrane that can provide a seal adequate to maintain a negative pressure at a tissue site for a given negative-pressure source. The cover125may have a high moisture-vapor transmission rate (MVTR) in some applications. For example, the MVTR may be at least 250 grams per square meter per twenty-four hours in some embodiments, measured using an upright cup technique according to ASTM E96/E96M Upright Cup Method at 38° C. and 10% relative humidity (RH). In some embodiments, an MVTR up to 5,000 grams per square meter per twenty-four hours may provide effective breathability and mechanical properties.

In some example embodiments, the cover125may be a polymer drape, such as a polyurethane film, that is permeable to water vapor but impermeable to liquid. Such drapes typically have a thickness in the range of 25-50 microns. For permeable materials, the permeability generally should be low enough that a desired negative pressure may be maintained. The cover125may comprise, for example, one or more of the following materials: polyurethane (PU), such as hydrophilic polyurethane; cellulosics; hydrophilic polyamides; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic acrylics; silicones, such as hydrophilic silicone elastomers; natural rubbers; polyisoprene; styrene butadiene rubber; chloroprene rubber; polybutadiene; nitrile rubber; butyl rubber; ethylene propylene rubber; ethylene propylene diene monomer; chlorosulfonated polyethylene; polysulfide rubber; ethylene vinyl acetate (EVA); co-polyester; and polyether block polyamide copolymers. Such materials are commercially available as, for example, Tegaderm® drape, commercially available from 3M Company, Minneapolis Minnesota; polyurethane (PU) drape; polyether block polyamide copolymer (PEBAX), for example; and INSPIRE 2301 and INSPIRE 2327 polyurethane films, commercially available from Expopack Advanced Coatings, Wrexham, United Kingdom. In some embodiments, the cover125may comprise INSPIRE 2301 having an MVTR (upright cup technique) of 2600 g/m2/24 hours and a thickness of about 30 microns.

An attachment device may be used to attach the cover125to an attachment surface, such as undamaged epidermis, a gasket, or another cover. The attachment device may take many forms. For example, an attachment device may be a medically-acceptable, pressure-sensitive adhesive configured to bond the cover125to epidermis around a tissue site. In some embodiments, for example, some or all of the cover125may be coated with an adhesive, such as an acrylic adhesive, which may have a coating weight of about 25-65 grams per square meter (g.s.m.). Thicker adhesives, or combinations of adhesives, may be applied in some embodiments to improve the seal and reduce leaks. Other example embodiments of an attachment device may include a double-sided tape, paste, hydrocolloid, hydrogel, silicone gel, or organogel.

The solution source145may also be representative of a container, canister, pouch, bag, or other storage component, which can provide a solution for instillation therapy. Compositions of solutions may vary according to a prescribed therapy, but examples of solutions that may be suitable for some prescriptions include hypochlorite-based solutions, silver nitrate (0.5%), sulfur-based solutions, biguanides, cationic solutions, and isotonic solutions.

In operation, the tissue interface120may be placed within, over, on, or otherwise proximate to a tissue site. If the tissue site is a wound, for example, the tissue interface120may partially or completely fill the wound, or it may be placed over the wound. The cover125may be placed over the tissue interface120and sealed to an attachment surface near a tissue site. For example, the cover125may be sealed to undamaged epidermis peripheral to a tissue site. Thus, the dressing110can provide a sealed therapeutic environment proximate to a tissue site, substantially isolated from the external environment, and the negative-pressure source105can reduce pressure in the sealed therapeutic environment.

The fluid mechanics of using a negative-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 negative-pressure therapy and instillation 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” negative pressure, for example.

In general, exudate and other fluid flow toward lower pressure along a fluid path. Thus, the term “downstream” may refer to a location in a fluid path relatively closer to a source of negative pressure or further away from a source of positive pressure. Conversely, the term “upstream” may refer to a location further away from a source of negative pressure or closer to a source of positive pressure. Similarly, it may be convenient to describe certain features in terms of fluid “inlet” or “outlet” in such a frame of reference. This orientation is generally presumed for purposes of describing various features and components herein. However, the fluid path may also be reversed in some applications, such as by substituting a positive-pressure source for a negative-pressure source.

Negative pressure applied across the tissue site through the tissue interface120in the sealed therapeutic environment can induce macro-strain and micro-strain in the tissue site. Negative pressure can also remove exudate and other fluid from a tissue site, which can be collected in container115.

In some embodiments, the controller130may receive and process data from one or more sensors, such as the first sensor135. The controller130may also control the operation of one or more components of the therapy system100to manage the pressure delivered to the tissue interface120. In some embodiments, controller130may include an input for receiving a desired target pressure and may be programmed for processing data relating to the setting and inputting of the target pressure to be applied to the tissue interface120. In some example embodiments, the target pressure may be a fixed pressure value set by an operator as the target negative pressure desired for therapy at a tissue site and then provided as input to the controller130. The target pressure may vary from tissue site to tissue site based on the type of tissue forming a tissue site, the type of injury or wound (if any), the medical condition of the patient, and the preference of the attending physician. After selecting a desired target pressure, the controller130can operate the negative-pressure source105in one or more control modes based on the target pressure and may receive feedback from one or more sensors to maintain the target pressure at the tissue interface120.

In some embodiments, the controller130may have a continuous pressure mode, in which the negative-pressure source105is operated to provide a constant target negative pressure for the duration of treatment or until manually deactivated. Additionally or alternatively, the controller may have an intermittent pressure mode. For example, the controller130can operate the negative-pressure source105to cycle between a target pressure and atmospheric pressure. For example, the target pressure may be set at a value of 135 mmHg for a specified period of time (e.g., 5 min), followed by a specified period of time (e.g., 2 min) of deactivation. The cycle can be repeated by activating the negative-pressure source105, which can form a square wave pattern between the target pressure and atmospheric pressure.

In some example embodiments, the increase in negative-pressure from ambient pressure to the target pressure may not be instantaneous. For example, the negative-pressure source105and the dressing110may have an initial rise time. The initial rise time may vary depending on the type of dressing and therapy equipment being used. For example, some therapy systems may increase negative pressure at a rate of about 20-30 mmHg/second, and other therapy systems may increase negative pressure at a rate of about 5-10 mmHg/second. If the therapy system100is operating in an intermittent mode, the repeating rise time may be a value substantially equal to the initial rise time.

In some example dynamic pressure control modes, the target pressure can vary with time. For example, the target pressure may vary in the form of a triangular waveform, varying between a negative pressure of 50 and 135 mmHg with a rise rate of negative pressure set at a rate of 25 mmHg/min. and a descent rate set at 25 mmHg/min. In other embodiments of the therapy system100, the triangular waveform may vary between negative pressure of 25 and 135 mmHg with a rise rate of about 30 mmHg/min and a descent rate set at about 30 mmHg/min.

In some embodiments, the controller130may control or determine a variable target pressure in a dynamic pressure mode, and the variable target pressure may vary between a maximum and minimum pressure value that may be set as an input prescribed by an operator as the range of desired negative pressure. The variable target pressure may also be processed and controlled by the controller130, which can vary the target pressure according to a predetermined waveform, such as a triangular waveform, a sine waveform, or a saw-tooth waveform. In some embodiments, the waveform may be set by an operator as the predetermined or time-varying negative pressure desired for therapy.

In some embodiments, the controller130may receive and process data, such as data related to instillation solution provided to the tissue interface120. Such data may include the type of instillation solution prescribed by a clinician, the volume of fluid or solution to be instilled to a tissue site (“fill volume”), and the amount of time prescribed for leaving solution at a tissue site (“dwell time”) before applying a negative pressure to the tissue site. The fill volume may be, for example, between 10 and 500 mL, and the dwell time may be between one second to 30 minutes. The controller130may also control the operation of one or more components of the therapy system100to instill solution. For example, the controller130may manage fluid distributed from the solution source145to the tissue interface120. In some embodiments, fluid may be instilled to a tissue site by applying a negative pressure from the negative-pressure source105to reduce the pressure at the tissue site, drawing solution into the tissue interface120. In some embodiments, solution may be instilled to a tissue site by applying a positive pressure from the positive-pressure source150to move solution from the solution source145to the tissue interface120. Additionally or alternatively, the solution source145may be elevated to a height sufficient to allow gravity to move solution into the tissue interface120.

The controller130may also control the fluid dynamics of instillation by providing a continuous flow of solution or an intermittent flow of solution. Negative pressure may be applied to provide either continuous flow or intermittent flow of solution. The application of negative pressure may be implemented to provide a continuous pressure mode of operation to achieve a continuous flow rate of instillation solution through the tissue interface120, or it may be implemented to provide a dynamic pressure mode of operation to vary the flow rate of instillation solution through the tissue interface120. Alternatively, the application of negative pressure may be implemented to provide an intermittent mode of operation to allow instillation solution to dwell at the tissue interface120. In an intermittent mode, a specific fill volume and dwell time may be provided depending, for example, on the type of tissue site being treated and the type of dressing being utilized. After or during instillation of solution, negative-pressure treatment may be applied. The controller130may be utilized to select a mode of operation and the duration of the negative pressure treatment before commencing another instillation cycle.

FIG.2is an exploded view of an example of the tissue interface120ofFIG.1, illustrating additional details that may be associated with some embodiments in which the tissue interface120comprises more than one layer. In the example ofFIG.2, the tissue interface comprises a first layer, such as a contact layer205, and a second layer, such as a manifold layer210. In some embodiments, the contact layer205may be disposed adjacent to the manifold layer210. For example, the contact layer205and the manifold layer210may be stacked so that the contact layer205is in contact with the manifold layer210. The contact layer205may also be heat-bonded or adhered to the manifold layer210in some embodiments. In some embodiments, the contact layer205optionally includes a low-tack adhesive, which can be configured to hold the tissue interface120in place while the cover125is applied. The low-tack adhesive may be continuously coated on the contact layer205or applied in a pattern.

The contact layer205may comprise or consist essentially of a means for controlling or managing fluid flow. In some embodiments, the contact layer205may be a fluid control layer comprising or consisting essentially of a liquid-impermeable, elastomeric material. For example, the contact layer205may comprise or consist essentially of a polymer film, such as a polyurethane film. In some embodiments, the contact layer205may comprise or consist essentially of the same material as the cover125. The contact layer205may also have a smooth or matte surface texture in some embodiments. A glossy or shiny finish finer or equal to a grade B3 according to the SPI (Society of the Plastics Industry) standards may be particularly advantageous for some applications. In some embodiments, variations in surface height may be limited to acceptable tolerances. For example, the surface of the contact layer205may have a substantially flat surface, with height variations limited to 0.2 millimeters over a centimeter.

In some embodiments, the contact layer205may be hydrophobic. The hydrophobicity of the contact layer205may vary, but may have a contact angle with water of at least ninety degrees in some embodiments. In some embodiments the contact layer205may have a contact angle with water of no more than 150 degrees. For example, in some embodiments, the contact angle of the contact layer205may be in a range of at least 90 degrees to about 120 degrees, or in a range of at least 120 degrees to 150 degrees. Water contact angles can be measured using any standard apparatus. Although manual goniometers can be used to visually approximate contact angles, contact angle measuring instruments can often include an integrated system involving a level stage, liquid dropper such as a syringe, camera, and software designed to calculate contact angles more accurately and precisely, among other things. Non-limiting examples of such integrated systems may include the FTÅ125, FTÅ200, FTÅ2000, and FTÅ4000 systems, all commercially available from First Ten Angstroms, Inc., of Portsmouth, VA, and the DTA25, DTA30, and DTA100 systems, all commercially available from Kruss GmbH of Hamburg, Germany. Unless otherwise specified, water contact angles herein are measured using deionized and distilled water on a level sample surface for a sessile drop added from a height of no more than 5 cm in air at 20-25° C. and 20-50% relative humidity. Contact angles herein represent averages of 5-9 measured values, discarding both the highest and lowest measured values. The hydrophobicity of the contact layer205may be further enhanced with a hydrophobic coating of other materials, such as silicones and fluorocarbons, either as coated from a liquid, or plasma coated.

The contact layer205may also be suitable for welding to other layers, including the manifold layer210. For example, the contact layer205may be adapted for welding to polyurethane foams using heat, radio frequency (RF) welding, or other methods to generate heat such as ultrasonic welding. RF welding may be particularly suitable for more polar materials, such as polyurethane, polyamides, polyesters and acrylates. Sacrificial polar interfaces may be used to facilitate RF welding of less polar film materials, such as polyethylene.

The area density of the contact layer205may vary according to a prescribed therapy or application. In some embodiments, an area density of less than 40 grams per square meter may be suitable, and an area density of about 20-30 grams per square meter may be particularly advantageous for some applications.

In some embodiments, for example, the contact layer205may comprise or consist essentially of a hydrophobic polymer, such as a polyethylene film. The simple and inert structure of polyethylene can provide a surface that interacts little, if any, with biological tissues and fluids, providing a surface that may encourage the free flow of liquids and low adherence, which can be particularly advantageous for many applications. Other suitable polymeric films include polyurethanes, acrylics, polyolefin (such as cyclic olefin copolymers), polyacetates, polyamides, polyesters, copolyesters, PEBAX block copolymers, thermoplastic elastomers, thermoplastic vulcanizates, polyethers, polyvinyl alcohols, polypropylene, polymethylpentene, polycarbonate, styreneics, silicones, fluoropolymers, and acetates. A thickness between 20 microns and 100 microns may be suitable for many applications. Films may be clear, colored, or printed. More polar films suitable for laminating to a polyethylene film include polyamide, co-polyesters, ionomers, and acrylics. To aid in the bond between a polyethylene and polar film, tie layers may be used, such as ethylene vinyl acetate, or modified polyurethanes. An ethyl methyl acrylate (EMA) film may also have suitable hydrophobic and welding properties for some configurations.

The contact layer205may have one or more passages, which can be distributed uniformly or randomly across the contact layer205. The passages may be bi-directional and pressure-responsive. For example, each of the passages generally may comprise or consist essentially of an elastic passage that is normally unstrained to substantially reduce liquid flow, and can expand or open in response to a pressure gradient. As illustrated in the example ofFIG.2, the passages may comprise or consist essentially of perforations215in the contact layer205. Perforations215may be formed by removing material from the contact layer205. For example, perforations215may be formed by cutting through the contact layer205. In the absence of a pressure gradient across the perforations215, the perforations215may be sufficiently small to form a seal or fluid restriction, which can substantially reduce or prevent liquid flow. Additionally, or alternatively, one or more of the passages may be or may function as an elastomeric valve that is normally closed when unstrained to substantially prevent liquid flow, and can open in response to a pressure gradient. In some examples, the passages may comprise or consist essentially of fenestrations in the contact layer205. Generally, fenestrations are a species of perforation, and may also be formed by removing material from the contact layer205. The amount of material removed and the resulting dimensions of the fenestrations may be up to an order of magnitude less than perforations.

In some embodiments, the perforations215may be formed as slots (or fenestrations formed as slits) in the contact layer205. In some examples, the perforations215may comprise or consist of linear slots having a length less than 4 millimeters and a width less than 1 millimeter. The length may be at least 2 millimeters, and the width may be at least 0.4 millimeters in some embodiments. A length of about 3 millimeters and a width of about 0.8 millimeters may be particularly suitable for many applications, and a tolerance of about 0.1 millimeter may also be acceptable. Such dimensions and tolerances may be achieved with a laser cutter, for example. Slots of such configurations may function as imperfect elastomeric valves that can substantially reduce liquid flow in a normally closed or resting state. For example, such slots may form a flow restriction without being completely closed or sealed. The slots can expand or open wider in response to a pressure gradient to allow increased liquid flow.

The manifold layer210generally comprises or consists essentially of a manifold220and one or more strips of spacer fabric225coupled to the manifold220. The manifold220can provide a means for collecting or distributing fluid across the tissue interface120under pressure. For example, the manifold220may be adapted to receive negative pressure from a source and distribute negative pressure through multiple apertures across the tissue interface120, which may have the effect of collecting fluid from across a tissue site and drawing the fluid toward the source. In some embodiments, the fluid path may be reversed or a secondary fluid path may be provided to facilitate delivering fluid, such as from a source of instillation solution, across the tissue interface120.

In some illustrative embodiments, the pathways of the manifold220may be interconnected to improve distribution or collection of fluids. In some illustrative embodiments, the manifold220may comprise or consist essentially of a porous material having interconnected fluid pathways. Examples of suitable porous material that comprise or can be adapted to form interconnected fluid pathways (e.g., channels) may include cellular foam, including open-cell foam such as reticulated foam; porous tissue collections; and other porous material such as gauze or felted mat that generally include pores, edges, and/or walls. Liquids, gels, and other foams may also include or be cured to include apertures and fluid pathways. In some embodiments, the manifold220may additionally or alternatively comprise projections that form interconnected fluid pathways. For example, the manifold220may be molded to provide surface projections that define interconnected fluid pathways.

In some embodiments, the manifold220may comprise or consist essentially of a reticulated foam having pore sizes and free volume that may vary according to needs of a prescribed therapy. For example, a reticulated foam having a free volume of at least 90% may be suitable for many therapy applications, and a foam having an average pore size in a range of 400-600 microns may be particularly suitable for some types of therapy. The tensile strength of the manifold220may also vary according to needs of a prescribed therapy. For example, the tensile strength of a foam may be increased for instillation of topical treatment solutions. The 25% compression load deflection of the manifold220may be at least 0.35 pounds per square inch, and the 65% compression load deflection may be at least 0.43 pounds per square inch. In some embodiments, the tensile strength of the manifold220may be at least 10 pounds per square inch. The manifold220may have a tear strength of at least 2.5 pounds per inch. In some embodiments, the manifold220may be a foam comprised of polyols such as polyester or polyether, isocyanate such as toluene diisocyanate, and polymerization modifiers such as amines and tin compounds. In some examples, the manifold layer210may be a reticulated polyurethane foam such as used in GRANUFOAM™ dressing or V.A.C. VERAFLO™ dressing, both available from KCI of San Antonio, Texas.

As further shown inFIG.2, the manifold220includes a first side230configured to face a tissue site, a second side235opposite the first side230, and a thickness TMbetween the first side230and the second side235. In some embodiments, the manifold220may comprise one or more manifold portions240. In some embodiments, the manifold portions240may be connected to one another. In other embodiments, the manifold portions240may be discontinuous.

FIG.3andFIG.3Aillustrate an example of the manifold layer210that can be associated with some embodiments of the tissue interface120ofFIG.2.FIG.3is a top view of the manifold layer210.FIG.3Ais a top detail view of the manifold layer210ofFIG.3. As shown inFIG.3, the manifold220may have a length LMand a width WM. The strips of spacer fabric225may extend across the manifold220in an extension direction DE. In some embodiments, the extension direction DEof the strips of spacer fabric225may be parallel to the width WMof the manifold220. In some embodiments, extension direction DEof the strips of spacer fabric225may be at an angle with respect to the width WMof the manifold220. As shown in the example ofFIG.3, in some embodiments, the strips of spacer fabric225may be parallel to one another and may be parallel to the width WMof the manifold220. In some embodiments, the strips of spacer fabric225may be parallel to one another and may be at an angle with respect to the width WMof the manifold220.

Each strip of spacer fabric225may comprise a first layer305, a second layer310, and a spacer layer315extending between the first layer305and the second layer310. Each strip of spacer fabric225may have a thickness TSfrom the first layer305to the second layer310. The first layer305may comprise a first fabric and the second layer310may comprise a second fabric. For example, the first layer305and the second layer310may each comprise a knit fabric. In some embodiments, the first layer305and the second layer310may each comprise a woven fabric. For example, the first layer305and the second layer310may each comprise a warp knitted fabric using one or more yarns. In some embodiments, the first layer305and the second layer310may comprise polyester yarn.

The first layer305and the second layer310may comprise multifilament yarns. For example, in some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have about 30 to about 150 filaments. In some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have about 50 to about 150 filaments. In some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have about 36 filaments. In some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have about 48 filaments. In some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have about 100 filaments. In some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have about 138 filaments.

In some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have a denier per filament of about 1 to about 6. In some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have a denier per filament of about 1.5. In some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have a denier per filament of about 2.4. In some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have a denier per filament of about 3.4. In some embodiments, the multifilament yarns used to form the first layer305and the second layer310may have a denier per filament of about 5.5.

The first layer305and the second layer310may each have a thickness of about 0.10 inches to about 0.30 inches. In some embodiments, the first layer305and the second layer310may each have a thickness of about 0.12 inches. In some embodiments, the first layer305and the second layer310may each have a thickness of about 0.15 inches. In some embodiments, the first layer305and the second layer310may each have a thickness of about 0.17 inches. In some embodiments, the first layer305and the second layer310may each have a thickness of about 0.25 inches.

The first layer305and the second layer310may each have a weight per unit area of about 5.0 ounces/yard2to about 25.0 ounces/yard2. In some embodiments, the first layer305and the second layer310may each have a weight per unit area of about 8.4 ounces/yard2. In some embodiments, the first layer305and the second layer310may each have a weight per unit area of about 10.2 ounces/yard2. In some embodiments, the first layer305and the second layer310may each have a weight per unit area of about 12.5 ounces/yard2. In some embodiments, the first layer305and the second layer310may each have a weight per unit area of about 22.8 ounces/yard2.

As shown in the example ofFIG.3A, the spacer layer315may comprise one or more pile yarns320extending between the first layer305and the second layer310. The pile yarns320may be interknitted with the first layer305and the second layer310. The first layer305and the second layer310may be integrated with one another by the pile yarns320. In some embodiments, the first layer305and the second layer310may be connected by a single pile yarn320. In some embodiments, each pile yarn320comprises monofilament yarn. In some embodiments, the pile yarn320may comprise polyester yarn. In some embodiments, the pile yarn320may have a denier per filament of about 30 to about 250. In some embodiments, the pile yarn320may have a denier per filament of about 32.9. In some embodiments, the pile yarn320may have a denier per filament of about 37.7. In some embodiments, the pile yarn320may have a denier per filament of about 107.9. In some embodiments, the pile yarn320may have a denier per filament of about 209.1.

In some embodiments, the first layer305and the second layer310may comprise multifilament polyester yarn having 138 filaments with a denier per filament of 1.5 and the pile yarn320may comprise a monofilament polyester yarn having a denier per filament of 37.7. In some embodiments, the first layer305and the second layer310may comprise multifilament polyester yarn having 100 filaments with a denier per filament of 3.4 and the pile yarn320may comprise a monofilament polyester yarn having a denier per filament of 209.1. In some embodiments, the first layer305and the second layer310may comprise multifilament polyester yarn having 36 filaments with a denier per filament of 2.4 and the pile yarn320may comprise a monofilament polyester yarn having a denier per filament of 32.9. In some embodiments, the first layer305and the second layer310may comprise multifilament polyester yarn having 48 filaments with a denier per filament of 5.5 and the pile yarn320may comprise a monofilament polyester yarn having a denier per filament of 107.9.

The one or more strips of spacer fabric225may be connective structures that couple the manifold portions240together. There may be a manifold portion240between each strip of spacer fabric225. The first layer305and the second layer310of each strip of spacer fabric225may be coupled to the manifold220in a variety of ways. For example, in some embodiments, the first layer305and the second layer310may be coupled to the manifold220with glue. In some embodiments, the first layer305and the second layer310may be coupled to the manifold220using a hot melt adhesive. In some embodiments, the first layer305and the second layer310may be welded to the manifold220using heat, radio frequency (RF) welding, or other methods to generate heat such as ultrasonic welding.

FIG.4is a side view of the manifold layer210ofFIG.3.FIG.4Ais a detail view of the manifold layer210ofFIG.3. As illustrated inFIG.4andFIG.4A, in some embodiments, the first layer305and the second layer310of each strip of spacer fabric225may be oriented perpendicular to the first side230and the second side235of the manifold220. The first layer305may form a first side of the strip of spacer fabric225and the second layer310may form a second side of the strip of spacer fabric225. The first side of each strip of spacer fabric225may be positioned perpendicular to the first side230and the second side235of the manifold220. The second side of each strip of spacer fabric225may be positioned perpendicular to the first side230and the second side235of the manifold220. The first layer305and the second layer310of each strip of spacer fabric225may be positioned in a plane parallel to the thickness TMof the manifold220. The spacer layer315may maintain the first layer305and the second layer310in a spaced-apart parallel relation. As shown inFIG.4A, the thickness TSof each strip of spacer fabric225may be perpendicular to the thickness TMof the manifold220.

Referring again toFIG.3, in some embodiments, the one or more strips of spacer fabric225may function as a manifold, for example, the spacer fabric225may be adapted to receive negative pressure from a source and distribute negative pressure through and/or between the first layer305, the second layer310, and the pile yarns320. In some embodiments, if the manifold layer210is subjected to negative pressure, fluid may be removed from between the first layer305and the second layer310of each spacer fabric225, drawing the first layer305and the second layer310toward one another, and reducing the thickness TSbetween the first layer305and the second layer310. Any manifold portions240coupled to the strips of spacer fabric225are likewise configured to be drawn toward one another if the manifold layer210is subjected to negative pressure. In some embodiments, the each of the strips of spacer fabric225may be more rigid along the extension direction DEthan in a direction perpendicular to the extension direction DE, the first layer305, and the second layer310. The strips of spacer fabric225may be configured to resist contraction parallel to the extension direction DEand may direct contraction perpendicular to the extension direction DE. If a manifold is subjected to negative pressure, it may tend to collapse or contract in all directions. The one or more strips of spacer fabric225may provide anisotropic properties to the manifold layer210. In some embodiments, the manifold layer210may be configured to anisotropically contract such that the manifold layer210contracts more in a first direction than in a second direction, wherein the first direction is perpendicular to the extension direction DEof the strip of spacer fabric225. As shown in the example ofFIG.3, wherein the extension direction DEof the strip of spacer fabric225is parallel to the width WMof the manifold220, the strip of spacer fabric225may be configured to bias against contraction of the manifold220parallel to the width WMof the manifold220and the strip of spacer fabric225may be configured to direct contraction of the manifold perpendicular to the width WMof the manifold220. The one or more strips of spacer fabric225may cause greater contraction along the length LMof the manifold220than along the width WMof the manifold220.

The properties of the one or more strips of spacer fabric225may be selected to tune the performance of the manifold layer210as desired for a particular therapy. For example, the anisotropic properties of the manifold layer210can be increased or decreased by modifying one or more of the thickness of the first layer305and the second layer310, the thickness TSbetween the first layer305and the second layer310, and the filament material, the number of filaments, the weight of the filaments, and the denier per filament used to manufacture the first layer305, the second layer310, and the pile yarn320.

FIG.5andFIG.5Aillustrate another example of the manifold layer210that can be associated with some embodiments of the tissue interface120ofFIG.2.FIG.5is an exploded view of an example of the manifold layer210.FIG.5Ais an assembled detail side view of the manifold layer210. As shown inFIG.5, in some embodiments, the manifold220may include one or more channels505extending into the manifold220on the second side235. The channel505may include a first wall510, a second wall515opposite the first wall510and a base wall520extending between the first wall510and the second wall515. The first wall510and the second wall515may be perpendicular to the first side230and the second side235of the manifold220. The first wall510and the second wall515may be parallel to the thickness TMof the manifold220. The base wall520may be parallel to the first side230and the second side235of the manifold220. The base wall520may be perpendicular to the thickness TMof the manifold220.

The channel505may have a width WCmeasured between the first wall510and the second wall515. The channel505may have a depth DCmeasured from the second side235of the manifold220to the base wall520of the channel505. In some embodiments, the depth DCof the channel505may be less than the thickness TMof the manifold220. For example, the depth DCof the channel505may be about 95% of the thickness TMof the manifold220. In another example, the depth DCof the channel505may be about 75% of the thickness TMof the manifold220. In yet another example, the depth DCof the channel505may be about 50% of the thickness TMof the manifold220. In yet another example, the depth DCof the channel505may be about 25% of the thickness TMof the manifold220. In some embodiments, the depth DCof the channel505may be equal to the thickness TMof the manifold220. In embodiments where the depth DCof the channel505is equal to the thickness TMof the manifold220, the channel505has no base wall520and forms a cut through the manifold220. The thickness TSof the strip of spacer fabric225may be equal to the width WCof the channel505. The strip of spacer fabric225may have a depth DS, which, in some embodiments, may be equal to the depth DCof the channel505.

As illustrated inFIG.5A, the strip of spacer fabric225may be disposed in the channel505, with the first layer305of the strip of spacer fabric225coupled to the first wall510of the channel505and the second layer310of the strip of spacer fabric225coupled to the second wall515of the channel505. In some embodiments, the strip of spacer fabric225may be coextensive with the channel505.

FIG.6is a top view of another example of the manifold layer210that can be associated with some embodiments of the tissue interface120ofFIG.2. In some embodiments, the manifold layer210may include a plurality of strips of spacer fabric225wherein some or all of the strips of spacer fabric225are oriented at an angle with respect to one another. For example, as shown inFIG.6, the manifold layer210may include a first strip of spacer fabric225a, a second strip of spacer fabric225b, a third strip of spacer fabric225c, a fourth strip of spacer fabric225d, and a fifth strip of spacer fabric225e. The first strip of spacer fabric225amay be at an angle θ1with respect to the second strip of spacer fabric225b, the second strip of spacer fabric225bmay be at an angle θ2with respect to the third strip of spacer fabric225c, the third strip of spacer fabric225cmay be at an angle θ3with respect to the fourth strip of spacer fabric225d, and the fourth strip of spacer fabric225dmay be at an angle θ4with respect to the fifth strip of spacer fabric225e. In some embodiments, some or all of the angles θ1, θ2, θ3, θ4, may be equal. In some embodiments, some or all of the angles θ1, θ2, θ3, θ4, may be different. In some embodiments, the first strip of spacer fabric225a, the second strip of spacer fabric225b, the third strip of spacer fabric225c, the fourth strip of spacer fabric225d, and the fifth strip of spacer fabric225emay be identical to the strip of spacer fabric225. In some embodiments, the first strip of spacer fabric225a, the second strip of spacer fabric225b, the third strip of spacer fabric225c, the fourth strip of spacer fabric225d, and the fifth strip of spacer fabric225emay all have the same properties (e.g., the thickness of the first layer305and the second layer310, the thickness TSof the strip of spacer fabric225, and the filament material, the number of filaments, the weight of the filaments, and the denier per filament used to manufacture the first layer305, the second layer310, and the pile yarn320). In some embodiments, one or more of the first strip of spacer fabric225a, the second strip of spacer fabric225b, the third strip of spacer fabric225c, the fourth strip of spacer fabric225d, and the fifth strip of spacer fabric225emay have different properties. The strips of spacer fabric225may be oriented in the manifold220in any way as may be desired for therapy. For example, a non-parallel arrangement of the strips of spacer fabric225may allow for preferential contraction in certain areas of the tissue interface120to allow the tissue interface120to conform around or to specific geometries or anatomies.

FIG.7andFIG.8illustrate another example of the manifold layer210that can be associated with some embodiments of the tissue interface120ofFIG.2.FIG.7is a top view of another example of the manifold layer210.FIG.8is a side view of the manifold layer210ofFIG.7. As shown inFIG.7, the manifold layer210may comprise or consist essentially of a plurality of strips of spacer fabric225, wherein each strip of spacer fabric225is coupled directly to one or more adjacent strips of spacer fabric225. For example, the first layer305of one strip of spacer fabric225may be coupled directly to the second layer310of an adjacent strip of spacer fabric225. As shown inFIG.8, the manifold layer210may have a first side805configured to face a tissue site, a second side810opposite the first side805, and a thickness between the first side805and the second side810, wherein the thickness is the depth DSof the spacer fabric225. The first layer305and the second layer310of each strip of spacer fabric225may be oriented perpendicular to the first side805and the second side810of the manifold layer210.

In some embodiments, one or more of the components of the dressing110may additionally be treated with an antimicrobial agent. For example, the manifold layer210may be coated with an antimicrobial agent. In some embodiments, the manifold layer210may comprise antimicrobial elements, such as fibers coated with an antimicrobial agent. Additionally or alternatively, some embodiments of the contact layer205may be a polymer coated or mixed with an antimicrobial agent. Suitable antimicrobial agents may include, for example, metallic silver, PHMB, iodine or its complexes and mixes such as povidone iodine, copper metal compounds, chlorhexidine, or some combination of these materials.

Additionally or alternatively, one or more of the components may be coated with a mixture that may include citric acid and collagen, which can reduce bio-films and infections. For example, the manifold layer210may be coated with such a mixture.

The cover125, the contact layer205, the manifold layer210, or various combinations may be assembled before application or in situ. For example, the contact layer205may be laminated to the manifold layer210, and the cover125may be laminated to the manifold layer210opposite the contact layer205in some embodiments. In some embodiments, one or more layers of the tissue interface120may coextensive. For example, the contact layer205and the manifold layer210may be cut flush with the edge of the cover125, exposing the edge of the manifold layer210. In other embodiments, the contact layer205may overlap the edge of the manifold layer210.

Referring now primarily toFIG.9andFIG.10, presented is another illustrative embodiment of a portion of the therapy system100.FIG.9andFIG.10depict the therapy system100assembled in stages at a tissue site, such as a linear wound905. InFIG.9, a closure device910, such as, for example, stitches915, close the linear wound905. Other closure devices910, such as epoxy or staples may be utilized to close the linear wound905. The linear wound905may include a portion through an epidermis920, dermis925, and subcutaneous tissue930of a patient.

Referring now toFIG.10, after the linear wound905is closed or prepared as described above, the dressing110may be disposed proximate to the linear wound905. The geometry and dimensions of the tissue interface120, the cover125, or both may vary to suit a particular application or anatomy. For example, the dressing110may be cut to size for a specific region or anatomical area, such as for amputations. The dressing110may be cut without losing pieces of the tissue interface120and without separation of the tissue interface120.

The tissue interface120can be placed over, on, or otherwise proximate to the linear wound905. In the example ofFIG.10, the contact layer205forms an outer surface of the dressing110, and can be placed over the tissue site, including the linear wound905and epidermis920. The contact layer205may be interposed between the manifold layer210and the tissue site, which can prevent direct contact between the manifold layer210and the linear wound905and epidermis920. In some embodiments, the strips of spacer fabric225are oriented substantially parallel to the linear wound905. For example, the extension direction DEof the one or more strips of spacer fabric225may be substantially parallel to the linear wound905. In some embodiments, the tissue interface120may be placed on the tissue site, such that the linear wound905is between two strips of spacer fabric225. In other embodiments, the tissue interface120may be placed on the tissue site, such that a strip of spacer fabric225overlays the linear wound905.

In some examples, the dressing110may include one or more attachment devices. In some embodiments, one or more of the attachment devices may comprise or consist essentially of an adhesive1005. In some examples the adhesive1005may be, for example, a medically-acceptable, pressure-sensitive adhesive that extends about a periphery, a portion, or an entire surface of each of the cover125. In some embodiments, for example, the adhesive1005may be an acrylic adhesive having a coating weight between 25-65 grams per square meter (g.s.m.). Thicker adhesives, or combinations of adhesives, may be applied in some embodiments to improve the seal and reduce leaks. In some embodiments, such a layer of the adhesive1005may be continuous or discontinuous. Discontinuities in the adhesive1005may be provided by apertures or holes (not shown) in the adhesive1005. The apertures or holes in the adhesive1005may be formed after application of the adhesive1005or by coating the adhesive1005in patterns on a carrier layer, such as, for example, a side of the cover125. Apertures or holes in the adhesive1005may also be sized to enhance the MVTR of the adhesive1005in some example embodiments

The adhesive1005can be disposed on a bottom side of the cover125, and the adhesive1005may pressed onto the cover125and epidermis920(or other attachment surface) to fix the dressing110in position and to seal the tissue interface120over the patient. In some embodiments, the adhesive1005can be disposed only around edges of the cover125.

FIG.10also illustrates one example of a fluid conductor1010and a dressing interface1015. As shown in the example ofFIG.10, the fluid conductor1010may be a flexible tube, which can be fluidly coupled on one end to the dressing interface1015. The dressing interface1015may be an elbow connector. In some examples, the tissue interface120can be applied to the tissue site before the cover125is applied over the tissue interface120. The cover125may include an aperture1020, or the aperture1020may be cut into the cover125before or after positioning the cover125over the tissue interface120. The position of the aperture1020may be off-center or adjacent to an end or edge of the cover125. In other examples, the aperture1020may be centrally disposed. The dressing interface1015can be placed over the aperture1020to provide a fluid path between the fluid conductor1010and the tissue interface120. In other examples, the fluid conductor1010may be inserted directly through the cover125into the tissue interface120.

If not already configured, the dressing interface1015may be disposed over the aperture1020and attached to the cover125. The fluid conductor1010may be fluidly coupled to the dressing interface1015and to the negative-pressure source105.

Negative pressure from the negative-pressure source105can be distributed through the fluid conductor1010and the dressing interface1015to the tissue interface120. The tissue interface120may contract in response to the application of negative pressure. In some embodiments, the manifold layer210of the tissue interface120is configured to anisotropically contract. For example, under an applied negative pressure, the manifold layer210may contract more in a first direction1025than in a second direction1030. The first direction1025may be perpendicular to the extension direction DEof the one or more strips of spacer fabric225. The preferential contraction along the first direction1025by the manifold layer210acts to pull the epidermis920toward the linear wound905aiding in closing the linear wound905.

The contact layer205can protect the epidermis920from irritation that could be caused by expansion, contraction, or other movement of the manifold layer210. The contact layer205can also substantially reduce or prevent exposure of a tissue site to the manifold layer210, which can inhibit growth of tissue into the manifold layer210.

Although the strips of spacer fabric225are shown oriented parallel to the linear wound905inFIG.10, it will be understood that in some embodiments, a tissue interface120may be applied to a tissue site wherein the one or more strips of spacer fabric225are oriented at an angle with respect to the linear wound905. For example, in some embodiments, the tissue interface120may be tuned to preferentially contract along the extension direction DEof the one or more strips of spacer fabric225by modifying the material properties of the spacer fabric225and/or the manifold220. In such embodiments, the strips of spacer fabric225may be oriented perpendicular to the linear wound905to aid in closure of the linear wound905.

The systems, apparatuses, and methods described herein may provide significant advantages over prior dressings. For example, closure of the linear wound905may be promoted by orienting the strips of spacer fabric225parallel to the linear wound905when the dressing110is applied to the tissue site. Contraction of the manifold layer210more in a first direction, perpendicular to the linear wound905, may be propagated by the manifold layer210and the cover125to the epidermis920, dermis925, and the subcutaneous tissue930. The anisotropic contraction provided by the spacer fabric may reduce the chance for dehiscence and aids in drawing the edges of the linear wound905together. The dressing110may reduce healing complications and may promote healing at the tissue site.

While shown in a few illustrative embodiments, a person having ordinary skill in the art will recognize that the systems, apparatuses, and methods described herein are susceptible to various changes and modifications that fall within the scope of the appended claims. Moreover, descriptions of various alternatives using terms such as “or” do not require mutual exclusivity unless clearly required by the context, and the indefinite articles “a” or “an” do not limit the subject to a single instance unless clearly required by the context. Components may be also be combined or eliminated in various configurations for purposes of sale, manufacture, assembly, or use. For example, in some configurations the dressing110, the container115, or both may be separated from other components for manufacture or sale. In other example configurations, the controller130may also be manufactured, configured, assembled, or sold independently of other components.

The appended claims set forth novel and inventive aspects of the subject matter described above, but the claims may also encompass additional subject matter not specifically recited in detail. For example, certain features, elements, or aspects may be omitted from the claims if not necessary to distinguish the novel and inventive features from what is already known to a person having ordinary skill in the art. Features, elements, and aspects described in the context of some embodiments may also be omitted, combined, or replaced by alternative features serving the same, equivalent, or similar purpose without departing from the scope of the invention defined by the appended claims.