Patent Description:
There is also widespread acceptance that cleansing a tissue site can be highly beneficial for new tissue growth. For example, a wound or a cavity can be washed out with a liquid solution for therapeutic purposes. These practices are commonly referred to as "irrigation" and "lavage" respectively. "Instillation" is another practice that generally refers to a process of slowly introducing fluid to a tissue site and leaving the fluid for a prescribed period of time before removing the fluid. For example, instillation of topical treatment solutions over a wound bed can be combined with negative-pressure therapy to further promote wound healing by loosening soluble contaminants in a wound bed and removing infectious material. As a result, soluble bacterial burden can be decreased, contaminants removed, and the wound cleansed.

While the clinical benefits of negative-pressure therapy and/or instillation therapy are widely known, improvements to therapy systems, components, and processes may benefit healthcare providers and patients.

New and useful dressings and systems for treating tissue in a negative-pressure therapy environment 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, in some embodiments, a dressing for treating tissue may be a composite of dressing layers, including a contact layer, a manifold layer, and an adhesive drape. The contact layer may include a perforated polymer film in some embodiments. The manifold layer may include a manifold having one or more of strips of spacer fabric in or coupled to the manifold in some examples. The manifold may include an open-cell foam in some examples. The one or more strips of spacer fabric may be inlaid partially or fully transverse in the manifold. In some examples, the one or more strips of spacer fabric may extend parallel across the manifold. In other examples, the one or more strips of spacer fabric may extend in one or more angles across the manifold. The strips of spacer fabric may allow for controlled contraction of the dressing in a manner that is tunable. In some embodiments, the dressing may be coupled to the patient such that the strips of spacer fabric may be oriented parallel to a tissue site, such as a linear wound. A negative pressure may be applied to the manifold layer and the strips of spacer fabric may promote medial or lateral contraction of the dressing to pull the linear wound closed. The lateral contraction of the dressing provided by the strips of spacer fabric may be propagated to tissue underlying the linear wound, reducing the chance of dehiscence and drawing the wound or edges of an incision together. Embodiments of the dressing may allow for a reduction in healing complications and promote healing of the tissue site. In some embodiments, the strips of spacer fabric may allow for preferential contraction in certain areas of the dressing to allow the dressing to conform around specific geometries or anatomies.

The dressing includes a manifold and a spacer fabric. The manifold has a first side configured to face the tissue site, a second side opposite the first side, a thickness between the first side and the second side, a first portion, and a second portion. The spacer fabric extends between the first portion and the second portion and comprises a first layer coupled to the first portion, a second layer coupled to the second portion, and a spacer layer extending between the first layer and the second layer. The first layer and the second layer are perpendicular to the first side of the manifold.

Some embodiments not according to the invention of a dressing may include a manifold having a first side configured to face a tissue site, a second side opposite the first side, and a thickness between the first side and the second side. The dressing may further include a channel extending into the manifold on the second side and having a depth measured from the second side. A spacer fabric may be disposed in the channel, wherein the spacer fabric may comprise a first layer, a second layer, and a spacer layer extending between the first layer and the second layer. The first layer and the second layer may be perpendicular to the first side of the manifold.

Other embodiments not according to the invention of a dressing for treating a tissue site with negative pressure may include a tissue interface comprising two or more strips of spacer fabric and a manifold between each strip of spacer fabric. In some embodiments, the two or more strips of spacer fabric may be at an angle relative to one another. In some embodiments, the two or more strips of spacer fabric may be configured to bias against contraction of the manifold parallel to the strips of spacer fabric.

Yet other embodiments not according to the invention of a dressing for use in treating a tissue site with negative pressure may comprise a manifold and a connective structure. The manifold may have a first side configured to face the tissue site, a second side opposite the first side, a thickness between the first side and the second side, a first portion, and a second portion. The connective structure may be coupled to the first portion and the second portion and may extend in an extension direction across the manifold. The dressing may be configured to anisotropically contract such that the dressing may be configured to contract more in a first direction than in a second direction, wherein the first direction is perpendicular to the extension direction of the connective structure.

A system for treating a tissue site with negative pressure is also described herein, wherein the system comprises a dressing, a fluid conductor configured to be fluidly coupled to the dressing, and a negative-pressure source configured to be fluidly coupled to the fluid conductor. The dressing comprises a manifold, a spacer fabric, and a cover. The manifold has a first side configured to face the tissue site, a second side opposite the first side, a thickness between the first side and the second side, a first portion, and a second portion. The spacer fabric extends between the first portion and the second portion and comprises a first layer coupled to the first portion, a second layer coupled to the second portion, and a spacer layer extending between the first layer and the second layer. The first layer and the second layer are perpendicular to the first side of the manifold. The cover is configured to be disposed over the manifold and the spacer fabric.

A method for treating a tissue site with negative pressure not according to the invention is also described herein, wherein some example embodiments include applying a tissue interface to the tissue site, covering the tissue interface with a cover to form a sealed space containing the tissue interface, fluidly coupling a fluid conductor to the tissue interface, fluidly coupling the fluid conductor to a negative-pressure source, and applying negative pressure from the negative-pressure source to the tissue interface through fluid conductor. The tissue interface may comprise a manifold and a spacer fabric. The manifold may have a first side configured to face the tissue site, a second side opposite the first side, a thickness between the first side and the second side, a first portion, and a second portion. The spacer fabric may extend between the first portion and the second portion and may comprise a first layer coupled to the first portion, a second layer coupled to the second portion, and a spacer layer extending between the first layer and the second layer. The first layer and the second layer may be perpendicular to the first side of the manifold. The method may further comprise contracting the tissue interface in response to an application of negative pressure to the tissue interface, wherein the tissue interface is configured to anisotropically contract such that the tissue interface is configured to contract more in a first direction than in a second direction, wherein the first direction is perpendicular to an extension direction of the spacer fabric.

Other 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.

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

The term "tissue site" in this context broadly refers to a wound, defect, or other treatment target located on or within tissue, including but not limited to, a surface wound, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. The term "tissue site" may also refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it may be desirable to add or promote the growth of additional tissue. For example, negative pressure may be applied to a tissue site to grow additional tissue that may be harvested and transplanted. A surface wound, as used herein, is a wound on a body that is exposed to the external environment, such as an injury or damage to the epidermis, dermis, and/or subcutaneous layers. Surface wounds may include ulcers or closed incisions, for example. A surface wound, as used herein, does not include wounds within an intra-abdominal cavity. A wound may include chronic, acute, traumatic, subacute, and dehisced wounds, partial-thickness burns, ulcers (such as diabetic, pressure, or venous insufficiency ulcers), flaps, and grafts, for example.

The therapy system <NUM> may include a source or supply of negative pressure, such as a negative-pressure source <NUM>, and one or more distribution components. A distribution component is preferably detachable and may be disposable, reusable, or recyclable. A dressing, such as a dressing <NUM>, and a fluid container, such as a container <NUM>, are examples of distribution components that may be associated with some examples of the therapy system <NUM>. As illustrated in the example of <FIG>, the dressing <NUM> may comprise or consist essentially of a tissue interface <NUM>, a cover <NUM>, or both in some embodiments.

The therapy system <NUM> may also include a source of instillation solution. For example, a solution source <NUM> may be fluidly coupled to the dressing <NUM>, as illustrated in the example embodiment of <FIG>. The solution source <NUM> may be fluidly coupled to a positive-pressure source, such as a positive-pressure source <NUM>, a negative-pressure source such as the negative-pressure source <NUM>, or both in some embodiments. A regulator, such as an instillation regulator <NUM>, may also be fluidly coupled to the solution source <NUM> and the dressing <NUM> to ensure proper dosage of instillation solution (e.g. saline) to a tissue site. For example, the instillation regulator <NUM> may comprise a piston that can be pneumatically actuated by the negative-pressure source <NUM> to draw instillation solution from the solution source during a negative-pressure interval and to instill the solution to a dressing during a venting interval. Additionally or alternatively, the controller <NUM> may be coupled to the negative-pressure source <NUM>, the positive-pressure source <NUM>, or both, to control dosage of instillation solution to a tissue site. In some embodiments, the instillation regulator <NUM> may also be fluidly coupled to the negative-pressure source <NUM> through the dressing <NUM>, as illustrated in the example of <FIG>.

Some components of the therapy system <NUM> 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 source <NUM> may be combined with the controller <NUM>, the solution source <NUM>, and other components into a therapy unit.

A negative-pressure supply, such as the negative-pressure source <NUM>, may be a reservoir of air at a negative pressure or may be a manual or electrically-powered device, such as a vacuum pump, a suction pump, a wall suction port available at many healthcare facilities, or a micro-pump, for example. "Negative pressure" generally refers to a pressure less than a local ambient pressure, such as the ambient pressure in a local environment external to a sealed therapeutic environment. In many cases, the local ambient pressure may also be the atmospheric pressure at which a tissue site is located. Alternatively, the pressure may be less than a hydrostatic pressure associated with tissue at the tissue site. Unless otherwise indicated, values of pressure stated herein are gauge pressures. References to increases in negative pressure typically refer to a decrease in absolute pressure, while decreases in negative pressure typically refer to an increase in absolute pressure. While the amount and nature of negative pressure provided by the negative-pressure source <NUM> may vary according to therapeutic requirements, the pressure is generally a low vacuum, also commonly referred to as a rough vacuum, between -<NUM> Hg (-<NUM> Pa) and -<NUM> Hg (-<NUM> kPa). Common therapeutic ranges are between -<NUM> Hg (-<NUM> kPa) and -<NUM> Hg (-<NUM> kPa).

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

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

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

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

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

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

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

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

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

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

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

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

In some embodiments, the controller <NUM> may receive and process data, such as data related to instillation solution provided to the tissue interface <NUM>. Such data may include the type of instillation solution prescribed by a clinician, the volume of fluid or solution to be instilled to a tissue site ("fill volume"), and the amount of time prescribed for leaving solution at a tissue site ("dwell time") before applying a negative pressure to the tissue site. The fill volume may be, for example, between <NUM> and <NUM>, and the dwell time may be between one second to <NUM> minutes. The controller <NUM> may also control the operation of one or more components of the therapy system <NUM> to instill solution. For example, the controller <NUM> may manage fluid distributed from the solution source <NUM> to the tissue interface <NUM>. In some embodiments, fluid may be instilled to a tissue site by applying a negative pressure from the negative-pressure source <NUM> to reduce the pressure at the tissue site, drawing solution into the tissue interface <NUM>. In some embodiments, solution may be instilled to a tissue site by applying a positive pressure from the positive-pressure source <NUM> to move solution from the solution source <NUM> to the tissue interface <NUM>. Additionally or alternatively, the solution source <NUM> may be elevated to a height sufficient to allow gravity to move solution into the tissue interface <NUM>.

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

<FIG> is an exploded view of an example of the tissue interface <NUM> of <FIG>, illustrating additional details that may be associated with some embodiments in which the tissue interface <NUM> comprises more than one layer. In the example of <FIG>, the tissue interface comprises a first layer, such as a contact layer <NUM>, and a second layer, such as a manifold layer <NUM>. In some embodiments, the contact layer <NUM> may be disposed adjacent to the manifold layer <NUM>. For example, the contact layer <NUM> and the manifold layer <NUM> may be stacked so that the contact layer <NUM> is in contact with the manifold layer <NUM>. The contact layer <NUM> may also be heat-bonded or adhered to the manifold layer <NUM> in some embodiments. In some embodiments, the contact layer <NUM> optionally includes a low-tack adhesive, which can be configured to hold the tissue interface <NUM> in place while the cover <NUM> is applied. The low-tack adhesive may be continuously coated on the contact layer <NUM> or applied in a pattern.

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

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

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

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

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

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

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

The manifold layer <NUM> generally comprises or consists essentially of a manifold <NUM> and one or more strips of spacer fabric <NUM> coupled to the manifold <NUM>. The manifold <NUM> can provide a means for collecting or distributing fluid across the tissue interface <NUM> under pressure. For example, the manifold <NUM> may be adapted to receive negative pressure from a source and distribute negative pressure through multiple apertures across the tissue interface <NUM>, which may have the effect of collecting fluid from across a tissue site and drawing the fluid toward the source. In some embodiments, the fluid path may be reversed or a secondary fluid path may be provided to facilitate delivering fluid, such as from a source of instillation solution, across the tissue interface <NUM>.

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

In some embodiments, the manifold <NUM> may comprise or consist essentially of a reticulated foam having pore sizes and free volume that may vary according to needs of a prescribed therapy. For example, a reticulated foam having a free volume of at least <NUM>% may be suitable for many therapy applications, and a foam having an average pore size in a range of <NUM>-<NUM> microns may be particularly suitable for some types of therapy. The tensile strength of the manifold <NUM> 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. The <NUM>% compression load deflection of the manifold <NUM> may be at least <NUM> pounds per square inch, and the <NUM>% compression load deflection may be at least <NUM> pounds per square inch. In some embodiments, the tensile strength of the manifold <NUM> may be at least <NUM> pounds per square inch. The manifold <NUM> may have a tear strength of at least <NUM> pounds per inch. In some embodiments, the manifold <NUM> may be a foam comprised of polyols such as polyester or polyether, isocyanate such as toluene diisocyanate, and polymerization modifiers such as amines and tin compounds. In some examples, the manifold layer <NUM> may be a reticulated polyurethane foam such as used in GRANUFOAM™ dressing or V. VERAFLO™ dressing, both available from KCI of San Antonio, Texas.

As further shown in <FIG>, the manifold <NUM> includes a first side <NUM> configured to face a tissue site, a second side <NUM> opposite the first side <NUM>, and a thickness TM between the first side <NUM> and the second side <NUM>. In some embodiments, the manifold <NUM> may comprise one or more manifold portions <NUM>. In some embodiments, the manifold portions <NUM> may be connected to one another. In other embodiments, the manifold portions <NUM> may be discontinuous.

<FIG> and <FIG> illustrate an example of the manifold layer <NUM> that can be associated with some embodiments of the tissue interface <NUM> of <FIG>. <FIG> is a top view of the manifold layer <NUM>. <FIG> is a top detail view of the manifold layer <NUM> of <FIG>. As shown in <FIG>, the manifold <NUM> may have a length LM and a width WM. The strips of spacer fabric <NUM> may extend across the manifold <NUM> in an extension direction DE. In some embodiments, the extension direction DE of the strips of spacer fabric <NUM> may be parallel to the width WM of the manifold <NUM>. In some embodiments, extension direction DE of the strips of spacer fabric <NUM> may be at an angle with respect to the width WM of the manifold <NUM>. As shown in the example of <FIG>, in some embodiments, the strips of spacer fabric <NUM> may be parallel to one another and may be parallel to the width WM of the manifold <NUM>. In some embodiments, the strips of spacer fabric <NUM> may be parallel to one another and may be at an angle with respect to the width WM of the manifold <NUM>.

Each strip of spacer fabric <NUM> may comprise a first layer <NUM>, a second layer <NUM>, and a spacer layer <NUM> extending between the first layer <NUM> and the second layer <NUM>. Each strip of spacer fabric <NUM> may have a thickness TS from the first layer <NUM> to the second layer <NUM>. The first layer <NUM> may comprise a first fabric and the second layer <NUM> may comprise a second fabric. For example, the first layer <NUM> and the second layer <NUM> may each comprise a knit fabric. In some embodiments, the first layer <NUM> and the second layer <NUM> may each comprise a woven fabric. For example, the first layer <NUM> and the second layer <NUM> may each comprise a warp knitted fabric using one or more yarns. In some embodiments, the first layer <NUM> and the second layer <NUM> may comprise polyester yarn.

The first layer <NUM> and the second layer <NUM> may comprise multifilament yarns. For example, in some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have about <NUM> to about <NUM> filaments. In some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have about <NUM> to about <NUM> filaments. In some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have about <NUM> filaments. In some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have about <NUM> filaments. In some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have about <NUM> filaments. In some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have about <NUM> filaments.

In some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have a denier per filament of about <NUM> to about <NUM>. In some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have a denier per filament of about <NUM>. In some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have a denier per filament of about <NUM>. In some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have a denier per filament of about <NUM>. In some embodiments, the multifilament yarns used to form the first layer <NUM> and the second layer <NUM> may have a denier per filament of about <NUM>.

The first layer <NUM> and the second layer <NUM> may each have a thickness of about <NUM> inches to about <NUM> inches. In some embodiments, the first layer <NUM> and the second layer <NUM> may each have a thickness of about <NUM> inches. In some embodiments, the first layer <NUM> and the second layer <NUM> may each have a thickness of about <NUM> inches. In some embodiments, the first layer <NUM> and the second layer <NUM> may each have a thickness of about <NUM> inches. In some embodiments, the first layer <NUM> and the second layer <NUM> may each have a thickness of about <NUM> inches.

The first layer <NUM> and the second layer <NUM> may each have a weight per unit area of about <NUM> ounces/yard<NUM> to about <NUM> ounces/yard<NUM>. In some embodiments, the first layer <NUM> and the second layer <NUM> may each have a weight per unit area of about <NUM> ounces/yard<NUM>. In some embodiments, the first layer <NUM> and the second layer <NUM> may each have a weight per unit area of about <NUM> ounces/yard<NUM>. In some embodiments, the first layer <NUM> and the second layer <NUM> may each have a weight per unit area of about <NUM> ounces/yard<NUM>. In some embodiments, the first layer <NUM> and the second layer <NUM> may each have a weight per unit area of about <NUM> ounces/yard<NUM>.

As shown in the example of <FIG>, the spacer layer <NUM> may comprise one or more pile yarns <NUM> extending between the first layer <NUM> and the second layer <NUM>. The pile yarns <NUM> may be interknitted with the first layer <NUM> and the second layer <NUM>. The first layer <NUM> and the second layer <NUM> may be integrated with one another by the pile yarns <NUM>. In some embodiments, the first layer <NUM> and the second layer <NUM> may be connected by a single pile yarn <NUM>. In some embodiments, each pile yarn <NUM> comprises monofilament yarn. In some embodiments, the pile yarn <NUM> may comprise polyester yarn. In some embodiments, the pile yarn <NUM> may have a denier per filament of about <NUM> to about <NUM>. In some embodiments, the pile yarn <NUM> may have a denier per filament of about <NUM>. In some embodiments, the pile yarn <NUM> may have a denier per filament of about <NUM>. In some embodiments, the pile yarn <NUM> may have a denier per filament of about <NUM>. In some embodiments, the pile yarn <NUM> may have a denier per filament of about <NUM>.

In some embodiments, the first layer <NUM> and the second layer <NUM> may comprise multifilament polyester yarn having <NUM> filaments with a denier per filament of <NUM> and the pile yarn <NUM> may comprise a monofilament polyester yarn having a denier per filament of <NUM>. In some embodiments, the first layer <NUM> and the second layer <NUM> may comprise multifilament polyester yarn having <NUM> filaments with a denier per filament of <NUM> and the pile yarn <NUM> may comprise a monofilament polyester yarn having a denier per filament of <NUM>. In some embodiments, the first layer <NUM> and the second layer <NUM> may comprise multifilament polyester yarn having <NUM> filaments with a denier per filament of <NUM> and the pile yarn <NUM> may comprise a monofilament polyester yarn having a denier per filament of <NUM>. In some embodiments, the first layer <NUM> and the second layer <NUM> may comprise multifilament polyester yarn having <NUM> filaments with a denier per filament of <NUM> and the pile yarn <NUM> may comprise a monofilament polyester yarn having a denier per filament of <NUM>.

The one or more strips of spacer fabric <NUM> may be connective structures that couple the manifold portions <NUM> together. There may be a manifold portion <NUM> between each strip of spacer fabric <NUM>. The first layer <NUM> and the second layer <NUM> of each strip of spacer fabric <NUM> may be coupled to the manifold <NUM> in a variety of ways. For example, in some embodiments, the first layer <NUM> and the second layer <NUM> may be coupled to the manifold <NUM> with glue. In some embodiments, the first layer <NUM> and the second layer <NUM> may be coupled to the manifold <NUM> using a hot melt adhesive. In some embodiments, the first layer <NUM> and the second layer <NUM> may be welded to the manifold <NUM> using heat, radio frequency (RF) welding, or other methods to generate heat such as ultrasonic welding.

<FIG> is a side view of the manifold layer <NUM> of <FIG>. <FIG> is a detail view of the manifold layer <NUM> of <FIG>. As illustrated in <FIG> and <FIG>, in some embodiments, the first layer <NUM> and the second layer <NUM> of each strip of spacer fabric <NUM> may be oriented perpendicular to the first side <NUM> and the second side <NUM> of the manifold <NUM>. The first layer <NUM> may form a first side of the strip of spacer fabric <NUM> and the second layer <NUM> may form a second side of the strip of spacer fabric <NUM>. The first side of each strip of spacer fabric <NUM> may be positioned perpendicular to the first side <NUM> and the second side <NUM> of the manifold <NUM>. The second side of each strip of spacer fabric <NUM> may be positioned perpendicular to the first side <NUM> and the second side <NUM> of the manifold <NUM>. The first layer <NUM> and the second layer <NUM> of each strip of spacer fabric <NUM> may be positioned in a plane parallel to the thickness TM of the manifold <NUM>. The spacer layer <NUM> may maintain the first layer <NUM> and the second layer <NUM> in a spaced-apart parallel relation. As shown in <FIG>, the thickness TS of each strip of spacer fabric <NUM> may be perpendicular to the thickness TM of the manifold <NUM>.

Referring again to <FIG>, in some embodiments, the one or more strips of spacer fabric <NUM> may function as a manifold, for example, the spacer fabric <NUM> may be adapted to receive negative pressure from a source and distribute negative pressure through and/or between the first layer <NUM>, the second layer <NUM>, and the pile yarns <NUM>. In some embodiments, if the manifold layer <NUM> is subjected to negative pressure, fluid may be removed from between the first layer <NUM> and the second layer <NUM> of each spacer fabric <NUM>, drawing the first layer <NUM> and the second layer <NUM> toward one another, and reducing the thickness TS between the first layer <NUM> and the second layer <NUM>. Any manifold portions <NUM> coupled to the strips of spacer fabric <NUM> are likewise configured to be drawn toward one another if the manifold layer <NUM> is subjected to negative pressure. In some embodiments, the each of the strips of spacer fabric <NUM> may be more rigid along the extension direction DE than in a direction perpendicular to the extension direction DE, the first layer <NUM>, and the second layer <NUM>. The strips of spacer fabric <NUM> may be configured to resist contraction parallel to the extension direction DE and may direct contraction perpendicular to the extension direction DE. If a manifold is subjected to negative pressure, it may tend to collapse or contract in all directions. The one or more strips of spacer fabric <NUM> may provide anisotropic properties to the manifold layer <NUM>. In some embodiments, the manifold layer <NUM> may be configured to anisotropically contract such that the manifold layer <NUM> contracts more in a first direction than in a second direction, wherein the first direction is perpendicular to the extension direction DE of the strip of spacer fabric <NUM>. As shown in the example of <FIG>, wherein the extension direction DE of the strip of spacer fabric <NUM> is parallel to the width WM of the manifold <NUM>, the strip of spacer fabric <NUM> may be configured to bias against contraction of the manifold <NUM> parallel to the width WM of the manifold <NUM> and the strip of spacer fabric <NUM> may be configured to direct contraction of the manifold perpendicular to the width WM of the manifold <NUM>. The one or more strips of spacer fabric <NUM> may cause greater contraction along the length LM of the manifold <NUM> than along the width WM of the manifold <NUM>.

The properties of the one or more strips of spacer fabric <NUM> may be selected to tune the performance of the manifold layer <NUM> as desired for a particular therapy. For example, the anisotropic properties of the manifold layer <NUM> can be increased or decreased by modifying one or more of the thickness of the first layer <NUM> and the second layer <NUM>, the thickness TS between the first layer <NUM> and the second layer <NUM>, and the filament material, the number of filaments, the weight of the filaments, and the denier per filament used to manufacture the first layer <NUM>, the second layer <NUM>, and the pile yarn <NUM>.

<FIG> and <FIG> illustrate another example of the manifold layer <NUM> that can be associated with some embodiments of the tissue interface <NUM> of <FIG>. <FIG> is an exploded view of an example of the manifold layer <NUM>. <FIG> is an assembled detail side view of the manifold layer <NUM>. As shown in <FIG>, in some embodiments, the manifold <NUM> may include one or more channels <NUM> extending into the manifold <NUM> on the second side <NUM>. The channel <NUM> may include a first wall <NUM>, a second wall <NUM> opposite the first wall <NUM> and a base wall <NUM> extending between the first wall <NUM> and the second wall <NUM>. The first wall <NUM> and the second wall <NUM> may be perpendicular to the first side <NUM> and the second side <NUM> of the manifold <NUM>. The first wall <NUM> and the second wall <NUM> may be parallel to the thickness TM of the manifold <NUM>. The base wall <NUM> may be parallel to the first side <NUM> and the second side <NUM> of the manifold <NUM>. The base wall <NUM> may be perpendicular to the thickness TM of the manifold <NUM>.

The channel <NUM> may have a width WC measured between the first wall <NUM> and the second wall <NUM>. The channel <NUM> may have a depth DC measured from the second side <NUM> of the manifold <NUM> to the base wall <NUM> of the channel <NUM>. In some embodiments, the depth DC of the channel <NUM> may be less than the thickness TM of the manifold <NUM>. For example, the depth DC of the channel <NUM> may be about <NUM>% of the thickness TM of the manifold <NUM>. In another example, the depth DC of the channel <NUM> may be about <NUM>% of the thickness TM of the manifold <NUM>. In yet another example, the depth DC of the channel <NUM> may be about <NUM>% of the thickness TM of the manifold <NUM>. In yet another example, the depth DC of the channel <NUM> may be about <NUM>% of the thickness TM of the manifold <NUM>. In some embodiments, the depth DC of the channel <NUM> may be equal to the thickness TM of the manifold <NUM>. In embodiments where the depth DC of the channel <NUM> is equal to the thickness TM of the manifold <NUM>, the channel <NUM> has no base wall <NUM> and forms a cut through the manifold <NUM>. The thickness TS of the strip of spacer fabric <NUM> may be equal to the width WC of the channel <NUM>. The strip of spacer fabric <NUM> may have a depth DS, which, in some embodiments, may be equal to the depth DC of the channel <NUM>.

As illustrated in <FIG>, the strip of spacer fabric <NUM> may be disposed in the channel <NUM>, with the first layer <NUM> of the strip of spacer fabric <NUM> coupled to the first wall <NUM> of the channel <NUM> and the second layer <NUM> of the strip of spacer fabric <NUM> coupled to the second wall <NUM> of the channel <NUM>. In some embodiments, the strip of spacer fabric <NUM> may be coextensive with the channel <NUM>.

<FIG> is a top view of another example of the manifold layer <NUM> that can be associated with some embodiments of the tissue interface <NUM> of <FIG>. In some embodiments, the manifold layer <NUM> may include a plurality of strips of spacer fabric <NUM> wherein some or all of the strips of spacer fabric <NUM> are oriented at an angle with respect to one another. For example, as shown in <FIG>, the manifold layer <NUM> may include a first strip of spacer fabric 225a, a second strip of spacer fabric 225b, a third strip of spacer fabric 225c, a fourth strip of spacer fabric 225d, and a fifth strip of spacer fabric 225e. The first strip of spacer fabric 225a may be at an angle Θ<NUM> with respect to the second strip of spacer fabric 225b, the second strip of spacer fabric 225b may be at an angle Θ<NUM> with respect to the third strip of spacer fabric 225c, the third strip of spacer fabric 225c may be at an angle Θ<NUM> with respect to the fourth strip of spacer fabric 225d, and the fourth strip of spacer fabric 225d may be at an angle Θ<NUM> with respect to the fifth strip of spacer fabric 225e. In some embodiments, some or all of the angles Θ<NUM>, Θ<NUM>, Θ<NUM>, Θ<NUM>, may be equal. In some embodiments, some or all of the angles Θ<NUM>, Θ<NUM>, Θ<NUM>, Θ<NUM>, may be different. In some embodiments, the first strip of spacer fabric 225a, the second strip of spacer fabric 225b, the third strip of spacer fabric 225c, the fourth strip of spacer fabric 225d, and the fifth strip of spacer fabric 225e may be identical to the strip of spacer fabric <NUM>. In some embodiments, the first strip of spacer fabric 225a, the second strip of spacer fabric 225b, the third strip of spacer fabric 225c, the fourth strip of spacer fabric 225d, and the fifth strip of spacer fabric 225e may all have the same properties (e.g., the thickness of the first layer <NUM> and the second layer <NUM>, the thickness TS of the strip of spacer fabric <NUM>, and the filament material, the number of filaments, the weight of the filaments, and the denier per filament used to manufacture the first layer <NUM>, the second layer <NUM>, and the pile yarn <NUM>). In some embodiments, one or more of the first strip of spacer fabric 225a, the second strip of spacer fabric 225b, the third strip of spacer fabric 225c, the fourth strip of spacer fabric 225d, and the fifth strip of spacer fabric 225e may have different properties. The strips of spacer fabric <NUM> may be oriented in the manifold <NUM> in any way as may be desired for therapy. For example, a non-parallel arrangement of the strips of spacer fabric <NUM> may allow for preferential contraction in certain areas of the tissue interface <NUM> to allow the tissue interface <NUM> to conform around or to specific geometries or anatomies.

<FIG> and <FIG> illustrate another example of the manifold layer <NUM> that can be associated with some embodiments of the tissue interface <NUM> of <FIG>. <FIG> is a top view of another example of the manifold layer <NUM>. <FIG> is a side view of the manifold layer <NUM> of <FIG>. As shown in <FIG>, the manifold layer <NUM> may comprise or consist essentially of a plurality of strips of spacer fabric <NUM>, wherein each strip of spacer fabric <NUM> is coupled directly to one or more adjacent strips of spacer fabric <NUM>. For example, the first layer <NUM> of one strip of spacer fabric <NUM> may be coupled directly to the second layer <NUM> of an adjacent strip of spacer fabric <NUM>. As shown in <FIG>, the manifold layer <NUM> may have a first side <NUM> configured to face a tissue site, a second side <NUM> opposite the first side <NUM>, and a thickness between the first side <NUM> and the second side <NUM>, wherein the thickness is the depth DS of the spacer fabric <NUM>. The first layer <NUM> and the second layer <NUM> of each strip of spacer fabric <NUM> may be oriented perpendicular to the first side <NUM> and the second side <NUM> of the manifold layer <NUM>.

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

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

The cover <NUM>, the contact layer <NUM>, the manifold layer <NUM>, or various combinations may be assembled before application or in situ. For example, the contact layer <NUM> may be laminated to the manifold layer <NUM>, and the cover <NUM> may be laminated to the manifold layer <NUM> opposite the contact layer <NUM> in some embodiments. In some embodiments, one or more layers of the tissue interface <NUM> may coextensive. For example, the contact layer <NUM> and the manifold layer <NUM> may be cut flush with the edge of the cover <NUM>, exposing the edge of the manifold layer <NUM>. In other embodiments, the contact layer <NUM> may overlap the edge of the manifold layer <NUM>.

Referring now primarily to <FIG> and <FIG>, presented is another illustrative embodiment of a portion of the therapy system <NUM>. <FIG> and <FIG> depict the therapy system <NUM> assembled in stages at a tissue site, such as a linear wound <NUM>. In <FIG>, a closure device <NUM>, such as, for example, stitches <NUM>, close the linear wound <NUM>. Other closure devices <NUM>, such as epoxy or staples may be utilized to close the linear wound <NUM>. The linear wound <NUM> may include a portion through an epidermis <NUM>, dermis <NUM>, and subcutaneous tissue <NUM> of a patient.

Referring now to <FIG>, after the linear wound <NUM> is closed or prepared as described above, the dressing <NUM> may be disposed proximate to the linear wound <NUM>. The geometry and dimensions of the tissue interface <NUM>, the cover <NUM>, or both may vary to suit a particular application or anatomy. For example, the dressing <NUM> may be cut to size for a specific region or anatomical area, such as for amputations. The dressing <NUM> may be cut without losing pieces of the tissue interface <NUM> and without separation of the tissue interface <NUM>.

The tissue interface <NUM> can be placed over, on, or otherwise proximate to the linear wound <NUM>. In the example of <FIG>, the contact layer <NUM> forms an outer surface of the dressing <NUM>, and can be placed over the tissue site, including the linear wound <NUM> and epidermis <NUM>. The contact layer <NUM> may be interposed between the manifold layer <NUM> and the tissue site, which can prevent direct contact between the manifold layer <NUM> and the linear wound <NUM> and epidermis <NUM>. In some embodiments, the strips of spacer fabric <NUM> are oriented substantially parallel to the linear wound <NUM>. For example, the extension direction DE of the one or more strips of spacer fabric <NUM> may be substantially parallel to the linear wound <NUM>. In some embodiments, the tissue interface <NUM> may be placed on the tissue site, such that the linear wound <NUM> is between two strips of spacer fabric <NUM>. In other embodiments, the tissue interface <NUM> may be placed on the tissue site, such that a strip of spacer fabric <NUM> overlays the linear wound <NUM>.

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

The adhesive <NUM> can be disposed on a bottom side of the cover <NUM>, and the adhesive <NUM> may pressed onto the cover <NUM> and epidermis <NUM> (or other attachment surface) to fix the dressing <NUM> in position and to seal the tissue interface <NUM> over the patient. In some embodiments, the adhesive <NUM> can be disposed only around edges of the cover <NUM>.

<FIG> also illustrates one example of a fluid conductor <NUM> and a dressing interface <NUM>. As shown in the example of <FIG>, the fluid conductor <NUM> may be a flexible tube, which can be fluidly coupled on one end to the dressing interface <NUM>. The dressing interface <NUM> may be an elbow connector. In some examples, the tissue interface <NUM> can be applied to the tissue site before the cover <NUM> is applied over the tissue interface <NUM>. The cover <NUM> may include an aperture <NUM>, or the aperture <NUM> may be cut into the cover <NUM> before or after positioning the cover <NUM> over the tissue interface <NUM>. The position of the aperture <NUM> may be off-center or adjacent to an end or edge of the cover <NUM>. In other examples, the aperture <NUM> may be centrally disposed. The dressing interface <NUM> can be placed over the aperture <NUM> to provide a fluid path between the fluid conductor <NUM> and the tissue interface <NUM>. In other examples, the fluid conductor <NUM> may be inserted directly through the cover <NUM> into the tissue interface <NUM>.

If not already configured, the dressing interface <NUM> may be disposed over the aperture <NUM> and attached to the cover <NUM>. The fluid conductor <NUM> may be fluidly coupled to the dressing interface <NUM> and to the negative-pressure source <NUM>.

Negative pressure from the negative-pressure source <NUM> can be distributed through the fluid conductor <NUM> and the dressing interface <NUM> to the tissue interface <NUM>. The tissue interface <NUM> may contract in response to the application of negative pressure. In some embodiments, the manifold layer <NUM> of the tissue interface <NUM> is configured to anisotropically contract. For example, under an applied negative pressure, the manifold layer <NUM> may contract more in a first direction <NUM> than in a second direction <NUM>. The first direction <NUM> may be perpendicular to the extension direction DE of the one or more strips of spacer fabric <NUM>. The preferential contraction along the first direction <NUM> by the manifold layer <NUM> acts to pull the epidermis <NUM> toward the linear wound <NUM> aiding in closing the linear wound <NUM>.

The contact layer <NUM> can protect the epidermis <NUM> from irritation that could be caused by expansion, contraction, or other movement of the manifold layer <NUM>. The contact layer <NUM> can also substantially reduce or prevent exposure of a tissue site to the manifold layer <NUM>, which can inhibit growth of tissue into the manifold layer <NUM>.

Although the strips of spacer fabric <NUM> are shown oriented parallel to the linear wound <NUM> in <FIG>, it will be understood that in some embodiments, a tissue interface <NUM> may be applied to a tissue site wherein the one or more strips of spacer fabric <NUM> are oriented at an angle with respect to the linear wound <NUM>. For example, in some embodiments, the tissue interface <NUM> may be tuned to preferentially contract along the extension direction DE of the one or more strips of spacer fabric <NUM> by modifying the material properties of the spacer fabric <NUM> and/or the manifold <NUM>. In such embodiments, the strips of spacer fabric <NUM> may be oriented perpendicular to the linear wound <NUM> to aid in closure of the linear wound <NUM>.

The dressings and systems described herein may provide significant advantages over prior dressings. For example, closure of the linear wound <NUM> may be promoted by orienting the strips of spacer fabric <NUM> parallel to the linear wound <NUM> when the dressing <NUM> is applied to the tissue site. Contraction of the manifold layer <NUM> more in a first direction, perpendicular to the linear wound <NUM>, may be propagated by the manifold layer <NUM> and the cover <NUM> to the epidermis <NUM>, dermis <NUM>, and the subcutaneous tissue <NUM>. The anisotropic contraction provided by the spacer fabric may reduce the chance for dehiscence and aids in drawing the edges of the linear wound <NUM> together. The dressing <NUM> may reduce healing complications and may promote healing at the tissue site.

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

Claim 1:
A dressing for use in treating a tissue site with negative pressure, the dressing comprising:
a manifold (<NUM>) having a first side (<NUM>) configured to face the tissue site, a second side (<NUM>) opposite the first side (<NUM>), a thickness between the first side (<NUM>) and the second side (<NUM>), a first portion (<NUM>), and a second portion (<NUM>); and
a spacer fabric (<NUM>) extending between the first portion (<NUM>) and the second portion (<NUM>), the spacer fabric (<NUM>) comprising:
a first layer (<NUM>) coupled to the first portion (<NUM>);
a second layer (<NUM>) coupled to the second portion (<NUM>); and
a spacer layer (<NUM>) extending between the first layer (<NUM>) and the second layer (<NUM>);
wherein the first layer (<NUM>) and the second layer (<NUM>) are perpendicular to the first side (<NUM>) of the manifold.