Dressing employing features for protection against maceration

Abstract

To provide dressings for treating a tissue site with negative pressure, which may include a dressing having multiple layers and incorporating a material adapted to neutralize proteolytic enzymes.SOLUTION: A dressing may include a first layer comprising a hydrophobic gel having a plurality of apertures. A material adapted to neutralize proteolytic enzymes may be applied to a surface of the first layer. The dressing may further include a second layer comprising a fenestrated film and coupled to the first layer. Additionally, the dressing may include a third layer comprising a manifold, which in some instances may be a polymeric foam. The dressing may further include a fourth layer comprising a polymer drape.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 867,001, entitled "Dressing Employing Features for Protection Against Maternity," filed June 26, 2019, which is incorporated herein by reference for all purposes.

[0002] The present invention as claimed herein relates generally to tissue treatment systems, and more particularly, but not exclusively, to dressings for tissue treatment using negative pressure and methods of using dressings for tissue treatment using negative pressure. [Background technology]

[0003] Clinical studies and clinical practice have shown that reducing pressure proximal to a tissue site can enhance and accelerate the growth of new tissue at the tissue site. While there are many applications of this phenomenon, it has proven particularly advantageous for treating wounds. Regardless of the cause of the wound, whether trauma, surgery, or another cause, proper wound care is critical to the outcome. Treatment of wounds or other tissues using reduced pressure may generally be referred to as "negative pressure therapy," but is also known by other names, including, for example, "negative pressure wound therapy," "reduced pressure therapy," "vacuum therapy," "negative pressure wound therapy," and "topical negative pressure." Negative pressure therapy can provide many benefits, including epithelial and subcutaneous tissue migration, improved blood flow, and minimal tissue deformation at the wound site. Collectively, these benefits can increase the development of granulation tissue and reduce healing time.

[0004] While the clinical benefits of negative pressure therapy are widely known, improvements in therapy systems, components, and processes can benefit healthcare providers and patients. Summary of the Invention

[0005] New and useful systems, devices, and methods for treating tissue in a negative pressure therapy environment are set forth in the accompanying claims. Exemplary embodiments are also provided to enable one of ordinary skill in the art to make and use the claimed subject matter.

[0006] Dressings and systems for treating tissue sites may incorporate one or more means for inhibiting excessive proteolytic enzyme activity in wound fluid. For example, tissue dressings may include a sacrificial protease substrate to reduce or prevent such proteases from degrading new tissue as it forms as part of wound healing. Normal endogenous levels of wound proteases are important for tissue remodeling during the healing process. For example, matrix metalloproteinases (MMPs) are one of the proteases typically present in wounds and can play an important role in the wound healing response. However, if in excess or if left in contact with healing areas of the wound site, such as the wound margin or periwound area, such enzymes can continuously degrade the new tissue that is forming. Prolonged contact with wound fluids, especially when high levels of proteases may be present, can also result in maceration of the wound margin or periwound area. Specifically, the presence of water in the periwound area can result in hydration of the stratum corneum, which can compromise the barrier function of typical healthy skin. Various proteolytic enzymes present in wound exudate can then subsequently penetrate healthy skin, resulting in maceration. These factors can also contribute to the failure of wounds to heal quickly or for the wound to heal for a long time.

[0007] Thus, in certain aspects, dressings incorporating one or more substrates for preventing the harmful or undesirable effects of wound fluids and associated proteolytic enzymes on healthy or healing skin are disclosed. Such substrates, e.g., one or more biopolymers, may function as sacrificial substrates for enzyme regulation or neutralization, as enzyme inactivators, and / or as enzyme sequestrants to reduce levels of proteases that may have negative effects on wound healing. They may also include one or more substrates for MMPs and other proteases. For example, potential MMP substrates include, but are not limited to, collagen, gelatin, elastin, casein, albumin, fibrinogen, fibronectin, and combinations and hydrolysates thereof. In some embodiments, it may be particularly advantageous to include a sacrificial substrate comprising collagen, which may be a suitable substrate for many of the MMPs most prevalent in wounds. In some cases, proteins for use as sacrificial substrates may be hydrolyzed or partially hydrolyzed by treatment with strong acid or base. Such treatment can fragment the protein of interest, generating more accessible peptide sequences for binding to proteases. As described below in the disclosed exemplary embodiments, the sacrificial proteolytic matrix may be integrated into tissue dressings and systems for use with negative pressure wound therapy.

[0008] For example, in some embodiments, a dressing for treating a tissue site may include a first layer, a second layer adjacent to the first layer, a third layer adjacent to the first layer on an opposite side from the second layer, a fourth layer adjacent to the third layer on an opposite side from the first layer, and a fifth layer adjacent to the fourth layer on an opposite side from the third layer. The first layer may include a hydrophobic gel having a plurality of apertures. The second layer may include a material adapted to neutralize protease. The third layer may include a polymeric film having a plurality of fluid-restricting portions configured to expand in response to a pressure gradient. The fourth layer may include a manifold. The fifth layer may include a polymeric drape. In some embodiments, the material adapted to neutralize protease of the second layer may include a sacrificial substrate. In some additional embodiments, the dressing may be fluidly coupled to a negative pressure source as part of a system for treating a tissue site.

[0009] In some additional embodiments, a dressing for treating a tissue site using negative pressure may include a first film, a second film bonded to the first film, a third film adjacent to the first film on an opposite side from the second film, and a manifold layer adjacent to the third film. The first film may include a perforated silicone gel coating. The second film may include an enzyme-modulating material. The third film may include a non-porous material and a plurality of fenestrations. The manifold layer may include a foam.

[0010] In a further embodiment, a dressing for treating a tissue site using negative pressure may include a first layer, a second layer, and a third layer adapted to be positioned adjacent to the first layer on an opposite side from the second layer. The first layer may include a hydrophobic gel having a plurality of apertures, and the second layer may include a material adapted to neutralize proteolytic enzymes and may have a plurality of fenestrations. The third layer may include a polymeric drape.

[0011] In some additional embodiments, a dressing for treating a tissue site using negative pressure may include a first layer, a second layer adapted to be bonded to the first layer, a third layer adapted to be positioned adjacent to the second layer on an opposite side of the first layer, a fourth layer adapted to be positioned adjacent to the third layer on an opposite side of the second layer, and a fifth layer adapted to be bonded to the fourth layer on an opposite side of the third layer. The first layer may include a hydrophobic gel having a plurality of apertures, the second layer may include a polymeric film having a plurality of fenestrations, and the third layer may include a manifold. The fourth layer may have a plurality of apertures and may include a material adapted to neutralize proteolytic enzymes. The fifth layer may include a polymeric drape.

[0012] In some further embodiments, a dressing for treating a tissue site may include a first layer, a second layer, and a third layer adapted to be disposed between the first and second layers. The first layer may have a plurality of apertures and may include a hydrophobic gel adhesive and a material adapted to neutralize proteolytic enzymes. The second layer may include a manifold, and the third layer may include a polymeric film having a plurality of fenestrations. The dressing may further include a fourth layer adapted to be coupled to the second layer on a side opposite the third layer, and the fourth layer may include a polymeric drape.

[0013] In some additional embodiments, a dressing for treating a tissue site may include a hydrophobic gel layer, an enzyme modulating layer adjacent to the hydrophobic gel layer, a fluid control layer adjacent to the hydrophobic gel layer on an opposite side from the enzyme modulating layer, and a manifold layer adjacent to the fluid control layer on an opposite side from the hydrophobic gel layer. The manifold layer may comprise a foam.

[0014] In yet some additional embodiments, a dressing for treating a tissue site using negative pressure may include a perforated silicone gel, a first film including apertures and an enzyme-modulating material, a second film including a plurality of fenestrations, a manifold, and a cover. The perforated silicone gel, first film, second film, manifold, and cover may be assembled in a laminated relationship such that the perforated silicone gel and cover encapsulate the second film and manifold. The first film may be configured to contact the tissue site.

[0015] In yet another embodiment, a dressing for treating a tissue site using negative pressure may include a first layer comprising an enzyme-modulating material, a second layer adapted to be bonded to the first layer, a third layer adapted to be bonded to the second layer on an opposite side from the first layer, and a fourth layer adapted to be positioned adjacent to the third layer on an opposite side from the second layer. The second layer may include a hydrophobic gel. The third layer may be in the form of a fenestrated film, and the fourth layer may include a manifold. The first layer may be in the form of a ring having an outer structural portion and an opening, the ring being adapted to be applied to a first surface of the second layer. Furthermore, the dressing may further include a fifth layer adapted to be bonded to the fourth layer on an opposite side from the third layer, and the fifth layer may include a polymeric drape. In some additional embodiments, the first layer may be applied as a pattern coating to the first surface of the second layer.

[0016] The objects, advantages and preferred modes of making and using the claimed subject matter will be best understood by referring to the accompanying drawings in conjunction with the following detailed description of illustrative embodiments. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a functional block diagram of an exemplary embodiment of a treatment system capable of providing negative pressure treatment in accordance with the present disclosure.

[0018] [Figure 2]2 is an assembled view of an example dressing showing additional details that may be relevant to some exemplary embodiments of the treatment system of FIG. 1. FIG.

[0019] [Figure 3] 1. FIG. 10 is an assembly view of another example dressing showing additional details that may be relevant to some exemplary embodiments of the treatment system of FIG.

[0020] [Figure 4] 4 is a schematic diagram of an exemplary configuration of an exemplary first layer of a dressing superimposed on an exemplary second layer of the dressing, showing additional details that may be relevant to some embodiments of the dressing of FIG.

[0021] [Figure 5] 1. FIG. 10 is an assembly view of another example dressing showing additional details that may be relevant to some exemplary embodiments of the treatment system of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] The following description of exemplary embodiments provides information to enable one skilled in the art to make and use the claimed subject matter, but may omit certain details already known in the art. Thus, the following detailed description is to be construed as illustrative and not limiting.

[0023] Exemplary embodiments may also be described herein with reference to the spatial relationships between or orientation of various elements as shown in the accompanying drawings. Generally, such relationships or orientations are in a frame of reference that is consistent with or relative to a patient in a position to receive treatment. However, those skilled in the art will understand that this frame of reference is not a strict requirement and is merely for convenience of explanation.

[0024] FIG. 1 is a simplified functional block diagram of an exemplary embodiment of a treatment system 100 capable of providing negative pressure therapy to a tissue site in accordance with the present disclosure.

[0025] 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, bone tissue, adipose tissue, muscle tissue, nerve tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendon, or ligament. Wounds can include, for example, chronic, acute, traumatic, subacute, and dehiscence wounds, partial thickness burns, ulcers (such as diabetic ulcers, pressure ulcers, or venous insufficiency ulcers), skin flaps, and transplanted tissue. The term "tissue site" can also refer to any area of tissue that is not necessarily an area where there is a wound or defect, but instead is an area where 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, which can then be harvested and transplanted.

[0026] Treatment system 100 may include a negative pressure source or supply, such as negative pressure source 105, and one or more distribution components. The distribution components are preferably detachable and may be disposable, reusable, or recyclable. Dressings, such as dressing 110, and fluid containers, such as container 115, are examples of distribution components that may be associated with some examples of treatment system 100. As shown in the example of FIG. 1, dressing 110 may comprise or consist essentially of tissue interface 120, cover 125, or both in some embodiments.

[0027] A fluid conduit is another illustrative example of a distribution component. In this context, "fluid conduit" broadly includes a tube, pipe, hose, conduit, or other structure having one or more lumens or open passages adapted to transport fluid between two ends. Typically, a tube is an elongated, cylindrical structure with some flexibility, although the geometry and stiffness may vary. Additionally, some fluid conduits may be molded into or integrally combined with other components. A distribution component may also include or comprise an interface or fluid port to facilitate coupling and decoupling of other components. In some embodiments, for example, a dressing interface may facilitate coupling a fluid conduit to a dressing 110. For example, such a dressing interface may be a SENSAT.RAC™ Pad available from Kinetic Concepts, Inc. (San Antonio, Texas).

[0028] The treatment system 100 may also include a regulator or controller, such as a controller 130. Additionally, the treatment system 100 may include sensors for measuring operating parameters and providing feedback signals indicative of the operating parameters to the controller 130. For example, as shown in FIG. 1, the treatment system 100 may include a first sensor 135 and a second sensor 140 coupled to the controller 130.

[0029] Some components of the treatment system 100 may be contained 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 source 105 may be combined with the controller 130 and other components into a therapy unit.

[0030] In general, components of treatment system 100 may be directly or indirectly coupled. For example, negative pressure source 105 may be directly coupled to reservoir 115 or indirectly coupled to dressing 110 via reservoir 115. Coupling may include fluid coupling, mechanical coupling, thermal coupling, electrical coupling, or chemical coupling (such as chemical bonding), or, in some contexts, some combination of couplings. For example, negative pressure source 105 may be electrically coupled to controller 130 and fluidly coupled to one or more distribution components to provide a fluid pathway to the tissue site. In some embodiments, components may also be coupled by physical proximity, by being integrated into a single structure, or by being formed from the same piece of material.

[0031] A negative pressure source, such as negative pressure source 105, may be a reservoir of air at negative pressure or may be a manual or powered device, such as a vacuum pump, a suction pump, a wall suction port available in many medical facilities, or a micropump. "Negative pressure" generally refers to a pressure less than the local ambient pressure, such as the ambient pressure in the local environment outside the sealed treatment environment. Often, the local ambient pressure may also be the atmospheric pressure where the tissue site is located. Alternatively, the pressure may be less than the hydrostatic pressure associated with the tissue at the tissue site. Unless otherwise indicated, pressure values described herein are gauge pressures. References to increased negative pressure typically refer to decreases in absolute pressure, and decreases in negative pressure typically refer to increases in absolute pressure. While the amount and nature of the negative pressure provided by negative pressure source 105 may vary depending on treatment requirements, the pressure is typically a low vacuum, also commonly referred to as a rough vacuum, between -5 mmHg (-667 Pa) and -500 mmHg (-66.7 kPa). A typical treatment range is -50mmHg (-6.7kPa) to -300mmHg (-39.9kPa).

[0032] Container 115 represents a container, canister, pouch, or other storage component that may be used to manage exudate and other fluids drawn from a tissue site. In many environments, a rigid container may be preferred or required for fluid collection, storage, and disposal. In other environments, fluids may be properly disposed of without being stored in a rigid container, and a reusable container may reduce waste and costs associated with negative pressure therapy.

[0033] A controller, such as controller 130, may be a microprocessor or computer programmed to operate one or more components of treatment system 100, such as negative pressure source 105. In some embodiments, for example, controller 130 may be a microcontroller, which generally includes an integrated circuit including a processor core and memory programmed to directly or indirectly control one or more operating parameters of treatment system 100. The operating parameters may include, for example, the power applied to negative pressure source 105, the pressure generated by negative pressure source 105, or the pressure delivered to tissue interface 120. Controller 130 is also preferably configured to receive one or more input signals, such as feedback signals, and is programmed to modify the one or more operating parameters based on the input signals.

[0034] Sensors, such as first sensor 135 and second sensor 140, are generally known in the art as any device operable to detect or measure a physical phenomenon or characteristic and generally provide a signal indicative of the detected or measured phenomenon or characteristic. For example, first sensor 135 and second sensor 140 may be configured to measure one or more operating parameters of treatment system 100. In some embodiments, first sensor 135 may be a transducer configured to measure pressure in a pneumatic path and convert the measurement into a signal indicative of the measured pressure. In some embodiments, for example, first sensor 135 may be a piezoresistive strain gauge. In some embodiments, second sensor 140 may optionally measure an operating parameter of negative pressure source 105, such as voltage or current. Preferably, signals from first sensor 135 and second sensor 140 are suitable as input signals to controller 130, although in some embodiments, some signal conditioning may be appropriate. For example, the signals may need to be filtered or amplified before they can be processed by controller 130. Typically, the signal is an electrical signal, but may be represented in other forms, such as an optical signal.

[0035] Tissue interface 120 may generally be adapted to partially or completely contact a tissue site. Tissue interface 120 may take many forms and may have many sizes, shapes, or thicknesses depending on various factors, such as the type of treatment being performed or the nature and size of the tissue site. For example, the size and shape of tissue interface 120 may be adapted to the contours of an irregularly shaped deep tissue site. Any or all of the surfaces of tissue interface 120 may have an uneven, rough, or jagged profile.

[0036] In some embodiments, the cover 125 may provide a barrier against bacteria and protection from physical trauma. The cover 125 may also be constructed from a material capable of reducing evaporative loss and providing a fluid seal between two components or two environments, such as between a treatment environment and a local external environment. The cover 125 may include or consist of, for example, an elastomeric film or membrane capable of providing a seal adequate to maintain the negative pressure of a given negative pressure source at the tissue site. The cover 125 may, in some applications, have a high moisture vapor transmission rate (MVTR). For example, the MVTR may be at least 250 grams per square meter per 24 hours as measured using the Upright Cup Method of ASTM E96 / E96M at 38°C and 10% relative humidity (RH). In some embodiments, an MVTR of up to 5,000 grams per square meter per 24 hours may provide effective breathability and mechanical properties.

[0037] In some exemplary embodiments, the cover 125 may be a polymer drape, such as a polyurethane film, that is permeable to water vapor but impermeable to liquids. Such drapes typically have a thickness in the range of 25 to 50 microns. For permeable materials, the permeability should generally be low enough so that the desired negative pressure can be maintained. The cover 125 may include, for example, one or more of the following materials: polyurethanes (PU), such as hydrophilic polyurethanes; cellulose derivatives; hydrophilic polyamides; polyvinyl alcohol; polyvinylpyrrolidone; hydrophilic acrylics; silicones, such as hydrophilic silicone elastomers; natural rubber; 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); copolyesters; and polyether block polyamide copolymers. Such materials are commercially available, for example, as Tegaderm® drapes available from 3M Company (Minneapolis, Minnesota); polyurethane (PU) drapes available from Avery Dennison Corporation (Pasadena, California), such as polyether block polyamide copolymer (PEBAX) from Arkema SA (Colombes, France); and Inspire 2301 and Inspire 2327 polyurethane films available from Expopack Advanced Coatings (Wrexham, United Kingdom). In some embodiments, the cover 125 has a thickness of 2600 g / m 2 / INSPIRE2301 having a 24 hour MVTR (upright cup method) and a thickness of approximately 30 microns.

[0038] An attachment device may be used to attach the cover 125 to a mounting surface, such as an intact epidermis, a gasket, or another cover. The attachment device may take many forms. For example, the attachment device may be a medically acceptable pressure-sensitive adhesive configured to bond the cover 125 to the epidermis around the tissue site. In some embodiments, for example, part or all of the cover 125 may be coated with an adhesive, such as an acrylic adhesive, which may have a coating weight of approximately 25 to 65 grams per square meter (gsm). In some embodiments, a thicker adhesive, or combination of adhesives, may be applied to improve the seal and reduce leakage. Other exemplary embodiments of attachment devices may include double-sided tape, glue, hydrocolloid, hydrogel, silicone gel, or organogel.

[0039] In operation, tissue interface 120 may be positioned within, on, over, or otherwise adjacent to a tissue site. For example, if the tissue site is a wound, tissue interface 120 may partially or completely occlude or be positioned over the wound. Cover 125 may be positioned over tissue interface 120 and sealed to a mounting surface adjacent the tissue site. For example, cover 125 may be sealed to intact epidermis surrounding the tissue site. Thus, dressing 110 can provide a sealed treatment environment adjacent the tissue site that is substantially isolated from the external environment, and negative pressure source 105 can reduce pressure in that sealed treatment environment.

[0040] The fluid dynamics of using a negative pressure source to reduce pressure in another component or location, such as within a sealed treatment environment, can be mathematically complex. However, the basic principles of fluid dynamics applicable to negative pressure therapy are generally well known to those skilled in the art, and the process of reducing pressure may be illustratively described herein as "delivering," "distributing," or "generating" negative pressure, for example.

[0041] Generally, exudate and other fluids flow along a fluid pathway toward lower pressure. Thus, the term "downstream" typically refers to something in a fluid pathway that is relatively closer to a negative pressure source or farther away from a positive pressure source. Conversely, the term "upstream" refers to something that is relatively farther away from a negative pressure source or closer to a positive pressure source. Similarly, it may be convenient to describe certain features in terms of a fluid "inlet" or "outlet" in such a frame of reference. This orientation is generally assumed for purposes of describing various features and components herein. However, fluid pathways may also be reversed in some applications, such as by replacing a negative pressure source with a positive pressure source, and this descriptive definition should not be construed as limiting.

[0042] In a sealed treatment environment, negative pressure applied across the tissue site via tissue interface 120 can induce macro- and micro-strains at the tissue site. The negative pressure can also remove exudate and other fluids from the tissue site, which can be collected in container 115.

[0043] In some embodiments, the controller 130 can receive and process data from one or more sensors, such as the first sensor 135. The controller 130 can also control the operation of one or more components of the treatment system 100 to manage the pressure delivered to the tissue interface 120. In some embodiments, the controller 130 can include an input for receiving a desired target pressure and can be programmed to process data regarding the setting and input of the target pressure to be applied to the tissue interface 120. In some exemplary embodiments, the target pressure can be a fixed pressure value, which is set by an operator as the target negative pressure desired for therapy at the tissue site and then provided as an input to the controller 130. The target pressure may vary from tissue site to tissue site based on the type of tissue forming the tissue site, the type of injury or wound (if any), the patient's health, and the attending physician's preferences. After selecting the desired target pressure, the controller 130 can operate the negative pressure source 105 in one or more control modes based on the target pressure and can receive feedback from one or more sensors to maintain the target pressure at the tissue interface 120.

[0044] FIG. 2 is an assembled view of the example dressing 110 of FIG. 1 , illustrating further details that may be relevant to some embodiments in which the tissue interface 120 includes two or more layers. The tissue interface 120 may have a first side 202 and a second side 204. In the example of FIG. 2 , the tissue interface 120 includes a first layer 205, a second layer 210, a third layer 215, and a fourth layer 220. The first layer 205, the second layer 210, the third layer 215, and the fourth layer 220 may be stacked in various configurations. For example, the third layer 215 may be positioned between the first layer 205 and the fourth layer 220. In some embodiments, the second layer 210 may be positioned adjacent to the first layer 205. For example, the second layer 210 may be positioned adjacent to the first layer 205 on the opposite side from the third layer 215. In other examples, the second layer 210 may be disposed between the first layer 205 and the third layer 215. Additionally, the fourth layer 220 may be disposed adjacent to the third layer 215 on the opposite side from the first layer 205. For example, the first layer 205, the second layer 210, the third layer 215, and the fourth layer 220 may be stacked such that the first layer 205 contacts the second layer 210 and the third layer 215 contacts the first layer 205 and the fourth layer 220. One or more of the first layer 205, the second layer 210, the third layer 215, and the fourth layer 220 may also be bonded to adjacent layers in some embodiments, although in some cases, one or more layers of the tissue interface 120, such as the fourth layer 220, may be freely disposed or positioned between other layers of the dressing 110 without being bonded or attached to an adjacent layer. The entire dressing 110, including the individual layers of the tissue interface 120, may be any number of different shapes based on the particular anatomical needs of the tissue site. For example, the dressing 110 and the included layers of the tissue interface 120 may have a square, rectangular, oval, circular, hexagonal, or other shape.

[0045] The first layer 205 may be a sealing layer that includes or consists essentially of a soft, pliable material suitable for providing a fluid seal with the tissue site and may have a substantially flat surface. For example, the first layer 205 may include, but is not limited to, silicone gel, soft silicone, hydrocolloid, hydrogel, polyurethane gel, polyolefin gel, hydrogenated styrene copolymer gel, foam gel, soft closed-cell foam such as adhesive-coated polyurethane and polyolefin, polyurethane, polyolefin, or hydrogenated styrene copolymer. In some embodiments, the first layer 205 may have a thickness of about 200 microns (μm) to about 1000 microns (μm). In some embodiments, the first layer 205 may have a hardness of about 5 Shore 00 to about 80 Shore 00. Furthermore, the first layer 205 may be composed of a hydrophobic or hydrophilic material. The first layer 205 may be tailored in thickness and / or adhesiveness depending on the overall arrangement and positioning of the other layers within the tissue interface 120. For example, the first layer 205 may include a silicone gel having a tackiness that may be adjusted by increasing or decreasing the tackifier concentration of the silicone gel. In some embodiments, the thickness of the silicone gel in the first layer 205 may be increased to increase the overall adhesion of the tissue interface 120 to the tissue site.

[0046] In some embodiments, first layer 205 may be a hydrophobic coated material. For example, first layer 205 may be formed by coating an intersticed material, such as a woven mesh, a nonwoven mesh, a molded mesh, or an extruded mesh, with a hydrophobic material. The hydrophobic coating material may be, for example, soft silicone.

[0047] The first layer 205 may have a peripheral region, such as a perimeter 225, surrounding or circumscribing an inner portion having at least one treatment opening 230. The first layer 205 may have an opening 235 disposed through the perimeter 225. The first layer 205 may also have corners 240 and edges 245. The corners 240 and edges 245 may be part of the perimeter 225. In some examples, the treatment opening 230 may be symmetrically and centrally disposed on the first layer 205, as shown in FIG. 2 . In some examples, the treatment opening 230 may generally correspond to the surface area of the fourth layer 220. For example, the treatment opening 230 may form a frame, window, or other opening around the surface of the fourth layer 220. The treatment opening 230 may allow communication of negative pressure and wound fluid between the second layer 210 and the third layer 215.

[0048] The openings 235 may be formed, for example, by cutting, by application of localized radio frequency (RF) or ultrasonic energy, or by other suitable techniques for forming openings. The openings 235 may have a uniform distribution pattern or may be randomly distributed in the first layer 205. The openings 235 in the first layer 205 may have many shapes, including, for example, circles, squares, stars, ellipses, polygons, slits, complex curves, linear shapes, triangles, or any combination of such shapes. Each of the openings 235 may have uniform or similar geometric characteristics. For example, in some embodiments, each of the openings 235 may be a circular opening having substantially the same diameter. In some embodiments, the diameter of each of the openings 235 may be between about 1 millimeter and about 50 millimeters. In other embodiments, the diameter of each of the openings 235 may be between about 1 millimeter and about 20 millimeters.

[0049] In other embodiments, the geometric characteristics of the openings 235 may vary. For example, the diameter of the openings 235 may vary depending on the location of the openings 235 within the first layer 205, as shown in FIG. 2. For example, in some embodiments, the openings 235 located in the periphery 225 may have a diameter of about 9.8 millimeters to about 10.2 millimeters. In some embodiments, the openings 235 located in the corners 240 may have a diameter of about 7.75 millimeters to about 8.75 millimeters.

[0050] At least one of the openings 235 in the periphery 225 of the first layer 205 may be positioned at an edge 245 of the periphery 225 and may have an inner cut that is open or exposed at the edge 245 and in laterally fluid communication with the edge 245. Lateral may refer to a direction toward the edge 245 and in the same plane as the first layer 205. As shown in the example of FIG. 2, the openings 235 in the periphery 225 may be disposed proximate to or at the edge 245 and in laterally fluid communication with the edge 245. The openings 235 disposed proximate to or at the edge 245 may be spaced substantially equidistantly around the periphery 225, as shown in the example of FIG. 2. Alternatively, the spacing of the openings 235 proximate to or at the edge 245 may be irregular.

[0051] The second layer 210 may include, or consist essentially of, a material suitable for modulating or neutralizing enzymes at the tissue site. Target enzymes, such as proteases, are enzymes that, if accumulated in excess or if left in prolonged contact with the tissue site, can cause maceration at or around the tissue site. The second layer 210 may provide the tissue interface 120 with a means for neutralizing proteases to prevent potential maceration at the tissue site. In particular, the second layer 210 may reduce or prevent the risk of maceration when the peri-wound area of the tissue site is exposed to wound exudate containing proteases.

[0052] The second layer 210 may include various materials suitable for neutralizing proteolytic enzymes. In some cases, the second layer 210 may include one or more materials that can function as a sacrificial substrate, an enzyme inactivator, an enzyme sequestrant, or a combination of such functions. In some embodiments, the second layer 210 may include a biologically derived polymer, including collagen, gelatin, a collagen-like protein, a collagen-like peptide, or any combination of these materials. The sacrificial substrate of the second layer 210 may also include hyaluronic acid, chondroitin sulfate, or a collagen-mimetic peptide, among others. Furthermore, the second layer 210 may additionally or alternatively include cellulose or a cellulose derivative, such as oxidized regenerated cellulose (ORC) or chemically modified cellulose. In some embodiments, the second layer 210 may include an enzyme sequestrant or inactivator in the form of a binding decoy molecule or a metal ion chelator. Exemplary chelators may include ethylenediaminetetraacetic acid (EDTA) and ethylene glycol tetraacetic acid (EGTA), among others. Enzyme inactivators can also include MMP inhibitors, such as tissue inhibitors of metalloproteinases (TIMPs), or small molecule protease inhibitors, such as thrombospondin-1, thrombospondin-2, elastase inhibitor 2, alpha 1 antitrypsin, pepstatin A, aprotinin, and leupeptin. Metalloprotein inhibitors with zinc-binding groups or copper analogs may also be useful in binding harmful metalloproteases or activating beneficial metalloproteases, and thus may act as enzyme sequestrants.

[0053] The second layer 210 may include various different combinations or mixtures of materials suitable for neutralizing proteolytic enzymes. For example, some embodiments of the second layer 210 may include a combination of gelatin and collagen. Some additional embodiments of the second layer 210 may include a combination of collagen and ORC materials. For example, the second layer 210 may include a composite of about 50% collagen and about 50% ORC by weight. In some preferred embodiments, the second layer 210 may include a composite of about 55% collagen and about 45% ORC by weight. However, the respective proportions of collagen and ORC may vary. For example, the second layer 210 may include a composite of collagen and ORC, where the amount of collagen ranges from 20% to 80% of the total weight of the second layer 210 and the amount of ORC ranges from 20% to 80% of the total weight of the second layer 210. In some embodiments, the second layer 210 may include or consist essentially of materials found in PROMOGRAN™ Matrix Wound Dressing, commercially available from Kinetic Concepts, Inc. (San Antonio, Texas).

[0054] The placement of the second layer 210 may vary depending on the particular application of the tissue interface 120. For example, the second layer 210 may be in the form of a sheet that substantially forms a portion of the first side 202 of the tissue interface 120. In some exemplary embodiments, as shown in FIG. 2, the second layer 210 may be sized to be positioned below the treatment opening 230 so as to cover the treatment opening 230 as well as a portion of the periphery 225 of the first layer 205 on the first side 202 of the tissue interface 120. As shown in FIG. 2, the second layer 210 may have a substantially oval shape that may generally correspond to the shape of the treatment opening 230 in the first layer 205. In some cases, the second layer 210 may include a lattice-like structure, whereby the enzyme neutralizing material is disposed across a substantial portion of the first side 202 of the tissue interface 120 while also allowing a substantial open area in the form of apertures or pores in the second layer 210 to allow sufficient communication of negative pressure and / or other gases and fluids between the tissue site and the other layers of the dressing 110. The lattice-like structure of the second layer 210 may include multiple segments of enzyme neutralizing material arranged to form the structure of the second layer 210, with multiple apertures disposed between the multiple segments of enzyme neutralizing material. For example, the lattice-like structure of the second layer 210 may include a first multiple segments of enzyme neutralizing material and a second multiple segments of enzyme neutralizing material. In some embodiments, each segment of the first multiple segments of enzyme neutralizing material may be arranged substantially parallel to the other segments of the first multiple segments of enzyme neutralizing material, and each segment of the second multiple segments of enzyme neutralizing material may be arranged substantially parallel to the other segments of the second multiple segments of enzyme neutralizing material. At least one of the first plurality of segments of enzyme-neutralizing material may intersect with one or more of the second plurality of segments of enzyme-neutralizing material, e.g., the first plurality of segments of enzyme-neutralizing material may be aligned substantially perpendicular to the second plurality of segments of enzyme-neutralizing material.

[0055] As also shown in FIG. 2 , the second layer 210 may not cover or overlap a significant outer portion of the perimeter 225 of the first layer 205, such that an adhesive material disposed on the underside of the cover 125, such as the adhesive 260 shown in FIG. 2 , may pass through at least some of the openings 235 in the perimeter 225 of the first layer 205 and contact and form a seal with an area of tissue, such as the epidermis, surrounding the tissue site. In some examples, the second layer 210 may block some portions of some of the openings 235, thereby preventing some of the adhesive 260 from directly contacting the tissue site. The openings 235 may be configured to allow a sufficient amount of the adhesive 260 to pass through the openings 235 in the perimeter 225 to form a sufficient seal with the attachment surface surrounding the tissue site.

[0056] The second layer 210 may also exist in a variety of other structural and material configurations. For example, the second layer 210 may have various shapes, such as a square, circular, or rectangular shape. Furthermore, regardless of shape, the second layer 210 may be in the form of a solid sheet or may be something like a grid-like structure with openings or apertures in the material of the second layer 210. In some embodiments, each of the openings may have a diameter of 1 mm to 10 mm. In some other examples, each of the openings may be in the form of a slot having a length of 1 mm to 10 mm and a width of 1 mm to 5 mm. For example, each of the openings may have a polygonal or square shape with sides having lengths of 1 mm to 10 mm. In some additional or alternative embodiments, the second layer 210 may include one or more enzyme-neutralizing materials dispersed in a pattern or in one or more segments throughout the second layer 210. For example, one portion of the second layer 210 may include collagen, and another portion of the second layer 210 may include oxidized regenerated cellulose (ORC). In another example, substantially the entire second layer 210 may comprise a mixture of collagen and ORC, with one section of the second layer 210 having a greater proportional amount of collagen and another section of the second layer 210 having a greater proportional amount of ORC. In some additional embodiments, the second layer 210 may comprise a blend of collagen and gelatin, which may provide some cost-saving advantages.

[0057] The second layer 210 may range in size and associated dimensions depending on the particular configuration of the tissue interface 120 and / or the dressing 110. In some embodiments, the second layer 210 may have a thickness of approximately 5 micrometers to 5000 micrometers. In some specific embodiments, the second layer 210 may have a thickness in the range of 50 micrometers to 100 micrometers. Additionally, the second layer 210 may have perforations or fenestrations to allow air to flow through the second layer 210 to effectively communicate negative pressure within the tissue interface 120.

[0058] The second layer 210 can also help reduce or prevent the presence of harmful or infectious agents within the tissue interface 120 and at the tissue site. For example, the material of the second layer 210 can capture and / or treat bacteria or other microbial agents that may be present in wound fluid and pose a risk to the tissue site. Thus, the second layer 210 can provide an antimicrobial effect to the tissue interface 120.

[0059] The third layer 215 may include or consist essentially of a means for controlling or managing fluid flow. In some embodiments, the third layer 215 may include or consist essentially of a liquid-impermeable elastomeric material. For example, the third layer 215 may include or consist essentially of a polymer film. The third layer 215 may also have a smooth or matte surface texture in some embodiments. For some applications, a polished or glossy finish, such as grade B3 or higher according to the Society of Plastics Industry (SPI) standard, may be particularly advantageous. In some embodiments, variations in surface height may be limited to an acceptable tolerance. For example, the surface of the third layer 215 may have a substantially flat surface with a height variation limited to 0.2 millimeters over 1 centimeter.

[0060] In some embodiments, the third layer 215 may be hydrophobic. The hydrophobicity of the third layer 215 may vary, but in some embodiments, the third layer 215 may have a contact angle with water of at least 90 degrees. In some embodiments, the third layer 215 may have a contact angle with water of 150 degrees or less. For example, in some embodiments, the contact angle of the third layer 215 may be in the range of at least 90 degrees to about 120 degrees, or in the range of at least 120 degrees to 150 degrees. The water contact angle may be measured using any standard device. The hydrophobicity of the third layer 215 may be further enhanced with hydrophobic coatings of other materials, such as silicones and fluorocarbons, coated from a liquid or plasma coated. In some embodiments, for example, the third layer 215 may include 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 at all, with biological tissue and fluids, providing a surface that can promote free flow and low adhesion of liquids, which may be particularly advantageous in many applications. Other suitable polymer films include polyurethane, acrylic, polyolefin (such as cyclic olefin copolymer), polyacetate, polyamide, polyester, copolyester, PEBAX block copolymer, thermoplastic elastomer, thermoplastic vulcanizate, polyether, polyvinyl alcohol, polypropylene, polymethylpentene, polycarbonate, styrenic, silicone, fluoropolymer, and acetate. Thicknesses between 20 microns and 100 microns may be suitable for many applications. The film may be clear, colored, or printed.

[0061] The third layer 215 may also be suitable for welding to other layers, including the fourth layer 220. For example, the third layer 215 may be adapted for welding to polyurethane foam using heat, RF welding, or other methods for generating heat, such as ultrasonic welding. RF welding may be particularly suitable for more polar materials, such as polyurethane, polyamide, polyester, and acrylate. A sacrificial polar interface may be used to facilitate RF welding of less polar film materials, such as polyethylene. For example, more polar films suitable for laminating to polyethylene film include polyamide, copolyester, ionomer, and acrylic. Tie layers, such as ethylene vinyl acetate or modified polyurethane, may be used to aid in bonding between the polyethylene and polar films. Ethyl methyl acrylate (EMA) film may also have hydrophobic and welding properties suitable for some configurations.

[0062] The areal density of the third layer 215 may vary depending on the therapy or application of the formulation. In some embodiments, an areal density of less than 40 grams per square meter may be suitable, and an areal density of about 20-30 grams per square meter may be particularly advantageous for some applications.

[0063] As shown in the example of FIG. 2 , the third layer 215 may have one or more fluid restriction portions 255, which may be uniformly or randomly distributed throughout the third layer 215. The fluid restriction portions 255 may be bidirectional and pressure-responsive. For example, the fluid restriction portions 255 may generally include or consist essentially of elastic passages that are normally in a relaxed state and capable of expanding in response to a pressure gradient to substantially reduce liquid flow. In some embodiments, the fluid restriction portions 255 may include or consist essentially of perforations in the third layer 215. The perforations may be formed by removing material from the third layer 215. For example, the perforations may be formed by cutting through the third layer 215, which may also deform the edges of the perforations in some embodiments. In the absence of a pressure gradient across the perforations, the passages may be small enough to form a seal or flow restriction, which can substantially reduce or prevent liquid flow. Additionally or alternatively, one or more of the fluid restrictions 255 may be elastomeric valves that are normally closed to substantially prevent liquid flow when unstrained and that can open in response to a pressure gradient. Fenestrations in the third layer 215 may be suitable valves for some applications. Fenestrations may also be formed by removing material from the third layer 215, although the amount of material removed and the resulting dimensions of the fenestrations may be an order of magnitude smaller than perforations and may not deform the edges.

[0064] For example, some embodiments of the fluid restriction portion 255 may include or consist essentially of one or more slots or combinations of slots in the third layer 215. In some examples, the fluid restriction portion 255 may include or consist of a linear slot having a length of less than 4 millimeters and a width of less than 1 millimeter. The length may be at least 2 millimeters, and in some embodiments, the width may be at least 0.4 millimeters. A length of approximately 3 millimeters and a width of approximately 0.8 millimeters may be particularly suitable for many applications. A tolerance of approximately 0.1 millimeters may also be acceptable. Such dimensions and tolerances may be achieved, for example, with a laser cutter. Slots of this configuration may function as imperfect valves that substantially reduce liquid flow in a normally closed or quiescent state. For example, such slots may form a flow restriction without completely closing or sealing. The slots may significantly expand or open in response to a pressure gradient to allow increased liquid flow.

[0065] 2, the fourth layer 220 may form the second side 204 of the tissue interface 120. The fourth layer 220 may include, or consist essentially of, a manifold or manifold layer that provides a means for collecting or distributing fluid under pressure across the tissue interface 120. For example, the fourth layer 220 may be adapted to receive negative pressure from a negative pressure source and distribute the negative pressure across the tissue interface 120 through a plurality of openings, which may have the effect of collecting fluid from all over the tissue site and drawing the fluid toward the negative pressure source.

[0066] In some exemplary embodiments, the fourth layer 220 may include multiple channels that can interconnect to improve fluid distribution or collection. In some embodiments, the fourth layer 220 may include, or consist essentially of, a porous material with interconnected fluid channels. For example, open-cell foams, reticulated foams, porous tissue aggregates, and other porous materials such as gauze or felt mats generally include pores, edges, and / or walls adapted to form interconnected fluid channels. Liquids, gels, and other foams may also include, or may harden to include, openings and fluid channels. In some embodiments, the fourth layer 220 may additionally or alternatively include protrusions that form the interconnected fluid channels. For example, the fourth layer 220 may be molded to provide surface protrusions that define the interconnected fluid channels. Some or all of the surfaces of the fourth layer 220 may have an uneven, rough, or jagged profile.

[0067] In some embodiments, the fourth layer 220 may comprise or consist essentially of a reticulated foam having a pore size and free volume that may vary depending on the needs of the prescribed therapy. For example, a reticulated foam with at least 90% free volume may be suitable for many treatment applications, while a foam with an average pore size in the range of 400-600 microns (40-50 pores per inch) may be particularly suitable for some types of treatment. The tensile strength of the fourth layer 220 may also vary depending on the needs of the prescribed therapy. For example, the tensile strength of the foam may be increased for instillation of a topical treatment solution. The 25% compressive load deflection of the fourth layer 220 may be at least 0.35 pounds per square inch, and the 65% compressive load deflection may be at least 0.43 pounds per square inch. In some embodiments, the tensile strength of the fourth layer 220 may be at least 10 pounds per square inch. The fourth layer 220 may have a tear strength of at least 2.5 pounds per square inch. In some embodiments, fourth layer 220 may be a foam composed of a polyol, such as a polyester or polyether, an isocyanate, such as toluene diisocyanate, and a polymerization modifier, such as an amine or a tin compound. In one non-limiting example, fourth layer 220 may be a reticulated polyurethane ether foam such as that used in GRANUFOAM™ dressings or VACVERAFLO™ dressings available from KCI (San Antonio, Texas).

[0068] The fourth layer 220 may include either or both hydrophobic and hydrophilic materials. In examples where the fourth layer 220 may be hydrophilic, the fourth layer 220 may also wick fluid away from the tissue site while continuing to distribute negative pressure to the tissue site. The wicking properties of the fourth layer 220 may draw fluid away from the tissue site by capillary flow or other wicking mechanisms. One example of a hydrophilic foam is an open-cell foam of polyvinyl alcohol, such as VACWHITEFOAM™ dressing available from Kinetic Concepts, Inc. (San Antonio, Texas). Other hydrophilic foams may include those made from polyethers. Other foams that may exhibit hydrophilic properties include hydrophobic foams that have been treated or coated to impart hydrophilic properties.

[0069] The fourth layer 220 generally has a first plane and a second plane opposite the first plane. The thickness of the fourth layer 220 between the first plane and the second plane may also vary depending on the needs of the prescribed therapy. For example, the thickness of the fourth layer 220 may be reduced to relieve stress on the other layers and to reduce tension on the surrounding tissue. The thickness of the fourth layer 220 may also affect the conformability of the fourth layer 220. In some embodiments, a thickness in the range of approximately 5 millimeters to 10 millimeters may be suitable.

[0070] The individual components of tissue interface 120, and more generally of dressing 110, may be adhered or otherwise secured to one another, for example, with solvent or non-solvent adhesives, or with heat welding, without adversely affecting fluid management. Additionally, dressing 110 may comprise different combinations of individual layers and components. For example, tissue interface 120 may be provided as a stand-alone product for application to a tissue site. In some further embodiments, the individual layers of tissue interface 120 and dressing 110 may be omitted.

[0071] In the example of FIG. 2, dressing 110 may further include an attachment device such as adhesive 260. Adhesive 260 may be, for example, a medically acceptable pressure-sensitive adhesive that extends around the periphery, a portion, or the entirety of cover 125. In some embodiments, for example, adhesive 260 may be an acrylic adhesive having a coating weight of 25 to 65 grams per square meter (gsm). In some embodiments, a thicker adhesive, or combination of adhesives, may be applied to improve the seal and reduce leakage. Adhesive 260 may be a layer having substantially the same shape as periphery 225 of first layer 205. In some embodiments, such a layer of adhesive 260 may be continuous or discontinuous. Discontinuities in adhesive 260 may be provided by openings or holes (not shown) in adhesive 260. The openings or holes in adhesive 260 may be formed after application of adhesive 260 or by coating adhesive 260 in a pattern onto a carrier layer, such as one side of cover 125. In some exemplary embodiments, the openings or holes in the adhesive 260 may also be sized to increase the MVTR of the dressing 110.

[0072] The cover 125, first layer 205, second layer 210, third layer 215, and fourth layer 220, or various combinations, may be assembled prior to application or in situ. For example, the first layer 205, second layer 210, third layer 215, and fourth layer 220 of the tissue interface 120 may be arranged in a stacked arrangement, with the cover 125, having adhesive 260 disposed on its underside, positioned over the layers of the tissue interface 120 to hold the tissue interface 120 in place on the tissue site. Thus, within the dressing 110, the individual layers of the tissue interface 120, such as the fourth layer 220, may allow for a degree of movement within the dressing 110. In other examples, the cover 125 may be laminated to the fourth layer 220 and a portion of the first layer 205; in some embodiments, the third layer 215 may be laminated to the first layer 205 and the fourth layer 220 on the side opposite the cover 125. The second layer 210 may also be bonded to the first layer 205 on the side opposite the third layer 215, and in some embodiments, may form a substantial portion of the first side 202 or tissue-facing surface of the tissue interface 120. In some embodiments, one or more layers of the tissue interface 120 may be coextensive. For example, the fourth layer 220 may be coextensive with the third layer 215, as shown in the embodiment of FIG. 2. In some embodiments, the dressing 110 may be provided as a single composite dressing. For example, the first layer 205 may be bonded to the cover 125 to enclose the third layer 215 and the fourth layer 220, with the second layer 210 bonded to the tissue-facing side of the first layer 205.

[0073] As shown in the example of FIG. 2 , in some embodiments, a release liner 265 may be attached to or positioned adjacent to a portion of the second layer 210 and the first layer 205 on the first side 202 of the tissue interface 120 to protect the adhesive 260 prior to use. The release liner 265 may also provide rigidity, for example, to aid in application of the dressing 110. The release liner 265 may be, for example, a cast paper, film, or polyethylene. Further, in some embodiments, the release liner 265 may be a polyester material such as polyethylene terephthalate (PET) or a similar polar semi-crystalline polymer. The use of a polar semi-crystalline polymer for the release liner 265 can substantially prevent wrinkling or other deformation of the dressing 110. For example, the polar semi-crystalline polymer may be highly oriented and resistant to softening, swelling, or other deformation that may occur when in contact with components of the dressing 110 or when subjected to temperature changes, environmental changes, or sterilization. In some embodiments, the release liner 265 may have a surface texture that can imprint on an adjacent layer, such as the first layer 205. Additionally, a release agent may be disposed on the side of the release liner 265 that is configured to contact the first layer 205. For example, the release agent may be a silicone coating and may have suitable release factors to facilitate manual removal of the release liner 265 without damaging or distorting the dressing 110. In some embodiments, the release agent may be, for example, a fluorocarbon or fluorosilicone. In other embodiments, the release liner 265 may be uncoated or may be used without a release agent.

[0074] FIG. 2 also illustrates an example of a fluid conduit 270 and a dressing interface 275. As shown in the example of FIG. 2, the fluid conduit 270 may be a flexible tube that can be fluidly coupled at one end to the dressing interface 275. The dressing interface 275 may be an elbow-type connector that can be positioned over an opening 280 in the cover 125 to provide a fluid pathway between the fluid conduit 270 and the tissue interface 120, as shown in the example of FIG. 2. In some embodiments, the fluid conduit 270 may also include a fluid delivery conduit for use with intravenous therapy. Furthermore, in some embodiments, the dressing interface 275 may include multiple fluid conduits, such as a conduit for communicating negative pressure and a fluid delivery conduit. For example, the dressing interface 275 may be a VACVERAT.RAC™ pad.

[0075] In some embodiments of the dressing 110, one or more components of the dressing 110 may be further treated with an antimicrobial agent. For example, the first layer 205, the second layer 210, the third layer 215, and / or the fourth layer 220 may be coated with an antimicrobial agent. In some embodiments, the third layer 215 may include a polymer coated with or mixed with an antimicrobial agent. In other examples, the cover 125, the fluid conduit 270, the dressing interface 275, or other portions of the dressing 110 may additionally or alternatively be treated with one or more antimicrobial agents. Suitable antimicrobial agents may include, for example, metallic silver, PHMB, complexes and mixtures thereof such as iodine or povidone-iodine, copper metal compounds, chlorhexidine, or some combination of these materials.

[0076] In use, the release liner 265 (if included) may be removed to expose the second layer 210 and a portion of the first layer 205, which may be positioned in, above, on, or otherwise adjacent to a tissue site, particularly a superficial tissue site and adjacent epidermis. The first layer 205, second layer 210, and third layer 215 may be interposed between the fourth layer 220 and the tissue site, thereby substantially reducing or eliminating adverse interactions with the fourth layer 220. For example, the first layer 205, with the second layer 210 bonded to the tissue-facing surface of the first layer 205 on the first side 202 of the tissue interface 120, may be positioned over the wound surface (including the wound edge) and intact epidermis to prevent direct contact with the fourth layer 220. Treatment of or placement of the dressing 110 on a superficial wound may involve placing the dressing 110 directly adjacent to the surface of the body or extending over at least a portion of the surface of the body. Treatment of superficial wounds tends not to involve placing the dressing 110 completely within the body or completely below the surface of the body, such as placing the dressing 110 within the abdominal cavity. In some applications, the second layer 210 may be positioned adjacent to the treatment opening 230 in the first layer 205 such that the second layer 210 can be positioned adjacent to, proximate to, or covering a tissue site between the treatment opening 230 in the first layer 205 and the tissue site. In some applications, at least a portion of the third layer 215 and the fluid restriction portion 255 may be exposed to the tissue site through gaps or openings in the first layer 205 and second layer 210. The peripheral portion 225 of the first layer 205 may be positioned adjacent to or proximate to tissue around or surrounding the tissue site. The first layer 205 may be sufficiently adhesive to hold the dressing 110 in place, but may also allow the dressing 110 to be removed or repositioned without causing trauma to the tissue site.

[0077] Removal of the release liner 265 may also expose the adhesive 260, allowing the cover 125 to be attached to a mounting surface. For example, the cover 125 may be attached to the epidermis around the tissue site around the fourth layer 220 and the third layer 215. The adhesive 260, in some embodiments, may be in fluid communication with the mounting surface through the openings 235 in at least the periphery 225 of the first layer 205. The adhesive 260 may also be in fluid communication with the edge 245 through the openings 235 exposed at the edge 245. The second layer 210 may be placed against the tissue site and may be surrounded by a portion of the periphery 225 of the first layer 205 and a portion of the adhesive 260 that passes through the openings 235 in the periphery 225 of the first layer 205. In some embodiments, the presence of voids, openings, or apertures in the second layer 210 allows a portion of the adhesive 260 to pass through the openings 235 in the first layer 205 and the openings in the second layer 210 to contact and adhere to the attachment surface surrounding the tissue site. Thus, to the extent that the second layer 210 may overlap the periphery 225 of the first layer 205, portions of the tissue site or the area surrounding the tissue site that may be adjacent the periphery 225 of the first layer 205 may come into contact with portions of each of the enzyme-neutralizing material of the first layer 205, the second layer 210, and the adhesive 260.

[0078] Once the dressing 110 is in the desired position, the adhesive 260 can be pressed through the openings 235 to bond the dressing 110 to an attachment surface, such as the epidermis, surrounding the tissue site. The openings 235 in the edge 245 may allow the adhesive 260 to flow around the edge 245 to enhance adhesion of the edge 245 to the attachment surface. In some embodiments, the adhesive strength of the adhesive 260 may vary at different locations on the dressing 110.

[0079] The geometry and dimensions of the tissue interface 120, the cover 125, or both may be varied to suit a particular application or anatomical structure. For example, the geometry or dimensions of the tissue interface 120 and the cover 125 may be adapted to provide an effective and secure seal against difficult anatomical surfaces, such as the elbow or heel, at and around the tissue site. Additionally or alternatively, the dimensions can be modified to increase the surface area of the first layer 205, enhance epithelial cell migration and proliferation at the tissue site, and reduce the likelihood of granulation tissue ingrowth.

[0080] 2 can provide a sealed treatment environment proximate to the tissue site that is substantially isolated from the external environment, and the negative pressure source 105 can reduce the pressure in the sealed treatment environment. Additionally, the dressing 110 can be reapplied or repositioned to repair air leaks caused by, for example, wrinkles and other discontinuities in the dressing 110. In some embodiments, the ability to repair leaks can increase the efficacy of the therapy and reduce power consumption.

[0081] If not already configured, the dressing interface 275 may be placed over the opening 280 and attached to the cover 125. The fluid conduit 270 may be fluidly coupled to the dressing interface 275 and the negative pressure source 105.

[0082] In some applications, a filler material may be disposed between the tissue site and the tissue interface 120, such as between the tissue site and the second layer 210 of the tissue interface 120. For example, if the tissue site is a superficial wound, a wound filler material may be applied from the interior of the wound to the periphery, and a portion of the second layer 210 and / or first layer 205 may be disposed around the wound and over the wound filler material. In some embodiments, the filler material may be a manifold, such as an open-cell foam. The filler material may, in some embodiments, comprise or consist essentially of the same material as the fourth layer 220.

[0083] Negative pressure applied through the tissue interface 120 can create a negative pressure differential across the fluid restriction 255 in the third layer 215, which can open or expand the fluid restriction 255 from their resting state. For example, in some embodiments in which the fluid restriction 255 may include a substantially closed fenestration through the third layer 215, a pressure gradient across the fenestration can cause the adjacent material of the third layer 215 to tense, increasing the size of the fenestration and allowing fluid movement through the fenestration, similar to the action of a duckbill valve. Opening the fluid restriction 255 can allow exudate and other fluids to move through the fluid restriction 255 and into the fourth layer 220 and reservoir 115. The change in pressure can also cause the fourth layer 220 to expand and contract, and the third layer 215 and portions of the first layer 205 can protect the epidermis from irritation caused by movement of the fourth layer 220. The third layer 215, the first layer 205, and the second layer 210 can also substantially reduce or prevent tissue exposure to the fourth layer 220 and inhibit tissue growth into the fourth layer 220.

[0084] When the negative pressure source 105 is removed or turned off, the pressure differential across the fluid restriction 255 can dissipate, causing the fluid restriction 255 to move to their quiescent state and preventing or reducing the rate at which exudate or other liquids can return to the tissue site through the third layer 215. The second layer 210 may provide an additional means for protecting the tissue site from prolonged contact with exudate containing proteolytic enzymes in the event that exudate returns through the fluid restriction 255 of the third layer 215 or otherwise bypasses the third layer 215 and contacts the tissue site through the first layer 205. Such a situation may be more likely in the application of highly exuding wounds or when there is a failure in the application, configuration, or function of the dressing 110 and / or negative pressure source 105 of the treatment system 100.

[0085] FIG. 3 is an assembly view of another example of a dressing 110, illustrating additional details that may be relevant to some embodiments. In particular, FIG. 3 illustrates another example of a second layer 210. Some of the components of the dressing 110 in FIG. 3 may be the same or similar to those of the dressing 110 in FIG. 2, although the arrangement and / or order of the layers of the dressing 110 in FIG. 3 may be different. While the exemplary embodiment of the dressing 110 shown in FIG. 3 omits some of the layers of the dressing 110 in FIG. 2, alternative embodiments may include one or more of the omitted layers in combination with the layers of the embodiment shown in FIG. 3. The second layer 210 in FIG. 3 may include one or more enzyme-modulating or enzyme-neutralizing materials as described with respect to the second layer 210 in FIG. 2 and may be in the form of a ring-shaped layer positioned adjacent to the first layer 205 on the first side 202 of the tissue interface 120. For example, the second layer 210 may be in the form of a ring-shaped layer having an outer structural portion 302 that includes one or more enzyme-neutralizing materials and an opening 304. In some alternative embodiments, the second layer 210 may have a different shape, such as a square, circular, or rectangular shape. In addition to or instead of being included as a separate layer, the material of the second layer 210 may be printed or pattern coated onto the surface of the first layer 205 on the first side 202 of the tissue interface 120.

[0086] In the embodiment shown in Figure 3, the first layer 205 may have an inner boundary 305 around an inner portion having a plurality of treatment openings 310. The inner boundary 305 may be located between the plurality of treatment openings 310 and the periphery 225. The inner boundary 305 may be substantially free of openings, as shown in the example of Figure 3. The inner portion including the plurality of treatment openings 310 may be symmetrical and centrally located within the first layer 205.

[0087] In some embodiments, the diameter of the openings 235 in the periphery 225 of the first layer 205 may be larger than the diameter of the treatment openings 310 in the interior portion of the first layer 205. For example, in some embodiments, the openings 235 located in the periphery 225 may have a diameter of about 9.8 millimeters to about 10.2 millimeters, and the openings 235 located in the corners 240 may have a diameter of about 7.75 millimeters to about 8.75 millimeters. In some embodiments, the treatment openings 310 located in the interior portion of the first layer 205 may have a diameter of about 1.8 millimeters to about 2.2 millimeters.

[0088] As shown in FIG. 3 , in some embodiments, the second layer 210 may have an oval ring shape that may be aligned with a portion of the first layer 205. The opening 304 may be fluidly coupled to one or more of the treatment openings 310. For example, the opening 304 may be aligned with one or more of the treatment openings 310, or the opening 304 may substantially surround the treatment opening 310. In some exemplary embodiments, the second layer 210 may be substantially aligned with the inner boundary 305 of the first layer 205. In some examples, the opening 304 may have a width of about 3 centimeters to about 35 centimeters. A width of about 12 centimeters to about 24 centimeters may be suitable for some embodiments. The second layer 210 may provide a form of barrier or boundary on the first side 202 of the tissue interface 120 so that proteolytic enzymes in fluids exuding from the tissue site may come into contact with a portion of the enzyme-neutralizing material of the second layer 210 before migrating outward from the center of the tissue site and the tissue interface 120 toward the peri-wound area.

[0089] 4 is a schematic diagram of the embodiment of the tissue interface 120 of FIG. 3 from the perspective of the first side 202 of the tissue interface 120. As shown in FIG. 4, the second layer 210 may be positioned relative to a portion of the first layer 205. For example, the first layer 205 may have a first surface 405 that forms at least a portion of the first side 202 of the tissue interface 120. The second layer 210 may also have a first surface 415 that forms at least a portion of the first side 202 of the tissue interface 120. As shown in FIG. 4, the second layer 210 may be positioned relative to the first layer 205 such that the second layer 210 contacts a substantial portion of the first surface 405 of the first layer 205.

[0090] 4 , the second layer 210 may be sized and positioned such that the second layer 210 substantially aligns with the inner boundary 305 of the first layer 205. The material of the second layer 210 may also align with a portion of the inner portion of the first layer 205 that includes the multiple treatment openings 310 and / or a portion of the periphery 225 of the first layer 205. In some examples, the second layer 210 may block or cover at least a portion of some of the openings 235 in the periphery 225 without interfering with proper adhesion of the dressing 110 to the tissue site. For example, a sufficient amount of adhesive 260 may be able to pass through the remaining openings 235 in the periphery 225 to form a sufficient seal around the tissue site. In some embodiments, the material of the second layer 210 may be printed or coated onto the first side 202 of the tissue interface 120 after assembly of the other layers of the dressing 110, such that the second layer 210 is applied partially to the surface of the first layer 205 and to portions of the adhesive 260 that may be exposed through openings 235 in the periphery 225 of the first layer 205.

[0091] The second layer 210 may be positioned to specifically protect the periphery of the tissue site or the peri-wound area from abundant proteolytic enzymes. For example, during administration of negative pressure therapy, fluid may be drawn from the tissue site and brought into contact with the first side 202 of the tissue interface 120. While the fluid may typically migrate through the multiple treatment openings 310 in the first layer 205 toward the openings 280 in the cover 125 of the dressing 110, in some cases, at least some of the fluid may also migrate laterally across the surface of the tissue site or the first side 202 of the tissue interface 120 toward the peri-wound area. By positioning the second layer 210 on the first side 202 of the tissue interface 120, fluid migrating toward the peri-wound area first passes through at least a portion of the second layer 210 before reaching the peri-wound area of the tissue site or the peri-wound area. As a result, the second layer 210 may, in effect, function as an enzyme-neutralizing filter through which fluid from the tissue site and central portion of the dressing 110 must pass before reaching the tissue site and / or outer portions of the dressing 110. Such an arrangement may minimize or prevent exposure of the wound margin and / or peri-wound area to wound fluid that may contain excess proteolytic enzymes. The second layer 210 may also protect the peri-wound area from proteolytic enzymes in the wound fluid that may migrate from other layers of the tissue interface 120 back toward the tissue site and potentially outward toward the peri-wound area.

[0092] FIG. 5 is an assembly diagram of another example of a dressing 110. For example, the individual layers of the tissue interface 120 in FIG. 5 may be arranged or stacked in a different order than the layers of the tissue interface 120 in FIG. 2. More specifically, in some embodiments, the second layer 210 in FIG. 5 may be disposed adjacent to the fourth layer 220 or between the fourth layer 220 and the cover 125 of the dressing 110. As shown in FIG. 5, the second layer 210 may have an oval shape similar to the other layers of the tissue interface 120, such as the third layer 215 and the fourth layer 220. In other examples, the second layer 210 in FIG. 5 may also have a different shape or configuration, such as a square, circular, or X-shaped configuration. Additionally or alternatively, the second layer 210 in FIG. 5 may include a lattice structure similar to that of FIG. 2. 5, in some embodiments, the second layer 210 may include a plurality of openings or apertures, such as perforations 505, to allow communication of negative pressure and transport of fluids, such as wound fluid, through the second layer 210 and toward the openings 280 in the cover 125 of the dressing 110. For example, the perforations 505 may each have a diameter of 1 mm to 10 mm, and in some embodiments, may have a circular shape with a diameter of 1 mm to 5 mm. In some additional embodiments, the second layer 210 may include a plurality of openings in the form of slots, each having a length of 1 mm to 5 mm and a width of 0.5 mm to 2 mm.

[0093] In some embodiments, the second layer 210 may include an enzyme-neutralizing material that may vary spatially across the second layer 210. In some embodiments, the enzyme-neutralizing material may be disposed within the second layer 210 or dispersed throughout the second layer 210 according to a gradient. For example, the second layer 210 may include a lower concentration of an enzyme-neutralizing material, such as one or more of a sacrificial substrate, an enzyme deactivator, or an enzyme sequestrant, in a central portion of the second layer 210, with the concentration of the enzyme-neutralizing material increasing with increasing distance from the center of the second layer 210 toward the edge or periphery of the second layer 210. In some embodiments, the enzyme-neutralizing material may have a circular concentration gradient with a higher concentration at the periphery than at the center. In some embodiments, the concentration may be between about 100 and 450 mg / cm.2 A concentration of about 1 to 75 mg / cm may be suitable for the peripheral area. 2 A concentration of enzyme neutralizing material may be suitable for the central portion. Including a higher concentration of enzyme neutralizing material in the peripheral portion of second layer 210, which may be proximate the periwound area, may ensure that the periwound area is not exposed to excessive levels of proteolytic enzymes that may result in maceration of the periwound tissue. Including a higher concentration of enzyme neutralizing material in the outer or peripheral portion of second layer 210 may improve the antimicrobial capabilities of second layer 210, ensuring that wound fluid that may migrate away from the central portion of tissue interface 120 and potentially toward the wound margin can be treated by second layer 210.

[0094] 5, dressing 110 may further include features designed to ensure the structural stability of dressing 110 over time, since some of the enzyme-neutralizing material in second layer 210 may be degraded by prolonged contact with wound fluid containing proteolytic enzymes. Although not specifically shown in FIG. 5, additional polymer welds may optionally be included in dressing 110, which pass through second layer 210 and join two or more layers surrounding second layer 210 to one another to prevent or minimize movement between or separation of the layers of dressing 110 from one another. For example, depending on the particular arrangement of layers in a particular embodiment of dressing 110, a polymer weld may pass completely through second layer 210 of dressing 110, or in other exemplary embodiments, any other layer containing enzyme-neutralizing material, to form a top adhesive layer, such as cover 125, with a base or sealing layer, such as first layer 205.

[0095] The tissue interface 120 and the dressing 110 may be provided with different combinations of individual layers and different combinations of materials within one or more of the layers. In some embodiments, instead of or in addition to being applied to a separate layer of the tissue interface 120, the enzyme-neutralizing material may be applied to one of the other layers of the tissue interface 120. For example, the various layers of the tissue interface 120 may be assembled, and then the enzyme-neutralizing material may be printed or coated onto the surface of the first layer 205 of the first side 202 of the tissue interface 120. Furthermore, in some additional embodiments, the material for reducing or neutralizing proteolytic activity in wound fluid may be included in additional or alternative portions of the tissue interface 120, and more generally, the dressing 110. For example, the material for reducing proteolytic activity may be combined with or integrated into the material of one or more of the other layers of the tissue interface 120. In an exemplary embodiment, one or more enzyme-neutralizing materials may be incorporated into the silicone adhesive formulation after curing of the first layer 205, in addition to or instead of being included as a separate enzyme-neutralizing layer.

[0096] In some further embodiments, additional materials for reducing or neutralizing protease activity may be added to one or more layers of tissue interface 120. For example, synthetic or naturally occurring protease inhibitors in the form of proteins, peptides, or small molecules may be added to an enzyme neutralizing layer, such as second layer 210, to provide an additional means for neutralizing protease activity. For example, protease inhibitors may include tissue inhibitors of metalloproteinases (TIMPs), thrombospondin-1, thrombospondin-2, elastase inhibitor 2, alpha-1 antitrypsin, pepstatin A, aprotinin, EDTA, leupeptin, and the like. Some examples of naturally occurring protease inhibitors include, but are not limited to, thionin, which is commonly found in potato tubers and is also known to contain antibacterial compounds; green tea catechins; cyanobacteria; and members of the families Fabaceae, Malvaceae, Rutaceae, Poaceae, and Moringa.

[0097] The systems, devices, and methods described herein can provide significant advantages. For example, the dressing 110 can be a fully integrated negative pressure therapeutic dressing that can be applied to a tissue site (including the periwound area) for extended wear to promote granulation, while providing the benefit of protecting the surrounding tissue site from maceration. For example, the inclusion of one or more substrates for neutralizing proteolytic enzymes in the tissue interface 120 and / or the dressing 110 can protect the tissue site, including the periwound area, by reducing or preventing potential adverse effects resulting from increased levels of inflammatory cells and proteases in the wound fluid. The one or more enzyme-neutralizing substrates can prevent excessive levels of enzyme proteases from contacting the tissue site while still allowing the proteases to have beneficial effects for promoting normal wound healing. For example, normal levels of proteases can help degrade denatured extracellular matrix (ECM), thereby exposing functional matrix to the healing tissue. The inclusion of one or more enzyme-neutralizing substrates can prevent disruptions to the wound healing system due to an increase in the number of proteases, resulting in a disruption in the ratio of proteases to their inhibitors, leading to degradation of the ECM formed during the wound healing process and the resulting inhibition of wound healing.

[0098] Such benefits may be particularly realized when applying the dressing 110 to tissue sites with high volumes of wound exudate, such as chronic wounds where managing the wound environment and moisture balance at the tissue site is particularly challenging. When applied to chronic wounds where increased levels of proteolytic enzymes may be present in wound fluid at the tissue site, including one or more enzyme-neutralizing materials in the layers of the dressing 110 may be particularly advantageous for achieving longer wear times. For example, longer wear times, such as up to seven days, may be achieved while minimizing the risk of maceration of the periwound area that may exist due to potential prolonged contact with wound fluid containing proteolytic enzymes. Furthermore, because the dressing 110 may also cover the wound periphery, providing an enzyme-neutralizing material in a layer between the other layers of the tissue interface 120 and the tissue site, such as the tissue-facing surface of the tissue interface 120, may provide particular protection to the wound periphery by neutralizing proteolytic enzymes found in wound exudate present at the surface of the tissue site. Thus, in many cases, proteolytic enzymes may be neutralized before contacting the periwound area, thereby preventing prolonged exposure of the wound margin, such as the wound periphery, to wound fluid and associated proteases and inflammatory cells. Additionally, the dressing 110 may provide macrostrain at the edges of a tissue site, such as a wound edge, while substantially reducing or preventing maceration of the surrounding periwound area.

[0099] The inclusion of an enzyme-neutralizing material in the dressing 110 may further provide an antimicrobial effect, which may also extend the usable life of the dressing 110. By providing an antimicrobial effect, the enzyme-neutralizing material may significantly reduce the risk of infection that may be associated with extended wear of the dressing, particularly when applied to infected or highly exuding wounds. Thus, the dressing 110 may provide a long-term wear solution that can prevent maceration and the potential accumulation of microbial material, while maintaining a good seal around the tissue site and not obstructing the pathway for negative pressure therapy.

[0100] While illustrated in several exemplary embodiments, those skilled in the art will recognize that the systems, devices, and methods described herein are capable of various modifications and variations within the scope of the appended claims. Furthermore, the description of various alternatives using terms such as "or" does not require mutual exclusivity unless clearly required by context, and the indefinite articles "a" or "an" do not limit reference to a single instance unless clearly required by context. Components may also be combined or excluded in various configurations for purposes of sale, manufacture, assembly, or use. For example, in some configurations, the dressing 110 may be separated from the other components for manufacture or sale. In other exemplary configurations, the dressing 110 or tissue interface 120 may also be manufactured, configured, assembled, or sold as a kit, independent of the other components.

[0101] The appended claims will recite the novelty and inventive step of the above-described subject matter, 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 they are not necessary to distinguish the novel and inventive features from those known to those skilled 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 as defined by the appended claims.

Claims

1. 1. A dressing for treating a tissue site, comprising: a first layer including a hydrophobic gel having at least one treatment opening; a second layer adjacent to the first layer, the second layer comprising a material adapted to neutralize proteolytic enzymes; a third layer adjacent to the first layer, the third layer including a polymer film having a plurality of fluid restriction portions configured to expand in response to a pressure gradient; a fourth layer adjacent to the third layer and on an opposite side of the third layer from the first layer, the fourth layer including a manifold; and a fifth layer adjacent to said fourth layer opposite said third layer, said fifth layer comprising a polymeric drape.

2. The dressing of claim 1 , wherein the material adapted to neutralize proteolytic enzymes comprises a sacrificial substrate.

3. 10. The dressing of claim 1, wherein the material adapted to neutralize proteolytic enzymes comprises an enzyme deactivator.

4. 10. The dressing of claim 1, wherein the material adapted to neutralize proteolytic enzymes comprises an enzyme sequestrant.

5. A dressing according to any preceding claim, wherein the second layer comprises a plurality of perforations.

6. A dressing according to any preceding claim, wherein the second layer comprises a plurality of fenestrations.

7. A dressing according to any preceding claim, wherein the second layer comprises a biologically derived polymer.

8. The dressing of claim 1 , wherein the second layer comprises collagen.

9. The dressing of claim 1 , wherein the second layer comprises gelatin.

10. The dressing of claim 1 , wherein the second layer comprises a collagen-like protein.

11. The dressing of claim 1 , wherein the second layer comprises a collagen-like peptide.

12. The dressing of claim 1 , wherein the second layer comprises cellulose or a cellulose derivative.

13. The dressing of claim 1 , wherein the second layer comprises collagen and oxidized regenerated cellulose.

14. A dressing according to any preceding claim, wherein the second layer forms a ring.

15. A dressing according to any preceding claim, wherein the second layer comprises a central opening.

16. The dressing of any one of claims 1 to 14, wherein the second layer includes an opening aligned with the treatment opening.

17. A dressing according to any preceding claim, wherein the second layer includes an opening having a width in the range of from about 3 centimetres to about 35 centimetres.

18. A dressing according to any preceding claim, wherein the second layer has a thickness of from 5 micrometers to 500 micrometers.

19. A dressing according to any preceding claim, wherein the second layer has a thickness of from 40 micrometers to 100 micrometers.

20. 10. The dressing of claim 1, wherein the second layer comprises about 20-80% by weight collagen and about 80-20% by weight ORC.

21. 10. The dressing of claim 1, wherein the second layer comprises about 55% by weight collagen and about 45% by weight ORC.

22. A dressing according to any preceding claim, wherein the hydrophobic gel of the first layer is a silicone gel.

23. A dressing according to any preceding claim, wherein the material adapted to neutralise proteolytic enzymes is present in a higher concentration in the peripheral portion of the second layer than in the central portion.

24. 24. A dressing according to any one of the preceding claims, wherein the material adapted to neutralise proteolytic enzymes is present in a concentration having a circular gradient that increases from a central portion of the second layer towards the periphery of the second layer.

25. A dressing according to any preceding claim, wherein the manifold comprises foam.

26. 26. The dressing of claim 25, wherein the foam is a polymer foam.

27. 26. The dressing of claim 25, wherein the foam is a polyurethane ether foam.

28. 26. The dressing of claim 25, wherein the foam is a reticulated polyurethane ether foam.

29. A dressing according to any preceding claim, wherein the manifold has a thickness of less than 7mm.

30. A dressing according to any preceding claim, wherein the polymeric film of the third layer is hydrophobic.

31. A dressing according to any preceding claim, wherein the polymeric film of the third layer is a polyethylene film.

32. A dressing according to any preceding claim, wherein the fluid restricting portion of the third layer comprises a plurality of slots, each of the slots having a length of less than 4mm.

33. A dressing according to any preceding claim, wherein the fluid restricting portion of the third layer comprises a plurality of slots, each of the slots having a length of less than 4mm and a width of less than 2mm.

34. A dressing according to any preceding claim, wherein the fluid restricting portion is coextensive with the polymeric film of the third layer.

35. A dressing according to any preceding claim, wherein the fluid restriction portion is coextensive with the manifold.

36. A dressing according to any preceding claim, further comprising a fluid port coupled to the fifth layer, the fluid port configured to be coupled to a fluid conduit.

37. A dressing according to any preceding claim, wherein the first and fifth layers are adapted to provide a liquid-tight seal.

38. 1. A system for treating a tissue site, comprising: A dressing according to any one of claims 1 to 37; a negative pressure source adapted to be fluidly coupled to the dressing.

39. 40. The system of claim 38, further comprising a fluid reservoir adapted to be fluidly coupled between the dressing and the negative pressure source.

40. 1. A dressing for treating a tissue site using negative pressure, comprising: a first layer comprising a perforated silicone gel coating; a second layer coupled to the first layer and comprising an enzyme modulating material; a polymeric drape adjacent to said first layer opposite said second layer, said polymeric drape including an adhesive coating.

41. 41. The dressing of claim 40, wherein the adhesive coating of the polymeric drape is adapted to pass through at least some of the perforations in the first layer.

42. a third layer positioned between the first layer and the polymeric drape, the third layer comprising a non-porous material and a plurality of fenestrations; 42. The dressing of claim 40 or 41, further comprising a manifold layer between the third layer and the polymeric drape.

43. A dressing according to any one of claims 40 to 42, wherein the first layer comprises a polyurethane film coated with the perforated silicone gel coating.

44. A dressing according to any one of claims 40 to 43, wherein the enzyme modulating material of the second layer comprises a sacrificial substrate.

45. 45. The dressing of claim 44, wherein the sacrificial matrix comprises collagen, gelatin, chemically modified cellulose, hyaluronic acid, chondroitin sulfate, collagen-mimetic peptides, or combinations thereof.

46. 41. The dressing of claim 40, wherein the enzyme modulating material of the second layer comprises an enzyme deactivator.

47. 47. The dressing of claim 46, wherein the enzyme deactivator comprises an MMP inhibitor, a small molecule protease inhibitor, or a combination thereof.

48. 41. The dressing of claim 40, wherein the enzyme modulating material of the second layer comprises an enzyme sequestrant.

49. 49. The dressing of claim 48, wherein the enzyme sequestering agent comprises a chelating agent.

50. 50. The dressing of claim 49, wherein the chelating agent comprises EDTA, EGTA, or a combination thereof.

51. 49. The dressing of claim 48, wherein the enzyme sequestrant comprises a metalloprotein inhibitor having at least one zinc-binding group.

52. 41. The dressing of claim 40, wherein the second layer comprises a biologically derived polymer.

53. 41. The dressing of claim 40, wherein the second layer comprises collagen.

54. 41. The dressing of claim 40, wherein the second layer comprises gelatin.

55. 41. The dressing of claim 40, wherein the second layer comprises a collagen-like protein.

56. 41. The dressing of claim 40, wherein the second layer comprises a collagen-like peptide.

57. 41. The dressing of claim 40, wherein the second layer comprises cellulose or a cellulose derivative.

58. 41. The dressing of claim 40, wherein the second layer comprises oxidized regenerated cellulose.

59. 59. A dressing according to any one of claims 40 to 58, wherein the enzyme modulating material of the second layer is present in a higher concentration in a peripheral portion of the second layer than in a central portion of the second layer.

60. 60. The dressing of any one of claims 40 to 59, further comprising a plurality of welds joining the first layer and the polymeric drape.

61. 61. The dressing of any one of claims 40 to 60, further comprising a protease inhibitor including TIMP, thrombospondin-1, thrombospondin-2, elastase inhibitor 2, alpha 1 antitrypsin, pepstatin A, aprotinin, EDTA, leupeptin, and combinations thereof.

62. A dressing according to any one of claims 42 to 61, wherein the manifold layer comprises foam.

63. 1. A dressing for treating a tissue site using negative pressure, comprising: a first layer comprising a hydrophobic gel having a plurality of openings; a second layer comprising a material adapted to neutralize proteolytic enzymes, the second layer having a plurality of fenestrations; a third layer adapted to be positioned adjacent said first layer opposite said second layer, said third layer comprising a polymeric drape.

64. 1. A dressing for treating a tissue site using negative pressure, comprising: a first layer comprising a hydrophobic gel having a plurality of openings; a second layer adapted to be bonded to the first layer, the second layer comprising a polymeric film having a plurality of fenestrations; a third layer adapted to be positioned adjacent to the second layer opposite the first layer, the third layer including a manifold; a fourth layer adapted to be positioned adjacent to the third layer opposite the second layer, the fourth layer having a plurality of openings and comprising a material adapted to neutralize proteolytic enzymes; and a fifth layer adapted to be joined to said fourth layer opposite said third layer, said fifth layer comprising a polymeric drape.

65. 65. The dressing of claim 64, wherein the plurality of openings in the fourth layer comprise slots having a length of less than 4 mm and a width of less than 2 mm.

66. 65. The dressing of claim 64, wherein the plurality of openings comprise perforations having a diameter of between 1 mm and 5 mm.

67. 65. The dressing of claim 64, wherein the fifth layer includes an adhesive coating on a surface adapted to be placed in periphery contact with the first layer.

68. 1. A dressing for treating a tissue site, comprising: a first layer comprising a hydrophobic gel adhesive and a material adapted to neutralize proteolytic enzymes, the first layer having a plurality of openings; a second layer including a manifold; a third layer adapted to be disposed between said first layer and said second layer, said third layer comprising a polymeric film having a plurality of fenestrations.

69. 69. The dressing of claim 68, further comprising a fourth layer adapted to be joined to the second layer opposite the third layer, the fourth layer comprising a polymeric drape.

70. 70. A dressing according to claim 68 or claim 69, wherein the hydrophobic gel adhesive comprises a perforated silicone gel.

71. 1. A dressing for treating a tissue site, comprising: a hydrophobic gel layer; an enzyme modulating layer adjacent to the hydrophobic gel layer; a fluid control layer adjacent to the hydrophobic gel layer opposite the enzyme modulating layer; a manifold layer adjacent to the fluid control layer opposite the hydrophobic gel layer, the manifold layer comprising foam.

72. The hydrophobic gel layer is A polyurethane film; a perforated silicone gel adhesive.

73. 73. The dressing of claim 71 or claim 72, wherein the enzyme modulating layer comprises a plurality of apertures.

74. 1. A dressing for treating a tissue site using negative pressure, comprising: a perforated silicone gel; a first film comprising an aperture and an enzyme modulating material; a second film including a plurality of fenestrations; and A manifold; a cover; the perforated silicone gel, the first film, the second film, the manifold, and the cover are assembled in a laminated relationship such that the perforated silicone gel and the cover enclose the second film and the manifold, and the first film is configured to contact the tissue site.

75. 1. A dressing for treating a tissue site using negative pressure, comprising: a first layer comprising an enzyme modulating material; a second layer adapted to be bonded to the first layer, the second layer comprising a hydrophobic gel; a third layer adapted to be bonded to the second layer opposite the first layer, the third layer comprising a fenestration film; and a fourth layer adapted to be positioned adjacent to the third layer opposite the second layer, the fourth layer including a manifold; The dressing, wherein the first layer is in the form of a ring having an outer structural portion and an opening, the ring adapted to be applied to the first surface of the second layer.

76. 76. The dressing of claim 75, further comprising a fifth layer adapted to be joined to the fourth layer opposite the third layer, the fifth layer comprising a polymeric drape.

77. 77. A dressing according to claim 75 or claim 76, wherein the first layer is applied as a pattern coating to the first surface of the second layer.

78. 10. A system, apparatus, and method substantially as described herein.

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