Dressings using features for protection against maceration

Abstract

A dressing for treating a tissue site using negative pressure is disclosed, which may include a dressing having multiple layers and incorporating a material adapted to neutralize proteolytic enzymes. In one exemplary embodiment, the dressing may include a first layer comprising a hydrophobic gel having a plurality of apertures. The 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 bonded to the first layer. Additionally, the dressing may include a third layer comprising a manifold, which may optionally be a polymer foam. The dressing may further include a fourth layer comprising a polymer drape.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 867,001, filed Jun. 26, 2019, entitled “Dressing Employing Features for Protection Against Maceration”, which is hereby incorporated by reference in its entirety for all purposes.

[0002] The present invention, as claimed in the appended claims, relates generally to tissue treatment systems, and more particularly, but not limited to, dressings for tissue treatment using negative pressure, and methods of using dressings for tissue treatment using negative pressure.

Background Art

[0003] In clinical research and clinical practice, it has been shown that reducing pressure proximal to a tissue site can enhance and accelerate the growth of new tissue at the tissue site. There are many applications of this phenomenon, but it has been found to be particularly advantageous for treating wounds. Whether due to trauma, surgery, or another cause, regardless of the cause of the wound, proper care of the wound is important for the outcome. The treatment of wounds or other tissues using reduced pressure can 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 closure”, and “local negative pressure”. Negative pressure therapy can provide many benefits including, but not limited to, the migration of epithelial and subcutaneous tissues, improved blood flow, and micro - deformation of tissues at the wound site. Collectively, these benefits can increase the development of granulation tissue and reduce the healing time.

[0004] The clinical benefits of negative pressure therapy are well known, but improvements in therapy systems, components, and processes can provide benefits to healthcare providers and patients.

Summary of the Invention

[0005] A novel and useful system, apparatus, and method for treating tissue in a negative pressure therapy environment are described in the appended 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 a tissue site may incorporate one or more means for inhibiting the excessive activity of proteolytic enzymes in wound fluid. For example, a tissue dressing may include a sacrificial proteolytic enzyme substrate to reduce or prevent such proteolytic enzymes from degrading new tissue when formed as part of wound healing. Normal endogenous levels of proteases in a wound are important for tissue remodeling during the healing process. For example, matrix metalloproteinases (MMPs) are one of the proteases typically present in a wound and can play an important role in the wound healing response. However, when excessive or when in contact with the healing region of the wound site, such as at the wound edge or around the wound, such enzymes can continuously degrade the new tissue being formed. Prolonged contact of wound fluid can also result in maceration of the wound edge or the area surrounding the wound, particularly when high levels of proteolytic enzymes may be present. Specifically, the presence of water in the area surrounding the wound can cause hydration of the stratum corneum, which can reduce the barrier function of typical healthy skin. Various proteolytic enzymes present in the wound exudate can then penetrate the subsequent healthy skin and cause maceration. These factors can also contribute to the wound not healing promptly or persisting.

[0007] Accordingly, in certain aspects, dressings incorporating one or more substrates for preventing the deleterious or unwanted effects of wound fluid and associated proteolytic enzymes on healthy or healing skin are disclosed. Such substrates, such as one or more biopolymers, may function as sacrificial substrates for enzyme modulation or neutralization, may function as enzyme inactivators, and / or may function as enzyme blockers for reducing the levels of proteolytic enzymes that can have a negative effect on wound healing. It may include one or more substrates for MMPs as well as other proteolytic enzymes. For example, possible 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 containing collagen, which may be a substrate suitable for many of the most common MMPs in wounds. In some cases, the protein for use as a sacrificial substrate may be hydrolyzed or partially hydrolyzed by treatment with strong acid or strong base. Such treatment can fragment the target protein and generate more accessible peptide sequences for binding to proteolytic enzymes. As described below in the disclosed exemplary embodiments, the sacrificial proteolytic substrate may be integrated with 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 the side opposite the second layer, a fourth layer adjacent to the third layer on the side opposite the first layer, and a fifth layer adjacent to the fourth layer on the side opposite the third layer. The first layer may include a hydrophobic gel having a plurality of openings. The second layer may include a material adapted to neutralize proteolytic enzymes. The third layer may include a polymeric film having a plurality of fluid restrictions 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 proteolytic enzymes in 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 coupled to the first film, a third film adjacent to the first film on the side opposite the second film, and a manifold layer adjacent to the third film. The first film may include a porous 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 apertures. The manifold layer may include a foam.

[0010] In further embodiments, 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 the side opposite the second layer. The first layer may include a hydrophobic gel having a plurality of openings, the second layer may include a material adapted to neutralize proteolytic enzymes and may have a plurality of apertures, and the third layer may include a polymeric drape.

[0011] In still some additional embodiments, a dressing for treating a tissue site may include a first layer, a second layer adapted to be coupled to the first layer, a third layer adapted to be positioned adjacent to the second layer on a side opposite the first layer, a fourth layer adapted to be positioned adjacent to the third layer on a side opposite the second layer, and a fifth layer adapted to be coupled to the fourth layer on a side opposite 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 apertures, and the third layer may include a manifold. The fourth layer may have a plurality of openings 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 layer and the second layer. The first layer may have a plurality of openings 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 apertures. 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 regulating layer adjacent to the hydrophobic gel layer, a fluid control layer adjacent to the hydrophobic gel layer on a side opposite the enzyme regulating layer, and a manifold layer adjacent to the fluid control layer on a side opposite the hydrophobic gel layer. The manifold layer may include a foam.

[0014] In some additional embodiments, a dressing for treating a tissue site using negative pressure may include a porous silicone gel, a first film including an aperture and an enzyme modulating material, a second film including a plurality of fenestrations, a manifold, and a cover. The porous silicone gel, the first film, the second film, the manifold, and the cover may be assembled in a stacked relationship in which the porous silicone gel and the cover enclose the second film and the 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 including an enzyme modulating material, a second layer adapted to be coupled to the first layer, a third layer adapted to be coupled to the second layer on an opposite side of the first layer, and a fourth layer adapted to be positioned adjacent to the third layer on an opposite side of 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 aperture, and the ring is adapted to be applied to a first surface of the second layer. Further, the dressing may further include a fifth layer adapted to be coupled to the fourth layer on an opposite side of 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 aspects of the claimed subject matter will be best understood by reference to the following detailed description of the exemplary embodiments in conjunction with the accompanying drawings.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0022] The following description of the exemplary embodiments provides information that enables those skilled in the art to make and use the subject matter recited in the appended claims, but may omit certain details that are already well known in the art. Accordingly, the following detailed description is to be construed as illustrative and not restrictive.

[0023] The exemplary embodiments may also be described herein with reference to the spatial relationships between the various elements shown in the accompanying drawings or the spatial orientation of the various elements. Generally, such relationships or orientations are aligned with or take a reference system with respect to a patient in the position being treated. However, it will be understood by those skilled in the art that this reference system is not a strict definition 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 that can provide negative pressure therapy to a tissue site according to the present specification.

[0025] As used in this context, the term "tissue site" broadly refers to a wound, defect, or other treatment target located on or within a 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 lacerated wounds, partial thickness burns, ulcers (such as diabetic ulcers, pressure ulcers, or venous insufficiency ulcers), skin flaps, and graft tissues. The term "tissue site" can also refer to any tissue area that is not necessarily an area with a wound or defect, but rather 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 that can be harvested and transplanted.

[0026] Treatment system 100 can 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 can be associated with some examples of treatment system 100. As shown in the example of FIG. 1, dressing 110 may include, consist essentially of, or in some embodiments both include tissue interface 120, cover 125.

[0027] A fluid conduit is another exemplary example of a distribution component. In this context, a "fluid conduit" broadly includes tubes, pipes, hoses, ducts, or other structures having one or more lumens or open paths adapted to convey fluid between two ends. Typically, a tube is an elongated cylindrical structure having some degree of flexibility, although the geometry and rigidity may vary. Also, some fluid conduits may be formed within other components or may be integrally combined with other components. The distribution component may also include or be provided with an interface or fluid port to facilitate the connection and separation 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.R.A.C (trademark) 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 a feedback signal 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 housed within or used in combination with other components, such as sensors, processing units, alarm indicators, memories, databases, software, display devices, or user interfaces, to further facilitate the therapy. For example, in some embodiments, the negative pressure source 105 may be combined with the controller 130 and other components to form a therapy unit.

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

[0031] A negative pressure supply, such as the negative pressure source 105, may be a reservoir of air at negative pressure or, for example, a manual or electric 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 a local ambient pressure, such as the ambient pressure in the local environment external to the sealed treatment environment. In many cases, the local ambient pressure can also be the atmospheric pressure at which the tissue site is located. Alternatively, the pressure can be less than the hydrostatic pressure associated with the tissue at the tissue site. Unless otherwise indicated, the pressure values described herein are gauge pressures. References to an increase in negative pressure typically refer to a decrease in absolute pressure, and a decrease in negative pressure typically refers to an increase in absolute pressure. The amount and nature of the negative pressure provided by the negative pressure source 105 may vary depending on the treatment requirements, but the pressure is generally a low vacuum, also commonly referred to as a rough vacuum, in the range of -5 mmHg (-667 Pa) to -500 mmHg (-66.7 kPa). A typical treatment range is -50 mmHg (-6.7 kPa) to -300 mmHg (-39.9 kPa).

[0032] Container 115 represents a container, canister, pouch, or other storage component that can be used to manage exudate and other fluids withdrawn from a tissue site. In many environments, a rigid container may be preferred or required for fluid collection, storage, and disposal. In other environments, the fluid may be appropriately discarded without being stored in a rigid container, and if the container is reusable, it can reduce the 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 the treatment system 100, such as the negative pressure source 105. In some embodiments, for example, controller 130 may be a microcontroller, which generally includes an integrated circuit comprising a processor core and a memory programmed to directly or indirectly control one or more operating parameters of the treatment system 100. The operating parameters may include, for example, the power applied to the negative pressure source 105, the pressure generated by the negative pressure source 105, or the pressure distributed to the 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 one or more operating parameters based on the input signals.

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

[0035] The tissue interface 120 may generally be adapted to contact the tissue site partially or completely. The 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 the tissue interface 120 may be adapted to the contour of a deep tissue site of irregular shape. Any or all of the surfaces of the tissue interface 120 may have a rough, uneven, or serrated profile.

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

[0037] In some exemplary embodiments, the cover 125 may be a polymeric 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 a permeable material, the permeability should generally be low enough such 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, polyvinyl pyrrolidone, 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 from 3M Company (Minneapolis Minnesota); polyurethane (PU) drapes from Avery Dennison Corporation (Pasadena, California), such as polyether block polyamide copolymers (PEBAX) manufactured by Arkema S.A. (Colombes, France), and Inspire 2301 and Inspire 2327 polyurethane films commercially available from Expopack Advanced Coatings (Wrexham, United Kingdom). In some embodiments, the cover 125 may include INSPIRE 2301 having an MVTR (upright cup method) of 2600 g / m 2 24 hours and a thickness of about 30 microns.

[0038] The attachment device may be used to attach the cover 125 to an attachment surface such as an intact epidermis, gasket, or another cover. The attachment device can 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, some or all of the cover 125 may be coated with an adhesive such as an acrylic adhesive that may have a coating weight of about 25 to 65 grams per square meter (g.s.m.). In some embodiments, a thicker adhesive, or combination of adhesives, may be applied to improve sealing and reduce leakage. Other exemplary embodiments of the attachment device can include double-sided tape, glue, hydrocolloid, hydrogel, silicone gel, or organogel.

[0039] During operation, the tissue interface 120 may be disposed within, on, over, or otherwise proximate to the tissue site. For example, if the tissue site is a wound, the tissue interface 120 may partially or completely occlude the wound, or may be disposed over the wound. The cover 125 may be disposed over the tissue interface 120 and sealed to an attachment surface in the vicinity of the tissue site. For example, the cover 125 may be sealed to the intact epidermis surrounding the tissue site. Thus, the dressing 110 can provide a sealed treatment environment substantially isolated from the external environment in proximity to the tissue site, and the negative pressure source 105 can reduce the pressure within that sealed treatment environment.

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

[0041] Generally, exudates and other fluids flow along a fluid path toward a lower pressure. Thus, the term "downstream" typically means within a fluid path that is relatively closer to a negative pressure source or farther from a positive pressure source. Conversely, the term "upstream" means relatively farther from a negative pressure source or closer to a positive pressure source. Similarly, it may be convenient to describe a feature from the perspective of the "inlet" or "outlet" of the fluid in such a reference system. This orientation is generally assumed for the purpose of describing various features and components herein. However, the fluid path may also be reversed in some applications, such as by replacing a negative pressure source with a positive pressure source, and this descriptive convention should not be construed as a limiting convention.

[0042] In a sealed treatment environment, the negative pressure applied across the tissue site via the tissue interface 120 can induce macro and micro strains at the tissue site. The negative pressure can also remove exudates and other fluids from the tissue site, and the exudates and other fluids can be collected within the 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 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 desired target negative pressure for therapy at the tissue site and is then provided to the controller 130 as an input. The target pressure can 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 status, and the preference of the attending physician. After selection of 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] Figure 2 is an assembly diagram of an example of the dressing 110 of FIG. 1, showing further details that may relate to some embodiments where 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 disposed between the first layer 205 and the fourth layer 220. In some embodiments, the second layer 210 may be disposed adjacent to the first layer 205. For example, the second layer 210 may be disposed adjacent to the first layer 205 on the side opposite the third layer 215. In other examples, the second layer 210 may be disposed between the first layer 205 and the third layer 215. Further, the fourth layer 220 may be disposed adjacent to the third layer 215 on the side opposite 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 coupled 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 coupled or attached to adjacent layers. The entire dressing 110, including the individual layers of the tissue interface 120, may be of any number of different shapes based on the specific anatomical requirements of the tissue site. For example, the dressing 110 and the layers included in 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 comprising or consisting essentially of a soft and flexible 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, foamed gel, a soft closed-cell foam such as polyurethane and polyolefin coated with an adhesive, polyurethane, polyolefin, or hydrogenated styrene copolymer. In some embodiments, the first layer 205 may have a thickness of from about 200 microns (μm) to about 1000 microns (μm). In some embodiments, the first layer 205 may have a hardness of from about 5 Shore OO to about 80 Shore OO. Further, the first layer 205 may be composed of a hydrophobic or hydrophilic material. The first layer 205 may be adjusted 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 an adhesiveness that may be adjusted by increasing or decreasing the concentration of an adhesion promoter in the silicone gel. In some embodiments, the thickness of the silicone gel of 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, the first layer 205 may be a hydrophobic-coated material. For example, the first layer 205 may be formed by coating a material having gaps, such as a woven mesh, non-woven mesh, molded mesh, or extruded mesh, with a hydrophobic material. The hydrophobic material for coating may be, for example, soft silicone.

[0047] The first layer 205 may have a peripheral region such as a peripheral portion 225 surrounding or around an inner portion having at least one treatment opening 230. The first layer 205 may have an opening 235 disposed through the peripheral portion 225. The first layer 205 may also have corners 240 and edges 245. The corners 240 and edges 245 may be part of the peripheral portion 225. In some examples, as shown in FIG. 2, the treatment opening 230 may be symmetrically and centrally disposed with respect to the first layer 205. In some examples, the treatment opening 230 may substantially 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 for the communication of negative pressure and wound fluid between the second layer 210 and the third layer 215.

[0048] The opening 235 may be formed, for example, by cutting, or by the application of local radio frequency (RF) or ultrasonic energy, or by other suitable techniques for forming an opening. The opening 235 may have a uniform distribution pattern or may be randomly distributed over the first layer 205. The openings 235 of the first layer 205 may have many shapes, including, for example, circular, square, star, elliptical, polygonal, slit, complex curve, linear, triangular, or any combination of such shapes. Each of the openings 235 may have uniform or similar geometric properties. 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 from about 1 millimeter to about 50 millimeters. In other embodiments, the diameter of each of the openings 235 may be from about 1 millimeter to about 20 millimeters.

[0049] In other embodiments, the geometric characteristics of the aperture 235 may vary. For example, the diameter of the aperture 235 may vary according to the position of the aperture 235 within the first layer 205, as shown in FIG. 2. For example, in some embodiments, the apertures 235 disposed in the peripheral portion 225 may have a diameter of from about 9.8 millimeters to about 10.2 millimeters. In some embodiments, the apertures 235 disposed in the corner portions 240 may have a diameter of from about 7.75 millimeters to about 8.75 millimeters.

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

[0051] The second layer 210 may comprise, or consist essentially of, a material suitable for modulating or neutralizing enzymes at the tissue site. Target enzymes such as proteolytic enzymes are enzymes that can cause maceration at or around the tissue site if they accumulate in excess or remain in contact with the tissue site for an extended period of time. The second layer 210 may provide means for neutralizing proteolytic enzymes to the tissue interface 120 to prevent possible maceration at the tissue site. In particular, the second layer 210 may reduce or prevent the risk of maceration when the wound surrounding area of the tissue site is exposed to wound exudate containing proteolytic enzymes.

[0052] The second layer 210 may include various materials that may be suitable for neutralizing proteolytic enzymes. In some cases, the second layer 210 may include one or more materials that may function as a sacrificial substrate, an enzyme inactivator, an enzyme blocker, or a combination of such functions. In some embodiments, the second layer 210 may include a biologically derived polymer that includes collagen, gelatin, collagen-like proteins, collagen-like peptides, or any combination of these materials. The sacrificial substrate of the second layer 210 may also include, among other things, hyaluronic acid, chondroitin sulfate, and collagen mimetic peptides. Further, the second layer 210 may additionally or alternatively include cellulose or a cellulose derivative, such as oxidized regenerated cellulose (ORC), or a chemically modified cellulose. In some embodiments, the second layer 210 may include an enzyme blocker or inactivator in the form of a binding decoy molecule or a metal ion chelator. Exemplary chelators can include, among other things, ethylenediaminetetraacetic acid (EDTA) and ethylene glycol tetraacetic acid (EGTA). 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, α1-antitrypsin, pepstatin A, aprotinin, and leupeptin. Metalloproteinase inhibitors having zinc-binding groups or copper analogs may also be useful in binding harmful metalloproteinases or activating beneficial metalloproteinases, and thus may also act as enzyme blockers.

[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 a collagen material and an ORC material. For example, the second layer 210 may include a complex of about 50 wt% collagen and about 50 wt% ORC, and in some preferred embodiments, the second layer 210 may include a complex of about 55 wt% collagen and about 45 wt% ORC. However, the respective ratios of collagen and ORC may vary. For example, the second layer 210 may include a complex 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 the materials found in PROMOGRAN™ Matrix Wound Dressing, commercially available from Kinetic Concepts, Inc. (San Antonio, Texas).

[0054] The arrangement of the second layer 210 may vary depending on the particular use of the tissue interface 120. For example, the second layer 210 may be in the form of a sheet that substantially forms a part 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 under the treatment opening 230 so as to cover the treatment opening 230 and a part 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 elliptical shape that generally corresponds to the shape of the treatment opening 230 of the first layer 205. In some cases, the second layer 210 may include a lattice structure, whereby a substantial opening region in the form of openings or pores of the second layer 210 is also enabled while the enzyme-neutralizing material is disposed over a significant portion of the first side 202 of the tissue interface 120 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 structure of the second layer 210 may include a plurality of segments of enzyme-neutralizing material arranged to form the structure of the second layer 210, with a plurality of openings disposed between the plurality of segments of enzyme-neutralizing material. For example, the lattice structure of the second layer 210 may include a first plurality of segments of enzyme-neutralizing material and a second plurality of segments of enzyme-neutralizing material. In some embodiments, each segment of the first plurality of segments of enzyme-neutralizing material may be arranged substantially parallel to the other segments of the first plurality of segments of enzyme-neutralizing material, and each segment of the second plurality of segments of enzyme-neutralizing material may be arranged substantially parallel to the other segments of the second plurality of segments of enzyme-neutralizing material. At least one of the first plurality of segments of enzyme-neutralizing material may intersect one or more of the second plurality of segments of enzyme-neutralizing material. For example, the first plurality of segments of enzyme-neutralizing material may be arranged 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 substantial outer portion of the peripheral portion 225 of the first layer 205. Thus, an adhesive material disposed beneath the cover 125, such as the adhesive 260 shown in FIG. 2, may pass through at least a portion of the openings 235 within the peripheral portion 225 of the first layer 205 and contact a tissue region, such as the epidermis around the tissue site, to form a seal. 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 such that a sufficient amount of the adhesive 260 passes through the openings 235 in the peripheral portion 225 to enable formation of a sufficient seal with the attachment surface surrounding the tissue site.

[0056] The second layer 210 may also exist in various other structural and material configurations. For example, the second layer 210 may have various shapes such as a square, circular, or rectangular shape. Further, regardless of the shape, the second layer 210 may be in the form of a solid sheet, or may be either a lattice structure having 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 of a length 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 across the second layer 210. For example, a 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 include a mixture of collagen and ORC, and one section of the second layer 210 may have a larger proportional amount of collagen, and another section of the second layer 210 may have a larger proportional amount of ORC. In some additional embodiments, the second layer 210 may include a blend of collagen and gelatin, which may provide some cost reduction advantages.

[0057] The second layer 210 may be in a range of sizes and related 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 about 5 micrometers to 5000 micrometers. In some particular embodiments, the second layer 210 may have a thickness in the range of 50 micrometers to 100 micrometers. Further, the second layer 210 may have perforations or fenestrations to allow air to flow through the second layer 210 in order to effectively communicate the negative pressure within the tissue interface 120.

[0058] The second layer 210 can also help reduce or prevent the presence of harmful or infectious substances 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 present in wound fluid that can pose a risk to the tissue site. Thus, the second layer 210 can provide an antibacterial effect to the tissue interface 120.

[0059] The third layer 215 may include or consist essentially of 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, in some embodiments, have a smooth surface texture or a matte surface texture. For some applications, a finish or gloss finish of grade B3 or higher according to SPI (Society of the Plastics Industry) standards may be particularly advantageous. In some embodiments, the surface height variations may be limited to acceptable tolerances. For example, the surface of the third layer 215 may have a substantially flat surface with height variations limited to 0.2 millimeters over a 1 centimeter span.

[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 contact angle with water may be 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 at least 120 degrees to 150 degrees. The water contact angle can be measured using any standard device. The hydrophobicity of the third layer 215 may be further enhanced by a hydrophobic coating of other materials such as silicone and fluorocarbon that are 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 hardly interacts with biological tissues and fluids, if any, and can provide a surface that promotes free flow of liquids and low adhesion, which can be particularly advantageous for 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, styrene-based, silicone, fluoropolymer, and acetate. A thickness of 20 microns to 100 microns may be suitable for many applications. The film may be transparent, 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 to weld to a 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 polyurethanes, polyamides, polyesters, and acrylates. A sacrificial polar interface may be used to facilitate RF welding of lower polarity film materials such as polyethylene. For example, higher polarity films suitable for laminating to a polyethylene film include polyamides, copolyesters, ionomers, and acrylates. A tie layer such as ethylene vinyl acetate or modified polyurethane may be used to assist in bonding polyethylene to the polar film. Ethyl methyl acrylate (EMA) films 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 prescribed therapy or application. In some embodiments, an areal density of less than 40 grams per square meter may be suitable, and an areal density of about 20 to 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 that may be distributed uniformly or randomly across 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 not stretched to substantially reduce the flow of liquid and are capable of expanding in response to a pressure gradient. In some embodiments, the fluid restriction portions 255 may include, or consist essentially of, perforations within the third layer 215. The perforations may be formed by removing material from the third layer 215. For example, the perforations can be formed by punching out the third layer 215, which can also, in some embodiments, deform the edges of the perforations. In the absence of a pressure gradient across the perforations, the passages may be small enough to form a seal or flow restriction that can substantially reduce or prevent the flow of liquid. Additionally or alternatively, one or more of the fluid restriction portions 255 may be elastomeric valves that are normally closed to substantially prevent the flow of liquid when not stretched and can open in response to a pressure gradient. An aperture within the third layer 215 can be a suitable valve for some applications. The aperture can also be formed by removing material from the third layer 215, but the amount of material removed and the resulting dimensions of the aperture may be an order of magnitude smaller than that of the perforations and may not require deforming 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 about 3 millimeters and a width of about 0.8 millimeters may be particularly suitable for many applications. A tolerance of about 0.1 millimeter may also be acceptable. Such dimensions and tolerances can be achieved, for example, with a laser cutter. A slot of such a configuration can function as an imperfect valve that substantially reduces the flow of liquid in a normally closed or stationary state. For example, such a slot may form a flow restriction without being completely closed or sealed. The slot can expand or open significantly in response to a pressure gradient to allow an increase in the flow of liquid.

[0065] As shown in the example of FIG. 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 means for collecting or distributing fluid across the tissue interface 120 under pressure. 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 across the tissue site and drawing the fluid toward the negative pressure source.

[0066] In some exemplary embodiments, the fourth layer 220 may include a plurality of pathways that are capable of interconnecting to improve fluid distribution or collection. In some embodiments, the fourth layer 220 may include or consist essentially of a porous material having interconnected fluid pathways. For example, other porous materials such as open-cell foams, reticulated foams, porous tissue aggregates, and mats of gauze or felt generally include pores, edges, and / or walls adapted to form interconnected fluid channels. Liquids, gels, and other foams may also include openings and fluid pathways or may be cured to include them. In some embodiments, the fourth layer 220 may additionally or alternatively include protrusions that form interconnected fluid pathways. For example, the fourth layer 220 may be shaped to provide surface protrusions that define interconnected fluid pathways. Some or all of the surfaces of the fourth layer 220 may have a concave-convex profile, a rough profile, or a serrated profile.

[0067] In some embodiments, the fourth layer 220 may comprise, or may consist essentially of, an open-cell foam having a pore size and free volume that may vary depending on the needs of the prescribed therapy. For example, an open-cell foam having at least 90% free volume may be suitable for many therapeutic applications, and a foam having an average pore size in the range of 400 - 600 microns (40 - 50 pores per inch) may be particularly suitable for some types of therapy. 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 the infusion of topical treatment solutions. The 25% compression load deflection of the fourth layer 220 may be at least 0.35 pounds per square inch, and the 65% compression load deflection may be at least 0.43 pounds per square inch. In some embodiments, the tensile strength of the 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 inch. In some embodiments, the fourth layer 220 may be a foam composed of a polyol such as polyester or polyether, an isocyanate such as toluene diisocyanate, and a polymerization regulator such as an amine and a tin compound. In a non-limiting example, the fourth layer 220 may be an open-cell polyurethane ether foam such as that used in GRANUFOAM™ dressing or V.A.C. VERAFLO™ dressing available from KCI (San Antonio, Texas).

[0068] The fourth layer 220 may include either or both of a hydrophobic material and a hydrophilic material. In an example where the fourth layer 220 may be hydrophilic, the fourth layer 220 may also draw fluid 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. An example of a hydrophilic foam is an open-cell foam of polyvinyl alcohol such as the V.A.C. WHITEFOAM (trademark) dressing available from Kinetic Concepts, Inc. (San Antonio, Texas). Other hydrophilic foams can include those made from polyethers. Other foams that may exhibit hydrophilic properties can include hydrophobic foams that have been treated or coated to impart hydrophilicity.

[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 prescription therapy. For example, the thickness of the fourth layer 220 may be decreased to relieve stress on other layers and to reduce tension on the surrounding tissue. The thickness of the fourth layer 220 can also affect the conformity of the fourth layer 220. In some embodiments, a thickness in the range of about 5 millimeters to 10 millimeters may be suitable.

[0070] The individual components of the tissue interface 120, and more generally of the dressing 110, may be adhered to or otherwise fixed to each other with a solvent or non-solvent adhesive or by heat welding, for example, without adversely affecting fluid management. Further, the dressing 110 may comprise different combinations of individual layers and components. For example, the 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 the tissue interface 120 and the dressing 110 may be omitted.

[0071] In the example of FIG. 2, the dressing 110 may further include an attachment device such as an adhesive 260. The adhesive 260 may be, for example, a medically acceptable pressure-sensitive adhesive that extends around the perimeter, a portion, or the entire cover 125. In some embodiments, for example, the adhesive 260 may be an acrylic adhesive having a coating weight of 25 to 65 grams per square meter (g.s.m.). In some embodiments, a thicker adhesive, or a combination of adhesives, may be applied to improve sealing and reduce leakage. The adhesive 260 may be a layer having substantially the same shape as the peripheral portion 225 of the first layer 205. In some embodiments, such a layer of the adhesive 260 may be continuous or discontinuous. The discontinuities in the adhesive 260 may be provided by openings or holes (not shown) in the adhesive 260. The openings or holes in the adhesive 260 may be formed after application of the adhesive 260 or by coating the adhesive 260 in a pattern on one side of a carrier layer, such as the 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] Cover 125, the first layer 205, the second layer 210, the third layer 215, and the fourth layer 220, or various combinations thereof, may be assembled before application or in situ. For example, the first layer 205, the second layer 210, the third layer 215, and the fourth layer 220 of the tissue interface 120 may be arranged in a stacked arrangement, and the cover 125 with the adhesive 260 disposed thereunder is disposed over the layers of the tissue interface 120 to hold the tissue interface 120 in a fixed position over the tissue site. Thus, within the dressing 110, the individual layers of the tissue interface 120, such as the fourth layer 220, can be allowed some movement within the dressing 110. In other examples, the cover 125 may be laminated to a portion of the fourth layer 220 and the first layer 205, and in some embodiments, the third layer 215 may be laminated to the fourth layer 220 on the side opposite the first layer 205 and the cover 125. The second layer 210 may also be coupled 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 of the tissue interface 120 or the side facing the tissue. In some embodiments, one or more layers of the tissue interface 120 may have the same extent. For example, the fourth layer 220 may have the same extent as the third layer 215, as shown in the embodiment of FIG. 2. In some embodiments, the dressing 110 can be provided as a single composite dressing. For example, the first layer 205 may be coupled to the cover 125 so as to surround the third layer 215 and the fourth layer 220, and the second layer 210 is coupled to the side of the first layer 205 facing the tissue.

[0073] As shown in the example of FIG. 2, in some embodiments, the 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 assist in the utilization 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 deformations of the dressing 110. For example, the polar semi-crystalline polymer may be highly oriented and resistant to softening, swelling, or other deformations that may occur when in contact with the 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 be imprinted onto an adjacent layer such as the first layer 205. Further, a release agent may be disposed on the side of the release liner 265 configured to contact the first layer 205. For example, the release agent may be a silicone coating and may have a release factor suitable for facilitating the manual removal of the release liner 265 without damaging or deforming 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 not be coated or may be used without a release agent.

[0074] FIG. 2 also shows 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 to the dressing interface 275 at one end. The dressing interface 275 can be an elbow-shaped connector that, as shown in the example of FIG. 2, is placed over the opening 280 of the cover 125 to provide a fluid path between the fluid conduit 270 and the tissue interface 120. In some embodiments, the fluid conduit 270 may also include a fluid delivery conduit for use in intravenous therapy. Further, in some embodiments, the dressing interface 275 may include a plurality of fluid conduits such as conduits for communicating negative pressure and fluid delivery conduits. For example, the dressing interface 275 may be a V.A.C. VERAT.R.A.C. (trademark) 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 be additionally or alternatively treated with one or more antimicrobial agents. Suitable antimicrobial agents can include, for example, metallic silver, PHMB, iodine or its complexes and mixtures such as povidone iodine, copper metal compounds, chlorhexidine, or certain combinations of these materials.

[0076] In use, the release liner 265 (if included) may be removed to expose a portion of the second layer 210 and the first layer 205, which may be disposed proximally, superiorly, above, or in another manner within the tissue site, particularly the surface tissue site and the adjacent epidermis. The first layer 205, the second layer 210, and the third layer 215 may be interposed between the fourth layer 220 and the tissue site, thereby substantially reducing or eliminating detrimental interactions with the fourth layer 220. For example, the first layer 205, where the second layer 210 is bonded to the surface of the first layer 205 facing the tissue of the first side 202 of the tissue interface 120, may be disposed over the wound surface (including the edges of the wound) and the uninjured epidermis to prevent direct contact with the fourth layer 220. Treating a surface wound or disposing the dressing 110 over a surface wound includes disposing the dressing 110 directly adjacent to the surface of the body or extending it over at least a portion of the surface of the body. Treating a surface wound does not tend to include disposing the dressing completely within the body, such as within the abdominal cavity, or completely beneath the surface of the body. In some applications, the second layer 210 may be disposed adjacent to, proximate to, or covering the treatment opening 230 of the first layer 205 such that the second layer 210 can be disposed adjacent to the tissue site between the treatment opening 230 of 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 the voids or openings of the first layer 205 and the second layer 210. The peripheral portion 225 of the first layer 205 may be disposed adjacent to or proximate to the tissue surrounding or around the tissue site. The first layer 205 can be sufficiently adhesive to hold the dressing 110 in place, but at the same time, it can also allow the dressing 110 to be removed or repositioned without traumatizing the tissue site.

[0077] Removing the release liner 265 also exposes the adhesive 260, and the cover 125 can be attached to the attachment surface. For example, the cover 125 may be attached to the epidermis around the tissue site surrounding the fourth layer 220 and the third layer 215. In some embodiments, the adhesive 260 may be in fluid communication with the attachment surface through the opening 235 at least in the peripheral portion 225 of the first layer 205. The adhesive 260 may also be in fluid communication with the edge 245 through the opening 235 exposed at the edge 245. The second layer 210 may be disposed relative to the tissue site and may be surrounded by a portion of the peripheral portion 225 of the first layer 205 and a portion of the adhesive 260 passing through the opening 235 in the peripheral portion 225 of the first layer 205. In some embodiments, since there are voids, openings, or apertures in the second layer 210, a portion of the adhesive 260 can pass through the opening 235 of the first layer 205 and the apertures of the second layer 210 to contact and adhere to the attachment surface surrounding the tissue site. Thus, in the range where the second layer 210 can overlap the peripheral portion 225 of the first layer 205, the portion of the tissue site or the region surrounding the tissue site that may be adjacent to the peripheral portion 225 of the first layer 205 may contact each of the first layer 205, the enzyme-neutralizing material of the second layer 210, and the adhesive 260.

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

[0079] The geometric shape and dimensions of the tissue interface 120, the cover 125, or both may vary to conform to a particular application or anatomical structure. For example, the geometric shape 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 elbows or heels 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 the movement and proliferation of epithelial cells at the tissue site, and reduce the potential for granulation tissue ingrowth.

[0080] Accordingly, the dressing 110 in the example of FIG. 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. Further, the dressing 110 may allow for reapplication or repositioning, for example, to correct air leakage caused by wrinkles and other discontinuities in the dressing 110. In some embodiments, the ability to correct leakage can increase the efficacy of the therapy and reduce power consumption.

[0081] If not yet 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 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 surface wound, a wound filler may be applied from within the wound to around the wound, and a portion of the second layer 210 and / or the first layer 205 may be disposed over the wound perimeter and the wound filler. In some embodiments, the filler may be a manifold such as an open-cell foam. The filler may, in some embodiments, comprise or consist essentially of the same material as the fourth layer 220.

[0083] The negative pressure applied through the tissue interface 120 can create a negative pressure differential across the fluid restriction portion 255 within the third layer 215, which can open or expand the fluid restriction portion 255 from their resting state. For example, in some embodiments where the fluid restriction portion 255 may include a substantially closed aperture through the third layer 215, the pressure gradient across the aperture can, similar to the operation of a duckbill valve, put the adjacent material of the third layer 215 in a stretched state and increase the size of the aperture to enable the movement of liquid through the aperture. By opening the fluid restriction portion 255, it can be made possible for exudate and other liquids to move through the fluid restriction portion 255 to the fourth layer 220 and the container 115. The change in pressure can also cause the fourth layer 220 to expand and contract, and the third layer 215 as well as a portion of the first layer 205 can protect the epidermis from the stimuli caused by the 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 the exposure of tissue to the fourth layer 220 and can inhibit the growth of tissue into the fourth layer 220.

[0084] When the negative pressure source 105 is removed or turned off, the pressure differential across the fluid restriction portion 255 can dissipate, the fluid restriction portion 255 moves to their resting state, and the rate at which exudate or other liquids can return through the third layer 215 to the tissue site can be prevented or reduced. The second layer 210 can provide an additional means for protecting the tissue site from long-term contact with exudate containing proteolytic enzymes when the exudate returns through the fluid restriction portion 255 of the third layer 215 or otherwise bypasses the third layer 215 and contacts the tissue site through the first layer 205. Such situations can be more likely to occur in the application of highly exuding wounds or when a malfunction occurs in the application, configuration, or function of the dressing 110 and / or the negative pressure source 105 of the treatment system 100.

[0085] FIG. 3 is an assembly diagram of another example of dressing 110 and shows further details that may be relevant to some embodiments. In particular, FIG. 3 shows another example of the second layer 210. Some of the components of the dressing 110 in FIG. 3 may be the same or similar to the components of the dressing 110 in FIG. 2, but the arrangement and / or order of the layers of the dressing 110 in FIG. 3 may be different. The exemplary embodiment of the dressing 110 shown in FIG. 3 omits some of the layers of the dressing 110 in FIG. 2, but 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-regulating 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 on the surface of the first layer 205 on the first side 202 of the tissue interface 120.

[0086] In the embodiment shown in FIG. 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 disposed 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 FIG. 3. The inner portion including the plurality of treatment openings 310 may be symmetric and centrally located within the first layer 205.

[0087] In some embodiments, the diameter of the opening 235 in the peripheral portion 225 of the first layer 205 may be greater than the diameter of the treatment opening 310 in the inner portion of the first layer 205. For example, in some embodiments, the opening 235 disposed in the peripheral portion 225 may have a diameter of about 9.8 millimeters to about 10.2 millimeters, and the opening 235 disposed in the corner portion 240 may have a diameter of about 7.75 millimeters to about 8.75 millimeters. In some embodiments, the treatment opening 310 disposed in the inner 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 elliptical 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 openings 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 barrier or boundary in the form on the first side 202 of the tissue interface 120 such that proteolytic enzymes of the fluid exuding from the tissue site may contact a portion of the enzyme-neutralizing material of the second layer 210 before moving outwardly from the center of the tissue site and the tissue interface 120 toward the area surrounding the wound.

[0089] FIG. 4 is a schematic view of an 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] As also shown in FIG. 4, the second layer 210 may be sized and positioned such that the second layer 210 is substantially aligned with the inner boundary 305 of the first layer 205. The material of the second layer 210 may also be aligned with a portion of the inner portion of the first layer 205 that includes the plurality of treatment apertures 310 and / or a portion of the peripheral portion 225 of the first layer 205. In some examples, the second layer 210 may occlude or cover at least a portion of some of the apertures 235 in the peripheral portion 225 without interfering with the 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 apertures 235 in the peripheral portion 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 the assembly of the other layers of the dressing 110 such that the second layer 210 is applied partially over the surface of the first layer 205 and to a portion of the adhesive 260 that is exposed through the apertures 235 within the peripheral portion 225 of the first layer 205.

[0091] The second layer 210 may be arranged to specifically protect the periphery of the tissue site or the area around the wound from abundant proteolytic enzymes. For example, during the implementation 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. The fluid can typically move through the plurality of treatment openings 310 of the first layer 205 towards the opening 280 of the cover 125 of the dressing 110, but in some cases, at least a portion of the fluid may also move laterally across the surface of the tissue site or the first side 202 of the tissue interface 120 towards the area around the wound. By arranging the second layer 210 on the first side 202 of the tissue interface 120, the fluid moving towards the area around the wound first passes through at least a portion of the second layer 210 before reaching the outer periphery of the tissue site or the area around the wound. As a result, the second layer 210 can actually function as an enzyme-neutralizing filter through which the fluid from the central portion of the tissue site and the dressing 110 must pass before reaching the outer portion of the tissue site and / or the dressing 110. Such an arrangement can minimize or prevent the exposure of the wound periphery and / or the area around the wound to wound fluid that may contain excessive proteolytic enzymes. The second layer 210 can also protect the area around the wound from proteolytic enzymes in the wound fluid that returns from other layers of the tissue interface 120 towards the tissue site and may in some cases move outward towards the area around the wound.

[0092] Figure 5 is an assembly diagram of another example of dressing 110. For example, the individual layers of the tissue interface 120 in Figure 5 may be arranged or stacked in an order different from that of the layers of the tissue interface 120 in Figure 2. More specifically, in some embodiments, the second layer 210 in Figure 5 may be adjacent to the fourth layer 220 or disposed between the fourth layer 220 of the dressing 110 and the cover 125. As shown in Figure 5, the second layer 210 may have an elliptical shape similar to 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 Figure 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 Figure 5 may include a lattice structure similar to that of Figure 2. As shown in Figure 5, in some embodiments, the second layer 210 includes a plurality of openings or apertures such as perforations 505 to enable the transfer of fluids such as wound fluid through the second layer 210 for the communication of negative pressure and towards the opening 280 within the cover 125 of the dressing 110. For example, each of the perforations 505 may 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 slot 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 varies spatially across the second layer 210. In some embodiments, the enzyme-neutralizing material may be disposed within the second layer 210 according to a gradient or dispersed throughout the second layer 210. For example, the second layer 210 may include an enzyme-neutralizing material such as one or more of a sacrificial substrate, an enzyme inactivator, or an enzyme blocker at a lower concentration in the central portion of the second layer 210, and the concentration of the enzyme-neutralizing material increases as the distance from the center of the second layer 210 towards the edge or periphery of the second layer 210 increases. In some embodiments, the enzyme-neutralizing material may have a circular concentration gradient with a higher concentration in the periphery than in the central portion. In some embodiments, about 100 - 450 mg / cm2 The concentration may be suitable for the peripheral portion, about 1 to 75 mg / cm 2 The concentration may be suitable for the central portion. By including a higher concentration of the enzyme-neutralizing material in the peripheral portion of the second layer 210, which may be close to the wound surrounding area, it may be ensured that the wound surrounding area is not exposed to excessive levels of proteolytic enzymes that could cause maceration of the tissue surrounding the wound. By including a higher concentration of the enzyme-neutralizing material on the outer or peripheral side of the second layer 210, the antibacterial ability of the second layer 210 may be improved, and it may be ensured that wound fluid, which may move away from the central portion of the tissue interface 120 and potentially towards the wound periphery, can be treated by the second layer 210.

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

[0095] The tissue interface 120 and the dressing 110 may be provided in different combinations of individual layers, as well as 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 on the first side 202 of the tissue interface 120. Further, in some additional embodiments, materials 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 with one or more of the materials of the other layers of the tissue interface 120. In an exemplary embodiment, in addition to or instead of being included as a separate enzyme-neutralizing layer, one or more enzyme-neutralizing materials may be incorporated into the cured silicone adhesive formulation of the first layer 205.

[0096] In some further embodiments, additional materials for reducing or neutralizing proteolytic enzyme activity may be added to one or more layers of the 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 the second layer 210 to provide an additional means for neutralizing proteolytic enzymes. For example, protease inhibitors may include, but are not limited to, metalloproteinase tissue inhibitor (TIMP), thrombospondin-1, thrombospondin-2, elastase inhibitor 2, α1-antitrypsin, pepstatin A, aprotinin, EDTA, leupeptin, and the like. Some examples of naturally occurring protease inhibitors include thionin, which is commonly contained 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 Araliaceae.

[0097] The systems, devices, and methods described herein can provide significant advantages. For example, dressing 110 can be a fully integrated negative pressure therapy dressing that can be applied to a tissue site (including around the wound) for long-term wear while providing the advantage of protecting the tissue site around the tissue from maceration and promoting granulation. For example, by including one or more substrates in the tissue interface 120 and / or the dressing 110 to neutralize proteolytic enzymes, the tissue site, including around the wound, can be protected by reducing or preventing potential harmful effects resulting from increased levels of inflammatory cells and proteases in the wound fluid. One or more enzyme-neutralizing substrates can prevent excessive levels of the enzyme protease from contacting the tissue site while still allowing the protease to have a beneficial effect for promoting normal wound healing. For example, standard levels of protease may help degrade the denatured extracellular matrix (ECM), which may make it possible to expose the functional matrix to the healing tissue. By including one or more enzyme-neutralizing substrates, disruptions in the wound healing system, such as degradation of the ECM formed during the wound healing process and accompanying inhibition of wound healing due to disruption of the ratio of protease to its inhibitor as a result of an increase in the number of proteases, can be prevented.

[0098] Such advantages can be particularly realized in the application of dressing 110 to tissue sites with a large amount of wound exudate, such as chronic wounds where the management of the wound environment and moisture balance at the tissue site is particularly difficult. When applied to chronic wounds where the level of proteolytic enzymes present in the wound fluid of the tissue site may increase, including one or more enzyme-neutralizing materials in the layers of dressing 110 can be particularly advantageous in achieving longer wear times. For example, longer wear times such as up to 7 days can be achieved while minimizing the risk of maceration to the surrounding wound area that may exist due to potential long-term contact with proteolytic enzyme-containing wound fluid. Further, since dressing 110 can also cover the wound perimeter, by providing an enzyme-neutralizing material in the layer between other layers of tissue interface 120 and the tissue site, such as the side of tissue interface 120 facing the tissue, the wound perimeter can be particularly protected by neutralizing proteolytic enzymes found in the wound exudate present on the surface of the tissue site. Thus, in many cases, the proteolytic enzymes are neutralized before contacting the surrounding wound area, thereby preventing the wound margins such as the wound perimeter from being exposed to the wound fluid and associated proteases and inflammatory cells for an extended period of time. Further, dressing 110 may substantially reduce or prevent maceration of the surrounding wound perimeter area while providing a large strain to the edges of the tissue site such as the wound edge.

[0099] Including an enzyme-neutralizing material in dressing 110 may further provide an antibacterial effect, which can also extend the useful life of dressing 110. By providing an antibacterial effect, the enzyme-neutralizing material can significantly reduce the risk of infection associated with long-term wear of the dressing, particularly when applied to infected wounds or very exuding wounds. Thus, dressing 110 can provide a long-term wearing solution that can maintain a good seal around the tissue site and prevent maceration and potential accumulation of microbial substances without interfering with the path for negative pressure therapy.

[0100] Although shown in several exemplary embodiments, those skilled in the art will understand that the systems, devices, and methods described herein are capable of various changes and modifications within the scope of the appended claims. Further, descriptions of various alternative forms using terms such as "or" do not require mutual exclusivity unless clearly required by the context, and the indefinite articles "a" or "an" do not limit the object to a single case unless clearly required by the context. The components may also be combined or excluded in various configurations for the purpose of sale, manufacture, assembly, or use. For example, in some configurations, the dressing 110 may be separated from other components for manufacture or sale. In other exemplary configurations, the dressing 110 or the tissue interface 120 may also be manufactured, configured, assembled, or sold as a kit independently of other components.

[0101] The appended claims recite the novelty and inventiveness of the above-described subject matter, but the claims may also cover additional subject matter not specifically described in detail. For example, a feature, element, or aspect may be omitted from the claims if it is not necessary to distinguish the claimed features having novelty and inventiveness 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 that serve the same, equivalent, or similar purposes without departing from the scope of the invention defined by the appended claims.

Claims

1. 1. A dressing for treating a tissue site, comprising: a perimeter including a hydrophobic gel, the perimeter having a plurality of openings and disposed about the inner portion; a first layer including a boundary between the periphery and the inner portion, at least a portion of the boundary being free of the opening; a second layer formed in a ring shape and including an opening located adjacent the boundary of the first layer, the second layer comprising a material adapted to neutralize proteolytic enzymes, the opening surrounding at least a portion of the inner portion of the first layer configured to contact a wound at the tissue site, the ring configured to be positioned at a periphery of a wound at the tissue site; a third layer adjacent to the first layer, the third layer comprising a polymeric film having a plurality of fluid restriction portions; 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, the 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 either or both of an enzyme sequestrant or an enzyme inactivator.

4. 10. The dressing of claim 1, wherein the second layer comprises any one or combination of collagen, gelatin, collagen-like proteins, collagen-like peptides, cellulose or cellulose derivatives.

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

6. The dressing of claim 1 , wherein the second layer has a thickness of from 5 micrometers to 500 micrometers.

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

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

9. 10. The dressing of claim 1, wherein the material adapted to neutralize proteolytic enzymes is present in higher concentrations in various portions of the second layer.

10. 1. A system for treating a tissue site, comprising: A dressing according to claim 1; a negative pressure source adapted to be fluidly coupled to the dressing.

11. 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, the enzyme modulating material of the second layer being present in a greater concentration in a peripheral portion of the second layer than in a central portion of the second layer; a polymeric drape on an opposite side of said first layer from said second layer, said polymeric drape including an adhesive coating.

12. 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; 12. The dressing of claim 11, further comprising a manifold layer between the third layer and the polymeric drape.

13. 12. The dressing of claim 11, wherein the enzyme modulating material of the second layer comprises a sacrificial substrate, the sacrificial substrate comprising collagen, gelatin, chemically modified cellulose, hyaluronic acid, chondroitin sulfate, collagen mimetic peptides, or combinations thereof.

14. 12. The dressing of claim 11, wherein the enzyme modulating material of the second layer comprises an enzyme deactivator, the enzyme deactivator comprising an MMP inhibitor, a small molecule protease inhibitor, or a combination thereof.

15. 12. The dressing of claim 11, wherein the enzyme modulating material of the second layer comprises an enzyme sequestrant.

16. 16. The dressing of claim 15, wherein the enzyme sequestering agent comprises a chelating agent, the chelating agent comprising EDTA, EGTA, or a combination thereof.

17. 16. The dressing of claim 15, wherein the enzyme sequestrant comprises a metalloprotein inhibitor having at least one zinc binding group.

18. 12. The dressing of claim 11, 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.

19. 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 to the first layer opposite the second layer, the third layer comprising a polymer drape; at least one polymeric weld passing through said second layer and configured to bond said first layer to said third layer.

20. 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 the fourth layer on a side opposite the third layer, the fourth layer comprising a polymeric drape, the fifth layer being positioned between the third layer and the fifth layer.

21. 1. A dressing for treating a tissue site, comprising: a first layer comprising a hydrophobic gel adhesive incorporating a material adapted to neutralize proteolytic enzymes in the hydrophobic gel adhesive, the material adapted to neutralize the proteolytic enzymes being incorporated into a silicone adhesive formulation after curing of the first layer; a second layer including a manifold; a third layer adapted to be disposed between said first layer and said second layer, the third layer comprising a polymeric film having a plurality of fenestrations.

22. 1. A dressing for treating a tissue site, comprising: a hydrophobic gel layer including a plurality of openings, a periphery disposed around an inner portion, and a boundary between the periphery and the inner portion, at least a portion of the boundary being free of the openings; an enzyme modulating layer formed in a ring shape and including an opening located adjacent the boundary of the hydrophobic gel layer, the opening surrounding at least a portion of the inner portion of the hydrophobic gel layer configured to contact a wound at the tissue site, the ring configured to be positioned at a periphery of a wound at the tissue site; 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 a foam.

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