Patent Description:
Depending on the medical circumstances, reduced pressure may be used for, among other things, reduced-pressure therapy to encourage granulation at a tissue site, draining fluids at a tissue site, closing a wound, reducing edema, promoting perfusion, and fluid management. Common dressings, systems, and methods may be susceptible to leaks and blockage that can cause a reduction in the efficiency of the therapy, or a complete loss of therapy. Such a situation can occur, for example, if the amount of fluid in the dressing or system exceeds the fluid capacity of the dressing or system. Prevention of leaks and blockages may be particularly important when only a limited power supply to the reduced pressure source and other components is available. Thus, improvements to dressings, systems, and methods that enhance the management of fluid extracted from a tissue site for increasing reliability, efficiency, and the useable life of the dressing and system are desirable.

Wound dressings suitable for negative pressure wound therapy are disclosed in <CIT>, <CIT>, <CIT> and <CIT>.

Shortcomings with certain aspects of tissue treatment dressings, systems, and methods are addressed as shown and described in a variety of illustrative, non-limiting embodiments herein.

Insofar as the term "embodiment(s)" is used in the following, or features are presented as being optional, this should be interpreted in such a way that the only protection sought is that of the invention claimed.

Reference(s) to "embodiment(s)" throughout the description which are not under the scope of the appended claims merely represent possible exemplary executions and are not part of the present invention.

Other aspects, features, and advantages of the illustrative embodiments will become apparent with reference to the drawings and detailed description that follow.

A more complete understanding of this specification may be obtained by reference to the following detailed description when taken in conjunction with the accompanying drawings wherein:.

In the following detailed description of non-limiting, illustrative embodiments, reference is made to the accompanying drawings that form a part hereof. Other embodiments may be utilized, and logical, structural, mechanical, electrical, and chemical changes may be made without departing from the scope of this specification. To avoid detail not necessary to enable those skilled in the art to practice the embodiments described herein, the description may omit certain information known to those skilled in the art. The following detailed description is provided without limitation and with the scope of the illustrative embodiments being defined by the appended claims.

Referring to the drawings, <FIG> depicts an embodiment of a system <NUM> for treating a tissue site <NUM> of a patient. The tissue site <NUM> may extend through or otherwise involve an epidermis <NUM>, a dermis <NUM>, and a subcutaneous tissue <NUM>. The tissue site <NUM> may be a sub-surface tissue site as depicted in <FIG> that extends below the surface of the epidermis <NUM>. Further, the tissue site <NUM> may be a surface tissue site (not shown) that predominantly resides on the surface of the epidermis <NUM>. The system <NUM> may provide therapy to, for example, the epidermis <NUM>, the dermis <NUM>, and the subcutaneous tissue <NUM>, regardless of the positioning of the system <NUM> or the type of tissue site. The system <NUM> may also be utilized without limitation at other tissue sites.

Further, the tissue site <NUM> may be the bodily tissue of any human, animal, or other organism, including bone tissue, adipose tissue, muscle tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, ligaments, or any other tissue. Treatment of tissue site <NUM> may include removal of fluids, e.g., exudate or ascites. As used herein, unless otherwise indicated, "or" does not require mutual exclusivity.

Continuing with <FIG>, the system <NUM> may include an interface manifold <NUM>, a dressing <NUM>, and a reduced-pressure source <NUM>. The interface manifold <NUM> may be adapted to be positioned proximate the tissue site <NUM>, such as, for example, by cutting or otherwise shaping the interface manifold <NUM> in any suitable manner to fit the tissue site <NUM>. As described below, the interface manifold <NUM> may be adapted to be positioned in fluid communication with the tissue site <NUM> to distribute reduced pressure to the tissue site <NUM>. In one embodiment, the interface manifold <NUM> may be positioned in contact with the tissue site <NUM>. The interface manifold <NUM> may be formed from any manifold material or flexible bolster material that provides a vacuum space, or treatment space, such as, for example, a porous and permeable foam or foam-like material, a member formed with pathways, a graft, or a gauze, etc. As a more specific, non-limiting example, the interface manifold <NUM> may be a reticulated, open-cell polyurethane or polyether foam that allows good permeability of fluids while under a reduced pressure. One such foam material is the VAC® GranuFoam® material available from Kinetic Concepts, Inc. (KCI) of San Antonio, Texas. Any material or combination of materials may be used as a manifold material for the interface manifold <NUM> provided that the manifold material is operable to distribute reduced pressure. The term "manifold" as used herein generally refers to a substance or structure that is provided to assist in applying reduced pressure to, delivering fluids to, or removing fluids from a tissue site. A manifold typically includes a plurality of flow channels or pathways. The plurality of flow channels may be interconnected to improve distribution of fluids provided to and removed from the area of tissue around the manifold. Examples of manifolds may include, without limitation, devices that have structural elements arranged to form flow channels, cellular foam, such as open-cell foam, porous tissue collections, and liquids, gels, and foams that include or cure to include flow channels.

A material with a higher or lower density than GranuFoam® material may be desirable for the interface manifold <NUM> depending on the application. Among the many possible materials, the following may be used: GranuFoam® material, Foamex® technical foam (www. com), a molded bed of nails structures, a patterned grid material such as those manufactured by Sercol Industrial Fabrics, 3D textiles such as those manufactured by Baltex of Derby, U. , a gauze, a flexible channel-containing member, a graft, etc. In some instances, ionic silver may be desirable to add to the foam by, for example, a micro bonding process. Other substances, such as anti-microbial agents, may be added to the foam as well.

In one embodiment, the interface manifold <NUM> may comprise a porous, hydrophobic material. The hydrophobic characteristics of the interface manifold <NUM> may prevent the interface manifold <NUM> from directly absorbing fluid, such as exudate, from the tissue site <NUM>, but allow the fluid to pass through.

Continuing with <FIG>, the dressing <NUM> may be adapted to provide reduced pressure from the reduced-pressure source <NUM> to the interface manifold <NUM>, and to store fluid extracted from the tissue site <NUM> through the interface manifold <NUM>. The dressing <NUM> may include a base layer <NUM>, an adhesive <NUM>, a sealing member <NUM>, and a fluid management assembly <NUM>. The dressing <NUM> may also include a conduit interface <NUM>.

Referring to <FIG>, the base layer <NUM> may have a periphery <NUM> surrounding a central portion <NUM> and a plurality of apertures <NUM> disposed through the periphery <NUM> and the central portion <NUM>. The base layer <NUM> may cover the interface manifold <NUM> and tissue surrounding the tissue site <NUM> such that the central portion <NUM> of the base layer <NUM> is positioned proximate the interface manifold <NUM> and the periphery <NUM> of the base layer <NUM> is positioned proximate the tissue surrounding the tissue site <NUM>. In this manner, the periphery <NUM> of the base layer <NUM> may surround the interface manifold <NUM>. Further, the apertures <NUM> in the base layer <NUM> may be in fluid communication with the interface manifold <NUM> and the tissue surrounding the tissue site <NUM>.

The apertures <NUM> in the base layer <NUM> may have any shape, such as, for example, circles, squares, stars, ovals, polygons, slits, complex curves, rectilinear shapes, triangles, or other shapes. Each aperture <NUM> of the plurality of apertures <NUM> may have a diameter. The diameter of each of the apertures <NUM> may be between about <NUM> to about <NUM>. The apertures <NUM> may have a uniform pattern or may be randomly distributed on the base layer <NUM>. The size and configuration of the apertures <NUM> may be designed to control the adherence of the dressing <NUM> to the epidermis <NUM> as described below.

The base layer <NUM> may be a soft material suitable for providing a fluid seal with the tissue site <NUM> as described herein. For example, the base layer <NUM> may comprise a silicone gel, a soft silicone, hydrocolloid, hydrogel, polyurethane gel, polyolefin gel, hydrogenated styrenic copolymer gels, a foamed gel, a soft closed cell foam such as polyurethanes and polyolefins coated with an adhesive, polyurethane, polyolefin, or hydrogenated styrenic copolymers. The base layer may have a thickness between about <NUM> microns (µm) and about <NUM> microns (µm). In one embodiment, the base layer <NUM> has a stiffness between about <NUM> Shore OO and about <NUM> Shore OO. The base layer <NUM> may be comprised of hydrophobic or hydrophilic materials.

In some embodiments, the base layer <NUM> may be a hydrophobic-coated material. For example, the base layer <NUM> may be formed by coating a spaced material, such as, for example, woven, nonwoven, molded, or extruded mesh with a hydrophobic material. The hydrophobic material for the coating may be a soft silicone, for example. In this manner, the adhesive <NUM> may extend through openings in the spaced material analogous to the apertures <NUM> described herein.

The adhesive <NUM> may be in fluid communication with the apertures <NUM> in at least the periphery <NUM> of the base layer <NUM>. In this manner, the adhesive <NUM> may be in fluid communication with the tissue surrounding the tissue site <NUM> through the apertures <NUM> in the base layer <NUM>. As shown in <FIG>, the adhesive <NUM> may extend through the plurality of apertures <NUM> to contact the epidermis <NUM> for securing the dressing <NUM> to, for example, the tissue surrounding the tissue site <NUM>. The apertures <NUM> may provide sufficient contact of the adhesive <NUM> to the epidermis <NUM> to secure the dressing <NUM> about the tissue site <NUM>. However, the configuration of the apertures <NUM> and the adhesive <NUM> may permit release and repositioning of the dressing <NUM> about the tissue site <NUM>.

The adhesive <NUM> may be any medically-acceptable adhesive. For example, the adhesive <NUM> may comprise an acrylic adhesive, rubber adhesive, high-tack silicone adhesive, polyurethane, or other adhesive substance. In some embodiments, the adhesive <NUM> may be a pressure-sensitive adhesive comprising an acrylic adhesive with coating weight of <NUM> grams/m<NUM> (gsm) to <NUM> grams/m<NUM> (gsm). The adhesive <NUM> may be a continuous or a discontinuous layer of material. Discontinuities in the adhesive <NUM> may be provided by apertures (not shown) in the adhesive <NUM>. The apertures 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 sealing member <NUM> adapted to face the epidermis <NUM>. Further, the apertures in the adhesive <NUM> may be sized to control the amount of the adhesive <NUM> extending through the apertures <NUM> in the base layer <NUM> to reach the epidermis <NUM>. The apertures in the adhesive <NUM> may also be sized to enhance the Moisture Vapor Transfer Rate (MVTR) of the dressing <NUM>.

Factors that may be utilized to control the adhesion strength of the dressing <NUM> may include the diameter and number of the apertures <NUM> in the base layer <NUM>, the thickness of the base layer <NUM>, the thickness and amount of the adhesive <NUM>, and the tackiness of the adhesive <NUM>. An increase in the amount of the adhesive <NUM> extending through the apertures <NUM> generally corresponds to an increase in the adhesion strength of the dressing <NUM>. A decrease in the thickness of the base layer <NUM> generally corresponds to an increase in the amount of adhesive <NUM> extending through the apertures <NUM>. Thus, the diameter and configuration of the apertures <NUM>, the thickness of the base layer <NUM>, and the amount and tackiness of the adhesive utilized may be varied to provide a desired adhesion strength for the dressing <NUM>. For example, the thickness of the base layer <NUM> may be about <NUM> microns. The adhesive layer <NUM> may have a thickness of about <NUM> microns. Further, the adhesive layer <NUM> may have a tackiness of about <NUM> grams per <NUM> centimeter wide strip. The diameter of the apertures <NUM> in the base layer <NUM> may be about <NUM> millimeters.

Continuing with <FIG>, the sealing member <NUM> may have a periphery <NUM> and a central portion <NUM>. The periphery <NUM> of the sealing member <NUM> may be positioned proximate the periphery <NUM> of the base layer <NUM> such that the central portion <NUM> of the sealing member <NUM> and the central portion <NUM> of the base layer <NUM> define an enclosure <NUM>. The adhesive <NUM> may be positioned at least between the periphery <NUM> of the sealing member <NUM> and the periphery <NUM> of the base layer <NUM>. The sealing member <NUM> may cover the tissue site <NUM> to provide a fluid seal and a sealed space <NUM> between the tissue site <NUM> and the sealing member <NUM> of the dressing <NUM>. Further, the sealing member <NUM> may cover tissue, such as a portion of the epidermis <NUM>, surrounding the tissue site <NUM> to provide the fluid seal between the sealing member <NUM> and the tissue site <NUM>.

The sealing member <NUM> may be formed from any material that allows for a fluid seal. A fluid seal may be a seal adequate to maintain reduced pressure at a desired site given the particular reduced pressure source or system involved. The sealing member <NUM> may comprise, for example, one or more of the following materials: hydrophilic polyurethane; cellulosics; hydrophilic polyamides; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic acrylics; hydrophilic silicone elastomers; an INSPIRE <NUM> material from Expopack Advanced Coatings of Wrexham, United Kingdom having, for example, an MVTR (inverted cup technique) of <NUM>/m<NUM>/<NUM> hours and a thickness of about <NUM> microns; a thin, uncoated polymer drape; natural rubbers; polyisoprene; styrene butadiene rubber; chloroprene rubber; polybutadiene; nitrile rubber; butyl rubber; ethylene propylene rubber; ethylene propylene diene monomer; chlorosulfonated polyethylene; polysulfide rubber; polyurethane (PU); EVA film; co-polyester; silicones; a silicone drape; a <NUM> Tegaderm® drape; a polyurethane (PU) drape such as one available from Avery Dennison Corporation of Pasadena, California; polyether block polyamide copolymer (PEBAX), for example, from Arkema, France; Expopack <NUM>; or other appropriate material.

The sealing member <NUM> may allow vapor and inhibit liquids from exiting the sealed space <NUM> provided by the dressing <NUM>. The sealing member <NUM> may be a flexible, breathable film having a high MVTR of, for example, at least about <NUM>/m<NUM> per <NUM> hours. The sealing member <NUM> may comprise a range of medically suitable films having a thickness between about <NUM> microns (µm) to about <NUM> microns (µm). In other embodiments, a low or no vapor transfer drape might be used.

The fluid management assembly <NUM> may be disposed in the enclosure <NUM> and may include a first wicking layer <NUM>, a second wicking layer <NUM>, and an absorbent layer <NUM>. The absorbent layer <NUM> may be positioned in fluid communication between the first wicking layer <NUM> and the second wicking layer <NUM>. The first wicking layer <NUM> may have a grain structure (not shown) adapted to wick fluid along a surface of the first wicking layer <NUM>. Similarly, the second wicking layer <NUM> may have a grain structure (not shown) adapted to wick fluid along a surface of the second wicking layer <NUM>. For example, the first and the second wicking layer <NUM>, <NUM> may wick or otherwise transport fluid in a lateral direction along the surfaces of the first and the second wicking layer <NUM>, <NUM>, respectively. Fluid may be transported in this manner with or without application of reduced pressure. The surfaces of the first and the second wicking layer <NUM>, <NUM> may be normal relative to the thickness of each of the first and the second wicking layer <NUM>, <NUM>. The wicking of fluid along the first and the second wicking layers <NUM>, <NUM> may enhance the distribution of the fluid over a surface area of the absorbent layer <NUM> that may increase absorbent efficiency and resist fluid blockages. Fluid blockages may be caused by, for example, fluid pooling in particular location in the absorbent layer <NUM> rather than being distributed more uniformly across the absorbent layer <NUM>. The laminate combination of the first and the second wicking layer <NUM>, <NUM> and the absorbent layer <NUM> may be adapted as described above to maintain an open structure, resistant to blockage, that can maintain fluid communication with, for example, the tissue site <NUM>.

Referring to the embodiments of the fluid management assembly <NUM> depicted in <FIG>, <FIG>, <FIG>, a peripheral portion <NUM> of the first wicking layer <NUM> may be coupled to a peripheral portion <NUM> of the second wicking layer <NUM> to define a wicking layer enclosure <NUM> between the first and the second wicking layer <NUM>, <NUM>. In some exemplary embodiments, the wicking layer enclosure <NUM> may surround or otherwise encapsulate the absorbent layer <NUM> between the first and the second wicking layer <NUM>, <NUM>.

Referring to <FIG>, the fluid management assembly <NUM> may include, without limitation, any number of wicking layers and absorbent layers as desired for treating a particular tissue site. For example, the absorbent layer <NUM> may be a plurality of absorbent layers <NUM> positioned in fluid communication between the first wicking layer <NUM> and the second wicking layer <NUM> as described above. Further, as depicted in <FIG>, at least one intermediate wicking layer <NUM> may be disposed in fluid communication between the plurality of absorbent layers <NUM>. Similar to the absorbent layer <NUM> described above, the plurality of absorbent layers <NUM> and the at least one intermediate wicking layer <NUM> may be positioned within the wicking layer enclosure <NUM>.

In the embodiments of <FIG>, sides 184a of the absorbent layers <NUM> may remain in fluid communication with one another for enhancing efficiency. Similarly, in the embodiment of <FIG>, sides 189a of the at least one intermediate wicking layer <NUM> may remain in fluid communication with one another and with the sides 184a of the absorbent layers <NUM>. Further, including additional absorbent layers <NUM> may increase the absorbent mass of the fluid management assembly <NUM> and generally provide greater fluid capacity. However, for a given absorbent mass, multiple light coat weight absorbent layers <NUM> may be utilized rather than a single heavy coat-weight absorbent layer <NUM> to provide a greater absorbent surface area for further enhancing the absorbent efficiency.

In one embodiment, the absorbent layer <NUM> may be a hydrophilic material or other absorbent material adapted to absorb fluid from, for example, the tissue site <NUM>. Materials suitable for the absorbent layer <NUM> may include Luquafleece® material, Texsus FP2326, BASF 402c, Technical Absorbents <NUM> available from Technical Absorbents (www. techabsorbents. com), sodium polyacrylate super absorbers, cellulosics (carboxy methyl cellulose and salts such as sodium CMC), or alginates. Materials suitable for the first and second wicking layers <NUM>, <NUM> may include any material having a grain structure capable of wicking fluid as described herein, such as, for example, Libeltex TDL2 80gsm.

The fluid management assembly <NUM> may be a pre-laminated structure manufactured at a single location or simply individual layers of material stacked upon one another as described above. Individual layers of the fluid management assembly <NUM> may be bonded or otherwise secured to one another without adversely affecting fluid management by, for example, utilizing a solvent or non-solvent adhesive, or by thermal welding.

In one embodiment, the enclosure <NUM> defined by the base layer <NUM> and the sealing member <NUM> may include an anti-microbial layer <NUM>. The addition of the anti-microbial layer <NUM> may reduce the probability of excessive bacterial growth within the dressing <NUM> to permit the dressing <NUM> to remain in place for an extended period. The anti-microbial layer <NUM> may be, for example, an additional layer included as a part of the fluid management assembly <NUM> as depicted in <FIG> and <FIG>, or a coating of an anti-microbial agent disposed in any suitable location within the dressing <NUM>. The anti-microbial layer <NUM> may be comprised of elemental silver or similar compound, for example.

Referring to <FIG>, <FIG>, and <FIG>, the conduit interface <NUM> may be positioned proximate to the sealing member <NUM> and in fluid communication with the dressing <NUM> through an aperture (not shown) in the sealing member <NUM> to provide reduced pressure from the reduced-pressure source <NUM> to the dressing <NUM>. The conduit interface <NUM> may comprise a medical-grade, soft polymer or other pliable material. As non-limiting examples, the conduit interface <NUM> may be formed from polyurethane, polyethylene, polyvinyl chloride (PVC), fluorosilicone, or ethylene-propylene, etc. In one illustrative, non-limiting embodiment, conduit interface <NUM> may be molded from DEHP-free PVC. The conduit interface <NUM> may be formed in any suitable manner such as by molding, casting, machining, or extruding. Further, the conduit interface <NUM> may be formed as an integral unit or as individual components and may be coupled to the dressing <NUM> by, for example, adhesive or welding.

The conduit interface <NUM> may carry an odor filter <NUM> adapted to substantially preclude the passage of odors from the tissue site <NUM> out of the sealed space <NUM>. Further, the conduit interface <NUM> may carry a primary hydrophobic filter <NUM> adapted to substantially preclude the passage of liquids out of the sealed space <NUM>. The odor filter <NUM> and the primary hydrophobic filter <NUM> may be disposed in the conduit interface <NUM> or other suitable location such that fluid communication between the reduced-pressure source <NUM> and the dressing <NUM> is provided through the odor filter <NUM> and the primary hydrophobic filter <NUM>. In one embodiment, the odor filter <NUM> and the primary hydrophobic filter <NUM> may be secured within the conduit interface <NUM> in any suitable manner, such as by adhesive or welding. In another embodiment, the odor filter <NUM> and the primary hydrophobic filter <NUM> may be positioned in any location in the dressing <NUM>, such as an aperture (not shown), that is in fluid communication with the atmosphere or with the reduced-pressure source <NUM>. The odor filter <NUM> may also be positioned in any suitable location in the system <NUM> that is in fluid communication with the tissue site <NUM>.

The odor filter <NUM> may be comprised of a carbon material in the form of a layer or particulate. For example, the odor filter <NUM> may comprise a woven carbon cloth filter such as those manufactured by Chemviron Carbon, Ltd. of Lancashire, United Kingdom (www. chemvironcarbon. The primary hydrophobic filter <NUM> may be comprised of a material that is liquid impermeable and vapor permeable. For example, the primary hydrophobic filter <NUM> may comprise a material manufactured under the designation MMT-<NUM> by W. Gore & Associates, Inc. of Newark, Delaware, United States, or similar materials. The primary hydrophobic filter <NUM> may be provided in the form of a membrane or layer.

Continuing with <FIG>, <FIG>, and <FIG>, the reduced-pressure source <NUM> may provide reduced pressure to the dressing <NUM> and the sealed space <NUM>. The reduced-pressure source <NUM> may be any suitable device for providing reduced pressure as described herein, such as, for example, a vacuum pump, wall suction, or other source.

As used herein, "reduced pressure" may refer to a pressure less than the ambient pressure at a tissue site being subjected to treatment. This reduced pressure may be less than the atmospheric pressure. The reduced pressure may also be less than a hydrostatic pressure at a tissue site. Unless otherwise indicated, values of pressure stated herein are gauge pressures. While the amount and nature of reduced pressure applied to a tissue site may vary according to the application, the reduced pressure may be between about -<NUM> Hg to about -<NUM> Hg. In some embodiments, the reduced pressure may be between about - <NUM> Hg to about -<NUM> Hg.

The reduced pressure delivered may be constant or varied (patterned or random) and may be delivered continuously or intermittently. Although the terms "vacuum" and "negative pressure" may be used to describe the pressure applied to the tissue site, the actual pressure applied to the tissue site may be more than the pressure normally associated with a complete vacuum. Consistent with the use herein, an increase in reduced pressure or vacuum pressure may refer to a relative reduction in absolute pressure. An increase in reduced pressure may correspond to a reduction in pressure (more negative relative to ambient pressure) and a decrease in reduced pressure may correspond to an increase in pressure (less negative relative to ambient pressure).

A conduit <NUM> having an internal lumen <NUM> may be coupled in fluid communication between the reduced-pressure source <NUM> and the dressing <NUM>. The conduit interface <NUM> may be coupled in fluid communication with the dressing <NUM> and adapted to connect between the conduit <NUM> and the dressing <NUM> for providing fluid communication with the reduced-pressure source <NUM>. The conduit interface <NUM> may be fluidly coupled to the conduit <NUM> in any suitable manner, such as, for example, by an adhesive, solvent or non-solvent bonding, welding, or interference fit. An aperture (not shown) in the sealing member <NUM> may provide fluid communication between the dressing <NUM> and the conduit interface <NUM>. In one embodiment, the conduit <NUM> may be inserted into the dressing <NUM> through an aperture (not shown) in the sealing member <NUM> to provide fluid communication with the reduced-pressure source <NUM> without utilization of the conduit interface <NUM>. The reduced-pressure source <NUM> may also be directly coupled in fluid communication with the dressing <NUM> and/or the sealing member <NUM>. The conduit <NUM> may be, for example, a flexible polymer tube. A distal end of the conduit <NUM> may include a coupling <NUM> for attachment to the reduced-pressure source <NUM>.

The conduit <NUM> may have a secondary hydrophobic filter <NUM> disposed in the internal lumen <NUM> such that fluid communication between the reduced-pressure source <NUM> and the dressing <NUM> is provided through the secondary hydrophobic filter <NUM>. The secondary hydrophobic filter <NUM> may be, for example, a porous, sintered polymer cylinder sized to fit the dimensions of the internal lumen <NUM> to substantially preclude liquid from bypassing the cylinder. The secondary hydrophobic filter <NUM> may also be treated with an absorbent material adapted to swell when brought into contact with liquid to block the flow of the liquid. The secondary hydrophobic filter <NUM> may be positioned at any location within the internal lumen <NUM>. However, positioning the secondary hydrophobic filter <NUM> within the internal lumen <NUM> closer toward the reduced-pressure source <NUM>, rather than the dressing <NUM>, may allow a user to detect the presence of liquid in the internal lumen <NUM>.

Referring now to <FIG> depicts the dressing <NUM> including a fluid management assembly <NUM> suitable for use with the dressing <NUM> and the system <NUM> as previously described. The fluid management assembly <NUM> may include a first wicking layer <NUM>, a second wicking layer <NUM>, and an absorbent layer <NUM> comprised of substantially the same materials and properties as those described above in connection with the fluid management assembly <NUM>. Thus, the first wicking layer <NUM>, the second wicking layer <NUM>, and the absorbent layer <NUM> may be analogous to the first wicking layer <NUM>, the second wicking layer <NUM>, and the absorbent layer <NUM>, respectively.

In the fluid management assembly <NUM>, the second wicking layer <NUM> may have a peripheral portion <NUM>. The second wicking layer <NUM> and the peripheral portion <NUM> of the second wicking layer <NUM> may be positioned in contact with the sealing member <NUM>. The absorbent layer <NUM> may have a peripheral portion <NUM> extending beyond the peripheral portion <NUM> of the second wicking layer <NUM>. The absorbent layer <NUM> may be positioned proximate to the second wicking layer <NUM> such that the peripheral portion <NUM> of the absorbent layer <NUM> is in contact with the sealing member <NUM> surrounding the peripheral portion <NUM> of the second wicking layer <NUM>. Similarly, the first wicking layer <NUM> may have a peripheral portion <NUM> extending beyond the peripheral portion <NUM> of the absorbent layer <NUM>. The first wicking layer <NUM> may be positioned proximate the absorbent layer <NUM> such that the peripheral portion <NUM> of the first wicking layer <NUM> is in contact with the sealing member <NUM> surrounding the peripheral portion <NUM> of the absorbent layer <NUM>. Further, the first wicking layer <NUM> may be positioned proximate the base layer <NUM>. Thus, at least the peripheral portions <NUM>, <NUM>, and <NUM> in contact with the sealing member <NUM> may be coupled to the sealing member <NUM>, such as, for example, by an adhesive coating disposed on a surface of the sealing member <NUM> facing the base layer <NUM>. The adhesive coating may be similar to the adhesive <NUM> applied across the surface of the sealing member <NUM> facing the base layer <NUM>. In the embodiment described above, the second wicking layer <NUM>, the absorbent layer <NUM>, and the first wicking layer <NUM> may respectively have increasing surface areas to enhance contact with the adhesive coating. In other embodiments, the fluid management assembly <NUM> may include any number of absorbent layers and wicking layers, arranged as described above, for treating a particular tissue site.

In operation of the system <NUM> according to one illustrative embodiment, the interface manifold <NUM> may be disposed proximate to the tissue site <NUM>. The dressing <NUM> may then be applied over the manifold <NUM> and the tissue site <NUM> to form the sealed space <NUM>. Specifically, the base layer <NUM> may be applied covering the interface manifold <NUM> and the tissue surrounding the tissue site <NUM>. The materials described above for the base layer <NUM> may have a tackiness for holding the dressing <NUM> initially in position. The tackiness may be such that if an adjustment is desired, the dressing <NUM> may be removed and reapplied. Once the dressing <NUM> is in the desired position, a force may be applied, such as hand pressure, on a side of the sealing member <NUM> facing outwards from the tissue site <NUM>. The force applied to the sealing member <NUM> may cause at least some portion of the adhesive <NUM> to extend through the plurality of apertures <NUM> and into contact with the tissue surrounding the tissue site <NUM>, such as the epidermis <NUM>, to releaseably adhere the dressing <NUM> about the tissue site <NUM>. In this manner, the configuration of the dressing <NUM> may provide an effective and reliable seal against challenging anatomical surfaces, such as an elbow or heal, at and around the tissue site <NUM>. Further, the dressing <NUM> may permit re-application or repositioning to, for example, correct air leaks caused by creases and other discontinuities in the dressing <NUM> and the tissue site <NUM>. The ability to rectify leaks may increase the reliability of the therapy and reduce power consumption.

As the dressing <NUM> comes into contact with fluid from the tissue site <NUM>, the fluid may move through the apertures <NUM> toward the fluid management assembly <NUM>, <NUM>. The fluid management assembly <NUM>, <NUM> may wick or otherwise move the fluid through the interface manifold <NUM> and away from the tissue site <NUM>. As described above, the interface manifold layer <NUM> may be adapted to communicate fluid from the tissue site <NUM> rather than store the fluid. Thus, relative to the interface manifold layer <NUM>, the fluid management assembly <NUM>, <NUM> may exhibit absorbent properties that may be more absorbent than any absorbent properties that may be exhibited by the interface manifold <NUM>. The fluid management assembly <NUM>, <NUM> being more absorbent than the manifold layer <NUM> may provide an absorbent gradient through the dressing <NUM> that attracts fluid from the tissue site <NUM> to the fluid management assembly <NUM>, <NUM>. Thus, fluid management assembly <NUM>, <NUM> may be adapted to wick, pull, draw, or otherwise attract fluid from the tissue site <NUM> through the manifold layer <NUM>. The fluid may initially come into contact with the first wicking layer <NUM>, <NUM>. The first wicking layer <NUM>, <NUM> may distribute the fluid laterally along the surface of the first wicking layer <NUM>, <NUM> for absorption and storage within the absorbent layer <NUM>, <NUM>. Similarly, fluid coming into contact with the second wicking layer <NUM>, <NUM> may be distributed laterally along the surface of the second wicking layer <NUM>, <NUM> for absorption within the absorbent layer <NUM>, <NUM>.

Claim 1:
A system for treating a tissue site, comprising:
an interface manifold (<NUM>) adapted to be positioned proximate the tissue site;
a dressing, comprising:
a base layer (<NUM>) having a periphery (<NUM>) surrounding a central portion (<NUM>) and a plurality of apertures (<NUM>) disposed through the periphery (<NUM>) and the central portion (<NUM>), wherein the base layer (<NUM>) is to cover the interface manifold and tissue surrounding the tissue site (<NUM>) ,
an adhesive (<NUM>) in fluid communication with the apertures (<NUM>) in the base layer, wherein, in use, the adhesive (<NUM>) extends through a plurality of the apertures (<NUM>) in the base layer (<NUM>) to contact the epidermis surrounding the tissue site through the apertures (<NUM>) in the base layer (<NUM>), for securing the dressing to the tissue surrounding the tissue site;
a sealing member (<NUM>) having a periphery (<NUM>) and a central portion (<NUM>), the periphery (<NUM>) of the sealing member (<NUM>) positioned proximate the periphery (<NUM>) of the base layer (<NUM>), wherein the central portion (<NUM>) of the sealing member (<NUM>) and the central portion (<NUM>) of the base layer (<NUM>) define an enclosure (<NUM>),
a first wicking layer (<NUM>) disposed in the enclosure (<NUM>),
a second wicking layer (<NUM>)disposed in the enclosure (<NUM>),
an absorbent layer (<NUM>) disposed between the first wicking layer (<NUM>) and the second wicking layer (<NUM>), and
a conduit interface (<NUM>) positioned proximate to the sealing member (<NUM>) and in fluid communication with the enclosure (<NUM>); and
a reduced-pressure source (<NUM>) adapted to be coupled in fluid communication with the conduit interface (<NUM>) to provide reduced pressure to the dressing.