Patent Description:
Treatment of wounds or other tissue with reduced 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," and "vacuum assisted closure," for example.

While the clinical benefits of negative-pressure therapy are widely known, the cost and complexity of negative-pressure therapy can be a limiting factor in its application, and the development and operation of negative-pressure systems, components, and processes continues to present significant challenges to manufacturers, healthcare providers, and patients. <CIT> discloses a releasable medical drape including a cover layer, pressure sensitive adhesive layer, and a soft-gel layer having a plurality of apertures.

The invention provides a drape according to claim <NUM>. A selection of optional features is set out in the dependent claims.

Illustrative embodiments are described in detail below with reference to the attached drawings, which are incorporated by reference herein, and wherein:.

<FIG> is a sectional view of an example embodiment of a negative-pressure therapy system <NUM> illustrating details that may be associated with some embodiments for treating a tissue site <NUM> with negative pressure. As shown in the illustrative embodiment of <FIG>, the negative-pressure therapy system <NUM> may include a dressing <NUM> fluidly coupled to a negative-pressure source <NUM>. In some embodiments, the negative-pressure source <NUM> may be fluidly coupled to the dressing <NUM> by a conduit, such as a tube <NUM>, and a connector, such as a connector <NUM>. The dressing <NUM> may generally include a drape, such as a drape <NUM>, and a tissue interface, such as a manifold <NUM>. The drape <NUM> may have a film layer <NUM>, a layer of a bonding adhesive <NUM>, and a mesh <NUM>. The drape <NUM> may be attached to an epidermis <NUM>.

In general, components of the negative-pressure therapy system <NUM> may be coupled directly or indirectly to each other. For example, the negative-pressure source <NUM> may be directly coupled to the connector <NUM> and indirectly coupled to the manifold <NUM> through the connector <NUM>. Components may be fluidly coupled to each other to provide a path for transferring fluids (such as, liquid, gas, or both liquid and gas) between the components.

In some embodiments, components may be fluidly coupled with a tube, such as the tube <NUM>, for example. A "tube," as used herein, broadly refers to a tube, pipe, hose, conduit, or other structure with one or more lumina adapted to convey fluids between two ends. 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 the manifold <NUM>, may be placed within, over, on, against, or otherwise adjacent to a tissue site. For example, the manifold <NUM> may be placed against the tissue site <NUM>, and the drape <NUM> may be placed over the manifold <NUM> and sealed to tissue proximate to the tissue site <NUM>. Tissue proximate to a tissue site is often undamaged epidermis peripheral to the tissue site. Thus, the drape <NUM> can provide a sealed therapeutic environment <NUM> proximate to the tissue site <NUM>. The sealed therapeutic environment <NUM> may be substantially isolated from the external environment, and the negative-pressure source <NUM> can reduce the pressure in the sealed therapeutic environment <NUM>. Negative pressure applied uniformly through a tissue interface in the sealed therapeutic environment <NUM> can induce macrostrain and microstrain in the tissue site <NUM>, as well as remove exudates and other fluids from the tissue site. The removed exudates and other fluids can be collected in a container and disposed of properly.

The fluid mechanics of using a negative-pressure source to reduce pressure in another component or location, such as within a sealed therapeutic environment <NUM>, 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. This orientation is generally presumed for purposes of describing various features and components of negative-pressure therapy systems herein. Thus, in the context of negative-pressure therapy, the term "downstream" typically implies something in a fluid path relatively closer to a negative-pressure source, and conversely, the term "upstream" implies something 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. However, a fluid path may also be reversed in some applications, such as by substituting a positive-pressure source, and this descriptive convention should not be construed as a limiting convention.

The term "tissue site" in this context broadly refers to a wound or 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, or ligaments. 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 tissue that are not necessarily wounded or defective, but are instead areas in which it may be desired to add or promote the growth of additional tissue. For example, negative pressure may be used in certain tissue areas to grow additional tissue that may be harvested and transplanted to another tissue location. In an illustrative embodiment, the tissue site <NUM> may be a wound that extends through the epidermis <NUM>, through a dermis <NUM>, and into subcutaneous tissue <NUM>.

"Negative pressure" generally refers to a pressure less than a local ambient pressure, such as the ambient pressure in a local environment external to the sealed therapeutic environment <NUM> provided by the drape <NUM>. In many cases, the local ambient pressure may also be the atmospheric pressure in a patient's vicinity. 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.

A negative-pressure source, 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 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 source may be housed within or used in conjunction with other components, such as sensors, processing units, alarm indicators, memory, databases, software, display devices, or operator interfaces that further facilitate negative-pressure therapy. While the amount and nature of negative pressure applied to a tissue site may vary according to therapeutic requirements, the pressure typically ranges between -<NUM> millimeters of mercury (mm Hg) (-<NUM> Pa) and -<NUM> Hg (-<NUM> kPa). Common therapeutic ranges are between -<NUM> Hg (-<NUM> kPa) and -<NUM> Hg (-<NUM> kPa).

A tissue interface, such as the manifold <NUM>, can generally be adapted to contact a tissue site or other layers of a dressing. A tissue interface may be partially or fully in contact with a tissue site. If a tissue site is a wound, for example, a tissue interface may partially or completely fill the wound, or may be placed over the wound. A tissue interface may take many forms, and may be 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 a tissue interface may be adapted to the contours of deep and irregular shaped tissue sites.

In some embodiments, a tissue interface may be a manifold, such as the manifold <NUM>. A "manifold" in this context generally includes any substance or structure providing a plurality of pathways adapted to collect or distribute fluid across a tissue site under negative pressure. For example, a manifold may be adapted to receive negative pressure from a source and distribute the negative pressure through multiple apertures across a tissue site, 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 across a tissue site.

In some illustrative embodiments, the pathways of a manifold may be channels interconnected to improve distribution or collection of fluids across a tissue site. 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 pathways. Liquids, gels, and other foams may also include or be cured to include apertures and flow channels. In some illustrative embodiments, a manifold may be a porous foam material having interconnected cells or pores adapted to uniformly (or quasi-uniformly) distribute negative pressure to a tissue site. The foam material may be either hydrophobic or hydrophilic. In one non-limiting example, a manifold may be an open-cell, reticulated polyurethane foam such as GranuFoam® dressing available from Kinetic Concepts, Inc.

In some embodiments, such as embodiments in which the manifold <NUM> may be made from a hydrophilic material, the manifold <NUM> may also wick fluid away from a tissue site while continuing to distribute negative pressure to the tissue site. The wicking properties of the manifold <NUM> 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. WhiteFoam® dressing available from Kinetic Concepts, Inc. 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.

A tissue interface may further promote granulation at a tissue site if pressure within a sealed therapeutic environment <NUM> is reduced. For example, any or all of the surfaces of the manifold <NUM> may have an uneven, coarse, or jagged profile that can induce microstrains and stresses at a tissue site if negative pressure is applied through the manifold <NUM>.

In some example embodiments, a tissue interface 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. The tissue interface may further serve as a scaffold for new cell-growth, or a scaffold material may be used in conjunction with the tissue interface to promote cell-growth. In general, a scaffold material may be a biocompatible or biodegradable 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.

In some embodiments, the drape <NUM> may provide a bacterial barrier and protection from physical trauma. The drape <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 be, 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. 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 about <NUM> microns to about <NUM> microns. For permeable materials, the permeability generally should be low enough that a desired negative pressure may be maintained.

An attachment device may be used to attach the drape <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 that extends about a periphery, a portion, or an entire sealing member. In some embodiments, for example, some or all of the drape <NUM> may be coated with an acrylic adhesive having a coating weight between about <NUM> grams per square meter (gsm) to about <NUM> gsm. 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.

A "container" broadly includes a canister, pouch, bottle, vial, or other fluid collection apparatus. A container, for example, can be used to manage exudates and other fluids withdrawn from a tissue site. In some embodiments, a container may be a component of a negative-pressure source, such as the negative-pressure source <NUM>.

A "connector," such as the connector <NUM>, may be used to fluidly couple a tube to a sealed therapeutic environment. The negative pressure developed by a negative-pressure source may be delivered through a tube to a connector. In one illustrative embodiment, a connector may be a T. ® Pad or Sensa T. ® Pad available from KCI of San Antonio, Texas. In one exemplary embodiment, the connector <NUM> may allow the negative pressure generated by the negative-pressure source <NUM> to be delivered to the sealed therapeutic environment <NUM>. In other exemplary embodiments, a connector may also be a tube inserted through a drape.

Negative-pressure therapy is increasingly being performed with smaller devices that use battery power rather than a connection to an electrical outlet. Use of battery power decreases the total power supply available to a device. As a result, power drains that would be considered negligible in a device powered through an electrical outlet connection may significantly reduce the performance of a battery-powered device. Power drains may be caused by low-level dressing leaks, for example, which can drain power by repeatedly triggering operation of the a negative-pressure source to maintain a therapeutic negative pressure at the tissue site. Power drains can shorten the useful life of a device by draining the device battery faster, requiring more frequent disposal of the device, recharging of the battery, or battery replacement. Leak detection techniques may help to identify some leaks that may be sealed by the user; however, low-level leaks can challenge the most sensitive leak detection systems and may often go undetected.

Low-level dressing leaks may occur between a drape and epidermis surrounding a tissue site if the drape fails to completely seal to the epidermis. Generally, a drape suitable for covering a tissue site for negative-pressure therapy may comprise a film having a thickness between about <NUM> microns and about <NUM> microns that is water-vapor permeable and formed of a polymer. The film, often formed of polyurethane, may be coated with an adhesive having a coating weight between about <NUM> gsm and about <NUM> gsm. The adhesive may often be acrylic-based and pressure sensitive. A standard acrylic adhesive may have a bond strength between about <NUM> Newton/centimeter (N/cm) and about <NUM> N/cm on stainless steel substrate at <NUM>° C at <NUM>% relative humidity based on the American Society for Testing and Materials ("ASTM") standard ASTM D3330. A pressure-sensitive adhesive increases in bond strength when pressed against the surface to which the adhesive is being bonded. In some applications, a pressure-sensitive adhesive may undergo a physical change when compressed against a surface. In other applications, a pressure-sensitive adhesive may flow into crevices of a surface when compressed, increasing the bond strength without undergoing a physical change. A drape using a standard acrylic adhesive as described above is generally suitable for a dressing where a negative-pressure source powered by a continuous power supply is available to compensate for a dressing leak.

Some drapes may use a bonding adhesive instead of the standard acrylic adhesive. A bonding adhesive may be an adhesive having a bond strength that is greater than the bond strength of a standard acrylic adhesive. In some embodiments, a bonding adhesive may be a type of acrylic adhesive. A bonding adhesive may be better for sealing, but the increased bond strength may cause significantly more discomfort if the drape is removed. In addition, removing a drape having a bonding adhesive may cause significant damage to delicate or damaged skin.

A drape that has a sealing adhesive can fill gaps between the drape and the epidermis to limit leaks and can be easy to remove with low discomfort to the patient. Generally, a sealing adhesive may have a lower bond strength than a standard acrylic adhesive and a bonding adhesive. Generally, a sealing adhesive may flow into gaps and crevices more readily than a standard acrylic adhesive or a bonding adhesive. Various sealing, gap-filling adhesives, such as silicone, hydrocolloids, and hydrogels, have been used but each can have drawbacks. For example, hydrogel adhesives are usually low tack and prone to swelling, creep, and mobility when used with fluid systems. Available hydrogels and hydrocolloids may not adhere well and may move when anchored. In another example, silicone adhesives can fill gaps and seal, but are not breathable and may lose mechanical bonding strength as the silicone adhesives interact with moisture during use. To counter these problems, silicone adhesives may require additional materials to secure the silicone adhesive to a patient. For example, a low-leak drape may be formed from two adhesive layers: a thick sealing adhesive, perhaps in the shape of a gasket or ring, and a thinner bonding adhesive layer used to keep the sealing adhesive in place. Low-leak drapes constructed in this way can be more complex than a drape using a single adhesive, increasing the complexity of manipulation and operation.

A hybrid drape having a thick sealing layer that is perforated and laminated over an adhesive-coated film can overcome many of these challenges. For example, a hybrid drape may include a film layer having a bonding adhesive applied directly to the film layer, and a sealing adhesive applied directly to the bonding adhesive. The sealing adhesive can be perforated to expose the bonding adhesive. When the drape is applied to a patient, the bonding adhesive can be pushed through the perforations of the sealing adhesive to secure the sealing adhesive to the patient. This laminated configuration may provide the benefits of the sealing adhesive and the bonding adhesive over the entire drape area. For example, the laminated configuration may be conformable and of sufficient strength to ensure an initial seal, can inhibit the development of typical low-level leaks, and can mechanically affix to an epidermis without secondary processes. The laminated configuration may also minimize application care by a user and can be removable with minimal trauma to a patient.

However, construction of a laminated configuration can require additional assembly steps and can increase an amount of materials that may be needed for drape construction, which can also significantly increase costs. In addition, as two layers of adhesive are applied to the film layer, the total thickness of the drape can significantly increase, reducing breathability of the drape. Still further, as two full layers of adhesive are applied, significantly more adhesive material is needed to construct the drape.

Other hybrid drapes may register a bonding adhesive and a sealing adhesive. These hybrid drapes apply both a bonding adhesive and a sealing adhesive directly to a film layer. The bonding adhesive and the sealing adhesive may each cover different portions of a film layer to reduce the overall thickness of a hybrid drape and decrease the amount of adhesive needed to construct the hybrid drape. However, the complexity of the manufacturing process may also increase costs relative to other drapes. While using less adhesive than the laminated hybrid drapes, registered hybrid drapes may still use more adhesive in construction than standard drapes.

Some hybrid drapes may use a gel coated mesh having mesh apertures with a diameter between about <NUM> millimeters (mm) and about <NUM>. However, a gel-coated mesh having apertures of this size may be unable to form a seal with a tissue site. The sealing properties of the gel-coated mesh may be improved by increasing an average diameter of the fibers used to form the mesh; however, the increased diameter of the fibers may also increase a prominence of a mesh where two fibers intersect. A prominence may be a relative height of a feature compared to surrounding features. If two fibers intersect so that a first fiber overlaps a second fiber, a prominence may be a distance between a top of a first fiber and the top of the second fiber. Generally, the prominence at an intersection of two fibers may be the diameter of the largest of the two intersecting fibers. Consequently, if the diameters of the fibers are increased to increase the sealing properties of a gel-coated mesh, the raised contours associated with fiber cross-over may create leaks that are difficult to seal.

As disclosed herein, the negative-pressure therapy system <NUM> can overcome these challenges and others by providing a substantially flat mesh coated with a sealing adhesive. In some embodiments, for example, the drape <NUM> may comprise a layer of a bonding adhesive coupled to a film layer, and a mesh layer coupled to the layer of bonding adhesive. The mesh layer may be a mesh formed of small diameter fibers and can be perforated to form bonding apertures. The mesh may be coated with a sealing adhesive.

<FIG> is an exploded perspective view, illustrating details that may be associated with some embodiments of the drape <NUM>. The film layer <NUM> may be liquid-impermeable and vapor-permeable, allowing vapor to egress and inhibiting liquid from exiting. The film layer <NUM> may be a flexible film that is breathable and may have a high moisture-vapor transfer rate (MVTR). For example, in some embodiments, the MVTR may be greater than or equal to about <NUM>/m<NUM>/24hours. The film layer <NUM> may be formed from a range of medically approved films that typically range in thickness from about <NUM> microns (µm) to about <NUM> microns (µm). In other embodiments, a drape having a low MVTR or that allows no vapor transfer may be used. The film layer <NUM> can also function as a barrier to liquids and microorganisms.

The film layer <NUM> may be formed from numerous materials, such as one or more of the following: hydrophilic polyurethane (PU), cellulosics, hydrophilic polyamides, polyvinyl alcohol, polyvinyl pyrrolidone, hydrophilic acrylics, hydrophilic silicone elastomers, and copolymers of these. In an illustrative embodiment, the film layer <NUM> may be formed from a breathable cast matt polyurethane film sold by Expopack Advanced Coatings of Wrexham, United Kingdom, under the name INSPIRE <NUM>. The illustrative film may have an MVTR (inverted cup technique) of <NUM>/m<NUM>/<NUM> hours and may be approximately <NUM> microns thick.

The bonding adhesive <NUM> may be coupled directly to the film layer <NUM>. The bonding adhesive <NUM> may be a medically-acceptable, pressure-sensitive adhesive. For example, the bonding adhesive <NUM> may be formed from an acrylic adhesive, rubber adhesive, high-tack silicone adhesive, polyurethane, or other substance. In some illustrative embodiments, the bonding adhesive <NUM> may be formed from an acrylic adhesive with a coating weight of about <NUM> gsm to about <NUM> gsm. The bonding adhesive <NUM> may also be a high-bond strength acrylic adhesive, patterrubber adhesive, high-tack silicone adhesive, or polyurethane, for example. In some embodiments, the bonding adhesive <NUM> may have a peel adhesion or resistance to being peeled from a stainless steel material between about 6N/<NUM> to about 10N/<NUM> on stainless steel substrate at <NUM>° C at <NUM>% relative humidity based on the ASTM D3330.

The bonding adhesive <NUM> may be a continuous layer of material or may be a layer with apertures (not shown). The apertures may be formed after application of the bonding adhesive <NUM> or may be formed by coating the bonding adhesive <NUM> in patterns on a carrier layer. The apertures may be sized to help control the resultant tackiness of the bonding adhesive <NUM>. The apertures may also be sized to enhance the MVTR of the drape <NUM>. The bonding adhesive <NUM> may couple the film layer <NUM> to the mesh <NUM>.

In some embodiments, the mesh <NUM> may be a polymeric mesh, such as Mepitel® produced by Molnlycke Health Care, Adaptic® produced by Systagenix, and Noveface produced by Zodiac Aerospace Group. In some embodiments, the mesh <NUM> may be substantially flat. For example, the mesh <NUM> may have a thickness <NUM>, and individual portions of the mesh <NUM> may have a minimal tolerance from the thickness <NUM>. In some embodiments, the thickness <NUM> of the mesh <NUM> may be about <NUM>, and the tolerance of the thickness <NUM> may be less than about <NUM>. In another exemplary embodiment, a tolerance of the thickness <NUM> of the mesh <NUM> may be less than about <NUM>. In other embodiments, a tolerance of the thickness <NUM> of the mesh <NUM> may be less than about <NUM>. In some embodiments, the mesh <NUM> may be formed with bonding apertures <NUM>. The bonding apertures <NUM> may be numerous shapes, for example, circles, squares, stars, ovals, polygons, slits, complex curves, rectilinear shapes, triangles, or other shapes.

<FIG> is a plan view, illustrating details that may be associate with some embodiments of the mesh <NUM>. Generally, a mesh may include a structure of connected strands of metal, fiber, or other flexible or ductile material having openings between the strands. In some embodiments, a mesh may have evenly spaced openings between adjacent strands. In some embodiments, the mesh <NUM> may have a plurality of fibers <NUM>. In some embodiments, the fibers <NUM> may be formed from a monofilament, a plurality of twisted monofilaments, a plurality of filaments, or a plurality of staple fibers. A filament may be a fiber that is formed in a continuous or near-continuous length. A monofilament may be a single filament. In some embodiments, a monofilament may be made from a single synthetic fiber of plastic, for example. Monofilaments may have a tensile strength related to a diameter of the monofilament and the type of material from which the monofilament is formed. A staple fiber may be a fiber of a selected standardized length, and the staple fiber may be formed of a suitable composition for used with a medical device. Each of the fibers <NUM> may have a diameter <NUM>. In some embodiments, the diameter <NUM> may be no greater than about <NUM>. The fibers <NUM> may be formed from a range of materials including, but not limited to, silicone, cellulose acetate, and other similar materials.

In some embodiments, antimicrobial agents may be added to the mesh <NUM>. In other embodiments, the fibers <NUM> may have antimicrobial properties. For example, in some embodiments, silver ions may be added to the fibers <NUM>. In still other embodiments, the fibers <NUM> may be formed from elastomers to permit easier coverage of complex contours.

The plurality of fibers <NUM> may be woven, knitted, knotted, linked or otherwise connected to form a regular pattern of mesh apertures. In some embodiments, each of the plurality of fibers <NUM> may be separated from adjacent fibers <NUM> to form mesh apertures <NUM>. In some embodiments, the fibers <NUM> may be separated a distance <NUM> from adjacent fibers, which may be between about <NUM> and about <NUM>. In some embodiments, each of the fibers <NUM> may be separated from adjacent fibers in a second direction by a distance <NUM>. In some embodiments, the distance <NUM> may be between about <NUM> and about <NUM>. In some embodiments, the first direction of the distance <NUM> and the second direction of the distance <NUM> may be perpendicular. In some embodiments, the distance <NUM> and the distance <NUM> may be the same. In other embodiments, the first direction of the distance <NUM> and the second direction of the distance <NUM> may be other angles, and the distance <NUM> and the distance <NUM> may not be the same.

In some embodiments, the mesh apertures <NUM> may have an average effective diameter of about <NUM>. An effective diameter of a non-circular area may be a diameter of a circular area having the same surface area as the non-circular area. For example, the surface area of a mesh aperture <NUM> where the distance <NUM> is <NUM> and the distance <NUM> is <NUM> may be <NUM><NUM>. The diameter of a circular area having a <NUM><NUM> surface area is about <NUM>; consequently, the effective diameter of the exemplary mesh aperture <NUM> is about <NUM>. Similarly, if the distance <NUM> is about <NUM> and the distance <NUM> is about <NUM>, the effective diameter of the mesh aperture <NUM> may be about <NUM>.

In some embodiments, the mesh <NUM> may include the bonding apertures <NUM>. The bonding apertures <NUM> may have a uniform pattern or may be randomly distributed on the mesh <NUM>. The bonding apertures <NUM> may be formed through one or more fibers <NUM>. In some embodiments, the bonding apertures <NUM> may extend into the mesh apertures <NUM>. Each bonding aperture <NUM> of the plurality of bonding apertures <NUM> may have an effective diameter. The average effective diameter of each bonding aperture <NUM> may be in the range of about <NUM> to about <NUM>.

In some embodiments, the mesh <NUM> may be coated with a gel, such as a sealing adhesive <NUM>. In some embodiments, the sealing adhesive <NUM> may have a coating weight of about <NUM> gsm to about <NUM> gsm. In other embodiments, the sealing adhesive <NUM> may have a coating weight greater than about <NUM> gsm. The coating of the mesh <NUM> with the sealing adhesive <NUM> may fill in a portion of each mesh aperture <NUM>. In some embodiments, the mesh apertures <NUM> may remain at least partially open after the coating of the mesh <NUM> with the sealing adhesive <NUM>.

A sealing adhesive may be a soft material that provides a good seal with the tissue site <NUM>. A sealing adhesive may be formed of a silicone gel (or soft silicone), hydrocolloid, hydrogel, polyurethane gel, polyolefin gel, hydrogenated styrenic copolymer gels, or foamed gels with compositions as listed, or soft closed cell foams (polyurethanes, polyolefins) coated with an adhesive (for example, <NUM> gsm - <NUM> gsm acrylic), polyurethane, polyolefin, or hydrogenated styrenic copolymers. In some embodiments, a sealing adhesive may have a stiffness between about <NUM> Shore OO and about <NUM> Shore OO. A sealing adhesive may be hydrophobic or hydrophilic. A sealing adhesive may be an adhesive having a low to medium tackiness, for example, a silicone polymer, polyurethane, or an additional acrylic adhesive. In some embodiments, a sealing adhesive may a bond strength between about <NUM>. 5N/<NUM> and about <NUM>. 5N/<NUM> on a stainless steel substrate at <NUM>° C at <NUM>% relative humidity based on ASTM D3330. A sealing adhesive may have a tackiness such that the sealing adhesive may achieve the bond strength above after a contact time of less than <NUM> seconds. Tackiness may be considered a bond strength of an adhesive after a very low contact time between the adhesive and a substrate. In an illustrative embodiment, a sealing adhesive may have a tackiness that may be about <NUM>% to about <NUM>% of the tackiness of a bonding adhesive.

In some embodiments, the bonding apertures <NUM> may be formed prior to coating of the mesh <NUM> with the sealing adhesive <NUM>. In other embodiments, the bonding apertures <NUM> may be formed in the mesh <NUM> following coating of the mesh <NUM> with the sealing adhesive <NUM>.

In some embodiments, the fibers <NUM> of the mesh <NUM> may form a plurality of intersections <NUM>. In some embodiments, an intersection <NUM> may be a location of the mesh <NUM> where at least two fibers <NUM> overlap, cross-over, or meet, for example.

<FIG> is a perspective view, illustrating additional details that may be associated with some embodiments of the mesh <NUM> of <FIG>. In some embodiments, the mesh <NUM> may be formed so that at each intersection <NUM>, the intersecting fibers <NUM> may be fused so that the intersection <NUM> is planar. In some embodiments, the mesh <NUM> may be molded, extruded, or expanded to form the mesh <NUM>. In embodiments where the mesh <NUM> is molded, extruded, or expanded, the fibers <NUM> at an intersection <NUM> may be fused or joined so that a prominence at the intersection <NUM> is less than about <NUM>. In some embodiments, the prominence at an intersection <NUM> may be about <NUM>. In some embodiments, a substantially flat mesh may have a thickness at the intersections <NUM> that may be substantially the same as a thickness of the mesh <NUM> surrounding the intersections <NUM>.

<FIG> is a side elevation view, illustrating additional details that may be associated with some embodiments of the mesh <NUM>. In some embodiments, the mesh <NUM> may be formed by weaving or knitting the fibers <NUM>. If the fibers <NUM> are woven or knitted, the intersections <NUM> may have a prominence <NUM>. In some embodiments, the prominence <NUM> of the fibers <NUM> at the intersections <NUM> may be equal to the diameter <NUM> of the fibers <NUM>. In some embodiments, the prominence <NUM> may be reduced by compressing the mesh <NUM> following weaving or knitting the fibers <NUM>. The prominences <NUM> of the fibers <NUM> may also be reduced by passing the mesh <NUM> through a calender, which may apply pressure to the mesh <NUM> to smooth out the mesh <NUM>. In some embodiments, the prominence <NUM> may be less than about <NUM>.

<FIG> is a sectional view, illustrating additional details that may be associated with some embodiments of the drape <NUM>. In the assembled state, the bonding adhesive <NUM> may be coupled to the film layer <NUM>, and the mesh <NUM> may be coupled to the bonding adhesive <NUM>. If the mesh <NUM> is placed proximate to or in contact with the epidermis <NUM>, the sealing adhesive <NUM> coating the mesh <NUM> may form sealing couplings <NUM> with the epidermis <NUM>. In some embodiments, the diameter <NUM> of the fibers <NUM>, the thickness of the sealing adhesive <NUM>, and the bonding apertures <NUM> may create a gap between the bonding adhesive <NUM> and the epidermis <NUM>.

<FIG> is a sectional view, illustrating additional details that may be associated with some embodiments of the drape <NUM> of <FIG> in a second position. If the drape <NUM> is in a desired location, pressure may be applied to the film layer <NUM>. The pressure may cause the bonding adhesive <NUM> to be pressed at least partially into contact with the epidermis <NUM> to form bonding couplings <NUM>. The bonding couplings <NUM> may provide secure, releasable mechanical fixation to the epidermis <NUM>. The sealing couplings <NUM> between the sealing adhesive <NUM> and the epidermis <NUM> may be sufficient to seal the film layer <NUM> to the epidermis <NUM>. The sealing couplings <NUM> may not be as mechanically strong as the bonding couplings <NUM> between the bonding adhesive <NUM> and the epidermis <NUM>. The bonding couplings <NUM> may also anchor the drape <NUM> to the epidermis <NUM>, inhibiting migration of the drape <NUM> and the sealing adhesive <NUM>.

The average effective diameter of the bonding apertures <NUM> of the sealing adhesive <NUM> may be varied as one control of the tackiness or adhesion strength of the drape <NUM>. In this regard, there may be an interplay between three main variables for each embodiment: the diameter <NUM> of the fibers <NUM>, the average effective diameter of the plurality of bonding apertures <NUM>, and the tackiness of the bonding adhesive <NUM>. The more bonding adhesive <NUM> that extends through the bonding apertures <NUM>, the stronger the bonding coupling <NUM>. The smaller the diameter <NUM> of the fibers <NUM>, the more the bonding adhesive <NUM> generally extends through the bonding apertures <NUM> and the greater the bonding coupling <NUM>. As an example of the interplay, if a very tacky bonding adhesive <NUM> is used and the diameter <NUM> of the fibers <NUM> of the mesh <NUM> is small, the average effective diameter of the plurality of bonding apertures <NUM> may be relatively smaller to maintain a same adhesion strength of the drape <NUM>.

In other embodiments, the mesh <NUM> may be formed from a perforated film which is then coated with the sealing adhesive <NUM> and laminated to the film layer <NUM> or the bonding adhesive <NUM>. In other embodiments, the mesh <NUM> may be coated with the bonding adhesive <NUM> and then pattern-coated with the sealing adhesive <NUM>. The mesh <NUM> may then be laminated directly to the film layer <NUM>. The bonding adhesive <NUM> may be exposed through the areas of the mesh <NUM> that were not pattern-coated with the sealing adhesive <NUM>.

In some embodiments, the adhesives may be mixed with blowing or expanding agents, for example organic and inorganic low temperature boiling point liquids. The blowing or expanding agents allow for the adhesives to expand under the application of heat or light to increase the thickness of the adhesive following deposition by one of the above described processes. The blowing or expanding agents may reduce the amount of adhesive needed and decrease the cost of production. In some embodiments, the application of heat or light may be delayed until application of the drape <NUM> to the epidermis <NUM> so that the contact area with the epidermis <NUM> may increase as the bonding adhesive <NUM> and the sealing adhesive <NUM> warm by contact with the epidermis <NUM>. The application of light or heat following application of the drape <NUM> to the epidermis <NUM> can provide a better seal for some embodiments of the drape <NUM> to the epidermis <NUM>.

A drape having a coated mesh may provide a lower cost solution that makes more efficient use of a sealing adhesive. The increase in efficiency of the use of a sealing adhesive may be accomplished without the complication of adding extruders and pattern coaters that may be required for pattern printing of adhesives. A drape having a coated mesh may have a higher MVTR than other drapes as the inclusion of mesh apertures can permit greater passage of moisture without interfering with sealing.

Although certain features and their advantages have been disclosed in the context of certain illustrative, non-limiting embodiments, it should be understood that various changes, substitutions, permutations, and alterations can be made without departing from the scope of the appended claims. It will be appreciated that features that may be described in connection to one embodiment may also be applicable to other embodiments. It will also be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. It will further be understood that reference to "an" item refers to one or more of those items.

The steps of the methods described herein may be carried out in a suitable order, or simultaneously where appropriate.

Where appropriate, aspects of the embodiments described above may be combined with aspects of the other embodiments described to form further examples having comparable or different properties and addressing the same or different problems.

Claim 1:
A drape (<NUM>) for a negative-pressure therapy system, comprising:
a film layer (<NUM>);
a layer of bonding adhesive (<NUM>) coupled to the film layer (<NUM>); and
a mesh (<NUM>) coated with a sealing adhesive (<NUM>) and coupled to the bonding adhesive (<NUM>),
wherein the mesh (<NUM>) comprises:
a plurality of mesh apertures (<NUM>), each mesh aperture comprising an effective diameter between <NUM> millimeters and <NUM> millimeters, and
a plurality of bonding apertures (<NUM>) formed in the mesh (<NUM>), each bonding aperture comprising an effective diameter in a range of <NUM> millimeters to <NUM> millimeters.