Composite dressings for improved granulation and reduced maceration with negative-pressure treatment

Abstract

To provide a novel and useful system, device, and method for treating tissue in a negative-pressure therapy environment.SOLUTION: A tissue interface 114 of a dressing 104 comprises a cover layer 116 including an adhesive 240 or the like, a first layer 205, a second layer 210, and a third layer 405. The first layer 205 is a manifold or manifold layer that provides means for collecting or distributing fluid across the tissue interface 114 under pressure. The second layer 210 comprises means for controlling or regulating the fluid flow or is formed from a liquid-impermeable elastomer material, polymer film or the like formed from such means (perforation or the like). The third layer 405 is a sealing layer formed from a soft, flexible material suitable for providing a fluid seal with the tissue site, and includes an aperture 420.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of the filing dates of U.S. Provisional Patent Application No. 62 / 516,540, entitled "TISSUE CONTACT INTERFACE," filed on June 7, 2017; U.S. Provisional Patent Application No. 62 / 516,550, entitled "COMPOSITE DRESSINGS FOR IMPROVED GRANULATION AND REDUCED MACERATION WITH NEGATIVE - PRESSURE TREATMENT," filed on June 7, 2017; and U.S. Provisional Patent Application No. 62 / 516,566, entitled "COMPOSITE DRESSINGS FOR IMPROVED GRANULATION AND REDUCED MACERATION WITH NEGATIVE - PRESSURE TREATMENT," filed on June 7, 2017, under 35 U.S.C. § 119(e). Each of these applications is hereby incorporated by reference in its entirety for all purposes.

[0002] The invention as claimed in the appended claims generally relates to tissue treatment systems, and more particularly, but without limitation, to dressings for tissue treatment and methods of using the dressings for tissue treatment.

Background Art

[0003] Clinical trials and medical treatment have shown that by applying reduced pressure in the vicinity of a tissue site, the growth of new tissue at the tissue site can be enhanced and accelerated. Although there are numerous applications of this phenomenon, it has been found that this phenomenon is particularly advantageous for the treatment of wounds. Regardless of whether the wound is caused by trauma, surgery, or another cause, appropriate wound care is important for the outcome. Treatment by applying reduced pressure to a wound or other tissue 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", "vacuum assisted closure", and "local negative pressure". Negative pressure therapy can provide a number of advantages, including movement of epithelial and subcutaneous tissue, improved blood flow, and micro-deformation of tissue at the wound site. Together, these advantages can increase the generation of granulation tissue and shorten the healing time.

[0004] It is also widely accepted that cleaning the tissue site can be very beneficial for the growth of new tissue. For example, a wound can be washed with a flow of a liquid solution, or a cavity can be lavaged using a liquid solution for therapeutic purposes. These actions are generally referred to as "irrigation" and "lavage", respectively. "Instillation" is another action that generally refers to the process of gradually introducing a fluid to a tissue site and leaving the fluid in place for a predetermined period before removing the fluid. For example, the instillation of a topical treatment solution onto a wound bed in combination with negative pressure therapy can further promote wound healing by loosening soluble contaminants and removing infectious agents within the wound bed. As a result, the soluble bacterial load can be reduced, contaminants can be removed, and the wound can be cleaned.

[0005] Although the clinical benefits of negative pressure therapy and / or instillation therapy are widely known, improvements in treatment systems, components, and processes can provide benefits to healthcare providers and patients. SUMMARY OF THE INVENTION

[0006] The appended claims set forth a new and useful system, apparatus, and method for treating tissue in a negative pressure therapy environment. Exemplary embodiments are also provided so that those skilled in the art can make and use the claimed subject matter.

[0007] For example, in some embodiments, the dressing for treating tissue can be a composite of dressing layers including a release film, a perforated polymer film, an open-cell foam, and an adhesive drape. Some dressings can also include an adhered silicone having perforations. The perforation pattern of the polymer film can be aligned with the perforation pattern of at least the central region of the silicone. In some embodiments, the perforations can be slits or slots. The open-cell foam can, in some examples, be a reticulated foam and can be relatively thin and hydrophobic so as to reduce the fluid holding capacity of the dressing. The foam can also be made thin to reduce the thickness of the dressing and increase flexibility, thereby enabling the dressing to follow the wound bed and other tissue sites under negative pressure.

[0008] More generally, some embodiments of the dressing can include a manifold having a first side and a second side opposite the first side, and a first layer adjacent to the first side and a second layer adjacent to the second side. In some examples, the first layer and the second layer can be adhered to the first side and the second side, respectively. A fluid restriction can be adjacent to the manifold and pass through at least one of the first layer and the second layer. The first layer and the second layer can also, in some embodiments, form a sleeve or envelope around the manifold. At least one of the first layer and the second layer can be configured to be disposed between the manifold and the tissue site during use. In some examples, the dressing can have a smooth or matte surface configured to contact the tissue site.

[0009] In some examples, the first layer and the second layer may each comprise or consist essentially of a polymer film. In more specific examples, the polymer film can be hydrophobic and can have a water contact angle greater than 90 degrees. Examples of suitable polymer films include, without limitation, polyethylene, polyurethane, acrylic resin, polyolefin, polyacetate, polyamide, polyester, polyether block amide, thermoplastic vulcanizate, polyether, and polyvinyl alcohol.

[0010] In some embodiments, the fluid restriction may comprise or consist essentially of elastic passages in the polymer film. In further embodiments, the elastic passages are normally closed, for example, closed when there is no pressure gradient. For example, the elastic passages respond to a pressure gradient. For example, the fluid restriction may comprise or consist essentially of an opening, slit, or slot in the polymer film that opens or expands in response to a pressure gradient.

[0011] In some embodiments, the manifold can comprise a foam, and in more detailed examples, can comprise or consist essentially of a reticulated polymer foam. A hydrophobic manifold having a thickness of less than 7 millimeters and at least 90% free volume may be suitable for many therapeutic applications.

[0012] In some embodiments, the dressing can comprise a manifold formed from a hydrophobic material, a film substantially enclosing the manifold, and a plurality of fluid passages through the film. The film can be formed from a hydrophobic material, and the plurality of fluid passages can be configured to expand in response to a pressure gradient across the film.

[0013] Some embodiments of the dressing can include a first layer of film, a second layer including a manifold adjacent to the first layer, a third layer of film adjacent to the manifold on the side opposite the first layer, and a plurality of fluid restriction portions passing through at least one of the first and third layers of film. The films of the first and third layers can each have a flat surface profile, and the plurality of fluid restriction portions can be configured to respond to a pressure gradient across the fluid restriction portions.

[0014] This specification also describes an apparatus for treating a tissue site using negative pressure. Some example embodiments include a tissue interface comprising a manifold and a film covering at least two sides of the manifold, the tissue interface in which the manifold and the film are formed from a hydrophobic material, a plurality of elastomeric valves passing through the film, the plurality of elastomeric valves configured to expand in response to a pressure gradient across the film, and a cover configured to be attached to the tissue site. The cover and the tissue interface can be configured such that the cover is attached to an attachment surface adjacent to the tissue site and assembled in a stacked relationship. The tissue interface can further include a sealing layer in some embodiments, the sealing layer being disposed adjacent to the film and configured to contact the tissue site. At least one aperture in the sealing layer can be fluidly coupled to at least one of the elastomeric valves in the film. Some embodiments of the apparatus can further include a negative pressure source fluidly coupled to the tissue interface.

[0015] In other examples, a method for promoting granulation in a surface wound can include the step of applying a dressing to the surface wound, the dressing comprising a manifold having a cover and a second surface opposite the first plane and the first surface, and a perforated polymer film covering at least the first plane and the second plane. The perforated polymer film can be sealed to the surface wound and can cover at least a portion of the wound perimeter adjacent to the surface wound. The cover can be attached to the epidermis surrounding the perforated polymer film. The dressing can be fluidly coupled to a source of negative pressure, and negative pressure from the source of negative pressure can be applied to the dressing.

[0016] Advantages of the subject matter according to the claims can include: (1) increased formation of granulation tissue (i.e., more rapid healing), (2) reduced peel force required to remove the dressing (i.e., ease of use, reduced pain during dressing change), (3) reduced time to apply the dressing (i.e., ease of use) and / or (4) reduced risk of maceration of the tissue surrounding the wound during treatment, and any one or all of these can enable a 7-day dressing (versus a 48-hour dressing change), improve treatment compliance, and reduce the cost of care. Other objects, advantages, and preferred forms of the subject matter according to the claims can be best understood by reference to the accompanying drawings in conjunction with the following detailed description of the exemplary embodiments.

Brief Description of the Drawings

[0017]

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FORM FOR CARRYING OUT THE INVENTION

[0018] 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 some details that are already well known in the art may be omitted. Accordingly, the following detailed description should be construed as illustrative rather than limiting.

[0019] In this specification, the exemplary embodiments may be described in relation to the spatial relationships between various elements shown in the accompanying drawings or the spatial orientations of various elements. Generally, such relationships or orientations correspond to a patient in place for treatment or assume a reference system for such a patient. However, as should be recognized by those skilled in the art, this reference system is not a strict definition but merely a convenient means for explanation.

[0020] FIG. 1 is a simplified functional block diagram of an exemplary embodiment of a treatment system 100 that can provide negative pressure therapy along with the dropping of a topical treatment solution to a tissue site, according to this specification.

[0021] 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, a surface wound, bone tissue, adipose tissue, muscle tissue, nerve tissue, skin tissue, vascular tissue, connective tissue, cartilage, tendon, or ligament. The term "tissue site" may also refer to any area of tissue that is not necessarily wounded or defective, but instead may be an area where it is desirable to add additional tissue or promote its growth. For example, negative pressure can be applied to a tissue site to grow additional tissue that can be harvested and transplanted. As used herein, a surface wound is a wound on the surface of the body that is exposed to the outside of the body, such as an injury or damage to the epidermis, dermis, and / or subcutaneous layer. Examples of surface wounds can include, for example, ulcers or closed incisions. As used herein, surface wounds do not include intraperitoneal wounds. Examples of wounds can include, for example, chronic, acute, traumatic, subacute, and dehisced wounds, intermediate depth burns, ulcers (such as diabetic ulcers, pressure ulcers, or venous insufficiency ulcers), flaps, and grafts.

[0022] Treatment system 100 can include, for example, a source or supply of negative pressure, such as negative pressure source 102, a dressing 104, a fluid container, such as container 106, and a regulator or controller, such as controller 108. Additionally, treatment system 100 can include a sensor that measures an operating parameter and provides a feedback signal indicative of the operating parameter to controller 108. For example, as shown in FIG. 1, treatment system 100 can include a pressure sensor 110, an electrical sensor 112, or both, coupled to controller 108. As shown in the example of FIG. 1, dressing 104 can comprise or consist essentially of one or more dressing layers, such as tissue interface 114, cover 116, or both, in some embodiments.

[0023] Treatment system 100 can also include a source of a dripping solution, such as, for example, physiological saline. For example, solution source 118 can be fluidly coupled to dressing 104, as shown in the embodiment of FIG. 1. In some embodiments, solution source 118 can be fluidly coupled to a positive pressure source, such as positive pressure source 120, a negative pressure source, such as negative pressure source 102, or both. To ensure an appropriate dosage of the dripping solution to the tissue site, a regulator, such as drip regulator 122, can also be fluidly coupled to solution source 118 and dressing 104. For example, drip regulator 122 can include a piston that can be pneumatically actuated by negative pressure source 102 to draw the dripping solution from the solution source during a negative pressure interval and drip the solution onto the dressing during an evacuation interval. Additionally or alternatively, controller 108 can be coupled to negative pressure source 102, positive pressure source 120, or both to control the dosage of the dripping solution to the tissue site. In some embodiments, drip regulator 122 can also be fluidly coupled to negative pressure source 102 through dressing 104, as shown in the example of FIG. 1.

[0024] Some components of treatment system 100 can be housed within or used with other components, such as a sensor, a processing device, an alarm indicator, a memory, a database, software, a display device, or a user interface that further facilitates treatment. For example, in some embodiments, negative pressure source 102 can be combined with solution source 118, controller 108, and other components to form a treatment unit.

[0025] Generally, the components of the treatment system 100 may be directly coupled or indirectly coupled. For example, the negative pressure source 102 can be directly coupled to the container 106 and indirectly coupled to the dressing 104 through the container 106. The couplings can include, depending on the context, fluid couplings, mechanical couplings, thermal couplings, electrical couplings or chemical couplings (such as chemical bonds), or any combination of couplings. For example, the negative pressure source 102 can be electrically coupled to the controller 108. The negative pressure source can be fluidly coupled to one or more distribution components that provide a fluid path to the tissue site. In some embodiments, the components can also be physically proximate, integrated into a single structure, or formed from the same piece of material, and thus coupled. For example, the tissue interface 114 and the cover 116 can be separate layers disposed adjacent to each other and can be joined to each other in some embodiments.

[0026] The distribution components are preferably detachable and can be disposable, reusable or recyclable. The dressing 104 and the container 106 are examples of distribution components. A fluid conductor is another exemplary example of a distribution component. A "fluid conductor" in this context includes a tube, pipe, hose, conduit, or other structure having one or more lumens or open paths adapted to convey fluid between two ends. Typically, a tube is an elongate cylindrical structure that is somewhat flexible, although the geometry and rigidity can be varied. Further, some fluid conductors can be fitted within other components or integrally coupled to other components in other ways. The distribution components can also include or comprise an interface or fluid port that facilitates the coupling and separation of other components including sensors and data communication devices. In some embodiments, for example, a dressing interface can facilitate the coupling of a fluid conductor to the dressing 104. For example, such a dressing interface can be a SENSAT.R.A.C. (trademark) pad available from KCI of San Antonio, Texas.

[0027] The negative pressure supply unit such as the negative pressure source 102 can be a storage unit for air at negative pressure, or can be a manual or electric device such as, for example, 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 that is lower than a local ambient pressure such as the ambient pressure in the local environment outside the sealed treatment environment. In many cases, the local ambient pressure can also be the atmospheric pressure at the location where 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 in this specification are gauge pressures. When referring to an increase in negative pressure, it generally refers to a decrease in absolute pressure, while a decrease in negative pressure generally refers to an increase in absolute pressure. The amount and nature of the negative pressure applied to the tissue site can be changed according to 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 (-9.9 kPa) to -300 mmHg (-39.9 kPa).

[0028] The container 106 represents a container, canister, pouch, or other storage component that can be used to manage exudates and other fluids withdrawn from the tissue site. In many environments, a rigid container may be preferred or desired for fluid collection, storage, and disposal. In other environments, fluids can be appropriately disposed of without rigid container storage, and reusable containers can reduce waste associated with negative pressure therapy and cut costs.

[0029] A controller, such as controller 108, can be a microprocessor or computer programmed to operate one or more components of the treatment system 100, such as negative pressure source 102. In some embodiments, for example, controller 108 can be a microcontroller, which generally comprises an integrated circuit including a processor core and memory programmed to directly or indirectly control one or more operating parameters of treatment system 100. Operating parameters can include, for example, the power applied to negative pressure source 102, the pressure generated by negative pressure source 102, or the pressure distributed to tissue interface 114. Controller 108 is also preferably configured to receive one or more input signals, such as a feedback signal, and is programmed to modify one or more operating parameters based on the input signals.

[0030] Sensors, such as pressure sensor 110 or electrical sensor 112, 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, pressure sensor 110 and electrical sensor 112 can be configured to measure one or more operating parameters of treatment system 100. In some embodiments, pressure sensor 110 can be a transducer configured to measure the pressure in the pneumatic path and convert the measurement into a signal indicative of the measured pressure. In some embodiments, for example, pressure sensor 110 can be a piezoresistive strain gauge. Electrical sensor 112 can optionally measure, in some embodiments, operating parameters of negative pressure source 102, such as voltage or current. Preferably, the signals from pressure sensor 110 and electrical sensor 112 are suitable as input signals to controller 108, although some signal conditioning may be appropriate in some embodiments. For example, the signal may need to be filtered or amplified before it can be processed by controller 108. Typically, the signal is an electrical signal, although it can be represented in other forms, such as an optical signal.

[0031] The tissue interface 114 can generally be adapted to contact the tissue site. The tissue interface 114 can contact the tissue site partially or completely. For example, if the tissue site is a wound, the tissue interface 114 can partially or completely fill the wound or be placed over the wound. The tissue interface 114 can take many forms and in some embodiments can have two or more layers. The tissue interface 114 can also 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 114 can be adapted to the contour of a deep and irregularly shaped tissue site.

[0032] In some embodiments, the cover 116 can provide protection from bacterial barriers and physical trauma. The cover 116 can also be composed of a material that can reduce evaporative losses and provide a fluid seal between two environments, such as between two components or between the treatment environment and the local external environment. The cover 116 can be, for example, an elastomeric film or membrane that can provide a seal suitable for maintaining negative pressure at the tissue site against a given negative pressure source. The cover 116 can have a high moisture vapor transmission rate (MVTR) in some applications. For example, the MVTR can be at least 300 g / m per 24 hours in some embodiments. 2It can be. In some example embodiments, the cover 116 can 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. In the case of a permeable material, the permeability rate generally must be low enough to be able to maintain the desired negative pressure. The cover 116 can include, for example, one or more of the following materials. That is, hydrophilic polyurethane, cellulose derivative, hydrophilic polyamide, polyvinyl alcohol, polyvinyl pyrrolidone, hydrophilic acrylic resin, hydrophilic silicone elastomer, for example, 14400 g / m 2 / 24 hours of MVTR (inverted cup technique) and a thickness of about 30 microns, INSPIRE 2301 material from Coveris Advanced Coatings in Wrexham, United Kingdom, uncoated polymeric drapes, natural rubber, polyisoprene, styrene-butadiene rubber, chloroprene rubber, polybutadiene, nitrile rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene monomer, chlorosulfonated polyethylene, polysulfide rubber, polyurethane (PU), EVA film, copolyester, silicone, silicone drape, 3M Tegaderm® drape, polyurethane (PU) drapes such as those available from Avery Dennison Corporation in Glendale, California, for example, polyether block polyamide copolymer (PEBAX) from Arkema in France, INSPIRE 2327, or other suitable materials.

[0033] The attachment device can be used to attach the cover 116 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 can be a medically acceptable pressure-sensitive adhesive configured to adhere the cover 116 to the epidermis around a tissue site such as a surface wound. In some embodiments, for example, part or all of the cover 116 can be coated with an adhesive such as an acrylic adhesive that can have an adhesion amount of 25 to 65 grams per square meter (g.s.m.). In some embodiments, a thicker adhesive, or a combination of adhesives, can be applied to improve sealing and reduce leakage. Other examples of embodiments of the attachment device can include double-sided tape, glue, hydrocolloid, hydrogel, silicone gel, or organogel.

[0034] The solution source 118 can also represent a container, canister, pouch, bag, or other storage component that can provide a solution for drop therapy. The composition of the solution can be changed according to the indicated therapy, but examples of solutions that can be suitable for some indications include hypochlorite-based solutions, silver nitrate (0.5%), sulfur-based solutions, biguanides, cationic solutions, and isotonic solutions.

[0035] The hydrodynamics of using a negative pressure source to reduce pressure in another component or location, such as within a sealed treatment environment, can be mathematically complex. However, the basic principles of hydrodynamics applicable to negative pressure therapy and drops are generally well known to those skilled in the art, and in this specification, the process of reducing pressure will be exemplified as, for example, "delivering", "distributing", or "generating" negative pressure.

[0036] Generally, exudates and other fluids flow along a fluid path toward the lower pressure. Thus, the term "downstream" typically means closer to a negative pressure source or farther from a positive pressure source in a fluid path. Conversely, the term "upstream" means farther from a negative pressure source or closer to a positive pressure source. Similarly, it may be convenient to describe some features regarding a fluid "inlet" or "outlet" in such a reference system. This orientation is generally assumed for the purpose of explaining various features and components herein. However, the fluid path can be reversed in some applications (such as by using a positive pressure source instead of a negative pressure source), and this explanatory convention should not be construed as a limiting convention.

[0037] FIG. 2 is an assembled view of an example of the dressing 104 of FIG. 1 and shows further details that can be associated with some embodiments in which the tissue interface 114 comprises more than one layer. In the example of FIG. 2, the tissue interface 114 comprises a first layer 205 and a second layer 210. In some embodiments, the first layer 205 can be disposed adjacent to the second layer 210. For example, the first layer 205 and the second layer 210 can be stacked such that the first layer 205 contacts the second layer 210. In some embodiments, it is also possible to bond the first layer 205 to the second layer 210.

[0038] The first layer 205 generally comprises or is essentially constituted by a manifold or a manifold layer that provides means for collecting or distributing fluid across the tissue interface 114 under pressure. For example, the first layer 205 can be adapted to receive a negative pressure from a negative pressure source and distribute the negative pressure through a plurality of apertures across the tissue interface 114, which can have the effect of collecting fluid from the tissue site and drawing the fluid toward the negative pressure source. In some embodiments, the fluid path can be reversed or a second fluid path can be provided to facilitate the delivery of fluid from a source such as a drip fluid source across the tissue interface 114.

[0039] In some exemplary embodiments, the pathways of the first layer 205 can be interconnected to facilitate the distribution or collection of fluids. In some exemplary embodiments, the first layer 205 can comprise or consist essentially of a porous material having interconnected fluid pathways. For example, open-cell foams, reticulated foams, aggregates of porous tissue, and other porous materials such as gauze or felt mats generally include pores, edges, and / or walls that are adapted to form interconnected fluid flow paths. Other suitable materials can include, for example, 3D textiles (Baltex, Muller, Heathcoates), non-woven fabrics (Libeltex, Freudenberg), 3D polymer structures (molded polymers, embossed and formed films, and fused films [Supracore]), and meshes. Liquids, gels, and other foams can also include or be cured to include apertures and fluid pathways. In some embodiments, the first layer 205 can further or alternatively comprise protrusions that form interconnected fluid pathways. For example, the first layer 205 can be shaped to provide surface protrusions that define interconnected fluid pathways. Any or all of the surfaces of the first layer 205 can have a non-uniform, rough, or jagged contour.

[0040] In some embodiments, the first layer 205 can comprise or consist essentially of a reticulated foam having a pore size and free volume that can be varied according to the needs of the indicated therapy. For example, a reticulated 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 may be particularly suitable for some types of therapy. The tensile strength of the first layer 205 can also be varied according to the needs of the indicated therapy. For example, the tensile strength of the foam can be increased for the dropping of a topical treatment solution. The 25% compression load deflection of the second layer 210 can be at least 0.35 pounds per square inch, and the 65% compression load deflection can be at least 0.43 pounds per square inch. In some embodiments, the tensile strength of the first layer 205 can be at least 10 pounds per square inch. The first layer 205 can have a tear strength of at least 2.5 pounds per inch. In some embodiments, the first layer 205 can be a foam composed of a polyol such as polyester or polyether, an isocyanate such as toluene diisocyanate, and polymerization regulators such as amines and tin compounds. In one non-limiting example, the first layer 205 can be a reticulated polyurethane foam such as the GRANUFOAM™ dressing or the V.A.C. VERAFLO™ dressing, both available from KCI of San Antonio, Texas.

[0041] The first layer 205 generally has a first plane and a second plane opposite the first plane. The thickness of the first layer 205 between the first plane and the second plane can also be varied according to the needs of the indicated therapy. For example, the thickness of the first layer 205 can be reduced to relieve stress on other layers and to reduce tension on the surrounding tissue. The thickness of the first layer 205 can also affect the comfort of the first layer 205. In some embodiments, a thickness in the range of about 5 millimeters to 10 millimeters may be suitable.

[0042] The second layer 210 can comprise or consist essentially of means for controlling or managing fluid flow. In some embodiments, the second layer 210 can comprise or consist essentially of a liquid-impermeable elastomeric material. For example, the second layer 210 can comprise or consist essentially of a polymer film. In some embodiments, the second layer 210 can also have a smooth or matte surface finish. For some applications, a surface finish or gloss finish better than or equal to Class B3 according to the SPI (Society of the Plastics Industry, Inc.) standard can be particularly advantageous. In some embodiments, the surface height variation can be limited to an acceptable tolerance. For example, the surface of the second layer can have a substantially flat surface, with the height variation limited to 0.2 millimeters per centimeter.

[0043] In some embodiments, the second layer 210 can be hydrophobic. The hydrophobicity of the second layer 210 can be modified, but in some embodiments can have a water contact angle of at least 90 degrees. In some embodiments, the second layer 210 can have a water contact angle of 150 degrees or less. For example, in some embodiments, the contact angle of the second layer 210 can be in the range of at least 90 degrees to about 120 degrees, or in the range of at least 120 degrees to 150 degrees. The water contact angle can be measured using any standard apparatus. A manual goniometer can be used to visually approximate the contact angle, but contact angle measuring instruments often require an integrated system that includes, among other things, a horizontal stage, a liquid dropper such as a syringe, a camera, and software designed to more accurately and precisely calculate the contact angle. Non-limiting examples of such integrated systems include the FTÅ125, FTÅ200, FTÅ2000, and FTÅ4000 systems, all commercially available from First Ten Angstroms, Inc., Portsmouth, VA, and the DTA25, DTA30, and DTA100 systems, all commercially available from Kruss GmbH, Hamburg, Germany. Unless otherwise specified, the water contact angle herein is measured using deionized distilled water on a horizontal sample surface for a sessile drop added from a height of 5 cm or less in air at 20 - 25°C and 20 - 50% relative humidity. The contact angles reported herein represent the average of 5 - 9 measurements, discarding both the highest and lowest measured values. The hydrophobicity of the second layer 210 can be further enhanced by a hydrophobic coating of other materials such as silicone and fluorocarbon, either coated from a liquid or plasma coated.

[0044] The second layer 210 may also be suitable for welding to other layers including the first layer 205. For example, the second layer 210 can be adapted to be welded to the polyurethane foam using other methods that generate heat, such as heat, radio frequency (RF) welding, or ultrasonic welding. RF welding may be particularly suitable for more polar materials such as polyurethane, polyamide, polyester, and acrylate. A sacrificial polar interface can be used to facilitate the RF welding of less polar film materials such as polyethylene.

[0045] The areal density of the second layer 210 can be varied according to the indicated therapy or application. In some embodiments, an areal density of less than 40 grams per square meter may be suitable, and for some applications, an areal density of about 20 - 30 grams per square meter may be particularly advantageous.

[0046] In some embodiments, for example, the second layer 210 may include or be composed of a hydrophobic polymer such as a polyethylene film. The simple and inert structure of polyethylene provides a surface that interacts very little, if at all, with biological tissues and fluids, 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 resin, polyolefin (such as cyclic olefin copolymer), polyacetate, polyamide, polyester, copolyester, PEBAX block copolymer, thermoplastic elastomer, thermoplastic vulcanizate, polyether, polyvinyl alcohol, polypropylene, polymethylpentene, polycarbonate, styrenic, silicone, fluoropolymer, and acetate. For many applications, a thickness of 20 microns to 100 microns may be suitable. The film may be transparent, colored, or printed. More polar films suitable for laminating to a polyethylene film include polyamide, copolyester, ionomer, and acrylic resin. A bonding layer such as ethylene vinyl acetate or modified polyurethane can be used to aid in bonding between polyethylene and the polar film. Ethyl methyl acrylate (EMA) film can also have suitable hydrophobic and welding properties for some configurations.

[0047] As shown in the example of FIG. 2, the second layer 210 can have one or more fluid restriction portions 220 that can be uniformly or randomly dispersed across the second layer 210. The fluid restriction portions 220 can be bidirectional and pressure-responsive. For example, each of the fluid restriction portions 220 can generally comprise or consist essentially of an elastic passageway that is normally unstretched so as to substantially reduce liquid flow, and can expand or open in response to a pressure gradient. In some embodiments, the fluid restriction portions 220 can comprise or consist essentially of perforations in the second layer 210. The perforations can be formed by removing material from the second layer 210. For example, the perforations can be formed by cutting into the second layer 210, and in some embodiments, such cuts can also deform the edges of the perforations. When there is no pressure gradient across the perforations, the passageways can be made small enough to form a seal or fluid restriction, thereby substantially reducing or preventing liquid flow. Additionally or alternatively, one or more of the fluid restriction portions 220 can be an elastomeric valve, which is normally closed to substantially prevent liquid flow when unstretched and can open in response to a pressure gradient. For some applications, an opening in the second layer 210 can be a suitable valve. The opening can also be formed by removing material from the second layer 210, but the amount of material removed and the resulting dimensions of the opening can be orders of magnitude smaller than the perforations and there is no possibility of deforming the edges.

[0048] For example, some embodiments of the fluid restriction portion 220 may include, or consist essentially of, one or more slits, slots, or combinations of slits and slots in the second layer 210. In some examples, the fluid restriction portion 220 may include or be composed of a linear slot having a length of less than 4 millimeters and a width of less than 1 millimeter. In some embodiments, the length can be at least 2 millimeters and the width can 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, and a tolerance of about 0.1 millimeter may also be acceptable. Such dimensions and tolerances can be achieved, for example, using a laser cutter. Slots of such a configuration can typically function as an imperfect valve that substantially reduces liquid flow in a closed or resting state. For example, such slots can form a fluid restriction without being completely closed or sealed. The slot can expand or open wider in response to a pressure gradient to allow an increase in liquid flow.

[0049] In the example of FIG. 2, the dressing 104 can further include a mounting device such as an adhesive 240. The adhesive 240 can be, for example, a medically acceptable pressure-sensitive adhesive that extends to the peripheral portion, part, or the entire cover 116. In some embodiments, for example, the adhesive 240 can be an acrylic adhesive having an adhesion amount of 25 to 65 grams per square meter (g.s.m.). In some embodiments, a thicker adhesive, or a combination of adhesives, can be provided to improve the sealing property and reduce leakage. In some embodiments, such a layer of the adhesive 240 can be continuous or discontinuous. The discontinuity in the adhesive 240 can be provided by an aperture or hole (not shown) in the adhesive 240. The aperture or hole in the adhesive 240 can be formed after the application of the adhesive 240 or by coating the adhesive 240 in some patterns on a carrier layer, such as on one side of the cover 116. The aperture or hole in the adhesive 240 can be sized in some exemplary embodiments to improve the MVTR of the dressing 104.

[0050] As shown in the example of FIG. 2, in some embodiments, the dressing 104 can include a release liner 245 to protect the adhesive 240 prior to use. The release liner 245 can also provide stiffness, for example, to assist in the deployment of the dressing 104. The release liner 245 can be, for example, a process paper, film, or polyethylene. Further, in some embodiments, the release liner 245 can 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 245 can substantially eliminate wrinkles or other deformations of the dressing 104. For example, the polar semi-crystalline polymer can be highly oriented and resistant to softening, swelling, or other deformations that may occur when in contact with the components of the dressing 104, or when subjected to temperature or environmental variations or sterilization. Further, a release agent can be disposed on the side of the release liner 245 configured to contact the second layer 210. For example, the release agent can be a silicone coating and can have a release factor suitable for facilitating the removal of the release liner 245 without damaging the dressing 104 by hand or deforming the dressing 104. In some embodiments, the release agent can be, for example, a fluorocarbon or fluorosilicone. In other embodiments, the release liner 245 can be uncoated or used without a release agent in other ways.

[0051] FIG. 2 also shows an example of a fluid conductor 250 and a dressing interface 255. As shown in the example of FIG. 2, the fluid conductor 250 can be a flexible tube that can be fluidly coupled to the dressing interface 255 at one end. The dressing interface 255 can be, as shown in the example of FIG. 2, an elbow connector that can be disposed over the aperture 260 of the cover 116 to provide a fluid path between the fluid conductor 250 and the tissue interface 114.

[0052] Figure 3 is a schematic diagram of an example of the second layer 210 and shows further details that can be associated with several embodiments. As shown in the example of Figure 3, the fluid restriction part 220 can be composed of one or more linear slots each having a length of about 3 millimeters. Figure 3 further shows an example of a uniform dispersion pattern of the fluid restriction part 220. In Figure 3, the fluid restriction part 220 has substantially the same spread as the second layer 210 and is dispersed across the second layer 210 in a grid of parallel rows and columns, where the slots are also parallel to each other. In some embodiments, as shown in the example of Figure 3, the rows can be arranged with a spacing of about 3 millimeters at the center, and the fluid restriction parts 220 in each of the rows can be arranged with a spacing of about 3 millimeters at the center. The fluid restriction parts 220 in adjacent rows may or may not be aligned. For example, adjacent rows can be shifted as shown in Figure 3, so that the fluid restriction parts 220 are aligned in every other row and spaced about 6 millimeters apart. The spacing of the fluid restriction parts 220 can be changed in some embodiments to increase the density of the fluid restriction parts 220 according to treatment requirements.

[0053] In some embodiments, one or more of the components of the dressing 104 can be further treated with an antibacterial agent. For example, the first layer 205 can be a foam, mesh, or non-woven fabric coated with an antibacterial agent. In some embodiments, the first layer can include antibacterial elements such as fibers coated with an antibacterial agent. Further or alternatively, some embodiments of the second layer 210 can be a polymer coated with an antibacterial agent or mixed with an antibacterial agent. In other examples, the fluid conductor 250 can be further or alternatively treated with one or more antibacterial agents. Suitable antibacterial agents can include, for example, metallic silver, PHMB, povidone iodine, iodine or its complexes and mixtures, copper metal compounds, chlorhexidine, or some combination of these substances.

[0054] Additionally or alternatively, one or more of the components can be coated with a mixture that can include citric acid and collagen and that can reduce biofilms and infections. For example, the first layer 205 can be a foam coated with such a mixture.

[0055] The individual components of the dressing 104 can be joined to each other or otherwise secured, for example, with a solvent or non-solvent adhesive or by heat welding, without adversely affecting fluid management.

[0056] The cover 116, the first layer 205, and the second layer 210, or various combinations, can be assembled before application or in situ. For example, in some embodiments, the cover 116 can be adhered to the first layer 205, and the second layer 210 can be adhered to the first layer 205 on the side opposite the cover 116. The second layer 210 can provide a smooth surface on the side opposite the first layer 205. In some embodiments, one or more layers of the tissue interface 114 can have the same extent. For example, as shown in the embodiment of FIG. 2, the second layer 210 can be cut in the same plane as the edge of the first layer 205 to expose the edge of the first layer 205. In other embodiments, the second layer 210 can overlap the edge of the first layer 205. In some embodiments, the dressing 104 can be provided as a single composite dressing. For example, the second layer 210 can be joined to the cover 116 so as to enclose the first layer 205, and the second layer 210 is configured to face the tissue site.

[0057] In use, the release liner 245 (if included) can be removed to expose the second layer 210, and the second layer 210 can be placed across, on, or otherwise adjacent to a tissue site, particularly a surface tissue site and the adjacent epidermis. The second layer 210 can be inserted between the first layer 205 and the tissue site and the adjacent epidermis, thereby substantially reducing or eliminating an adverse interaction with the first layer 205. For example, the second layer 210 can be placed over a surface wound (including the edges of the wound) and the intact epidermis so as to prevent direct contact with the first layer 205. Treatment of a surface wound or placement of a dressing 104 over a surface wound includes placing the dressing 104 immediately adjacent to the surface of the body or spreading it over at least a portion of the surface of the body. Treatment of a surface wound does not include placing the dressing entirely within the body, such as placing the dressing in the abdominal cavity, or entirely under the surface of the body. Around the second layer 210 and the first layer 205, the cover 116 can be sealed to an attachment surface, such as the epidermis at the periphery of the tissue site.

[0058] The geometric shape and dimensions of the tissue interface 114, the cover 116, or both can be modified to conform to a particular application or anatomical structure. For example, the geometric shape or dimensions of the tissue interface 114 and the cover 116 can be adapted to provide an effective and secure seal against anatomical surfaces that are difficult to seal, such as the elbow or heel, at and around the tissue site. Additionally or alternatively, the dimensions can be modified to increase the surface area relative to the second layer 210 so as to promote epithelial cell migration and proliferation at the tissue site and reduce the potential for ingrowth of granulation tissue.

[0059] Thus, the dressing 104 of 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 102 can apply a reduced pressure within the sealed treatment environment. The negative pressure within the sealed environment can push the first layer 205 into the second layer 210, thereby deforming the surface of the second layer 210 in some embodiments to provide a non-uniform, rough, or jagged profile that can cause macroscopic and microscopic strains at the tissue site. The negative pressure applied through the tissue interface 114 can also result in a negative differential pressure across the fluid restriction 220 in the second layer 210, thereby allowing the restriction 220 to open to permit the movement of exudates and other liquids from the first layer 205 and into the container 106 through the restriction 220. For example, in some embodiments where the fluid restriction 220 can comprise a perforation through the second layer 210, the pressure gradient across the perforation can distort the adjacent material of the second layer 210, similar to the operation of a duckbill valve, to increase the size of the perforation to permit liquid movement therethrough.

[0060] In some embodiments, the first layer 205 can be hydrophobic to minimize liquid retention or accumulation in the dressing 104. In other embodiments, the first layer 205 can be hydrophilic. In examples where the first layer 205 can be hydrophilic, the first layer 205 can also be capable of absorbing fluid from the tissue site while the negative pressure is being distributed to the tissue site. The wicking properties of the first layer 205 can pull fluid away from the tissue site, for example, by capillary flow or other wicking mechanisms. Examples of hydrophilic first layers 205 are polyvinyl alcohol, open cell foams such as the V.A.C. WHITEFOAM™ dressing available from KCI of San Antonio, Tex. Other hydrophilic foams can include those made from polyethers. Other foams that can exhibit hydrophilic characteristics can include hydrophobic foams that have been treated or coated to provide hydrophilicity.

[0061] When the negative pressure source 102 is removed or turned off, the differential pressure across the fluid restriction portion 220 can disappear, whereby the fluid restriction portion 220 can return to an unstressed or stationary state, preventing or reducing the rate of return of exudate or other liquid through the second layer 210 to the tissue site.

[0062] In some applications, a filler can also be disposed between the tissue site and the second layer 210. For example, if the tissue site is a surface wound, a wound filler can be applied inwardly relative to the perimeter of the wound, and the second layer 210 can be disposed over the perimeter of the wound and the wound filler. In some embodiments, the filler can be a manifold such as an open cell foam. The filler can, in some embodiments, comprise or consist essentially of the same materials as the first layer 205.

[0063] Additionally or alternatively, the tissue interface 114 can be formed into a strip, for example, suitable for use as a bridge or for filling a tunneling wound. For some embodiments, a strip having a width of about 5 millimeters to 30 millimeters can be suitable.

[0064] Additionally or alternatively, the second layer 210 can comprise reinforcing fibers to increase its tensile strength, which can be advantageous for use within tunneling wounds.

[0065] Additionally or alternatively, a dripping solution or other fluid can be dispensed into the dressing 104, thereby increasing the pressure within the tissue interface 114. The increase in pressure within the tissue interface 114 can result in a positive differential pressure across the fluid restriction portions 220 in the second layer 210, thereby opening or expanding the fluid restriction portions 220 from their stationary state and enabling the dripping solution or other fluid to be dispensed to the tissue site.

[0066] Figure 4 is an assembly diagram of another example of the dressing 104 of FIG. 1, showing further details that can be associated with some embodiments in which the tissue interface 114 can comprise additional layers. In the example of FIG. 4, the tissue interface 114 comprises a third layer 405 in addition to the first layer 205 and the second layer 210. In some embodiments, the third layer 405 can be adjacent to the second layer 210 on the side opposite the first layer 205. In some embodiments, the third layer 405 can also be joined to the second layer 210.

[0067] The third layer 405 can comprise or consist essentially of a sealing layer formed from a soft and flexible material suitable for providing a fluid seal with the tissue site and can have a substantially flat surface. For example, the third layer 405 can include, without limitation, silicone gel, soft silicone, hydrophilic colloid, hydrogel, polyurethane gel, polyolefin gel, hydrogenated styrene copolymer gel, foamed gel, adhesive, polyurethane, polyolefin or hydrogenated styrene copolymer coated soft open-cell foams such as polyurethane and polyolefin. In some embodiments, the third layer 405 can have a thickness of from about 200 microns (μm) to about 1000 microns (μm). In some embodiments, the third layer 405 can have a hardness of from about 5 Shore OO to about 80 Shore OO. Further, the third layer 405 can be composed of a hydrophobic or hydrophilic material.

[0068] In some embodiments, the third layer 405 can be a hydrophobic coated material. For example, the third layer 405 can be formed by coating a spaced material such as, for example, a woven fabric, non-woven fabric, molded or extruded mesh with a hydrophobic material. The hydrophobic material for the coating can be, for example, soft silicone.

[0069] The third layer 405 can have a peripheral portion 410 surrounding or around the inner portion 415 and an aperture 420 disposed through the peripheral portion 410 and the inner portion 415. The inner portion 230 can, in some examples, correspond to the surface area of the first layer 205. The third layer 405 can also have corners 425 and edges 430. The corners 425 and edges 430 can be part of the peripheral portion 410. The third layer 405 can have an inner boundary portion 435 around the inner portion 415 disposed between the inner portion 415 and the peripheral portion 410. As shown in the example of FIG. 3, the inner boundary portion 435 can be substantially free of apertures 420. In some examples, as shown in FIG. 3, the inner portion 415 is symmetric and can be centered in the third layer 405.

[0070] The aperture 420 can be formed, for example, by cutting, or by application of local RF or ultrasonic energy, or by other suitable techniques for forming an opening. The aperture 420 can have a uniform distribution pattern or can be randomly dispersed over the third layer 405. The apertures 420 in the third layer 405 can have many shapes, including, for example, circular, square, star, oval, polygonal, slit, complex curve, linear shape, triangle, or any combination of such shapes.

[0071] Each of the apertures 420 can have uniform or similar geometric properties. For example, in some embodiments, each of the apertures 420 can be a circular aperture having substantially the same diameter. In some embodiments, the diameter of each of the apertures 420 can be from about 1 millimeter to about 50 millimeters. In other embodiments, the diameter of each of the apertures 420 can be from about 1 millimeter to about 20 millimeters.

[0072] In other embodiments, the geometric properties of the aperture 420 can be changed. For example, as shown in FIG. 4, the diameter of the aperture 420 can be changed according to the position of the aperture 420 in the third layer 405. In some embodiments, the diameter of the aperture 420 at the peripheral portion 410 of the third layer 405 can be made larger than the diameter of the aperture 420 at the inner portion 415 of the third layer 405. For example, in some embodiments, the aperture 420 disposed at the peripheral portion 410 can have a diameter of about 9.8 millimeters to about 10.2 millimeters. In some embodiments, the aperture 420 disposed at the corner portion 425 can have a diameter of about 7.75 millimeters to about 8.75 millimeters. In some embodiments, the aperture 420 disposed at the inner portion 415 can have a diameter of about 1.8 millimeters to about 2.2 millimeters.

[0073] At least one of the apertures 420 at the peripheral portion 410 of the third layer 405 can be positioned at the edge 430 of the peripheral portion 410 and can have an internal cutout that is open or exposed at the edge 430 and is in lateral fluid communication with the edge 430. The lateral direction shall refer to the direction in the same plane as the third layer 405 that is directed towards the edge 430. As shown in the example of FIG. 4, the aperture 420 at the peripheral portion 410 can be positioned in proximity to or at the edge 430 and in lateral fluid communication with the edge 430. As shown in the example of FIG. 3, the apertures 420 positioned in proximity to or at the edge 430 can be arranged substantially equidistantly spaced apart across the peripheral portion 410. Alternatively, the spacing between the apertures 420 in proximity to or at the edge 430 can be irregular.

[0074] As shown in the example of FIG. 4, in some embodiments, a release liner 245 can be attached to or positioned adjacent to the third layer 405 to protect the adhesive 240 before use. In some embodiments, the release liner 245 can have a surface texture that can be engraved onto an adjacent layer such as the third layer 405. Further, a release agent can be disposed on the side of the release liner 245 configured to contact the third layer 405.

[0075] FIG. 5 is a schematic diagram of a configuration example of the aperture 420 and shows further details that can be associated with some embodiments of the third layer 405. In some embodiments, the aperture 420 shown in FIG. 5 can be associated only with the inner portion 415. In the example of FIG. 5, the aperture 420 is generally circular and has a diameter of about 2 millimeters. FIG. 5 also shows an example of a uniform dispersion pattern of the apertures 420 in the inner portion 415. In FIG. 5, the apertures 420 are dispersed across the inner portion 415 in a grid of parallel rows and columns. As shown in the example of FIG. 5, within each row and column, the apertures 420 can be equidistant from each other. FIG. 5 shows one configuration example that can be particularly suitable for many applications, where the apertures 420 are spaced approximately 6 millimeters apart and offset by 3 millimeters along each row and column.

[0076] FIG. 6 is a schematic view of a third layer 405 as an example of FIG. 5 superimposed on the second layer 210 of FIG. 3, showing further details that can be associated with some example embodiments of the tissue interface 114. For example, as shown in FIG. 6, in some embodiments, the fluid restriction 220 can be aligned with, overlap, be positioned with, or otherwise fluidly coupled to the aperture 420. In some embodiments, one or more of the fluid restrictions 220 can be aligned with or only partially aligned with the aperture 420 only at the inner portion 415. The fluid restrictions 220 in the example of FIG. 6 are generally configured such that each of the fluid restrictions 220 is aligned with only one of the apertures 420. In other examples, one or more of the fluid restrictions 220 can be aligned with two or more of the apertures 420. For example, any one or more of the fluid restrictions 220 can be a perforation or opening that extends across two or more of the apertures 420. Additionally or alternatively, one or more of the fluid restrictions 220 may not be aligned with any of the apertures 420.

[0077] As shown in the example of FIG. 6, the aperture 420 can be sized to expose a portion of the second layer 210, the fluid restriction 220, or both, through the third layer 405. In some embodiments, one or more of the apertures 235 can be sized to expose two or more of the fluid restrictions 220. For example, some or all of the apertures 235 can be sized to expose two or more of the fluid restrictions 220. In some examples, the length of each of the fluid restrictions 220 can be substantially equal to the diameter of each of the apertures 420. More generally, the average dimension of the fluid restrictions 220 is substantially similar to the average dimension of the apertures 420. For example, the aperture 420 can be elliptical in some embodiments, and the length of each of the fluid restrictions 220 can be substantially equal to the major axis or the minor axis. However, in some embodiments, the dimensions of the fluid restrictions 220 can exceed the dimensions of the aperture 420, and the size of the aperture 420 can limit the effective size of the fluid restrictions 220 exposed on the lower surface of the dressing 104.

[0078] The individual components of the dressing 104 in the example of FIG. 4 can be joined to each other or otherwise fixed without adversely affecting fluid management, for example, using a solvent adhesive or a non-solvent adhesive, or using thermal welding. Further, the second layer 210 or the first layer 205 can be joined to the boundary 435 of the third layer 405 in any suitable manner, such as by welding or by an adhesive.

[0079] Cover 116, the first layer 205, the second layer 210, the third layer 405, or various combinations thereof can be assembled before application or in situ. For example, in some embodiments, the cover 116 can be adhered to the first layer 205, and the second layer 210 can be adhered to the first layer 205 on the side opposite to the cover 116. In some embodiments, the third layer 405 can also be coupled to the second layer 210 on the side opposite to the first layer 205. In some embodiments, one or more layers of the tissue interface 114 can have the same extent. For example, as shown in the embodiment of FIG. 4, the second layer 210, the third layer 405, or both can be cut in the same plane as the edge of the first layer 205 to expose the edge of the first layer 205. In other embodiments, the second layer 210, the third layer 405, or both can overlap the edge of the first layer 205. In some embodiments, the dressing 104 can be provided as a single composite dressing. For example, the third layer 405 can be coupled to the cover 116 so as to enclose the first layer 205 and the second layer 210, and the third layer 405 is configured to face the tissue site. Additionally or alternatively, the second layer 210, the third layer 405, or both can be disposed on both sides of the first layer 205 and joined together so as to enclose the first layer 205.

[0080] In use, the release liner 245 (if included) can be removed to expose the third layer 405 of the example of FIG. 4, and the third layer 405 can be disposed across, on, or otherwise in proximity to a tissue site, particularly a surface tissue site and adjacent epidermis. The third layer 405 and the second layer 210 can be inserted between the first layer 205 and the tissue site, thereby substantially reducing or eliminating an adverse interaction with the first layer 205. For example, the third layer 405 can be disposed over a surface wound (including the wound edges) and intact epidermis to prevent direct contact with the first layer 205. In some applications, the inner portion 415 of the third layer 405 can be positioned adjacent to, in proximity to, or covering the tissue site. In some applications, at least a portion of the second layer 210, the fluid restriction 220, or both can be exposed to the tissue site through the third layer 405. The peripheral edge 410 of the third layer 405 can be positioned adjacent to or in proximity to tissue surrounding or surrounding the tissue site. The third layer 405 can be sufficiently adhesive to hold the dressing 104 in place while also allowing the dressing 104 to be removed or repositioned without trauma to the tissue site.

[0081] By removing the release liner 245 of the example of FIG. 4, the adhesive 240 can also be exposed, and a cover 116 can be attached to an attachment surface such as the peripheral epidermis with respect to the tissue site around the second layer 210 and the first layer 205. For example, the adhesive 240 can be in fluid communication with the attachment surface through the aperture 420, at least at the peripheral edge 410 of the third layer 405. The adhesive 240 can also be in fluid communication with the edge 430 through the aperture 420 exposed at the edge 430.

[0082] Once the dressing 104 is in the desired position, the adhesive 240 can be pushed through the aperture 420 to adhere the dressing 104 to the attachment surface. The aperture 420 at the edge 430 allows the adhesive 240 to flow around the edge 430 to facilitate attachment of the edge 430 to the attachment surface.

[0083] In some embodiments, the apertures or holes in the third layer 405 can be sized to control the amount of adhesive 240 that is in fluid communication with the aperture 420. For a given geometry of the corner 425, the relative size of the aperture 420 can be configured to maximize the surface area of the adhesive 240 that is exposed and in communication through the aperture 420 at the corner 425. For example, as shown in FIG. 3, the edges 430 can intersect at substantially right angles, i.e., about 90 degrees, to define the corner 425. In some embodiments, the corner 425 can have a radius of about 10 millimeters. Further, in some embodiments, three of the apertures 420 having a diameter of from about 7.75 millimeters to about 8.75 millimeters can be positioned in a triangular configuration at the corner 425 to maximize the exposed surface area to the adhesive 240. In other embodiments, depending on the selected geometry of the corner 425, the size and number of the apertures 420 at the corner 425 can be adjusted as needed to maximize the exposed surface area of the adhesive 240. Further, the apertures 420 at the corner 425 can be fully contained within the third layer 405, substantially preventing lateral fluid communication outside of the corner 425. By fully containing the apertures 420 within the third layer 405 at the corner 425, the fluid communication of the adhesive 240 outside of the corner 425 can be substantially prevented, improving the handling of the dressing 104 during deployment at the tissue site. Further, the absence of substantially any adhesive 240 outside of the corner 425 can increase the flexibility of the corner 425 to improve comfort.

[0084] In some embodiments, the adhesion strength of the adhesive 240 can be varied at different locations of the dressing 104. For example, the adhesive 240 can have a relatively low adhesion strength at locations adjacent to the third layer 405 where the aperture 420 is relatively large, and can have a relatively high adhesion strength at locations where the aperture 420 is relatively small. The adhesive 240 having a relatively low adhesion strength in combination with a relatively large aperture 420 can provide an adhesion comparable to that of the adhesive 240 having a relatively high adhesion strength at locations having a relatively small aperture 420.

[0085] The geometric shape and dimensions of the tissue interface 114, the cover 116, or both can be varied to conform to a particular application or anatomical structure. For example, the geometric shape or dimensions of the tissue interface 114 and the cover 116 can be adapted to provide an effective and secure seal against anatomical structures that are difficult to seal, such as the elbow or heel, at and around the tissue site. Additionally or alternatively, the dimensions can be varied to increase the surface area relative to the third layer 405 to promote the movement and growth of epithelial cells at the tissue site and reduce the potential for ingrowth of granulation tissue.

[0086] Further, the dressing 104 can be enabled to reduce or eliminate leaks that may be caused by folds or other discontinuities in the dressing 104 or at the tissue site by reapplication or repositioning. By being able to correct leaks, in some embodiments, the reliability of treatment can be improved and the power consumption can be reduced.

[0087] Accordingly, the dressing 104 of the example of FIG. 4 can provide a sealed treatment environment that is substantially isolated from the external environment and is proximate to the tissue site, and the negative pressure source 102 can reduce pressure within the sealed treatment environment. The third layer 405 can provide an effective and secure seal against anatomical surfaces that are difficult to seal, such as the elbow or heel, at or around the tissue site. Further, the dressing 104 can be capable of correcting air leakage caused by folds and other discontinuities of the dressing 104, for example, by reapplication or repositioning. By being able to correct the leakage, in some embodiments, the efficacy of the treatment can be increased and the power consumption can be reduced.

[0088] If not already configured, the dressing interface 255 can be placed over the aperture 260 and attached to the cover 116. The fluid conductor 250 can be fluidly coupled to the dressing interface 255 and to the negative pressure source 102.

[0089] The negative pressure applied through the tissue interface 114 can create a negative differential pressure across the fluid restriction 220 in the second layer 210, thereby opening or expanding the fluid restriction 220. For example, in some embodiments where the fluid restriction 220 can comprise a substantially closed aperture through the second layer 210, the pressure gradient across the aperture can distort the adjacent material of the second layer 210 and increase the dimensions of the aperture, similar to the operation of a duckbill valve, to allow movement of liquid therethrough. By opening the fluid restriction 220, movement of exudates and other liquids through the first layer 205 and into the container 106 through the fluid restriction 220 can be enabled. The change in pressure can also cause the first layer 205 to expand and contract, and the inner boundary 435 can protect the epidermis from irritation. The second layer 210 and the third layer 405 can also substantially reduce or prevent exposure of tissue to the first layer 205, thereby preventing growth of tissue into the first layer 205.

[0090] When the negative pressure source 102 is removed or turned off, the differential pressure across the fluid restriction 220 can disappear, and the fluid restriction 220 can close to prevent exudate or other liquid from returning to the tissue site through the second layer 210.

[0091] In some applications, a filler can also be disposed between the tissue site and the third layer 405. For example, when the tissue site is a surface wound, a wound filler can be applied inside the periphery of the wound, and the third layer 405 can be disposed over the periphery of the wound and the wound filler. In some embodiments, the filler can be a manifold such as an open-cell foam. In some embodiments, the filler can include or be substantially composed of the same material as the first layer 205.

[0092] Additionally or alternatively, a dripping solution or other fluid can be dispensed onto the dressing 104, thereby increasing the pressure at the tissue interface 114. The increase in pressure at the tissue interface 114 can create a positive differential pressure across the fluid restriction 220 in the second layer 210, thereby opening the fluid restriction 220 to allow the dripping solution or other fluid to be dispensed to the tissue site.

[0093] FIG. 7 is a top view of another example of the third layer 405 and shows further details that can be associated with some embodiments. As shown in the example of FIG. 7, the third layer 405 can have one or more elastomeric valves 705 instead of or in addition to the aperture 420 in the inner portion 415. The valve 705 can be included in the third layer 405 instead of or in addition to the second layer 210. In some embodiments where the third layer 405 includes one or more of the valves 705, the second layer 210 can be omitted. For example, in some embodiments, the tissue interface 114 can be essentially composed of the first layer 205 and the third layer 405 of FIG. 7 with the valve 705 disposed in the inner portion 415.

[0094] Figures 8 and 9 show other configuration examples of valve 705, where each valve 705 generally comprises a combination of cross slits or cross-shaped slits.

[0095] Figure 10 is an assembly diagram of another example of the tissue interface 114 of FIG. 1. In the example of FIG. 10, the second layer 210 is disposed adjacent to two surfaces of the first layer 205. In some embodiments, for example, the second layer 210 can be bonded to or mechanically joined in other ways to the two surfaces of the first layer 205. Additionally or alternatively, the third layer 405 can be disposed adjacent to one or more surfaces of the first layer 205, or can be disposed adjacent to the second layer 210, as shown in the example of FIG. 10. In some embodiments, the third layer 405 can form a sleeve or envelope around the first layer 205, the second layer 210, or both.

[0096] Figure 11 is a perspective view of another configuration example of the first layer 205 and the second layer 210. In the example of FIG. 11, the second layer 210 can form a sleeve around the first layer 205. For example, the second layer 210 can be folded or wound around the first layer 205, and the edges of the second layer 215 can be attached to each other. In other examples, the edges can be attached to form a sleeve before inserting the first layer 205, or the edges can be attached to the first layer 205. As shown in the example of FIG. 11, the second layer 210 can leave one or more edges of the first layer 205 exposed. The configuration example of FIG. 11 can be used in combination with or in place of other configurations of the first layer 205 and the second layer 210 described above.

[0097] Figure 12 is a partial cutaway view of another configuration example of the first layer and the second layer 210. In the example of FIG. 12, the second layer 210 can form an envelope around the first layer 205. For example, the second layer 210 can be disposed on two surfaces of the first layer 205, and the edges can be mechanically joined to each other around the first layer 205 to form an envelope. The configuration example of FIG. 12 can be used in combination with or in place of other configurations of the first layer 205 and the second layer 210 described above.

[0098] The systems, devices, and methods described herein can provide significant advantages compared to conventional dressings. For example, some dressings for negative pressure therapy may require time and skill to be properly sized and applied to achieve a good fit and seal. In contrast, some embodiments of dressing 104 provide a negative pressure dressing that is easy to apply and reduces the time to apply and remove. In some embodiments, for example, dressing 104 can be applied to a tissue site (including over the wound perimeter) in one step without cutting to a certain size, while providing or improving many of the advantages of other negative pressure therapy dressings that require sizing. Such advantages can include excellent manifolding, favorable granulation, protection of surrounding tissue from maceration, protection of the tissue site from shed material, and low trauma and high seal bonding. These features can be particularly advantageous for surface wounds having a moderate depth and medium to high levels of exudate. Some embodiments of dressing 104 can remain on the tissue site for at least 5 days, and some embodiments can remain for at least 7 days. The antimicrobial agent on dressing 104 can extend the useful life of dressing 104 by reducing or eliminating the risk of infection associated with long-term use, particularly in infected or heavily exuding wounds.

Example

[0099] Some of the advantages associated with the systems, devices, and methods described herein can be further demonstrated by the following non-limiting examples.

[0100] Example 1 - Evaluation of Dressings in a Porcine Model of Full Thickness Excisional Wounds

[0101] Objective The primary objective of this investigation was to evaluate embodiments of dressings having the above-described characteristics (referred to herein as "GM") in relation to V.A.C. Therapy and V.A.C. VERAFLO Therapy, compared to conventional V.A.C. Therapy using GRANUFOAM dressing and other Advanced Wound Care dressings without V.A.C. Therapy. Wounds were evaluated for granulation tissue formation, the presence of maceration in the skin surrounding the wound, and ease of dressing removal, as defined below. i. Histological evaluation of granulation tissue thickness ii. Peel strength test iii. Visual evaluation of bleeding iv. Visual evaluation of dressing particles remaining on the wound bed after dressing removal v. Histological evaluation of dressing particles, necrosis, bleeding, edema, and inflammation vi. Maceration of intact skin (tissue water content) vii. Histological evaluation of intact skin for bacteria, edema, and inflammation

[0102] Test articles and controls TIFF2025084747000002.tif110170

[0103] Animal model This investigation was conducted using the animal model outlined below. TIFF2025084747000003.tif49170

[0104] Investigation design TIFF2025084747000004.tif69170TIFF2025084747000005.tif75170

[0105] Surgical procedure Defect wound creation - Day 0 The initial pilot animals (Group 1) received all wound creation and treatment prior to scheduling treatment for the additional animals in Groups 2 and 3. Up to 10 full-thickness skin defect wounds (approx. 3 x 7.5 cm) (up to 5 wounds on each side of the spine) were created on each animal using a sterile template. There was a space between each of the wounds (at least about 6 cm from wound edge to wound edge between adjacent wounds, sufficient space between all wounds to properly place dressings and drapes). If the length of the animal's back did not provide sufficient space for 10 wounds and dressings (determined on Day 0), 8 wounds (4 on each side of the spine) were created. A surgical scalpel blade was used to surgically create the wounds down to but not through the subcutaneous fascia layer (just above the muscle). If disruption of the subcutaneous fascia layer occurred, it was recorded in the study records. Care was taken not to shave the area around the wounds during wound creation. Efforts were made to maintain the spine between the apex of the shoulder and the coccygeal prominence and create wounds on two paravertebral sites. Hemostasis was obtained using direct pressure with sterile gauze. In cases of excessive bleeding not controlled by direct pressure, hemostatic forceps were used to clamp the bleeding source. During creation of the other wounds, the wound sites were maintained moist using sterile 0.9% saline-soaked gauze. The wounds were photographed.

[0106] Application of Dressings and Negative Pressure Therapy Following wound creation (Day 0), the test article or control article was applied to all wounds. On Day 4 (Group 3 only), the test article or control article was applied to wounds where the dressing had been removed.

[0107] On the indicated dressing change days (after the peel test, TEWL, visual observation, and photography), the area around the wounds was gently wiped clean and dried with sterile 0.9% saline-soaked gauze. Dressings were applied to the individual wound sites by a randomization method.

[0108] Regardless of the type of dressing for a particular wound, an adhesive such as benzoin was placed on the skin surrounding the outermost periphery of the test article margin, leaving an approximately 1 cm outer periphery around the wound free of benzoin and surrounding the wound perimeter region with the adhesive. This means that there is no possibility of the benzoin adhesive being applied to the skin around the middle wound, as the benzoin adhesive may affect the EpiD reading. The adhesive was placed on the skin in any area where the V.A.C.® drape was applied. Alternatively (or additionally), Hollister (medical grade silicone adhesive) was applied as an additional adhesive to help maintain the seal.

[0109] For test article wounds versus (test articles undergoing V.A.C.® therapy) and / or test articles undergoing V.A.C. VERAFLO™ therapy (test articles using V.A.C. VERAFLO™ therapy with saline), a pair of electrodes (e.g., aluminum sheet or wire) was applied such that the electrodes were positioned in the wound perimeter region (under the test article but above the skin around the wound).

[0110] When applicable, the skin directly under the strip of the foam bridge was covered with a V.A.C.® drape for protection. Each cross-linked wound group was covered with a V.A.C.® drape included in the dressing kit, a hole was made in the drape, and a SENSAT.R.A.C.™ pad or V.A.C. VERAT.R.A.C.™ pad (when applicable) was attached directly over the hole as per the instructions for use (IFU). Each pad was maintained in place and each side of the pad was surrounded with a V.A.C.® drape to ensure an airtight seal.

[0111] The V.A.C. ULTA™ unit was present in the surgical set on the day of wound creation and was properly connected to each pad to confirm that each wound group remained properly sealed following application.

[0112] To check the seal around the wound, negative pressure wound therapy (NPWT) was initiated at a continuous vacuum pressure of -125 mmHg using the SEAL CHECK™ function in the V.A.C. ULTA™ unit. Once appropriate seal was confirmed, the V.A.C. ULTA™ unit was turned off and this procedure was repeated if applicable. Following all seal checks, an additional layer of V.A.C.® drape was placed around the edges to reinforce the seal and prevent leakage.

[0113] For wounds receiving V.A.C. VERAFLO™ therapy, the Fill Assist™ function was used to determine the amount of fluid (i.e., normal saline) necessary to saturate the dressing in the paired wound. These determinations were appropriately made for each wound pair at each dressing change. V.A.C. VERAFLO™ therapy NPWT was initiated at a continuous vacuum pressure of -125 mmHg using the SEAL CHECK™ function in the V.A.C. ULTA™ unit. Once appropriate seal was confirmed, the V.A.C. ULTA™ unit was turned off and this procedure was repeated if applicable. Following all seal checks, an additional layer of V.A.C.® drape was placed around the edges to reinforce the seal and prevent leakage. The soak / rest time per cycle was 10 minutes and the NPWT time per cycle was 3.5 hours at a target pressure of -125 mmHg.

[0114] To prevent dressing movement, the entire area covered with the V.A.C.® drape was covered with a tear-resistant mesh (e.g., organza material) secured with V.A.C.® drape, Elastikon® or equivalent.

[0115] Interim dressing change - Day 4, Group 3 only Resistance readings were taken from under the dressing. For one wound from each treatment pair, a peel force test on the wound was performed. Unless the dressing was intended to stay in place, the dressing was removed by hand for the other half of each wound pair (i.e., TANPT and TANPTI (n = 2 animals)). Wound evaluations were performed (if applicable) and photographs were taken.

[0116] Peel Test and Observation A peel force test was performed on one wound from each treatment pair (the same wound as the dressing change if applicable). For the wounds where the dressing was removed, TEWL was performed, wound evaluations were performed, and photographs were taken.

[0117] For groups 1 and 2 (day 4), peel force tests, TEWL, and evaluations were performed on five wounds. The remaining five wounds were collected with the dressing in situ for histopathological processing and evaluation.

[0118] For group 3 (day 7), peel force tests, TEWL, and evaluations were performed on five wounds. The remaining five wounds were collected with the dressing in situ for histopathological processing and evaluation.

[0119] The peel force test was performed on an inclined operating table. The peel force test was performed using a device that flips the edge of the test material while measuring the force required to peel the dressing from the wound at an angle of approximately 180° to the peel tester. A digital protractor was used to confirm the angle. The peel strength value indicates the ease with which the test material can be removed from the wound bed. Removal of the test material was performed using a 20N Shimpo Digital Force Gauge attached to a Shimpo Motorized Test Stand and controlled via a computer equipped with LabView.

[0120] Using a scalpel, a boundary line was gently drawn on the drape over the control for the peel test, taking care not to interfere with the internal tissue growth into the side of the dressing. During the treatment with the test article for the peel test, the excess dressing not in contact with the wound was removed using a scalpel. This was done by cutting the dressing along the sides, bottom, and top at locations where the outer edges of the wound were visible after negative pressure therapy. Using a clip, the inner end of the dressing or dressing tab was attached to a force gauge (without drawing a boundary line on the dressing). Then, the dressing was pulled from the wound (from the inside to the outside) at a constant speed in the inside-to-outside direction. After measuring the peel force, an evaluation was performed. Continuous peel force readings were recorded by LabView via the force gauge and saved for each wound. Following the peel test, the dressing was saved for analysis of the tissue remaining within the dressing.

[0121] Figure 13 demonstrates the results (N) of the maximum peel force measurements on day 7 following dressing application and removal for the test articles (designated as "TANPT" and "TANPTI") and the control dressing. As shown, the peel force required for the test articles was relatively significantly lower, with or without V.A.C. VERAFLO (trademark) therapy.

[0122] After the peel force test and TEWL measurement, two biopsy punches (5 mm or not exceeding 8 mm each) were collected from the center of each wound, if applicable.

[0123] Trans-epidermal water loss The moisture level at the dressing - skin (intact) interface was determined using the Moisture Meter EpiD Compact from Delfin Technologies (Kuopio, Finland). These measurements were taken immediately after wound generation on day 0, on dressing change days (if applicable), and at the end prior to euthanasia. The EpiD Compact instrument was used to measure the skin's relative permittivity. Four consecutive moisture measurements were collected from the intact skin of each animal, near the middle between the wound and the edge of the wound pad where the test article and advanced wound dressing were located, on the day of wound generation (day 0). On dressing change days and at the end (if applicable), four consecutive moisture measurements were collected. These measurements were repeated for each available wound site for each animal. All measurements / data were recorded.

[0124] Wound evaluation Overall observation During dressing change and / or at the end - procedure, wound observations were made and recorded as follows. · Wound bleeding - none, mild, moderate or severe · Overall observation - dry (dull / matte), wet (shiny appearance), moist (presence of fluid), eschar (thin black and firm - looking tissue), slough (removable yellowish layer) and its location at the wound site · Exudate - none, serous (thin, watery, clear), serosanguinous (thin, pale - red to pink), sanguineous (thin, bright - red), purulent (opaque yellow - brown to yellow, thin or thick)

[0125] Dressing and tissue residue Following the dressing removal or peel test, dressing residue (small particles and large pieces) was evaluated. After removal of the dressing from the wound, the dressing residue in the wound was visually evaluated and recorded. All removed dressings were visually evaluated for tissue residue and photographed digitally.

[0126] Figure 14 demonstrates that tissue internal growth was significantly reduced by TANPT and TANPTI.

[0127] Histopathology When the wound site was in 70% ethanol, it was immediately processed. When placed in NBF, the wound was transferred to 70% ethanol for a period of time before further processing according to the standard procedure for histopathology test sites. The wound site + dressing (if intact) was embedded in an extra-large paraffin block, and the entire site was cut transversely once at a thickness of approximately 5 μm, and the resulting slides were stained with hematoxylin and eosin (H&E). Before processing and embedding in paraffin, an overall image of the cut surface of the specimen was taken. Extra-large slides were used to accommodate the entire tissue section including the border of the unaffected skin on all sides.

[0128] A board-certified veterinary pathologist semi-quantitatively evaluated the histopathological response on a scale of 1 - 5 (1 = very mild, 2 = mild, 3 = moderate, 4 = severe, 5 = very severe), unless otherwise specified. Microscopic evaluation of all stained sections for tissue morphological changes to the wound, including but not limited to granulation tissue thickness and characteristics, amount of granulation tissue embedded in the dressing (if applicable), tissue inflammation, edema, vascularity (if applicable), presence of bacteria, necrosis, and other relevant factors, as judged by the pathologist. The area around the wound was evaluated for features consistent with maceration as judged by the pathologist.

[0129] 2D photographs of individual wound sites 2D photographs of individual wound sites were taken at the following time points. · Day 0 (newly created wounds) - all wounds · Day 4 after dressing removal and before application of a new dressing (day of dressing change or end day if applicable) - all wounds 2D photographs of the newly removed dressing adjacent to the wound were taken · Day 7 after dressing removal and before euthanasia 2D photographs of the newly removed dressing adjacent to the wound were taken

[0130] Histopathological evaluation of individual wound sites The photomicrograph in Fig. 15 demonstrates that there was significantly more granulation formation with TANPT than with NPT and NPTI.

[0131] Furthermore, Fig. 16 is a graphical representation comparing the granulation tissue thickness on day 7 between the test treatment and the control treatment. TANPT and TANPTI showed relatively significantly higher granulation tissue thickness.

[0132] Investigation conclusion The data demonstrate that the test article has unexpectedly positive results and improves when combined with the V.A.C.VERAFLO™ therapy. The test article with the V.A.C.VERAFLO™ therapy demonstrated relatively superior performance by showing an increase in granulation tissue thickness, a reduction in tissue ingrowth, an epithelialization rate, and an average angiogenesis score.

[0133] Furthermore, by day 7, all treatments with the test article showed significantly larger granulation tissue than NPT and NPTI. The rate of increase in granulation depth (measured after a 7-day treatment period) using the test article was at least 75% in the case of NPT and 200% in the case of NPTI. No evidence of adverse events or safety issues was found. The moisture in the tissue surrounding the wound decreased over time (in all treatment groups), reducing the risk of maceration.

[0134] All treatments with the test article also showed an unexpectedly significant reduction in tissue ingrowth, as demonstrated by a significant reduction in the peel force. After 7 days of either continuous V.A.C.® therapy or V.A.C.VERAFLO™ therapy without dressing change, the peel force required to remove the test article was less than 2 N. Specifically, a peel force of 1.8 N was used to remove the TANPTI test article and 1.5 N was used to remove the TANPT test article. Compared to CA1 with V.A.C.® therapy, the peel force was reduced by 87% and 89% respectively.

[0135] 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 modifications and changes within the scope of the appended claims. Further, the description of various alternative examples using terms such as "or" does not require mutual exclusivity unless clearly necessary from the context, and the articles "a" or "an" do not limit the subject to a single instance unless clearly necessary from the context.

[0136] The features, elements, and aspects described in connection with some embodiments may also be omitted, combined, or replaced with alternative features that serve the same, equivalent, or similar purposes without departing from the scope of the invention as defined by the appended patent claims. For example, one or more of the features of some layers can be combined with the features of other layers to provide an equivalent function. Alternatively or additionally, one or more of the fluid restrictors 220 can have a shape similar to the shape described by way of example for the valve 705. In other examples, the second layer 210, the third layer 405, or some combination of the second layer 210 and the third layer 405 can be coupled to both sides of the first layer 205.

[0137] It is also possible to combine or remove the components in various configurations for the purpose of sale, manufacture, assembly, or use. For example, in some configurations, the dressing 104, the container 106, or both can be separated from other components for manufacture or sale. In other configurations, the components of the dressing 104 can also be manufactured, constructed, assembled, or sold independently or as a kit.

[0138] The appended claims set forth novel and inventive aspects of the above-described subject matter, but may also encompass additional subject matter that is not specifically recited in detail. For example, some features, elements or aspects may be omitted from the claims where they are known to those of ordinary skill in the art and thus not necessary to identify novel and inventive features. Features, elements and aspects described in connection with some embodiments may also be omitted, combined, or replaced with alternative features that serve the same, equivalent or similar purpose, without departing from the scope of the invention as defined by the appended claims.

Claims

1. 1. A dressing for treating a tissue site using negative pressure, comprising: a manifold having a first surface and a second surface opposite the first surface; a first layer adjacent the first surface and a second layer adjacent the second surface, each layer comprising a polymer film; a plurality of fluid restriction features in the polymer film adjacent at least the first surface; A dressing comprising:

2. 2. The dressing of claim 1, wherein the polymeric film is hydrophobic.

3. 10. The dressing of claim 1, wherein said polymeric film has a water contact angle of greater than 90 degrees.

4. 4. A dressing according to any one of claims 1 to 3, characterized in that the polymer film is a polyethylene film.

5. 4. A dressing according to claim 1, wherein the polymer film is selected from the group consisting of polyethylene, polyurethane, acrylic, polyolefin, polyacetate, polyamide, polyester, polyether block amide, thermoplastic vulcanizate, polyether and polyvinyl alcohol.

6. 4. A dressing according to claim 1, wherein the polymer film is a polyethylene film having an areal density of less than 30 grams per square meter.

7. 7. The dressing of claim 1, wherein the fluid restricting portion comprises a plurality of slots configured to permit fluid flow while preventing exposure of the manifold to the tissue site.

8. 7. A dressing according to any preceding claim, wherein the fluid restriction portion comprises a plurality of slots, each of said slots having a length of less than 4 millimeters.

9. 7. A dressing according to any preceding claim, wherein the fluid restriction portion comprises a plurality of slots, each of said slots having a width of less than 2 millimeters.

10. 7. A dressing according to any preceding claim, wherein the fluid restriction portion comprises a plurality of slots, each of said slots having a length of less than 4 millimeters and a width of less than 2 millimeters.

11. 11. The dressing of claim 10, wherein said width is less than 1 millimeter.

12. 11. The dressing of claim 10, wherein said length is less than 3 millimeters and said width is less than 1 millimeter.

13. 11. The dressing of claim 10, wherein said width is at least 0.5 millimeters.

14. 11. The dressing of claim 10, wherein said length is at least 2 millimeters.

15. 7. A dressing according to any one of claims 1 to 6, wherein the fluid restriction portion comprises or consists essentially of an elastomeric valve in the polymer film, which is normally closed.

16. 16. The dressing of claim 15, wherein the elastomeric valve is a fenestrated valve.

17. 16. The dressing of claim 15, wherein the elastomeric valve is a slit.

18. 16. A dressing according to any one of claims 15, wherein the fluid restriction portion comprises a plurality of slits in the polymer film, each of the slits having a length of less than 4 millimeters.

19. 20. The dressing of claim 18, wherein said length is less than 3 millimeters.

20. 20. A dressing according to claim 18 or 19, wherein said length is at least 2 millimetres.

21. 21. A dressing according to any preceding claim, wherein the plurality of fluid restriction portions of the polymeric film are on the first surface and adjacent the second surface.

22. 22. A dressing according to any preceding claim, wherein the fluid restriction portion is coextensive with the polymeric film.

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

24. 24. A dressing according to any preceding claim, wherein the first layer and the second layer are laminated to the manifold.

25. 24. A dressing according to any preceding claim, wherein the first and second layers form a sleeve around the manifold.

26. 26. The dressing of claim 25, wherein at least one edge of the manifold is exposed through the sleeve.

27. 27. The dressing of any one of claims 25-26, wherein the sleeve is configured for insertion between the manifold and the tissue site.

28. 28. A dressing according to any one of claims 25 to 27, wherein the sleeve has an exposed surface which is smooth.

29. 28. A dressing according to any one of claims 25 to 27, wherein the sleeve has an exposed surface which is matt.

30. 28. A dressing according to any one of claims 25 to 27, wherein the sleeve has an exposed surface that is non-rough.

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

32. 32. The dressing of claim 31 wherein the foam is a polymer foam.

33. 32. A dressing according to claim 31 wherein the foam is a polyurethane ether foam.

34. 32. The dressing of claim 31 wherein the foam is an open cell foam.

35. 32. The dressing of claim 31 wherein the foam is reticulated.

36. 32. The dressing of claim 31 wherein the foam is a reticulated polymer foam.

37. 32. The dressing of claim 31 wherein the foam is a reticulated polyurethane ether foam.

38. 35. A dressing according to any one of claims 31 to 34, wherein the foam is reticulated and has a free volume of at least 90%.

39. A dressing according to any one of claims 31 to 38, wherein the foam is porous and has an average pore size in the range 400 to 600 microns.

40. 40. A dressing according to any one of the preceding claims, wherein the manifold has a thickness of less than 7 millimeters.

41. 40. A dressing according to any preceding claim, wherein the manifold has a thickness in the range 2 millimetres to 7 millimetres.

42. 42. A dressing according to any preceding claim, wherein the manifold is hydrophobic.

43. 43. A dressing according to any preceding claim, wherein the fluid restriction features are distributed in a uniform pattern across the polymeric film.

44. 44. A dressing according to claim 43, wherein the uniform pattern comprises a grid of parallel rows and columns.

45. 45. A dressing according to any one of claims 1 to 44, the fluid restriction features are distributed across the polymer film in parallel rows and columns; the rows are spaced approximately 3 millimeters apart on center; A dressing wherein the fluid restriction portions in each of said rows are spaced approximately 3 millimeters apart on center.

46. 46. ​​A dressing according to claim 45, wherein the fluid restriction features in adjacent rows are offset.

47. 47. A dressing according to any one of the preceding claims, a drape positioned over the sleeve adjacent the second surface; a fluid port coupled to the drape and fluidly coupled to the manifold through the drape and the sleeve; A dressing further comprising:

48. 48. The dressing of any one of claims 1 to 47, further comprising a sealing layer adjacent to the sleeve, the sealing layer having a plurality of apertures fluidly coupled to the fluid restriction portion.

49. 48. The dressing of any one of claims 1 to 47, further comprising a sealing layer coupled to the sleeve, the sealing layer comprising a hydrophobic gel having a plurality of apertures aligned with the fluid restricting portion.

50. 48. The dressing of any one of claims 1 to 47, further comprising a sealing layer coupled to the sleeve, the fourth layer comprising a hydrophobic gel having a plurality of apertures aligned with at least some of the plurality of fluid restricting portions.

51. 48. The dressing of any one of claims 1 to 47, further comprising a sealing layer coupled to the sleeve, the sealing layer comprising a hydrophobic gel having a plurality of apertures coextensive with the sealing layer, and substantially all of the plurality of apertures being aligned with the fluid restricting portion.

52. 52. A dressing according to any one of claims 48 to 51, wherein the sealing layer comprises a silicone gel.

53. 52. A dressing according to any one of claims 48 to 51, wherein the sealing layer comprises adhered silicone.

54. 48. The dressing of any one of claims 1 to 47, further comprising a sealing layer coupled to the sleeve, the sealing layer having a plurality of apertures adjacent the fluid restriction portion and an areal density of less than 300 grams per square meter.

55. 55. A dressing according to any one of claims 48 to 54, wherein the sealing layer has a hardness of from about 5 Shore OO to about 80 Shore OO.

56. 56. The dressing of any one of claims 48 to 55, wherein the sealing layer is configured to be interposed between the manifold and the tissue site.

57. 57. A dressing according to any one of claims 48 to 56, wherein the fluid restriction portion has an average dimension not substantially exceeding the average dimension of the apertures.

58. 58. A dressing according to any one of claims 48 to 57, wherein the aperture limits the effective size of the fluid restriction portion.

59. 59. A dressing according to any one of claims 48 to 58, wherein the drape and sealing layer encapsulate the sleeve and manifold.

60. 59. A dressing according to any one of claims 48 to 58, wherein the sealing layer has a smooth lower surface.

61. 59. The dressing of any one of claims 48 to 58, wherein the sealing layer is configured to provide a fluid-tight seal with the tissue site.

62. 62. The dressing of any one of claims 48 to 61, wherein the drape and sealing layer enclose the manifold and sleeve, the sealing layer adapted for contact with the tissue site.

63. 63. A dressing according to any one of claims 47 to 62, wherein the drape comprises a polymeric film.

64. 64. A dressing according to any one of claims 25 to 63, wherein the sleeve is joined to the manifold.

65. 65. A dressing according to any one of claims 47 to 64, wherein the drape has an outer edge extending beyond the manifold and the sleeve, and a layer of adhesive is disposed on the outer edge.

66. 66. The dressing of any one of claims 1-65, wherein the dressing comprises a smooth surface configured for contact with the tissue site.

67. 66. The dressing of any one of claims 1-65, wherein the dressing comprises a matte surface configured for contact with the tissue site.

68. 66. The dressing of any one of claims 1-65, wherein the dressing comprises a surface that is non-rough and configured for contact with the tissue site.

69. 69. The dressing of any one of claims 1 to 68, wherein the manifold has a roughened underside so as not to be exposed to tissue when the dressing is placed over the tissue site.

70. 1. A dressing for treating a tissue site using negative pressure, comprising: a manifold formed from a hydrophobic material; a film substantially enclosing the manifold, the film being formed from a hydrophobic material; a plurality of fluid passages through the film, the plurality of fluid passages being configured to expand in response to a pressure gradient across the film; A dressing comprising:

71. 71. The dressing of claim 70, a polymeric drape bonded to the film; a hydrophobic gel bonded to the film on an opposite side to the polymeric drape, the hydrophobic gel having an areal density of less than 300 grams per square meter; a plurality of apertures through the hydrophobic gel fluidly coupled to at least some of the plurality of fluid passages through the film; A dressing further comprising:

72. 72. A dressing according to claim 70 or 71, wherein the film forms a sleeve around the manifold.

73. 72. A dressing according to claim 70 or 71, wherein the film forms an envelope around the manifold.

74. 1. A dressing for treating a tissue site using negative pressure, comprising: a first layer comprising a first film having a flat surface texture; a second layer adjacent to the first layer, the second layer comprising a manifold; a third layer adjacent to the second layer opposite the first layer, the third layer comprising a second film having a flat surface texture; a plurality of fluid restriction sections through the first film, the plurality of fluid restriction sections being configured to respond to a pressure gradient across the fluid restriction sections; A dressing comprising:

75. 75. The dressing of claim 74, wherein the plurality of fluid restricting portions pass through the first film and the second film.

76. 76. A dressing according to claim 74 or 75, a fourth layer bonded to the third layer opposite the first layer, the third layer being a polymeric drape; and a fifth layer bonded to the first layer opposite the second layer, the fifth layer comprising a gel having an areal density of less than 300 grams per square meter and a hardness of from about 5 Shore OO to about 80 Shore OO; a plurality of apertures through the fifth layer aligned with at least some of the plurality of fluid restrictions; A dressing further comprising:

77. 1. An apparatus for treating a tissue site using negative pressure, comprising: a tissue interface comprising a manifold and a film covering at least two sides of the manifold, the manifold and the film being formed from a hydrophobic material; a plurality of elastomeric valves through the film, the plurality of elastomeric valves being configured to expand in response to a pressure gradient across the film; a cover configured to be attached to the tissue site; Equipped with The device, wherein the cover and the tissue interface are assembled in a laminated relationship such that the cover is adapted to be attached to a mounting surface adjacent the tissue site.

78. 78. The device of claim 77, wherein the film is configured to be interposed between the manifold and the tissue site.

79. 80. The apparatus of claim 77 or 78, wherein the film comprises a polymeric film having an areal density of less than 30 grams per square meter.

80. 80. The device of any one of claims 77 to 79, wherein the film comprises a polymer film having a water contact angle of greater than 90 degrees.

81. 81. Apparatus according to any one of claims 77 to 80, wherein the film has a surface that varies in height by no more than 0.2 millimeters per centimeter.

82. 82. The device of any one of claims 77 to 81, wherein the tissue interface further comprises a sealing layer adjacent to the film and configured to contact the tissue site, and at least one aperture in the sealing layer fluidly coupled to at least one of the elastomeric valves in the film.

83. 83. The device of claim 82, wherein at least one of the apertures is configured to expose at least a portion of the film to the tissue site.

84. 84. The device of any one of claims 82-83, wherein at least one of the apertures is configured to expose at least some of the elastomeric valve to the tissue site.

85. 83. The apparatus of claim 82, wherein at least some portion of the film is exposed through at least one of the apertures.

86. 83. The device of claim 82, wherein at least some portion of the elastomeric valve is exposed through the aperture in the third layer.

87. 1. A dressing for treating a tissue site using negative pressure, comprising: a first layer comprising a film having a flat surface texture; a second layer adjacent to the first layer, the second layer comprising a manifold; a plurality of fluid restriction sections through the film, the plurality of fluid restriction sections being configured to respond to a pressure gradient across the fluid restriction sections; A dressing comprising:

88. 1. A system for treating a tissue site, comprising: A dressing or device according to any one of claims 1 to 87; a source of negative pressure fluidly coupled to said dressing or said device; A system comprising:

89. 90. The system of claim 88, further comprising a fluid reservoir fluidly coupled between the dressing and the source of negative pressure.

90. 90. Use of a dressing, device or system according to any one of claims 1 to 89 for at least 5 days to promote granulation using a negative pressure source.

91. 90. Use of a dressing, device or system according to any one of claims 1 to 89 using a negative pressure source to minimise tissue ingrowth for at least 5 days.

92. 1. A method of treating a superficial wound using negative pressure, comprising: applying a dressing or device according to any one of claims 1 to 87 to a tissue site; sealing the dressing or device to an epidermis adjacent the tissue site; fluidly coupling the dressing or device to a source of negative pressure; applying negative pressure from the negative pressure source to the dressing or device; The method according to claim 1, further comprising:

93. 93. The method of claim 92, wherein the manifold is not substantially exposed to the tissue site during the step of applying negative pressure.

94. 94. The method of claim 92 or 93, wherein at least one of the first layer and the second layer is configured to not be exposed to the tissue site during the step of applying negative pressure.

95. 95. The method of any one of claims 92 to 94, wherein the step of applying the dressing comprises placing at least a portion of the dressing over an edge of the superficial wound.

96. 96. The method of any one of claims 92 to 95, wherein the fluid restriction is opened by applying negative pressure.

97. 97. The method of claim 96, further comprising the step of reducing the negative pressure from the negative pressure source, wherein reducing the negative pressure source causes the fluid restriction to close.

98. 98. The method of any one of claims 92 to 97, further comprising the steps of fluidly connecting a fluid container between the dressing and the negative pressure source, and transferring exudate from the dressing to the fluid container.

99. 99. The method of any one of claims 92-98, further comprising the step of applying a manifold between the dressing and the surface wound.

100. 1. A method for promoting granulation in a superficial wound, comprising: applying a dressing to the superficial wound, the dressing comprising a manifold having a first side and a second side opposite the first side, and a perforated polymeric film covering at least the first side; applying negative pressure from a negative pressure source to the dressing to promote granulation; Including, The method, wherein the perforated polymeric film is hydrophobic and is applied to the superficial wound.

101. 101. The method of claim 100, wherein the perforated polymeric film is polyethylene.

102. 102. The method of any one of claims 100-101, wherein the perforated polymeric film has a smooth surface that is applied to the surface wound.

103. 103. The method of any one of claims 100 to 102, further comprising: sealing the perforated polymeric film to the surface wound and covering at least a portion of a wound perimeter adjacent the surface wound; attaching the cover to a skin around the perforated polymeric film; fluidly coupling the dressing to the source of negative pressure; The method further comprising:

104. 104. The method of any one of claims 100 to 103, wherein the dressing remains on the superficial wound for at least 5 days.

105. 104. The method of any one of claims 100 to 103, wherein the dressing remains on the superficial wound for at least 7 days.

106. 106. The method of any one of claims 100-105, wherein the perforated polymeric film substantially prevents exposure of tissue at the surface wound to the manifold and inhibits tissue growth into the manifold.

107. 107. The method of any one of claims 100 to 106, further comprising the step of applying a wound packing material between the perforated polymeric film and the superficial wound.

108. 108. The method of claim 107, wherein the wound packing is applied inside the wound perimeter.

109. 109. The method of claim 107 or 108, wherein the wound packing material is a foam.

110. 110. The method of any one of claims 100 to 109, wherein the dressing substantially prevents maceration around the wound.

111. 20. A system, apparatus and method substantially as described herein.

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