US20180353334A1 - Tissue Contact Interface - Google Patents

Abstract

An apparatus, system, and method for closing an opening through a surface of a tissue site is described. The apparatus includes an apposition layer adapted to be positioned over the opening. The apposition layer is formed from a material having a firmness factor, and has a plurality of holes extending through the apposition layer. The holes form a void space and have a perforation shape factor and a strut angle configured to collapse the apposition layer in a first direction relative to a second direction. A sheet having a plurality of perforations is configured to surround the apposition layer, the sheet having a plurality of perforations. The apposition layer generates a closing force in the first direction that is substantially parallel to the surface of the tissue site to close the opening in response to application of a negative pressure.

Description

RELATED APPLICATION
• This application claims the benefit, under 35 U.S.C. § 119(e), of the filing of U.S. Provisional Patent Application Ser. No. 62/516,540, entitled “TISSUE CONTACT INTERFACE,” filed Jun. 7, 2017; U.S. Provisional Patent Application Ser. No. 62/516,550, entitled “COMPOSITE DRESSINGS FOR IMPROVED GRANULATION AND REDUCED MACERATION WITH NEGATIVE-PRESSURE TREATMENT” filed Jun. 7, 2017; and U.S. Provisional Patent Application Ser. No. 62/516,566, entitled “COMPOSITE DRESSINGS FOR IMPROVED GRANULATION AND REDUCED MACERATION WITH NEGATIVE-PRESSURE TREATMENT” filed Jun. 7, 2017, each of which is incorporated herein by reference for all purposes.
TECHNICAL FIELD
• The invention set forth in the appended claims relates generally to tissue treatment systems and more particularly, but without limitation, to a dressing having a contracting layer for assisting in closure of linear tissue sites.
BACKGROUND
• Clinical studies and practice have shown that reducing pressure in proximity to a tissue site can augment and accelerate growth of new tissue at the tissue site. The applications of this phenomenon are numerous, but it has proven particularly advantageous for treating wounds. Regardless of the etiology of a wound, whether trauma, surgery, or another cause, proper care of the wound is important to the outcome. Treatment of wounds or other tissue with negative pressure may be commonly referred to as “negative-pressure therapy,” but is also known by other names, including “negative-pressure wound therapy,” “reduced-pressure therapy,” “vacuum therapy,” “vacuum-assisted closure,” and “topical negative-pressure,” for example. Negative-pres sure therapy may provide a number of benefits, including migration of epithelial and subcutaneous tissues, improved blood flow, and micro-deformation of tissue at a wound site. Together, these benefits can increase development of granulation tissue and reduce healing times.
• While the clinical benefits of negative-pressure therapy are widely known, improvements to therapy systems, components, and processes may further benefit healthcare providers and patients.
BRIEF SUMMARY
• New and useful systems, apparatuses, and methods for closing an opening through a surface of a tissue site are set forth in the appended claims. Illustrative embodiments are also provided to enable a person skilled in the art to make and use the claimed subject matter. For example, a system for closing an opening through a surface of a tissue site is described. The system can include an apposition layer adapted to be positioned over the opening. The apposition layer may be formed from a material having a firmness factor, and have a plurality of holes extending through the apposition layer. The holes can form a void space and have a perforation shape factor and a strut angle configured to collapse the apposition layer in a first direction relative to a second direction. A first layer can be adapted to be positioned below the apposition layer, the first layer having at least one perforation. A second layer can be adapted to be positioned above the apposition layer, the second layer having at least one perforation. The system can also include a dressing adapted to cover the apposition layer to form a sealed space, and a negative-pressure source adapted to be fluidly coupled to the sealed space to provide negative pressure to the sealed space. The apposition layer can generate a closing force in the first direction that is substantially parallel to the surface of the tissue site to close the opening in response to application of a negative pressure.
• Alternatively, other example embodiments include an apparatus for closing an opening through a surface of a tissue site. The apparatus can include a contracting layer adapted to be positioned over the opening. The contracting layer is formed from a material having a firmness factor, and has a plurality of holes extending through the contracting layer. The holes form a void space and have a perforation shape factor and a strut angle configured to collapse the apposition layer in a first direction relative to a second direction. The apparatus may further include a lower layer adapted to be positioned below the contracting layer, the lower layer having at least one perforation, and an upper layer adapted to be positioned above the contracting layer, the upper layer having at least one perforation. The contracting layer generates a closing force in the first direction that is substantially parallel to the surface of the tissue site to close the opening in response to application of a negative pressure.
• A method for closing an opening through a surface of a tissue site is also described. An apposition layer can be encapsulated in a sheet having an upper layer above the apposition layer and a lower layer below the apposition layer, the sheet having at least one perforation in the upper layer and at least one perforation in the lower layer. The apposition layer can be positioned over the opening. The apposition layer may be adapted to be positioned adjacent the opening and formed from a material having a firmness factor and a plurality of holes extending through the apposition layer to form a void space. The holes have a perforation shape factor and a strut angle causing the apposition layer to collapse in a direction substantially perpendicular to the opening. The apposition layer can be collapsed parallel to the surface of the tissue site to generate a closing force.
• Objectives, advantages, and a preferred mode of making and using the claimed subject matter may be understood best by reference to the accompanying drawings in conjunction with the following detailed description of illustrative embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a sectional view with a portion shown in elevation of an illustrative example of a system for treating a tissue site having a dressing deployed at the tissue site;
• FIG. 2 is a plan view of a base layer of the dressing ofFIG. 1, illustrating additional details that may be associated with some embodiments;
• FIG. 3 is an exploded view of the dressing ofFIG. 1, illustrating additional details that may be associated with some embodiments;
• FIG. 4 is detail view of a portion of the dressing ofFIG. 1, illustrating additional details that may be associated with some embodiments;
• FIG. 5 is a plan view of an apposition layer of the system ofFIG. 1, illustrating additional details that may be associated with some embodiments;
• FIG. 6A is a plan view of the apposition layer ofFIG. 5 in a first position, illustrating additional details that may be associated with some embodiments;
• FIG. 6B is a detail view of a portion of the holes of the apposition layer ofFIG. 6A, illustrating additional details that may be associated with some embodiments;
• FIG. 6C is a plan view of the apposition layer ofFIG. 6A in a second position, illustrating additional details that may be associated with some embodiments;
• FIG. 7 is a schematic view of a hole of the apposition layer ofFIG. 6A having a perforation shape factor, illustrating additional details that may be associated with some embodiments;
• FIG. 8 is a schematic view of a hole of the apposition layer ofFIG. 6A having another perforation shape factor, illustrating additional details that may be associated with some embodiments;
• FIG. 9 is a schematic view of a hole of the apposition layer ofFIG. 6A having another perforation shape factor, illustrating additional details that may be associated with some embodiments;
• FIG. 10 is an exploded view of the apposition layer and the dressing ofFIG. 1 disposed over the tissue site, illustrating additional details that may be associated with some embodiments;
• FIG. 11 is a perspective view of the apposition layer and the dressing disposed over the tissue site in a first position, illustrating additional details that may be associated with some embodiments;
• FIG. 12 is a perspective view of the apposition layer and the dressing disposed over the tissue site in a second position, illustrating additional details that may be associated with some embodiments;
• FIG. 13A is a perspective section view of another apposition layer that may be used with the negative-pressure therapy system ofFIG. 1, illustrating additional details that may be associated with some embodiments;
• FIG. 13B is a sectional view the apposition layer ofFIG. 13A in a first position taken alongline13B-13B, illustrating additional details that may be associated with some embodiments;
• FIG. 13C is a sectional view of the apposition layer ofFIG. 13A in a second position, illustrating additional details that may be associated with some embodiments;
• FIG. 14 is a perspective view of a another apposition layer that may be used with the negative-pressure therapy system ofFIG. 1, illustrating additional details that may be associated with some embodiments; and
• FIG. 15 is a perspective view of another apposition layer that may be used with the negative-pressure therapy system ofFIG. 1, illustrating additional details that may be associated with some embodiments.
DESCRIPTION OF EXAMPLE EMBODIMENTS
• The following description of example embodiments provides information that enables a person skilled in the art to make and use the subject matter set forth in the appended claims, but may omit certain details already well-known in the art. The following detailed description is, therefore, to be taken as illustrative and not limiting.
• The example embodiments may also be described herein with reference to spatial relationships between various elements or to the spatial orientation of various elements depicted in the attached drawings. In general, such relationships or orientation assume a frame of reference consistent with or relative to a patient in a position to receive treatment. However, as should be recognized by those skilled in the art, this frame of reference is merely a descriptive expedient rather than a strict prescription.
• Referring to the drawings,FIG. 1 depicts an illustrative embodiment of asystem102 for treating atissue site104 of a patient. Thetissue site104 may extend through or otherwise involve anepidermis106, adermis108, and asubcutaneous tissue110. Thetissue site104 may be a sub-surface tissue site as depicted inFIG. 1 that may extend below atissue surface105 of theepidermis106. Further, thetissue site104 may predominantly reside on thetissue surface105 of theepidermis106, such as, for example, an incision. Regardless of the positioning of thesystem102 or the type oftissue site104, thesystem102 may provide therapy to, for example, theepidermis106, thedermis108, and thesubcutaneous tissue110. Thesystem102 may also be used without limitation at other tissue sites.
• Thetissue site104 may be the bodily tissue of any human, animal, or other organism. Treatment of thetissue site104 may include the removal of fluids, such as exudate or ascites. The term “tissue site” in this context may also broadly refer to a wound or a defect located on or within tissue, including but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, ligaments, or any other tissue. A wound may include chronic, acute, traumatic, subacute, and dehisced wounds, partial-thickness burns, ulcers (such as diabetic, pressure, or venous insufficiency ulcers), flaps, and grafts, for example. The term “tissue site” may also refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it may be desirable to add or promote the growth of additional tissue. For example, negative pressure may be used at a tissue site to grow additional tissue that may be harvested and transplanted to a tissue site at another location.
• A tissue site may also refer to a linear tissue site. A linear tissue site may generally refer to a tissue site having an elongated shape, such as an incision having a length substantially greater than its width. An incision may have edges that may be substantially parallel, particularly if the incision is caused by a scalpel, knife, razor, or other sharp blade. Other examples of a linear tissue site may include a laceration, a puncture, or other separation of tissue, which may have been caused by trauma, surgery, or degeneration. In some embodiments, a linear tissue site may also be an incision in an organ adjacent a fistula. In some embodiments, a linear tissue site may be an incision or puncture in otherwise healthy tissue that extends up to 40 cm or more in length. In some embodiments, a linear tissue site may also vary in depth. For example, an incision may have a depth that extends up to 15 cm or more or may be subcutaneous depending on the type of tissue and the cause of the incision.
• Thesystem102 may include a tissue interface, such as aninterface manifold120, a contracting layer, such as anapposition layer146, a dressing124, and a negative-pressure source128. Theinterface manifold120 may be adapted to be positioned proximate to or adjacent to thetissue site104, such as, for example, by cutting or otherwise shaping theinterface manifold120 to fit thetissue site104. In other embodiments, theinterface manifold120 may be omitted. Theapposition layer146 may have athickness126 and be enclosed by asheet147 and positioned over theinterface manifold120 and thetissue site104. And the dressing124 may be positioned over theapposition layer146 and theinterface manifold120. The negative-pressure source128 can be coupled to the dressing through aconduit interface148.
• The dressing124 may include abase layer132, anadhesive layer136, afluid management assembly144, and a cover, such as a sealingmember140. Thebase layer132 may be positioned over theapposition layer146, theinterface manifold120, and thetissue surface105 of theepidermis106. Thebase layer132 may include a plurality ofapertures160 extending through thebase layer132. Thefluid management assembly144 may be positioned over thebase layer132. The sealingmember140 can be positioned over thefluid management assembly144. In some embodiments, a periphery of the sealingmember140 may be sealed to a periphery of thebase layer132 by theadhesive layer136 to form anenclosure172 containing thefluid management assembly144. Components of the dressing124 may be added or removed to suit particular applications.
• Theconduit interface148 may be coupled to thedressing124. The conduit interface may be coupled to the sealingmember140 so that theconduit interface148 fluidly communicates with theenclosure172. Theconduit interface148 may include anodor filter194 and a firsthydrophobic filter195. Theconduit interface148 can be fluidly coupled to the negative-pressure source128 through aconduit196 having aninternal lumen197. In some embodiments, theconduit196 may be coupled to the negative-pressure source through acoupling198 of the negative-pressure source128. A secondaryhydrophobic filter199 may be disposed in the fluid path through thecoupling198. Aliquid trap192 may be disposed in the fluid path between theconduit interface148 and the negative-pressure source128. For example, theconduit196 may comprise two or more conduits. A first conduit fluidly coupled between theconduit interface148 and theliquid trap192, and a second conduit fluidly coupled between theliquid trap192 and the negative-pressure source128.
• In general, components of thesystem102 may be coupled directly or indirectly. For example, the negative-pressure source128 may be directly coupled to theliquid trap192 and indirectly coupled to the dressing124 through theliquid trap192. Components may be fluidly coupled to each other to provide a path for transferring fluids (i.e., liquid and/or gas) between the components.
• In some embodiments, components may be fluidly coupled through a tube, such as theconduit196. A “conduit” or “tube,” as used herein, broadly refers to a tube, pipe, hose, conduit, or other structure with one or more lumina adapted to convey a fluid between two ends. Typically, a tube is an elongated, cylindrical structure with some flexibility, but the geometry and rigidity may vary. In some embodiments, components may additionally or alternatively be coupled by virtue of physical proximity, being integral to a single structure, or being formed from the same piece of material. Coupling may also include mechanical, thermal, electrical, or chemical coupling (such as a chemical bond) in some contexts.
• In operation, a tissue interface, such as aninterface manifold120, may be placed within, over, on, or otherwise proximate to a tissue site. A cover, such as the sealingmember140, may be placed over a tissue interface and sealed to tissue near a tissue site. For example, theinterface manifold120 may be placed over thetissue site104, and the sealingmember140 may be sealed to undamaged epidermis peripheral to thetissue site104, for example, to thetissue surface105. Thus, a cover can provide a sealed therapeutic environment or a sealedspace174 proximate to thetissue site104 that is substantially isolated from the external environment, and the negative-pressure source128 may reduce the pressure in the sealedspace174.
• The fluid mechanics of using a negative-pressure source to reduce pressure in another component or location, such as within a sealed therapeutic environment, can be mathematically complex. However, the basic principles of fluid mechanics applicable to negative-pressure therapy are generally well-known to those skilled in the art, and the process of reducing pressure may be described illustratively herein as “delivering,” “distributing,” or “generating” negative pressure, for example.
• In general, exudates and other fluids flow toward lower pressure along a fluid path. Thus, the term “downstream” typically refers to a position in a fluid path relatively closer to a negative-pressure source. Conversely, the term “upstream” refers to a position relatively further away from a negative-pressure source. Similarly, it may be convenient to describe certain features in terms of fluid “inlet” or “outlet” in such a frame of reference. This orientation is generally presumed for purposes of describing various features and components of negative-pressure therapy systems herein. However, the fluid path may also be reversed in some applications (such as by substituting a positive-pressure source for a negative-pressure source) and this descriptive convention should not be construed as a limiting convention.
• “Negative pressure” generally refers to a pressure less than a local ambient pressure, such as the ambient pressure in a local environment external to a sealed therapeutic environment provided by the dressing124. In many cases, the local ambient pressure may also be the atmospheric pressure at which a tissue site is located. Alternatively, the pressure may be less than a hydrostatic pressure associated with tissue at the tissue site. Unless otherwise indicated, values of pressure stated herein are gauge pressures. Similarly, references to increases in negative pressure typically refer to a decrease in absolute pressure, while decreases in negative pressure typically refer to an increase in absolute pressure. While the amount and nature of negative pressure applied to a tissue site may vary according to therapeutic requirements, the pressure is generally a low vacuum, also commonly referred to as a rough vacuum, between −5 mm Hg (−667 Pa) and −500 mm Hg (−66.7 kPa). Common therapeutic ranges are between −75 mm Hg (−9.9 kPa) and −300 mm Hg (−39.9 kPa).
• A negative-pressure supply, such as the negative-pressure source128, may be a reservoir of air at a negative pressure, or may be a manual or electrically-powered device that can reduce the pressure in a sealed volume, such as a vacuum pump, a suction pump, a wall suction port available at many healthcare facilities, or a micro-pump, for example. A negative-pressure supply may be housed within or used in conjunction with other components, such as sensors, processing units, alarm indicators, memory, databases, software, display devices, or user interfaces that further facilitate therapy. For example, in some embodiments, the negative-pressure source128 may be combined with controllers and other components into a therapy unit. A negative-pressure supply may also have one or more supply ports configured to facilitate coupling and de-coupling the negative-pressure supply to one or more distribution components.
• Theinterface manifold120 can be generally adapted to contact a tissue site. Theinterface manifold120 may be partially or fully in contact with the tissue site. If the tissue site is a wound, for example, theinterface manifold120 may partially or completely fill the wound, or may be placed over the wound. Theinterface manifold120 may take many forms, and may have many sizes, shapes, or thicknesses depending on a variety of factors, such as the type of treatment being implemented or the nature and size of a tissue site. For example, the size and shape of theinterface manifold120 may be adapted to the contours of deep and irregular shaped tissue sites. Moreover, any or all of the surfaces of theinterface manifold120 may have projections or an uneven, course, or jagged profile that can induce strains and stresses on a tissue site, which can promote granulation at the tissue site.
• In some illustrative embodiments, the pathways of a manifold may be interconnected to improve distribution or collection of fluids across a tissue site. In some illustrative embodiments, a manifold may be a porous foam material having interconnected cells or pores. For example, cellular foam, open-cell foam, reticulated foam, porous tissue collections, and other porous material such as gauze or felted mat generally include pores, edges, and/or walls adapted to form interconnected fluid channels. Liquids, gels, and other foams may also include or be cured to include apertures and fluid pathways. In some embodiments, a manifold may additionally or alternatively comprise projections that form interconnected fluid pathways. For example, a manifold may be molded to provide surface projections that define interconnected fluid pathways.
• The average pore size of a foam may vary according to needs of a prescribed therapy. For example, in some embodiments, theinterface manifold120 may be a foam having pore sizes in a range of 400-600 microns. The tensile strength of theinterface manifold120 may also vary according to needs of a prescribed therapy. For example, the tensile strength of a foam may be increased for instillation of topical treatment solutions. In one non-limiting example, theinterface manifold120 may be an open-cell, reticulated polyurethane foam such as GranuFoam® dressing or VeraFlo® foam, both available from Kinetic Concepts, Inc. of San Antonio, Tex.
• Theinterface manifold120 may be either hydrophobic or hydrophilic. In an example in which theinterface manifold120 may be hydrophilic, theinterface manifold120 may also wick fluid away from a tissue site, while continuing to distribute negative pressure to the tissue site. The wicking properties of theinterface manifold120 may draw fluid away from a tissue site by capillary flow or other wicking mechanisms. An example of a hydrophilic foam is a polyvinyl alcohol, open-cell foam such as V.A.C. WhiteFoam® dressing available from Kinetic Concepts, Inc. of San Antonio, Tex. Other hydrophilic foams may include those made from polyether. Other foams that may exhibit hydrophilic characteristics include hydrophobic foams that have been treated or coated to provide hydrophilicity.
• Theinterface manifold120 may further promote granulation at a tissue site when pressure within the sealed therapeutic environment is reduced. For example, any or all of the surfaces of theinterface manifold120 may have an uneven, coarse, or jagged profile that can induce microstrains and stresses at a tissue site if negative pressure is applied through theinterface manifold120.
• In some embodiments, theinterface manifold120 may be constructed from bioresorbable materials. Suitable bioresorbable materials may include, without limitation, a polymeric blend of polylactic acid (PLA) and polyglycolic acid (PGA). The polymeric blend may also include without limitation polycarbonates, polyfumarates, and capralactones. Theinterface manifold120 may further serve as a scaffold for new cell-growth, or a scaffold material may be used in conjunction with theinterface manifold120 to promote cell-growth. A scaffold is generally a substance or structure used to enhance or promote the growth of cells or formation of tissue, such as a three-dimensional porous structure that provides a template for cell growth. Illustrative examples of scaffold materials include calcium phosphate, collagen, PLA/PGA, coral hydroxy apatites, carbonates, or processed allograft materials.
• The sealingmember140 may be formed from a material that allows for a fluid seal. A fluid seal may be a seal adequate to maintain negative pressure at a desired site given the particular negative pressure source or system involved. The sealingmember140 may comprise, for example, one or more of the following materials: hydrophilic polyurethane; cellulosics; hydrophilic polyamides; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic acrylics; hydrophilic silicone elastomers; an INSPIRE 2301 material from Expopack Advanced Coatings of Wrexham, United Kingdom having, for example, an MVTR (inverted cup technique) of 14400 g/m²/24 hours and a thickness of about 30 microns; a thin, uncoated polymer drape; natural rubbers; 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; co-polyester; silicones; a silicone drape; a 3M Tegaderm® drape; a polyurethane (PU) drape such as one available from Avery Dennison Corporation of Pasadena, Calif.; polyether block polyamide copolymer (PEBAX), for example, from Arkema, France; Expopack 2327; or other appropriate material.
• The sealingmember140 may be vapor permeable and liquid impermeable, thereby allowing vapor and inhibiting liquids from exiting the sealedspace174 provided by the dressing124. In some embodiments, the sealingmember140 may be a flexible, breathable film, membrane, or sheet having a high MVTR of, for example, at least about 300 g/m²per 24 hours. In other embodiments, a low or no vapor transfer drape may be used. The sealingmember140 may comprise a range of medically suitable films having a thickness between about 25 microns (μm) to about 50 microns (μm).
• An attachment device, such as theadhesive layer136, may be used to attach the sealingmember140 to an attachment surface, such as undamaged epidermis, a gasket, another cover, or thebase layer132. The attachment device may take many forms. For example, an attachment device may be a medically-acceptable, pressure-sensitive adhesive that extends about a periphery, a portion, or an entire sealing member. In some embodiments, for example, some or all of the sealingmember140 may be coated with an acrylic adhesive having a coating weight between 25-65 grams per square meter (g.s.m.). Thicker adhesives, or combinations of adhesives, may be applied in some embodiments to improve the seal and reduce leaks. Other example embodiments of an attachment device may include a double-sided tape, paste, hydrocolloid, hydrogel, silicone gel, or organogel.
• In some embodiments, theadhesive layer136 may be deformable or flowable. For example, theadhesive layer136 may comprise an acrylic adhesive, rubber adhesive, high-tack silicone adhesive, polyurethane, or other adhesive substance. In some embodiments, theadhesive layer136 may be a pressure-sensitive adhesive comprising an acrylic adhesive. Theadhesive layer136 may be continuous or discontinuous. Discontinuities in theadhesive layer136 may be provided by the apertures (not shown) in theadhesive layer136. The apertures in theadhesive layer136 may be formed after application of theadhesive layer136 or by coating theadhesive layer136 in patterns on a carrier layer, such as, for example, a side of the sealingmember140 adapted to face thetissue surface105 of theepidermis106. The apertures in theadhesive layer136 may also be sized to enhance the Moisture Vapor Transfer Rate (MVTR) of the dressing124, described further herein.
• A fluid storage device, such as thefluid management assembly144, may be an example of a device to configured to store liquids in thedressing124. Thefluid management assembly144 may include a firstdressing wicking layer176, a seconddressing wicking layer180, and anabsorbent layer184. The firstdressing wicking layer176 is positioned adjacent to thebase layer132, and theabsorbent layer184 is positioned adjacent the firstdressing wicking layer176. The seconddressing wicking layer180 may be positioned over theabsorbent layer184 and peripheries of the firstdressing wicking layer176 and the seconddressing wicking layer180 may be coupled to each other to form awicking layer enclosure188 containing theabsorbent layer184. In some embodiments, ananti-microbial layer190 may be disposed in thewicking layer enclosure188 between the firstdressing wicking layer176 and theabsorbent layer184. In some embodiments, thewicking layer enclosure188 may surround or otherwise encapsulate theabsorbent layer184 between the firstdressing wicking layer176 and the seconddressing wicking layer180.
• In some embodiments, theabsorbent layer184 may be in fluid communication with the firstdressing wicking layer176 and the seconddressing wicking layer180. The firstdressing wicking layer176 may have a grain structure adapted to wick fluid along a surface of the firstdressing wicking layer176. Similarly, the seconddressing wicking layer180 may have a grain structure adapted to wick fluid along a surface of the seconddressing wicking layer180. For example, the firstdressing wicking layer176 and the seconddressing wicking layer180 may wick or otherwise transport fluid in a lateral direction along the surfaces of the firstdressing wicking layer176 and the seconddressing wicking layer180, respectively. The surface of the firstdressing wicking layer176 may be normal relative to the thickness of the firstdressing wicking layer176, and the surface of the seconddressing wicking layer180 may be normal relative to the thickness of the seconddressing wicking layer180. The wicking of fluid along the firstdressing wicking layer176 and the seconddressing wicking layer180 may enhance the distribution of the fluid over a surface area of theabsorbent layer184, which may increase absorbent efficiency and resist fluid blockages. Fluid blockages may be caused by, for example, fluid pooling in a particular location in theabsorbent layer184 rather than being distributed more uniformly across theabsorbent layer184. The laminate combination of the firstdressing wicking layer176, the seconddressing wicking layer180, and theabsorbent layer184 may be adapted as described above to maintain an open structure, resistant to blockage, capable of maintaining fluid communication with, for example, thetissue site104.
• Thefluid management assembly144 may include, without limitation, any number of wicking layers and absorbent layers as desired for treating a particular tissue site. For example, theabsorbent layer184 may be a plurality ofabsorbent layers184 positioned in fluid communication between the firstdressing wicking layer176 and the seconddressing wicking layer180. Further, in some embodiments, at least one intermediate wicking layer may be disposed in fluid communication between the plurality ofabsorbent layers184. Similar to theabsorbent layer184, the plurality ofabsorbent layers184 and the at least one intermediate wicking layer may be positioned within thewicking layer enclosure188. In some embodiments, theabsorbent layer184 may be disposed between the sealingmember140 and theinterface manifold120, and the firstdressing wicking layer176 and the seconddressing wicking layer180 may be omitted.
• In some embodiments, theabsorbent layer184 may be a hydrophilic material adapted to absorb fluid from, for example, thetissue site104. Materials suitable for theabsorbent layer184 may include, without limitation, super absorbent polymers and similar absorbent materials; Luquafleece® material; TEXSUS FP2326; BASF 402C; Technical Absorbents 2317, available from Technical Absorbents, Ltd. of Lincolnshire, United Kingdom; sodium polyacrylate super absorbers; cellulosics (carboxy methyl cellulose and salts such as sodium CMC); or alginates. Materials suitable for the firstdressing wicking layer176 and the seconddressing wicking layer180 may include, without limitation, any material having a grain structure capable of wicking fluid as described herein, such as, for example, LIBELTEX TDL2, 80 gsm, or similar materials, which may be non-woven.
• Thefluid management assembly144 may be manufactured as a pre-laminated structure, or supplied as individual layers of material that can be stacked upon one another as described above. Individual layers of thefluid management assembly144 may be bonded or otherwise secured to one another without adversely affecting fluid management by, for example, utilizing a solvent or non-solvent adhesive, or by thermal welding. Further, thefluid management assembly144 may be coupled to the border of thebase layer132 in any suitable manner, such as, for example, by a weld or an adhesive. The border, being free of theapertures160 as described herein, may provide a flexible barrier between thefluid management assembly144 and thetissue site104 for enhancing comfort.
• The addition of theanti-microbial layer190 may reduce the probability of excessive bacterial growth within the dressing124 to permit the dressing124 to remain in place for an extended period. Theanti-microbial layer190 may be, for example, an additional layer included as a part of thefluid management assembly144, or a coating of an anti-microbial agent disposed in any suitable location within the dressing124. Theanti-microbial layer190 may be comprised of elemental silver or a similar compound, for example. In some embodiments, the anti-microbial agent may be formulated in any suitable manner and associated with other components of thedressing124.
• The dressing124 may be modified in various embodiments to suit a particular application. In some embodiments, theabsorbent layer184 may be omitted from thefluid management assembly144, which may be beneficial, but not required, for communicating fluid exterior to or away from the dressing124 and thetissue site104 for offsite or remote storage. In such an embodiment, the firstdressing wicking layer176 and the seconddressing wicking layer180 may wick or draw fluid away from thetissue site104 for transport to a location exterior to thedressing124. Further, the configuration of the firstdressing wicking layer176 and the seconddressing wicking layer180 described herein may preference fluid away from thetissue site104 and prevent the fluid from returning to thetissue site104 prior to removal of the fluid from the dressing124, for example, by the application of negative pressure. Thewicking layer enclosure188 may enhance this ability to preference fluid away from thetissue site104 and to prevent the fluid from returning to thetissue site104.
• The dressing124 may be further modified in various embodiments that may be suitable for some applications that communicate fluid from thetissue site104 exterior to thedressing124. For example, in some embodiments, the firstdressing wicking layer176 or the seconddressing wicking layer180 may be omitted along with theabsorbent layer184 and thebase layer132. In such an embodiment, the dressing124 may comprise the sealingmember140 and one of the firstdressing wicking layer176 or the seconddressing wicking layer180 for disposing in the sealedspace174 between the sealingmember140 and thetissue site104. Further, in some embodiments, thefluid management assembly144 may be omitted from the dressing124, and a dressing manifold (not shown) may be positioned in theenclosure172 in place of thefluid management assembly144. The dressing manifold may be configured as a layer and may be comprised of any material suitable for removing fluids from a tissue site through a plurality of pores, pathways, or flow channels as described herein, such as, without limitation, a foam, a woven material, a cast silicone, a polyurethane material, or any of the materials recited for theinterface manifold120. Further, in some embodiments, the dressing124 may be modified by omitting thebase layer132 and replacing thefluid management assembly144 with the above-described dressing manifold. In such an embodiment, the dressing124 may comprise the sealingmember140 and the dressing manifold for disposing in the sealedspace174 between the sealingmember140 and thetissue site104. Further, in some embodiments, theabsorbent layer184 may be omitted and replaced with the dressing manifold such that the dressing manifold is positioned between the firstdressing wicking layer176 and the seconddressing wicking layer180.
• A dressing interface, such as theconduit interface148 may be positioned proximate to a cover and in fluid communication with the sealedspace174 provided by the dressing124. For example, theconduit interface148 may be in fluid communication with the dressing124 through an aperture in the sealingmember140. Theconduit interface148 may provide negative pressure from the negative-pressure source128 to thedressing124. Theconduit interface148 may also be adapted to be positioned in fluid communication with theinterface manifold120.
• Theconduit interface148 may comprise a medical-grade, soft polymer or other pliable material. As non-limiting examples, theconduit interface148 may be formed from polyurethane, polyethylene, polyvinyl chloride (PVC), fluorosilicone, or ethylene-propylene. In some illustrative, non-limiting embodiments, theconduit interface148 may be molded from DEHP-free PVC. Theconduit interface148 may be formed in any suitable manner such as by molding, casting, machining, or extruding. Further, theconduit interface148 may be formed as an integral unit or as individual components and may be coupled to the dressing124 by, for example, adhesive or welding.
• In some embodiments, theconduit interface148 may be formed of an absorbent material having absorbent and evaporative properties. The absorbent material may be vapor permeable and liquid impermeable, thereby being configured to permit vapor to be absorbed into and evaporated from the material through permeation while inhibiting permeation of liquids. The absorbent material may be, for example, a hydrophilic polymer such as a hydrophilic polyurethane. Although the term hydrophilic polymer may be used in the illustrative embodiments that follow, any absorbent material having the properties described herein may be suitable for use in thesystem102. Further, the absorbent material or hydrophilic polymer may be suitable for use in various components of thesystem102 as described herein.
• The use of such a hydrophilic polymer for theconduit interface148 may permit liquids in theconduit interface148 to evaporate, or otherwise dissipate, during operation. For example, the hydrophilic polymer may allow the liquid to permeate or pass through theconduit interface148 as vapor, in a gaseous phase, and evaporate into the atmosphere external to theconduit interface148. Such liquids may be, for example, condensate or other liquids. Condensate may form, for example, as a result of a decrease in temperature within theconduit interface148, or other components of thesystem102, relative to the temperature at thetissue site104. Removal or dissipation of liquids from theconduit interface148 may increase visual appeal and prevent odor. Further, such removal of liquids may also increase efficiency and reliability by reducing blockages and other interference with the components of thesystem102.
• Theconduit interface148 may carry theodor filter194 adapted to substantially preclude the passage of odors from thetissue site104 out of the sealedspace174. Further, theconduit interface148 may carry the firsthydrophobic filter195 adapted to substantially preclude the passage of liquids through the firsthydrophobic filter195. Theodor filter194 and the firsthydrophobic filter195 may be disposed in theconduit interface148 or other suitable location such that fluid communication between the negative-pressure source128 and the dressing124 is provided through theodor filter194 and the firsthydrophobic filter195. In some embodiments, theodor filter194 and the firsthydrophobic filter195 may be secured within theconduit interface148 in a suitable manner, such as by adhesive or welding. In other embodiments, theodor filter194 or the firsthydrophobic filter195 may be omitted, or positioned proximate to an exit location in thesystem102 or the dressing124 that is in fluid communication with the atmosphere, the negative-pressure source128, or the optional therapy unit.
• Theodor filter194 may be comprised of a carbon material in the form of a layer or particulate. For example, theodor filter194 may comprise a woven carbon cloth filter such as those manufactured by Chemviron Carbon, Ltd. of Lancashire, United Kingdom. The firsthydrophobic filter195 may be comprised of a material that is liquid impermeable and vapor permeable. For example, the firsthydrophobic filter195 may comprise a material manufactured under the designation MMT-314 by W.L. Gore & Associates, Inc. of Newark, Del., United States, or similar materials. The firsthydrophobic filter195 may be provided in the form of a membrane or layer.
• Theliquid trap192 is representative of a container, canister, pouch, or other storage component, which can be used to manage exudates and other fluids withdrawn from a tissue site. In many environments, a rigid container may be preferred or required for collecting, storing, and disposing of fluids. In other environments, fluids may be properly disposed of without rigid container storage, and a re-usable container could reduce waste and costs associated with negative-pressure therapy.
• Similar to theconduit interface148, theliquid trap192, and other components of thesystem102, may also be formed of an absorbent material or a hydrophilic polymer. The absorptive and evaporative properties of the hydrophilic polymer may also facilitate removal and dissipation of liquids residing in theliquid trap192, and other components of thesystem102, by evaporation. Such evaporation may leave behind a substantially solid or gel-like waste. The substantially solid or gel-like waste may be cheaper to dispose than liquids, providing a cost savings for operation of thesystem102. The hydrophilic polymer may be used for other components in thesystem102 where the management of liquids is beneficial.
• In some embodiments, the absorbent material or hydrophilic polymer may have an absorbent capacity in a saturated state that is substantially equivalent to the mass of the hydrophilic polymer in an unsaturated state. The hydrophilic polymer may be fully saturated with vapor in the saturated state and substantially free of vapor in the unsaturated state. In both the saturated state and the unsaturated state, the hydrophilic polymer may retain substantially the same physical, mechanical, and structural properties. For example, the hydrophilic polymer may have a hardness in the unsaturated state that is substantially the same as a hardness of the hydrophilic polymer in the saturated state. The hydrophilic polymer and the components of thesystem102 incorporating the hydrophilic polymer may also have a size that is substantially the same in both the unsaturated state and the saturated state. Further, the hydrophilic polymer may remain dry, cool to the touch, and pneumatically sealed in the saturated state and the unsaturated state. The hydrophilic polymer may also remain substantially the same color in the saturated state and the unsaturated state. In this manner, this hydrophilic polymer may retain sufficient strength and other physical properties to remain suitable for use in thesystem102. An example of such a hydrophilic polymer is offered under the trade name Techophilic HP-93A-100, available from The Lubrizol Corporation of Wickliffe, Ohio, United States. Techophilic HP-93A-100 is an absorbent hydrophilic thermoplastic polyurethane capable of absorbing 100% of the unsaturated mass of the polyurethane in water and having a durometer or Shore Hardness of about 83 Shore A.
• Theconduit196 may have theinternal lumen197 and may be fluidly coupled between the negative-pressure source128 and thedressing124. Theinternal lumen197 may have an internal diameter between about 0.5 millimeters to about 3.0 millimeters. In some embodiments, the internal diameter of theinternal lumen197 may be between about 1 millimeter to about 2 millimeters. Theconduit interface148 may be coupled in fluid communication with the dressing124 and adapted to connect between theconduit196 and the dressing124 for providing fluid communication with the negative-pressure source128. Theconduit interface148 may be fluidly coupled to theconduit196 in a suitable manner, such as, for example, by an adhesive, solvent or non-solvent bonding, welding, or interference fit. An aperture in the sealingmember140 may provide fluid communication between the dressing124 and theconduit interface148. For example, theconduit interface148 may be in fluid communication with theenclosure172 or the sealedspace174 through the aperture in the sealingmember140. In some embodiments, theconduit196 may be inserted into the dressing124 through the aperture in the sealingmember140 to provide fluid communication with the negative-pressure source128 without use of theconduit interface148. The negative-pressure source128 may also be directly coupled in fluid communication with the dressing124 or the sealingmember140 without use of theconduit196. In some embodiments, theconduit196 may be, for example, a flexible polymer tube. A distal end of theconduit196 may include acoupling198 for attachment to the negative-pressure source128.
• Theconduit196 may have the secondaryhydrophobic filter199 disposed in theinternal lumen197 such that fluid communication between the negative-pressure source128 and the dressing124 is provided through the secondaryhydrophobic filter199. The secondaryhydrophobic filter199 may be, for example, a porous, sintered polymer cylinder sized to fit the dimensions of theinternal lumen197 to substantially preclude liquid from bypassing the cylinder. The secondaryhydrophobic filter199 may also be treated with an absorbent material adapted to swell when brought into contact with liquid to block the flow of the liquid. The secondaryhydrophobic filter199 may be positioned at any location within theinternal lumen197. However, positioning the secondaryhydrophobic filter199 within theinternal lumen197 closer toward the negative-pressure source128, rather than the dressing124, may allow a user to detect the presence of liquid in theinternal lumen197.
• In some embodiments, theconduit196 and thecoupling198 may be formed of an absorbent material or a hydrophilic polymer as described above for theconduit interface148. In this manner, theconduit196 and thecoupling198 may permit liquids in theconduit196 and thecoupling198 to evaporate, or otherwise dissipate, as described above for theconduit interface148. Theconduit196 and thecoupling198 may be, for example, molded from the hydrophilic polymer separately, as individual components, or together as an integral component. Further, a wall of theconduit196 defining theinternal lumen197 may be extruded from the hydrophilic polymer. Theconduit196 may be less than about 1 meter in length, but may have any length to suit a particular application.
• FIG. 2 is a plan view of thebase layer132 of the dressing124 ofFIG. 1, illustrating additional details that may be associated with some embodiments. Thebase layer132 may have aperiphery152 surrounding acentral portion156, and the plurality ofapertures160 are disposed through theperiphery152 and thecentral portion156. Thebase layer132 may also havecorners158 and edges159. Thecorners158 and theedges159 may be part of theperiphery152. One of theedges159 may meet another of theedges159 to define one of thecorners158. Further, thebase layer132 may have aborder161 substantially surrounding thecentral portion156 and positioned between thecentral portion156 and theperiphery152. In some embodiments, theborder161 may be free of theapertures160. In some embodiments, thebase layer132 may be adapted to cover theinterface manifold120 or theapposition layer146 and tissue surrounding thetissue site104 such that thecentral portion156 of thebase layer132 is positioned adjacent to or proximate to theinterface manifold120 or theapposition layer146, and theperiphery152 of thebase layer132 is positioned adjacent to or proximate to thetissue surface105 surrounding thetissue site104. In such embodiments, theperiphery152 of thebase layer132 may surround theinterface manifold120 or theapposition layer146. Further, theapertures160 in thebase layer132 may be in fluid communication with theinterface manifold120 and thetissue surface105 surrounding thetissue site104.
• Theapertures160 in thebase layer132 may have a variety of shapes, such as, circles, squares, stars, ovals, polygons, slits, complex curves, rectilinear shapes, triangles, or other shapes. Theapertures160 may be formed by cutting (such as laser cutting), by application of local RF energy, punching, or other suitable techniques for forming an opening. Each of theapertures160 of the plurality ofapertures160 may be substantially circular in shape, having a diameter and an area. The diameter of each of theapertures160 may define the area of each of theapertures160. For example, the area of one of theapertures160 may be defined by multiplying the square of half the diameter of theaperture160 by the value 3.14. Thus, the following equation may define the area of one of the apertures160: Area=3.14*(diameter/2)̂2.
• The area of theapertures160 described in the illustrative embodiments herein may be substantially similar to the area in other embodiments (not shown) for theapertures160 that may have non-circular shapes. The diameter of each of theapertures160 may be substantially the same, or each of the diameters may vary depending, for example, on the position of theaperture160 in thebase layer132. For example, the diameter of theapertures160 in theperiphery152 of thebase layer132 may be larger than the diameter of theapertures160 in thecentral portion156 of thebase layer132. Further, the diameter of each of theapertures160 may be between about 1 millimeter to about 50 millimeters. In some embodiments, the diameter of each of theapertures160 may be between about 1 millimeter to about 20 millimeters. Theapertures160 may have a uniform pattern or may be randomly distributed on thebase layer132. The size and configuration of theapertures160 may be designed to control the adherence of the dressing124 to theepidermis106 as described below.
• In some embodiments, theapertures160 positioned in theperiphery152 may beapertures160a, theapertures160 positioned at thecorners158 of theperiphery152 may beapertures160b, and theapertures160 positioned in thecentral portion156 may beapertures160c. In some embodiments, theapertures160amay have an area greater than theapertures160b. Further, theapertures160bmay have an area greater than theapertures160c. The dimensions of thebase layer132 may be increased or decreased, for example, substantially in proportion to one another to suit a particular application.
• Theapertures160amay have a diameter between about 9.8 millimeters to about 10.2 millimeters. Theapertures160bmay have a diameter between about 7.75 millimeters to about 8.75 millimeters. Theapertures160cmay have a diameter between about 1.8 millimeters to about 2.2 millimeters. The diameter of each of theapertures160amay be separated from one another by a distance A between about 2.8 millimeters to about 3.2 millimeters. Further, the diameter of at least one of theapertures160amay be separated from the diameter of at least one of theapertures160bby the distance A. The diameter of each of theapertures160bmay also be separated from one another by the distance A. A center of one of theapertures160cmay be separated from a center of another of theapertures160cin a first direction by a distance B between about 2.8 millimeters to about 3.2 millimeters. In a second direction transverse to the first direction, the center of one of theapertures160cmay be separated from the center of another of theapertures160cby a distance C between about 2.8 millimeters to about 3.2 millimeters. The distance B and the distance C may be increased for theapertures160cin thecentral portion156 being positioned proximate to or at theborder161 compared to theapertures160cpositioned away from theborder161.
• Thecentral portion156 of thebase layer132 may be substantially square with each side of thecentral portion156 having a length D between about 100 millimeters to about 108 millimeters. In some embodiments, the length D may be between about 106 millimeters to about 108 millimeters. Theborder161 of thebase layer132 may have a width E between about 4 millimeters to about 11 millimeters and may substantially surround thecentral portion156 and theapertures160cin thecentral portion156. In some embodiments, the width E may be between about 9 millimeters to about 10 millimeters. Theperiphery152 of thebase layer132 may have a width F between about 25 millimeters to about 35 millimeters and may substantially surround theborder161 and thecentral portion156. In some embodiments, the width F may be between about 26 millimeters to about 28 millimeters. Further, theperiphery152 may have a substantially square exterior with each side of the exterior having a length G between about 154 millimeters to about 200 millimeters. In some embodiments, the length G may be between about 176 millimeters to about 184 millimeters. Although thecentral portion156, theborder161, and theperiphery152 of thebase layer132 are depicted as having a substantially square shape, these and other components of thebase layer132 may have any shape to suit a particular application. Further, the dimensions of thebase layer132 as described herein may be increased or decreased, for example, substantially in proportion to one another to suit a particular application. The use of the dimensions in the proportions described above may enhance the cosmetic appearance of a tissue site. For example, these proportions may provide a surface area for thebase layer132, regardless of shape, that is sufficiently smooth to enhance the movement and proliferation of epithelial cells at thetissue site104, and reduce the likelihood of granulation tissue in-growth into thedressing124.
• Thebase layer132 may be a soft, pliable material suitable for providing a fluid seal with thetissue site104 as described herein. For example, thebase layer132 may comprise a silicone gel, a soft silicone, hydrocolloid, hydrogel, polyurethane gel, polyolefin gel, hydrogenated styrenic copolymer gel, a foamed gel, a soft closed cell foam such as polyurethanes and polyolefins coated with an adhesive as described below, polyurethane, polyolefin, or hydrogenated styrenic copolymers. Thebase layer132 may have a thickness between about 500 microns (μm) and about 1000 microns (μm). In some embodiments, thebase layer132 may have a stiffness between about 5Shore 00 and about 80Shore 00. Further, in some embodiments, thebase layer132 may be comprised of hydrophobic or hydrophilic materials.
• In some embodiments (not shown), thebase layer132 may be a hydrophobic-coated material. For example, thebase layer132 may be formed by coating a spaced material, such as, for example, woven, nonwoven, molded, or extruded mesh with a hydrophobic material. The hydrophobic material for the coating may be a soft silicone, for example. In this manner, theadhesive layer136 may extend through openings in the spaced material analogous to theapertures160.
• FIG. 3 is an exploded view of the dressing124 ofFIG. 1, illustrating additional details that may be associated with some embodiments. Arelease liner162 may be attached to or positioned adjacent to thebase layer132 to protect theadhesive layer136 prior to application of the dressing124 to thetissue site104. Thefluid management assembly144 may be disposed over thebase layer132. In some embodiments, thefluid management assembly144 may be disposed over thecentral portion156 so that theapertures160care in fluid communication with thefluid management assembly144. Preferably, thefluid management assembly144 may be bounded by theborder161 inboard of theperiphery152 of thebase layer132. Theadhesive layer136 may be disposed over theperiphery152. In some embodiments, theadhesive layer136 may be a ring surrounding thefluid management assembly144. Theadhesive layer136 may be bounded by theedges159 of thebase layer132 and theborder161. The sealingmember140 may be disposed over theadhesive layer136 and thefluid management assembly144. The sealingmember140 can be coupled to theadhesive layer136. The sealingmember140 may include anaperture170 formed near a center of the sealingmember140.
• Prior to application of the dressing124 to thetissue site104, thebase layer132 may be positioned between the sealingmember140 and therelease liner162. Removal of therelease liner162 may expose thebase layer132 and theadhesive layer136 for application of the dressing124 to thetissue site104. Therelease liner162 may also provide stiffness to assist with, for example, deployment of thedressing124. Therelease liner162 may be, for example, a casting paper, a film, or polyethylene. Further, therelease liner162 may be a polyester material such as polyethylene terephthalate (PET), or similar polar semi-crystalline polymer. The use of a polar semi-crystalline polymer for therelease liner162 may substantially preclude wrinkling or other deformation of thedressing124. For example, the polar semi-crystalline polymer may be highly orientated and resistant to softening, swelling, or other deformation that may occur when brought into contact with components of the dressing124, or when subjected to temperature or environmental variations, or sterilization. Further, a release agent may be disposed on a side of therelease liner162 that is configured to contact thebase layer132. For example, the release agent may be a silicone coating and may have a release factor suitable to facilitate removal of therelease liner162 by hand and without damaging or deforming thedressing124. In some embodiments, the release agent may be fluorosilicone. In other embodiments, therelease liner162 may be uncoated or otherwise used without a release agent.
• A periphery of the sealingmember140 may be positioned proximate to theperiphery152 of thebase layer132 such that a central portion of the sealingmember140 and thecentral portion156 of thebase layer132 define theenclosure172. Theadhesive layer136 may be positioned at least between the periphery of the sealingmember140 and theperiphery152 of thebase layer132. In some embodiments, a portion of the periphery of the sealingmember140 may extend beyond theperiphery152 of thebase layer132. In other embodiments, the periphery of the sealingmember140 may be positioned in contact with thetissue surface105 surrounding thetissue site104 to provide the sealedspace174 without thebase layer132. Thus, theadhesive layer136 may also be positioned at least between the periphery of the sealingmember140 and thetissue surface105 surrounding thetissue site104. Theadhesive layer136 may be disposed on a surface of the sealingmember140 adapted to face thetissue site104 and thebase layer132.
• In some embodiments, theadhesive layer136 may be a layer having substantially the same shape as theperiphery152 of thebase layer132. Theadhesive layer136 may be exposed to at least theapertures160bin at least theperiphery152 of thebase layer132. Theadhesive layer136 may be positioned adjacent to, or positioned in fluid communication with, at least theapertures160bin at least theperiphery152 of thebase layer132.
• FIG. 4 is a detail view of a portion of the dressing124 ofFIG. 1, illustrating additional details that may be associated with some embodiments. Theadhesive layer136 may be exposed to or in fluid communication with thetissue surface105 surrounding thetissue site104 through at least theapertures160bin thebase layer132. Theadhesive layer136 may extend, deform, or be pressed through at least the plurality ofapertures160bto contact thetissue surface105 of theepidermis106 for securing the dressing124 to, for example, thetissue surface105 surrounding thetissue site104. At least theapertures160bmay provide sufficient contact of theadhesive layer136 to thetissue surface105 of theepidermis106 to secure the dressing124 about thetissue site104. However, the configuration of at least theapertures160band theadhesive layer136 may permit release and repositioning of the dressing124 about thetissue site104.
• In some embodiments, theapertures160bat thecorners158 of theperiphery152 may be smaller than theapertures160ain other portions of theperiphery152. For a given geometry of thecorners158, the smaller size of theapertures160bcompared to theapertures160amay enhance or increase the surface area of theadhesive layer136 exposed to theapertures160band to tissue through theapertures160bat thecorners158. The size and number of theapertures160bin thecorners158 may be adjusted as necessary, depending on the chosen geometry of thecorners158, to enhance or increase the exposed surface area of theadhesive layer136 as described herein.
• Similar to theapertures160bin thecorners158, any of theapertures160 may be adjusted in size and number to increase the surface area of theadhesive layer136 exposed to or in fluid communication with theapertures160 for a particular application or geometry of thebase layer132. For example, in some embodiments (not shown) theapertures160b, or apertures of another size, may be positioned in theperiphery152 and at theborder161. Similarly, theapertures160b, or apertures of another size, may be positioned as described herein in other locations of thebase layer132 that may have a complex geometry or shape.
• Factors that may be utilized to control the adhesion strength of the dressing124 may include the diameter, area, and number of theapertures160 in thebase layer132, the thickness of thebase layer132, the thickness and amount of theadhesive layer136, and the tackiness of theadhesive layer136. An increase in the amount of theadhesive layer136 extending through theapertures160 may correspond to an increase in the adhesion strength of thedressing124. A decrease in the thickness of thebase layer132 may correspond to an increase in the amount ofadhesive layer136 extending through theapertures160. Thus, the diameter, area, and configuration of theapertures160, the thickness of thebase layer132, and the amount and tackiness of the adhesive utilized may be varied to provide a desired adhesion strength for thedressing124.
• In some embodiments, the tackiness of theadhesive layer136 may vary in different locations of thebase layer132. For example, in locations of thebase layer132 where theapertures160 are comparatively large, such as theapertures160a, theadhesive layer136 may have a lower tackiness than other locations of thebase layer132 where theapertures160 are smaller, such as theapertures160band160c. In this manner, locations of thebase layer132 havinglarger apertures160 and a lower tackiness of theadhesive layer136 may have an adhesion strength comparable to locations havingsmaller apertures160 and a higher tackiness of theadhesive layer136.
• For low-acuity tissue sites, i.e., tissue sites that do not produce large amounts of fluids, a storage container, such as theliquid trap192 may provide more capacity than is needed. In some cases, a patient with a low acuity tissue site may be mobile. To increase a patient's mobility, some dressings include an absorbent component, such as thefluid management assembly144, to store liquid produced by the tissue site during therapy. By including an absorbent component in the dressing, the dressing is able to provide a sealed space for therapy without requiring a patient to carry a secondary storage device. Such dressings are a useful tool for the provision of negative-pressure therapy.
• Dressings for low-acuity tissue sites may often be what is considered a peel-and-place dressing. A peel-and-place dressing can be a dressing that is manufactured to include a plurality of components, permitting a user to simply expose an adhesive portion of the dressing and apply the dressing over the tissue site. Such peel-and-place dressings are often sized to provide coverage of a variety of tissue sites.
• For some ambulatory patients, the tissue site, while low-acuity, may nonetheless benefit from the application of a closing force or an apposition force to encourage closure of the tissue site. A closing force may be a force that is substantially parallel to thetissue surface105 and urges opposing sides of a tissue site toward each other to close an opening of the tissue site. Closure of an opening may help maintain a healing environment for internal structures of a tissue site, as well as inhibit entry of bacteria or other harmful substances into the tissue site. For example, a linear tissue site, such as a surgical incision, may be a low-acuity tissue site; however, a surgical incision may be prone to opening during movement. As a result, an ambulatory patient may benefit from additional closing forces, forces generally parallel to thetissue surface105 that urge an opening to close, encouraging the surgical incision to remain closed. However, many devices used to provide a closing force are not suitable for use with a peel and place dressing. For example, the device used to provide a closing force may be bulky, causing the peel-and-place dressing to be unable to seal around the device. Other devices may need additional components to prevent further trauma to a tissue site. The additional components may prevent the peel-and-place dressing from forming a seal around the tissue site, or may inhibit the transmission of negative pressure to the tissue site. Some peel-and-place devices overcome these issues by providing a peel-and-place dressing that includes a closing device. Such devices provide both dressing liquid storage and a closing force; however, they may not be customizable for different wounds, preventing dynamic placement of the device.
• Thesystem102 having the dressing124 can provide a peel-and-place dressing having a customizable closing device for dynamic application of a closing force to a tissue site. For example, thesystem102 may include theapposition layer146. Theapposition layer146 may be customized to selectively apply a closing or apposition force to a tissue site. The dressing124 may also supply negative pressure and store liquid produced by the tissue site in the dressing. Theapposition layer146 may also be sizeable to provide apposition forces to an irregularly shaped tissue site, or to a discontinuous tissue site. Theapposition layer146 may also be customizable to provide apposition forces to a non-linear tissue site, such as a curved incision.
• FIG. 5 is a plan view, illustrating additional details that may be associated with some embodiments of theapposition layer146. Asheet147 may be disposed on a surface of theapposition layer146. Thesheet147 may be positioned on a surface of theapposition layer146 intended to contact theinterface manifold120 or thetissue surface105 surrounding thetissue site104. Thesheet147 can also encapsulate theapposition layer146. For example, thesheet147 may surround all surfaces of theapposition layer146. For example, thesheet147 may comprise a continuous sheet of material, thesheet147 can be wrapped around theapposition layer146 and coupled to itself, for example, by adhering, welding, bonding, or otherwise securing, to encapsulate theapposition layer146. In other embodiments, thesheet147 may comprise an first layer or upper layer and a second layer or lower layer. The first layer can be disposed over theapposition layer146 and the second layer can be disposed under theapposition layer146. The first layer and the second layer can be coupled to each other. In some embodiments, thesheet147 may be wrapped around theapposition layer146 without otherwise securing it to itself, allowing friction following the application of negative pressure to hold thesheet147 in position. In other embodiments, thesheet147 may be cut to an approximate size of a surface of theapposition layer146. Thesheet147 may be coupled to the surface of theapposition layer146 to secure thesheet147 to theapposition layer146. For example, thesheet147 may be welded or bonded to the surface of theapposition layer146, such as with an acrylic adhesive.
• Thesheet147 may have at least one perforation and, preferably, a plurality ofperforations149. For example, the first layer may have at least one perforation and the second layer may have at least one perforation. Each of theperforations149 can have an effective diameter of about 2 mm or less. An effective diameter of a non-circular area may be defined as a diameter of a circular area having the same surface area as the non-circular area. Theperforations149 may have a pitch of about 3 mm. Pitch describes a spacing between objects having translational symmetry. Theperforations149 may have a pitch betweenadjacent perforations149 in orthogonal directions. The pitch of theperforations149 may be parallel to edges of thesheet147. In some embodiments, adjacent rows ofperforations149 may be offset. For example, a first row ofperforations151 may have a pitch of 3 mm parallel to an edge of thesheet147. A second row ofperforations153 adjacent to the first row ofperforations149 may be offset so that a center of eachperforation149 is equidistant from the centers ofadjacent perforations149 in the adjacent rows. In this manner, theperforations149 may be regularly spaced across thesheet147. In other embodiments, the pitch betweenadjacent perforations149 may not be regularly repeating, may not be parallel to edges of thesheet147, and may not be continuous across thesheet147.
• Thesheet147 may be formed from silicone having a coat weight between about 100 gsm and about 200 gsm. In other embodiments, thesheet147 may be formed from a hydrogel that has been cross-linked sufficient to prevent absorption, dissociation, mobility, and breakdown or a polyurethane having a thickness of about 50 microns to about 200 microns. In some embodiments, thesheet147 may be coated onto a non-woven scrim layer. The non-woven scrim layer may have a coating weight of about 25 gsm to about 100 gsm, corresponding to a thickness of about 25 microns to 100 microns. The scrim layer may be formed from polyurethane, polyamide, polyester, or cellulosic material. The hydrogel of thesheet147 may be coated on one or both sides of the scrim layer. In other embodiments, thesheet147 may be coated onto a mesh scrim layer or formed without the use of a scrim. Thesheet147 may be provided in sheets having a length of about 200 mm. Thesheet147 may be adherent, permitting thesheet147 to adhere to theapposition layer146 and theinterface manifold120. If thesheet147 is adherent, thesheet147 may have a peel force between about 0.5N/25 mm and about 6N/25 mm. The peel forces is the measure of the average force required to part two materials bonded by an adhesive.
• Thesheet147 may mimic thebase layer132 in operation and benefits to the healing of a tissue site. For example, thesheet147 may aid in scar reduction of an incisional tissue site. Thesheet147 may prevent ingrowth into layers or bodies disposed over thesheet147, such as theapposition layer146. Thesheet147 may also act as a comfort layer, aiding in pain free application of therapy.
• Theapposition layer146 may include a plurality ofholes602 or perforations extending through theapposition layer146 to formwalls608 extending through theapposition layer146. In some embodiments, thewalls608 may be generally parallel to a thickness of theapposition layer146. In other embodiments, thewalls608 may be generally perpendicular to a surface of theapposition layer146. In some embodiments, theholes602 may have an ellipsoid shape as shown.
• FIG. 6A is a plan view, illustrating additional details that may be associated with some embodiments of theapposition layer146 disposed over thetissue site104 so that theapposition layer146 may be proximate to thetissue surface105. Thesheet147 is not shown to aid in illustration of features of theapposition layer146. Theapposition layer146 may be formed from a foam. For example, cellular foam, open-cell foam, reticulated foam, or porous tissue collections, may be used to form theapposition layer146. In some embodiments, theapposition layer146 may be formed of GranuFoam®, grey foam, or Zotefoam. Grey foam may be a polyester polyurethane foam having about 60 pores per inch (ppi). Zotefoam may be a closed-cell crosslinked polyolefin foam. Theapposition layer146 can also be formed from a polyvinyl alcohol (PVA) foam or a 3D foam. In one non-limiting example, theapposition layer146 may be an open-cell, reticulated polyurethane foam such as GranuFoam® dressing available from Kinetic Concepts, Inc. of San Antonio, Tex.; in other embodiments, theapposition layer146 may be an open-cell, reticulated polyurethane foam such as a VeraFlo® foam, also available from Kinetic Concepts, Inc., of San Antonio, Tex.
• In some embodiments, theapposition layer146 may be formed from a foam that is mechanically or chemically compressed to increase the density of the foam at ambient pressure. A foam that is mechanically or chemically compressed may be referred to as a compressed foam or a felted foam. A compressed foam may be characterized by a firmness factor (FF) that can be defined as a ratio of the density of a foam in a compressed state to the density of the same foam in an uncompressed state. For example, a firmness factor (FF) of 5 may refer to a compressed foam having a density that is five times greater than a density of the same foam in an uncompressed state. Mechanically or chemically compressing a foam may reduce a thickness of the foam at ambient pressure when compared to the same foam that has not been compressed. Reducing a thickness of a foam by mechanical or chemical compression may increase a density of the foam, which may increase the firmness factor (FF) of the foam. Increasing the firmness factor (FF) of a foam may increase a stiffness of the foam in a direction that is parallel to a thickness of the foam. For example, increasing a firmness factor (FF) of theapposition layer146 may increase a stiffness of theapposition layer146 in a direction that is parallel to thethickness126 of theapposition layer146. In some embodiments, theapposition layer146 may have a thickness of about 6 mm. In other embodiments, thethickness126 may be between about 5 mm and about 10 mm. In some embodiments, a compressed foam may be a compressed GranuFoam®. GranuFoam® may have a density of about 0.03 grams per centimeter³(g/cm³) in its uncompressed state. If the GranuFoam® is compressed to have a firmness factor (FF) of 5, the GranuFoam® may be compressed until the density of the GranuFoam® is about 0.15 g/cm³. VeraFlo® foam may also be compressed to form a compressed foam having a firmness factor (FF) up to 5.
• The firmness factor (FF) may also be used to compare compressed foam materials with non-foam materials. For example, a Supracor® material may have a firmness factor (FF) that allows Supracor® to be compared to compressed foams. In some embodiments, the firmness factor (FF) for a non-foam material may represent that the non-foam material has a stiffness that is equivalent to a stiffness of a compressed foam having the same firmness factor. For example, if theapposition layer146 is formed from Supracor®, theapposition layer146 may have a stiffness that is about the same as the stiffness of a compressed GranuFoam® material having a firmness factor (FF) of 3. Generally, a material having a firmness factor (FF) of about 1 may have a stiffness of about 5 kPa. A stiffness of 5 kPa requires the application of about 5 kPa to compress the material to 50% of its original thickness. A material having a firmness factor (FF) of about 3 corresponds to the application of about 15 kPa to compress the material to 50% of its original thickness, that is, a stiffness of about 15 kPa. Theapposition layer146 may have a stiffness between about 10 kPa to about 20 kPa.
• Generally, if a compressed foam is subjected to negative pressure, the compressed foam exhibits less deformation than a similar uncompressed foam. If theapposition layer146 is formed of a compressed foam, thethickness126 of theapposition layer146 may deform less than if theapposition layer146 is formed of a comparable uncompressed foam. The decrease in deformation may be caused by the increased stiffness as reflected by the firmness factor (FF). If subjected to the stress of negative pressure, theapposition layer146 formed of compressed foam may flatten less than theapposition layer146 that is formed from uncompressed foam. Consequently, when negative pressure is applied to theapposition layer146, the stiffness of theapposition layer146 in the direction parallel to thethickness126 of theapposition layer146 allows theapposition layer146 to be more compliant or compressible in other directions, e.g., a direction parallel to thetissue surface105 or in a direction perpendicular to a lesion, incision, or opening of thetissue site104. The foam material used to form a compressed foam may be either hydrophobic or hydrophilic. The pore size of a foam material may vary according to needs of theapposition layer146 and the amount of compression of the foam. For example, in some embodiments, an uncompressed foam may have pore sizes in a range of about 400 microns to about 600 microns. If the same foam is compressed, the pore sizes may be smaller than when the foam is in its uncompressed state. In some embodiments, theapposition layer146 may have awidth610. Thewidth610 may be between about 15 mm and about 40 mm.
• Theapposition layer146 may cover a lesion, incision, or opening in thetissue surface105 of thetissue site104. In some embodiments, theapposition layer146 may have afirst orientation line627 and asecond orientation line629 that is perpendicular to thefirst orientation line627. Thefirst orientation line627 may be parallel to anedge632 of theapposition layer146 and thesecond orientation line629 may be parallel to anedge634 of theapposition layer146. In some embodiments, thefirst orientation line627 and thesecond orientation line629 may be used to refer to the desired directions of contraction for theapposition layer146. For example, if thefirst orientation line627 is oriented parallel to the lesion, incision, or opening, the desired direction of contraction may be parallel to thesecond orientation line629 and perpendicular to thefirst orientation line627. Generally, theapposition layer146 may be placed at thetissue site104 so that thefirst orientation line627 is parallel to the lesion, incision, or opening and may cover portions of thetissue surface105 on one or more sides of the lesion, incision, or opening. In some embodiments, thefirst orientation line627 may be coincident with the lesion, incision, or opening. Theapposition layer146 may include the plurality ofholes602 or perforations extending through theapposition layer146. In some embodiments, thewalls608 of theholes602 may extend through theapposition layer146 parallel to thethickness126 of theapposition layer146. In some embodiments, theholes602 may have an ovoid shape as shown.
• Referring more specifically toFIG. 7, asingle hole602 having an ovoid shape is shown. Thehole602 may include acenter636, aperimeter638, and a perforation shape factor (PSF). For reference, thehole602 may have an X-axis642 extending through thecenter636 parallel to thefirst orientation line627, and a Y-axis640 extending through thecenter636 parallel to thesecond orientation line629. In some embodiments, the perforation shape factor (PSF) of thehole602 may be defined as a ratio of aline segment644 on the Y-axis640 extending from thecenter636 to theperimeter638 of thehole602, to aline segment646 on theX-axis642 extending from thecenter636 to theperimeter638 of thehole602. If a length of theline segment644 is 2.5 mm and the length of theline segment646 is 2.5 mm, the perforation shape factor (PSF) would be 2.5/2.5 or about 1.
• Referring toFIG. 8, if thehole602 is rotated relative to thefirst orientation line627 and thesecond orientation line629 so that a major axis of the hole628 is parallel to thesecond orientation line629 and a minor axis of thehole602 is parallel to thefirst orientation line627, the perforation shape factor (PSF) may change. For example, the perforation shape factor (PSF) is now the ratio of a line segment660 on the Y-axis640 extending from thecenter636 to theperimeter638 of the hole628, to aline segment662 on theX-axis642 extending from thecenter636 to theperimeter638 of the hole628. If a length of the line segment660 is 5 mm and the length of theline segment662 is 2.5 mm, the perforation shape factor (PSF) would be 5/2.5 or about 2.
• Referring toFIG. 9, if thehole602 is rotated relative to thefirst orientation line627 and thesecond orientation line629 so that a major axis of thehole602 is parallel to thefirst orientation line627 and a minor axis of thehole602 is parallel to thesecond orientation line629, the perforation shape factor (PSF) may change. For example, the perforation shape factor (PSF) is now the ratio of aline segment664 on the Y-axis640 extending from thecenter636 to theperimeter638 of the hole628, to aline segment666 on theX-axis642 extending from thecenter636 to theperimeter638 of thehole602. If a length of theline segment664 is 2.5 mm and the length of theline segment666 is 5 mm, the perforation shape factor (PSF) would be 2.5/5 or about ½.
• Referring toFIG. 6B, a portion of theapposition layer146 ofFIG. 6A is shown. Theapposition layer146 may include the plurality ofholes602 aligned in a pattern of parallel rows. The pattern of parallel rows may include afirst row648 of theholes602, asecond row650 of theholes602, and athird row652 of theholes602. TheX-axis642 ofFIGS. 8, 9, and10 of eachhole602 may be parallel to thefirst orientation line627 ofFIG. 7B. Thecenters636 of theholes602 in adjacent rows, for example, thefirst row648 and thesecond row650, may be characterized by being offset from thesecond orientation line629 along thefirst orientation line627. In some embodiments, a line connecting the centers of adjacent rows may form a strut angle (SA) with thefirst orientation line627. For example, afirst hole602A in thefirst row648 may have a center637A, and asecond hole602B in thesecond row650 may have a center637B. Astrut line654 may connect the center637A with the center637B. Thestrut line654 may form anangle656 with thefirst orientation line627. Theangle656 may be the strut angle (SA) of theapposition layer146. In some embodiments, the strut angle (SA) may be less than about 60°. In other embodiments, the strut angle (SA) may be between about 30° and about 70° relative to thefirst orientation line627. As described above, if negative pressure is applied to theapposition layer146, theapposition layer146 may be more compliant or compressible in a direction perpendicular to thefirst orientation line627. By increasing the compressibility of theapposition layer146 in a direction perpendicular to thefirst orientation line627, theapposition layer146 may collapse to apply theclosing force631 to the lesion, incision, or opening of thetissue site104, as described in more detail herein.
• In some embodiments, thecenters636 of theholes602 in alternating rows, for example, the center637A of thefirst hole602A in thefirst row648 and acenter636C of ahole602C in thethird row652, may be spaced from each other parallel to thesecond orientation line629 by alength658. In some embodiments, thelength658 may be greater than an effective diameter of thehole602. If thecenters636 ofholes602 in alternating rows are separated by thelength658, thewalls608 parallel to thefirst orientation line627 may be considered continuous. Generally, thewalls608 may be continuous if thewalls608 do not have any discontinuities or breaks betweenholes602.
• Regardless of the shape of theholes602, theholes602 in theapposition layer146 may leave void spaces in theapposition layer146 and on the surface of theapposition layer146 so that only thewalls608 of theapposition layer146 remain with a surface available to contact the surface of thetissue site104. It may be desirable to minimize thewalls608 so that theholes602 may collapse, causing theapposition layer146 to collapse the closingforce631 in a direction perpendicular to thefirst orientation line627. However, it may also be desirable not to minimize thewalls608 so much that theapposition layer146 becomes too fragile for sustaining the application of a negative pressure. The void space percentage (VS) of theholes602 may be equal to the percentage of the volume or surface area of the void spaces created by theholes602 to the total volume or surface area of theapposition layer146. In some embodiments, the void space percentage (VS) may be between about 40% and about 60%. In other embodiments, the void space percentage (VS) may be about 56%.
• In some embodiments, an effective diameter of theholes602 may be selected to permit flow of particulates through theholes602. In some embodiments, eachhole602 may have an effective diameter of about 7 mm. In other embodiments, eachhole602 may have an effective diameter between about 2.5 mm and about 20 mm.
• FIG. 6C is a plan view of theapposition layer146 in a second position, illustrating additional details that may be associated with some embodiments. Theholes602 may form a pattern depending on the geometry of theholes602 and the alignment of theholes602 between adjacent and alternating rows in theapposition layer146 with respect to thefirst orientation line627. If theapposition layer146 is subjected to negative pressure, theholes602 of theapposition layer146 may collapse, causing theapposition layer146 to collapse along thesecond orientation line629 perpendicular to thefirst orientation line627. If theapposition layer146 is positioned on a tissue surface of thetissue site104 so that thefirst orientation line627 coincides with the lesion, incision, or opening, theapposition layer146 may generate a closingforce631 along thesecond orientation line629 such that the tissue surface is contracted in the same direction to facilitate closure of the lesion, incision, or opening. The closingforce631 may be optimized by adjusting the factors described above as set forth in Table 1 below. In some embodiments, theholes602 may be ovular, have a strut angle (SA) of approximately 47°, a void space percentage (VS) of about 56%, a firmness factor (FF) of 5, a perforation shape factor (PSF) of 1, and an effective diameter of about 7 mm (where the major axis is about 8 mm and the minor axis is about 5 mm). If theapposition layer146 is subjected to a negative pressure of about −125 mm Hg, theapposition layer146 may assert the closingforce631 of approximately 13.5 N.
• In some embodiments, theapposition layer146 and thesheet147 may be disposed within a subcutaneous tissue site. If disposed in a subcutaneous tissue site, theapposition layer146 and thesheet147 may approximate the subcutaneous tissue.
• A closing force, such as the closingforce631, generated by a apposition layer, such as theapposition layer146, may be related to a compressive force generated by applying negative pressure at a therapy pressure to a sealed therapeutic environment. For example, the closingforce631 may be proportional to a product of a therapy pressure (TP) in the sealed therapeutic environment or a sealedspace174, the compressibility factor (CF) of theapposition layer146, and a surface area (A) of theapposition layer146. The relationship is expressed as follows:
• 
  Closing force α(TP*CF*A)
• In some embodiments, the therapy pressure TP is measured in N/m², the compressibility factor (CF) is dimensionless, the area (A) is measured in m², and the closing force is measured in Newtons (N). The compressibility factor (CF) resulting from the application of negative pressure to a contracting layer may be, for example, a dimensionless number that is proportional to the product of the void space percentage (VS) of a contracting layer, the firmness factor (FF) of the contracting layer, the strut angle (SA) of the holes in the contracting layer, and the perforation shape factor (PSF) of the holes in the contracting layer. The relationship is expressed as follows:
• 
  Compressibility Factor(CF)α(VS*FF*sin(SA)*PSF)
• Based on the above formulas, contracting layers formed from different materials with holes of different shapes were manufactured and tested to determine the closing force of the contracting layers. For each contracting layer, the therapy pressure TP was about −125 mmHg and the dimensions of the contracting layer were about 200 mm by about 53 mm so that the surface area (A) of the contracting layer was about 106 cm²or 0.0106 m². Based on the two equations described above, the closing force for a Supracor® contracting layer114 having a firmness factor (FF) of 3 was about 13.3 where the Supracor® contracting layer114 had hexagonal holes702 with a distance between opposite vertices of 5 mm, a perforation shape factor (PSF) of 1.07, a strut angle (SA) of approximately 66°, and a void space percentage (VS) of about 55%. A similarly dimensioned GranuFoam® contracting layer114 generated the closingforce631 of about 9.1 Newtons (N).

• TABLE 1
  						Major
  				Hole		diam.	Closing
  Material	VS	FF	SA	Shape	PSF	(mm)	force

  GranuFoam ®	56	5	47	Ovular	1	10	13.5
  Supracor ®	55	3	66	Hexagon	1.1	5	13.3
  GranuFoam ®	40	5	63	Triangle	1.1	10	12.2
  GranuFoam ®	54	5	37	Circular	1	5	11.9
  GranuFoam ®	52	5	37	Circular	1	20	10.3
  Grey Foam	N/A	5	N/A	Horizontal	N/A	N/A	9.2
  				stripes
  GranuFoam ®	55	5	66	Hexagon	1.1	5	9.1
  GranuFoam ®	N/A	5	N/A	Horizontal	N/A	N/A	8.8
  				stripes
  Zotefoam	52	3	37	Circular	1	10	8.4
  GranuFoam ®	52	5	37	Circular	1	10	8.0
  GranuFoam ®	52	5	64	Circular	1	10	7.7
  GranuFoam ®	56	5	66	Hexagon	1.1	10	7.5
  Grey Foam	N/A	3	N/A	Horizontal	N/A	N/A	7.2
  				stripes
  Zotefoam	52	3	52	Circular	1	20	6.8
  GranuFoam ®	N/A	3	N/A	Horizontal	N/A	N/A	6.6
  				Striping
  GranuFoam ®	52	5	52	Circular	1	20	6.5
  GranuFoam ®	N/A	5	N/A	Vertical	N/A	N/A	6.1
  				Stripes
  GranuFoam ®	N/A	1	N/A	None	N/A	N/A	5.9
  GranuFoam ®	N/A	3	N/A	Vertical	N/A	N/A	5.6
  				stripes
  GranuFoam ®	52	1	37	None	1	10	5.5

• FIG. 10 is a perspective view of theapposition layer146 and the dressing124, illustrating additional details associated with some embodiments. In operation, theapposition layer146 covered by thesheet147 may be positioned over thetissue site104. Thesheet147 contacts thetissue surface105 and adheres theapposition layer146 to thetissue surface105, holding theapposition layer146 on thetissue surface105. Preferably, theapposition layer146 is aligned with thetissue site104 so that a length of theapposition layer146 is generally parallel an opening of thetissue site104. Theapposition layer146 may be bisected by the opening of thetissue site104 so that theapposition layer146 contacts a portion of thetissue surface105 on opposite sides of the opening of thetissue site104.
• The dressing124 can be positioned over the apposition layer and thesheet147. Preferably, the dressing124 is aligned with theapposition layer146 so that thecentral portion156 of thebase layer132 is over theapposition layer146.
• FIG. 11 is a perspective view of theapposition layer146 and the dressing124 adhered to thetissue surface105, illustrating additional details that may be associated with some embodiments. Some components of the dressing124 are not shown inFIG. 11 to aid in illustration of the described features. While components may not be shown, the components can be included. As shown inFIG. 11, theapposition layer146 is bordered by theborder161 of thebase layer132. In other embodiments, theapposition layer146 may extend into theborder161 or further.
• FIG. 12 is a perspective view of theapposition layer146 and the dressing124 during negative-pressure therapy, illustrating additional details that may be associated with some embodiments. As shown, theapposition layer146 generates the closingforce631 urging the opening of thetissue site104 closed. Theapposition layer146 can generate the closingforce631 while also distributing fluids from thetissue site104 into thefluid management assembly144.
• FIG. 13A is a perspective section view of anotherapposition layer1646, illustrating additional details that may be associated with some embodiments. Theapposition layer1646 may be similar to and operate as described above with respect to theapposition layer146. For example, theapposition layer1646 includes a plurality ofholes1602. The plurality ofholes1602 may be similar to and operate as described above with respect to the plurality ofholes602 of theapposition layer146. Theapposition layer1646 may also have athickness1626. Thethickness1626 may be similar to and operate as described above with respect to thethickness126 of theapposition layer146. Theapposition layer1646 may also include a plurality ofwalls1608. The plurality ofwalls1608 may be similar to and operate as described above with respect to the plurality ofwalls608 of theapposition layer146. In some embodiments, theapposition layer1646 may include a film (not shown) encapsulating theapposition layer1646. The film may be similar to and operate as described above with respect to thesheet147 of theapposition layer146.
• Theapposition layer1646 may have afirst end1648 and asecond end1650 opposite thefirst end1648. In some embodiments, thefirst end1648 and thesecond end1650 may be a width of theapposition layer1646. Theapposition layer1646 may include afirst side1652 extending between thefirst end1648 and thesecond end1650. Theapposition layer1646 also includes asecond side1654 opposite thefirst side1652. The apposition layer may also include atop surface1656 and abottom surface1658 opposite thetop surface1656. Edges are formed at the intersection of thetop surface1656 with thefirst side1652 and thesecond side1654. Similarly, edges are formed at the intersection of thebottom surface1658 and thefirst side1652 and thesecond side1654. The edge between thetop surface1656 and thefirst side1652 may be removed to form a firstangled surface1620. The firstangled surface1620 may be a beveled or chamfered surface, forming anangle1660 with thetop surface1656. In some embodiments theangle1660 may be about 45 degrees. In other embodiments, theangle1660 may be between about 20 degrees and about 75 degrees. Similarly, the edge between thetop surface1656 and thesecond side1654 may be removed to form a secondangled surface1622; the edge between thebottom surface1658 and thefirst side1652 may be removed to form a thirdangled surface1624; and the edge between thebottom surface1658 and thesecond side1654 may be removed to form a fourthangled surface1628. Each of the secondangled surface1622, the thirdangled surface1624, and the fourthangled surface1628 may form an angle with the respectivetop surface1656 and thebottom surface1658 that is similar to theangle1660. In some embodiments, the firstangled surface1620, the secondangled surface1622, the thirdangled surface1624, and the fourthangled surface1628 may include theholes1602.
• FIG. 13B is a cross-sectional view of theapposition layer1646 ofFIG. 13A taken alongline13B-13B, illustrating additional details that may be associated with some embodiments. In at least some embodiments, a sealingmember1640 may be positioned over theapposition layer1646, creating a sealed space that includes theapposition layer1646. The sealingmember1640 may be similar to and operate as described above with respect to the sealingmember140 ofFIG. 1. If placed over theapposition layer1646, the sealingmember1640 may be in contact with thetop surface1656 and contoured to contact the firstangled surface1620 and the secondangled surface1622 of theapposition layer1646. Gaps may be formed between the thirdangled surface1624 and tissue adjacent the tissue site and the fourthangled surface1628 and tissue adjacent the adjacent tissue. As illustrated inFIG. 10B, theapposition layer1646 is in a first position. In the first position, thebottom surface1658 may contact a surface of a tissue site, for example, undamaged tissue adjacent the tissue site. In the first position, a sealed space formed by the sealingmember1640 that includes theapposition layer1646 may be at an ambient pressure.
• FIG. 13C is a cross-sectional view of theapposition layer1646 ofFIG. 13A in a second position, illustrating additional details that may be associated with some embodiments. If fluid is drawn from the sealed spaced formed by the sealingmember1640, generating a negative pressure, theapposition layer1646 may be drawn down into the second position or compressed position. In the second position, any gaps formed between the thirdangled surface1624 and the tissue adjacent the tissue site or between the fourthangled surface1628 and the tissue adjacent the tissue site may close. The thirdangled surface1624 and the fourthangled surface1628 may contact the tissue adjacent the tissue site. Closing of the gap between thirdangled surface1624 and the fourthangled surface1628 may draw the firstangled surface1620 and the secondangled surface1622 downward and inward. Theangle1660 of the firstangled surface1620 and the secondangled surface1622 may transition the sealingmember1640 in a smooth manner, minimizing any local disturbance of the tissue adhered to the sealingmember1640. In some embodiments, the gap between the firstangled surface1620 and the secondangled surface1622 may collapse under partial application of negative pressure, for example, under a negative pressure less than about 120 mm Hg. Collapse under partial application of negative pressure may decrease the angle of adherence, mitigating the application of load and reducing the amount of skin reddening or blister formation that may occur from theapposition layer1646. Furthermore, the firstangled surface1620, the secondangled surface1622 may decrease the total volume of the sealing space formed by the sealingmember1640, requiring removal of less fluid to generate a therapeutic negative pressure than a similar apposition layer having sides formed by right angles.
• Theapposition layer1646 transitioning from the first position to the second position may generate an apposition force at the tissue site. For example, theapposition layer1646 may generate anapposition force1662 from thefirst side1652 toward thesecond side1654 and from thesecond side1654 toward thefirst side1652. Theapposition layer1646 can be positioned over a tissue site, such as an incision where thefirst side1652 is on a first side of the incision and thesecond side1654 is on a second side of the incision, so that theapposition layer1646 straddles the incision. Theapposition force1662 can draw the opposing sides of the incision toward each other, encouraging the incision to close.
• FIG. 14 is a perspective view of another embodiment of anapposition layer1746, illustrating additional details that may be associated with some embodiments. The apposition layers described herein can be sized. For example, theapposition layer1746 can be provided in strips and cut to size to a desired size to cover a tissue site. Theapposition layer1746 may be similar to and operate as described above with respect to theapposition layer146. Some tissue sites may be irregularly shaped. For example, a tissue site1704 may be formed from two incisions, ahorizontal incision1705 and avertical incision1703. In some embodiments, thevertical incision1703 may intersect thehorizontal incision1705 near a center of thehorizontal incision1705. The intersection of thehorizontal incision1705 and thevertical incision1703 may cause the tissue site1704 to be shaped like a “T.” Theapposition layer1746 can be formed to have a shape matching the shape of the tissue site. For example, theapposition layer1746 may comprise strips of theapposition layer1746 that can be formed to match the tissue site, for example by cutting. In the illustrated embodiment, theapposition layer1746 may include afirst apposition layer1745 and asecond apposition layer1747. Thefirst apposition layer1745 may be cut to a length of thevertical incision1703, and thesecond apposition layer1747 may be cut to a length of thehorizontal incision1705. Thefirst apposition layer1745 can be placed over thevertical incision1703 and thesecond apposition layer1747 can be positioned over thehorizontal incision1705. Thefirst apposition layer1745 and thesecond apposition layer1747 may include a sheet (not shown) similar to thesheet147 of theapposition layer146. After placement over thetissue site104, thefirst apposition layer1745 and thesecond apposition layer1747 may be covered by an appropriately sized dressing, such as the dressing124. The dressing124 may be sized so that theborder161 of thebase layer132 surrounds theapposition layer1746. During operation, a negative-pressure source may be coupled to the dressing124 and operated to draw down the dressing124 and theapposition layer1746. Thefirst apposition layer1745 may develop an apposition force perpendicular to thevertical incision1703, and thesecond apposition layer1747 may develop an apposition force perpendicular to thehorizontal incision1705, urging the tissue site1704 closed as described above with respect to theapposition layer146.
• In other embodiments, the tissue site1704 may be discontinuous. For example, thevertical incision1703 may not intersect thehorizontal incision1705. Thefirst apposition layer1745 may be placed over thevertical incision1703 and thesecond apposition layer1747 can be placed over thehorizontal incision1705. Thefirst apposition layer1745 may not abut thesecond apposition layer1747, providing an area uncovered by theapposition layer1746. In this manner, theapposition layer1746 may provide apposition forces where needed, and provide no apposition forces where not needed.
• FIG. 15 is a perspective view of another embodiment of an apposition layer1846, illustrating additional details that may be associated with some embodiments. The apposition layers described herein can be customized. For example, the apposition layer1846 can be provided in strips and cut to provide a curvature or an angled portion to cover a similarly shaped tissue site. The apposition layer1846 may be similar to and operate as described above with respect to theapposition layer146. Some tissue sites may be irregularly shaped. For example, atissue site1804 may be curved. The apposition layer1846 can be formed to have a shape matching the shape of the tissue site. For example, the apposition layer1846 may comprise strips of the apposition layer1846 that can be formed to match the tissue site, for example by cutting. In the illustrated embodiment, the apposition layer1846 may be curved to match the radius of curvature of thetissue site1804. For example, the apposition layer1846 may have a plurality cuts1870 formed along a first side of the apposition layer1846. Thecuts1870 may segment the apposition layer1846, permitting the apposition layer1846 to expand along the side having thecuts1870. The expansion of the side of the apposition layer1846 having thecuts1870 causes the opposite side to contract, curing the apposition layer1846. In some embodiments, thecuts1870 permit the apposition layer1846 to match the curvature of thetissue site1804. The apposition layer1847 may also be cut to a length of thetissue site1804. The apposition layer1846 may include a sheet (not shown) similar to thesheet147 of theapposition layer146. After placement over thetissue site104, the apposition layer1846 may be covered by an appropriately sized dressing, such as the dressing124. The dressing124 may be sized so that theborder161 of thebase layer132 surrounds the apposition layer1846. During operation, a negative-pressure source may be coupled to the dressing124 and operated to draw down the dressing124 and the apposition layer1846. The first apposition layer1845 may develop an apposition force perpendicular to thetissue site1804, urging thetissue site1804 closed as described above with respect to theapposition layer146.
• The systems, apparatuses, and methods described herein may provide significant advantages. For example, the apposition layers described herein can permit apposition forces to be applied with a peel-and-place negative-pressure dressing. The addition of apposition forces by the apposition layer does not require modifications to peel-and-place dressings, allowing additional therapies to be performed without increasing the complexity of application of the therapy device. The apposition layers described herein further permit customization that can allow an apposition layer to be customized to a particular tissue site, such as a contoured tissue site, or even a discontinuous tissue site. Furthermore, the apposition layers described herein permit a clinician to selectively place apposition force within a negative pressure dressing. Selective placement may allow areas that may be damaged by apposition forces to still receive negative pressure therapy. The apposition layers can also manifold pressure and fluid into the absorbent structure of a dressing. The apposition layers described herein can also maintain a position while a dressing is being placed over the apposition layer through the use of the sheet to envelop the apposition layer. The sheet, often formed of silicone, may also help reduce scar formation and can be particularly advantageous in a surgical dressing used for aesthetic reasons.
• While shown in a few illustrative embodiments, a person having ordinary skill in the art will recognize that the systems, apparatuses, and methods described herein are susceptible to various changes and modifications. Moreover, descriptions of various alternatives using terms such as “or” do not require mutual exclusivity unless clearly required by the context, and the indefinite articles “a” or “an” do not limit the subject to a single instance unless clearly required by the context. Components may be also be combined or eliminated in various configurations for purposes of sale, manufacture, assembly, or use.
• The appended claims set forth novel and inventive aspects of the subject matter described above, but the claims may also encompass additional subject matter not specifically recited in detail. For example, certain features, elements, or aspects may be omitted from the claims if not necessary to distinguish the novel and inventive features from what is already known to a person having ordinary skill in the art. Features, elements, and aspects described or illustrated in the context of some example embodiments may also be omitted or combined with features, elements, and aspects of other example embodiments. Features, elements, and aspects described herein may also be combined or replaced by alternative features serving the same, equivalent, or similar purpose without departing from the scope of the invention defined by the appended claims.

Claims (48)

1. A system for closing an opening through a surface of a tissue site, the system comprising:

an apposition layer adapted to be positioned over the opening, the apposition layer comprising:

a material having a firmness factor, and

a plurality of holes extending through the apposition layer, the holes forming a void space and having a perforation shape factor and a strut angle configured to collapse the apposition layer in a first direction relative to a second direction;

a first layer adapted to be positioned below the apposition layer, the first layer having at least one perforation;

a second layer adapted to be positioned above the apposition layer, the second layer having at least one perforation;

a dressing adapted to cover the apposition layer to form a sealed space; and

a negative-pressure source adapted to be fluidly coupled to the sealed space to provide negative pressure to the sealed space;

wherein the apposition layer generates a closing force in the first direction that is substantially parallel to the surface of the tissue site to close the opening in response to application of the negative pressure.

2. The system ofclaim 1, wherein the first layer and the second layer each comprise a silicone adhesive.

3. The system ofclaim 1, wherein the first layer and the second layer each comprise a silicone adhesive having a coating weight between about 100 gsm and about 200 gsm.

4. The system ofclaim 1, wherein the first layer and the second layer each comprise a polyurethane material.

5. The system ofclaim 1, wherein the first layer and the second layer each comprise a hydrogel.

6. The system ofclaim 1, wherein the first layer and the second layer comprise a single, continuous sheet of material.

7. The system ofclaim 1, wherein the at least one perforation of the first layer comprises a plurality of perforations.

8. The system ofclaim 7, wherein the at least one perforation of the second layer comprises a plurality of perforations.

9. The system ofclaim 1, wherein the at least one perforation of the second layer comprises a plurality of perforations.

10. The system ofclaim 1, wherein the plurality of holes have an average effective diameter of about 5 mm.

11. The system ofclaim 1, wherein the plurality of holes are formed in two or more parallel rows.

12. The system ofclaim 1, wherein the strut angle is about 90 degrees.

13. The system ofclaim 1, wherein the strut angle is less than about 90 degrees.

14. The system ofclaim 1, wherein the perforation shape factor of each hole is less than about 1.

15. The system ofclaim 1, wherein a thickness of the apposition layer is about 15 mm.

16. The system ofclaim 1, wherein the firmness factor is about 5.

17. The system ofclaim 1, wherein the firmness factor is about 3.

18. The system ofclaim 1, wherein a shape of each hole of the plurality of holes is elliptical.

19. The system ofclaim 1, wherein the apposition layer comprises a felted foam.

20. The system ofclaim 1, wherein the dressing comprises:

a base layer having a plurality of apertures extending through the base layer, at least a portion of the plurality of apertures configured to transmit fluid across the base layer;

a fluid management assembly positioned over the base layer, the fluid management assembly comprising:

a first wicking layer;

an absorbent disposed over the first wicking layer, and

a second wicking layer disposed over the absorbent and having a periphery coupled to a periphery of the first wicking layer to enclose the absorbent;

a sealing member disposed over the fluid management assembly; and

an adhesive layer positioned between a periphery of the base layer and the sealing member, the adhesive layer coupling the base layer to the sealing member to enclose the fluid management assembly.

21. The system ofclaim 20, wherein the plurality of apertures in the base layer comprise:

a first group of apertures disposed in a center portion of the base layer and having a first diameter;

a second group of apertures disposed in a perimeter portion of the base layer and having a second diameter, the first group of apertures and the second group of apertures separated by a border; and

the second group of apertures having an average diameter that is larger than the average diameter of the first group of apertures.

22. An apparatus for closing an opening through a surface of a tissue site, the apparatus comprising:

an contracting layer adapted to be positioned over the opening, the contracting layer comprising:

a material having a firmness factor, and

a plurality of holes extending through the contracting layer, the holes forming a void space and having a perforation shape factor and a strut angle configured to collapse the contracting layer in a first direction relative to a second direction;

a lower layer adapted to be positioned below the contracting layer, the lower layer having at least one perforation; and

an upper layer adapted to be positioned above the contracting layer, the upper layer having at least one perforation;

wherein the contracting layer generates a closing force substantially parallel to the surface of the tissue site to close the opening in response to application of a negative pressure.

23. The apparatus ofclaim 22, wherein the lower layer and the upper layer each comprise a silicone adhesive.

24. The apparatus ofclaim 22, wherein the lower layer and the upper layer each comprise a silicone adhesive having a coating weight between about 100 gsm and about 200 gsm.

25. The apparatus ofclaim 22, wherein the lower layer and the upper layer each comprise a polyurethane material.

26. The apparatus ofclaim 22, wherein the lower layer and the upper layer each comprise a hydrogel.

27. The apparatus ofclaim 22, wherein the lower layer and the upper layer comprise a single, continuous sheet of material.

28. The apparatus ofclaim 22, wherein the at least one perforation of the lower layer comprises a plurality of perforations.

29. The apparatus ofclaim 28, wherein the at least one perforation of the upper layer comprises a plurality of perforations.

30. The apparatus ofclaim 22, wherein the at least one perforation of the upper layer comprises a plurality of perforations.

31. The apparatus ofclaim 22, wherein the plurality of holes have an average effective diameter of about 5 mm.

32. The apparatus ofclaim 22, wherein the plurality of holes are formed in two or more parallel rows.

33. The apparatus ofclaim 22, wherein the strut angle is about 90 degrees.

34. The apparatus ofclaim 22, wherein the strut angle is less than about 90 degrees.

35. The apparatus ofclaim 22, wherein the perforation shape factor of each hole is less than about 1.

36. The apparatus ofclaim 22, wherein a thickness of the contracting layer is about 15 mm.

37. The apparatus ofclaim 22, wherein the firmness factor is about 5.

38. The apparatus ofclaim 22, wherein the firmness factor is about 3.

39. The apparatus ofclaim 22, wherein a shape of each hole of the plurality of holes is elliptical.

40. The apparatus ofclaim 22, wherein the contracting layer comprises a compressed foam.

41. The apparatus ofclaim 22, further comprising a dressing configured to form a sealed space over the contracting layer, the dressing comprising:

a base layer having a plurality of apertures extending through the base layer, at least a portion of the plurality of apertures configured to transmit fluid across the base layer;

a fluid management assembly positioned over the base layer, the fluid management assembly comprising:

a first wicking layer;

an absorbent disposed over the first wicking layer, and

a second wicking layer disposed over the absorbent and having a periphery coupled to a periphery of the first wicking layer to enclose the absorbent;

a sealing member disposed over the fluid management assembly; and

an adhesive layer positioned between a periphery of the base layer and the sealing member, the adhesive layer coupling the base layer to the sealing member to enclose the fluid management assembly.

42. The apparatus ofclaim 41, wherein the plurality of apertures in the base layer comprise:

a first group of apertures disposed in a center portion of the base layer and having a first diameter;

a second group of apertures disposed in a perimeter portion of the base layer and having a second diameter, the first group of apertures and the second group of apertures separated by a border; and

the second group of apertures having an average diameter that is larger than the average diameter of the first group of apertures.

43. A method for closing an opening through a surface of a tissue site, the method comprising:

encapsulating an apposition layer in a sheet having an upper layer above the apposition layer and a lower layer below the apposition layer, the sheet having at least one perforation in the upper layer and at least one perforation in the lower layer;

positioning the apposition layer over the opening, the apposition layer adapted to be positioned adjacent the opening and formed from a material having a firmness factor and a plurality of holes extending through the apposition layer to form a void space, the holes having a perforation shape factor and a strut angle causing the apposition layer to collapse in a direction substantially perpendicular to the opening; and

collapsing the apposition layer parallel to the surface of the tissue site to generate a closing force.

44. The method ofclaim 43, further comprising:

positioning a sealing member over the apposition layer;

sealing the sealing member to tissue surrounding the tissue site to form a sealed space; and

fluidly coupling a negative-pressure source to the sealed space.

45. The method ofclaim 44, wherein collapsing the apposition layer comprises:

supplying negative pressure to the sealed space with the negative-pressure source.

46. The method ofclaim 45, wherein collapsing the apposition layer comprises:

supplying negative pressure to the apposition layer.

47. The method ofclaim 45, wherein collapsing the apposition layer comprises:

collapsing the apposition layer in response to a supply of negative pressure; and

drawing edges of the apposition layer toward a center of the apposition layer in response to the collapse of the holes of the apposition layer.

48. (canceled)

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