WO2022096971A1

WO2022096971A1 - Moisture transporting dressing with pressure indicating pad

Info

Publication number: WO2022096971A1
Application number: PCT/IB2021/059517
Authority: WO
Inventors: Rachel MALONE; Christian Stephenson; David WARDE; Christopher Brian Locke
Original assignee: Kci Licensing, Inc.; Systagenix Wound Management, Limited
Priority date: 2020-11-03
Filing date: 2021-10-15
Publication date: 2022-05-12

Abstract

Some examples of a dressing may include a drape coupled to a contact layer at an outer region of the dressing to define an interior space. A pressure indicating layer may be disposed within the interior space. The pressure indicating layer may include a plurality of perforations. An absorbent material may be disposed within the interior space.

Description

MOISTURE TRANSPORTING DRESSING WITH PRESSURE INDICATING PAD

CROSS-REFERENCE TO REEATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Application No. 63/109,099, filed on November 3, 2020, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The invention set forth in the appended claims relates generally to tissue treatment systems and more particularly, but without limitation, to dressings, systems, methods, compositions, and other apparatuses for application to a tissue site, such as a wound.

BACKGROUND

[0003] A wide variety of materials and devices, generally characterized as “dressings,” are generally known in the art for use in treating an injury, defect, or other disruption of tissue. Such disruptions of tissue may be the result of trauma, surgery, or disease, and may affect skin or other tissues. In general, dressings may control bleeding, absorb exudate, ease pain, assist in debriding tissue, protect tissue from infection, and/or otherwise promote healing and protect tissue from further damage, for example, when placed on a patient’s epidermis and substantially overlaying the wound.

[0004] Some dressings may protect tissue from, or even assist in the treatment of infections associated with wounds. Infections can retard wound healing, and, if left untreated, can result in tissue loss, systemic infections, septic shock, and death. In some instances, the application of reduced pressure, such as negative pressure, to a dressing and a tissue site may enhance the treatment of the tissue site.

[0005] Further, clinical studies and practice have shown that reducing pressure in proximity to a tissue site can augment and accelerate growth of new tissue at the tissue site. The Applications of this phenomenon are numerous, but it has proven particularly advantageous for treating wounds. Regardless of the etiology of a wound, whether trauma, surgery, or some other cause, proper care of the wound is important to the outcome of treatment. 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,” “vacuum-assisted closure,” and “topical negative-pressure,” for example. Negative-pressure therapy may provide a number of benefits, including the migration of epithelial and subcutaneous tissues, improved blood flow, and the micro-deformation of tissue at a wound site. Together, these benefits can increase the development of granulation tissue and reduce healing times.

[0006] While the clinical benefits of dressings and negative-pressure therapy are widely known, improvements to therapy systems, components, and processes may benefit healthcare providers and patients. BRIEF SUMMARY

[0007] New and useful systems, apparatuses, and methods for treating tissue are set forth in the appended claims. Illustrative embodiments are provided to enable a person skilled in the art to make and use the claimed subject matter.

[0008] For example, in some embodiments, a dressing may include a drape coupled to a contact layer at an outer region of the dressing to define an interior space. A pressure indicating layer may be disposed within the interior space. The pressure indicating layer may include a plurality of perforations. An absorbent layer may be disposed within the interior space. According to example embodiments, the pressure indicating layer may be disposed in the interior space adjacent to the drape. In some embodiments, the absorbent layer may be disposed in the interior space adjacent to the contact layer. In illustrative embodiments, the pressure indicating layer includes an aperture layer between a colored elastomer layer and a lensing layer. For example, the aperture layer may have one or more apertures. In some embodiments, the colored elastomer layer may be configured to contact the lensing layer through one or more of the apertures in response to a pressure applied to a surface of the pressure indicating layer. In illustrative embodiments, each perforation may be a circle. In some embodiments, each perforation may include a diameter in a range of about 1 mm to about 4 mm. In example embodiments, each perforation may be spaced a distance about 5 mm center to center from any adjacent perforation. In some embodiments, an edge of each perforation may be spaced a distance of about 5 mm from an edge of any adjacent perforation. According to illustrative embodiments, the absorbent layer may include a hydrophilic foam. In example embodiments, the absorbent layer may include a first wicking layer coupled to a second wicking layer at a periphery of the first wicking layer to form an envelope. In some embodiments, a superabsorbent material may be disposed inside the envelope.

[0009] Further, in some example embodiments, a method for providing a visual indication of pressure may be provided. The method may include the steps of providing a dressing, applying a pressure to a first area on a surface of the dressing, and observing a color change of the dressing through a surface of the dressing. In illustrative embodiments, the method may also include applying the dressing to a tissue site on a patient, marking an area of the dressing with a color change at a first time ti, and repositioning the patient so pressure is applied to a second area on the surface of the dressing, with the second area being different from the first area. For example, the dressing may include a drape coupled to a contact layer at an outer region of the dressing to define an interior space. In some embodiments, a pressure indicating layer may be disposed within the interior space adjacent to the drape, and the pressure indicating layer may have a plurality of perforations. In illustrative embodiments, an absorbent layer may be disposed within the interior space adjacent to the contact layer. In example embodiments, the pressure indicating layer may include an aperture layer between a colored elastomer layer and a lensing layer. For example, the aperture layer may have one or more apertures. According to some embodiments, the colored elastomer layer may be configured to contact the lensing layer through one or more of the apertures in response to the pressure applied to the surface of the dressing. In example embodiments of the method, the step of observing a color change of the dressing through a surface of the dressing may include observing the colored elastomer layer through the lensing layer and the drape.

[0010] A system for treating a tissue site with negative pressure is also described herein, wherein some example embodiments may include a manifold configured to be positioned adjacent to the tissue site and a dressing configured to be positioned over the tissue site and the manifold and seal to tissue adjacent to the tissue site to form a sealed space. The dressing may include a drape coupled to a contact layer at an outer region of the dressing to define an interior space, a pressure indicating layer disposed within the interior space, the pressure indicating layer having a first plurality of perforations, and an absorbent layer disposed within the interior space. The system may also include a negativepressure source configured to provide negative pressure to the sealed space. In some embodiments, the pressure indicating layer may be disposed in the interior space adjacent to the drape, and the pressure indicating layer may be disposed in the interior space adjacent to the pressure indicating layer. In illustrative embodiments, the pressure indicating layer may include an aperture layer between a colored elastomer layer and a lensing layer, and the aperture layer may include one or more apertures. For example, the colored elastomer layer may be configured to contact the lensing layer through one or more of the apertures in response to a pressure applied to a surface of the pressure indicating layer. In example embodiments, each perforation may be a circle. For example, each perforation may have a diameter in a range of about 1 mm to about 4 mm.

[0011] Other example embodiments may include a dressing with a cover coupled to a wicking layer near a periphery of the wicking layer to define an interior space. The dressing may include a pressure indicating layer disposed within the interior space adjacent to the cover, and a moisture retaining layer disposed within the interior space adjacent to the wicking layer. In some embodiments, the dressing may further include a contact layer coupled to the wicking layer opposite the cover. In example embodiments, the contact layer may include a plurality of perforations. In illustrative embodiments, the contact layer may include a silicone adhesive. In some embodiments, a periphery of the contact layer may be substantially coextensive with a periphery of the wicking layer. In example embodiments, a periphery of the contact layer may be substantially coextensive with a periphery of the cover. According to some embodiments, the wicking layer may be configured to wick fluid laterally across at least a portion of the wicking layer. In illustrative embodiments, a moisture transport region may be defined on the wicking layer between a periphery of the wicking layer and a periphery of the moisture retaining layer. In some embodiments, the wicking layer may be configured to wick fluid from at least one of the plurality of perforations across the wicking layer to the moisture transport region. In example embodiments, the cover may include a polyurethane material. For example, the cover may exhibit a thickness of about 30 micrometers. According to illustrative embodiments, the cover may exhibit a moisture vapor transmission rate (MVTR) in a range of about 250 g/m²/24 hours to about 5,000 g/m²/24 hours. In some embodiments, the cover may be optically transparent. [0012] In example embodiments, the moisture retaining layer may include a hydrophilic foam. In illustrative embodiments, the moisture retaining layer may include a first wicking layer coupled to a second wicking layer at a periphery of the first wicking layer to form an envelope. According to some embodiments, an absorbent material may be disposed within the envelope. For example, the absorbent material may include a superabsorbent. In example embodiments, the pressure indicating layer may include an aperture layer having one or more apertures, an elastomer layer adjacent to the aperture layer, and a lensing layer adjacent to the aperture layer opposite the elastomer layer. For example, the aperture layer may include a single aperture. In some embodiments, the aperture layer may include multiple apertures. For example, the multiple apertures may be substantially identical. In illustrative embodiments, the aperture layer may include a mesh layer. In some embodiments, the aperture layer may have a thickness in a range of about 0.01 mm to about 5 mm. According to example embodiments, the elastomer layer may include a colored silicone material. For example, the elastomer layer may exhibit a hardness on the Shore OOO, Shore OO, or Shore A scale. In some embodiments, the lensing layer may include a lenticular lens array. For example, the lenticular lens array may exhibit a lens density in a range of about 10 lenses per linear inch to about 500 lenses per linear inch. Example embodiments of the lenticular lens array may be formed from material having a refractive index in a range of about 1.49 to about 1.636. In some embodiments, the dressing may further include a border region on the moisture retaining layer between a periphery of the moisture retaining layer and a periphery of the pressure indicating layer. For example, the periphery of the pressure indicating layer may bound an area covering about 90% to about 95% of an area bounded by the periphery of the moisture retaining layer.

[0013] According to illustrative embodiments, a plurality of moisture indicators may be disposed on the border region of the moisture retaining layer. For example, each moisture indicator may include a top layer configured to transition from an opaque state in a dry state to an optically transparent state in a wet state . In some embodiments, the moisture indicator may include an indicator layer adjacent to the top layer. In example embodiments, the top layer may exhibit a refractive index in a range of about 1.0 to about 1.5 in the wet state. Some embodiments of the top layer include a plurality of fibers forming a porous structure. For example, each of the fibers may exhibit a refractive index of about 1.33. In some embodiments, the indicator layer may include a wicking material. In illustrative embodiments, the indicator layer may be marked with a symbol. In example embodiments, the indicator layer may be colored.

[0014] Objectives, advantages, and a preferred mode of making and using the claimed subject matter may be understood best by reference to the accompanying drawings in conjunction with the following detailed description of illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is an exploded view of an example embodiment of a dressing in accordance with this specification; [0016] Figure 2 is an isometric view of an assembled example of the dressing of Figure 1;

[0017] Figure 3 is a cross-sectional view of the example dressing of Figure 2, taken at line 3- 3, applied to a tissue site in accordance with this specification;

[0018] Figure 4 is a detail view, taken at reference FIG. 4 in Figure 3, illustrating details that may be associated with some example embodiments of the example dressing of Figure 3;

[0019] Figure 5 illustrates additional details that may be associated with the detail view of Figure 4 in some embodiments of the dressing of Figure 3;

[0020] Figure 6 illustrates additional details that may be associated with the detail view of Figure 4 in some example embodiments of the dressing of Figure 3;

[0021] Figure 7 illustrates additional details that may be associated with the detail view of Figure 4 in some example embodiments of the dressing of Figure 3;

[0022] Figure 8 is an exploded view of another example embodiment of a dressing in accordance with this specification;

[0023] Figure 9 is an isometric view of an assembled example of the dressing of Figure 8;

[0024] Figure 10 is a cross-sectional view of the example dressing of Figure 9, taken at line 10-10, applied to a tissue site in accordance with this specification;

[0025] Figure 11 is a block diagram of an example embodiment of a therapy system that can provide negative-pressure treatment and instillation treatment in accordance with this specification; and

[0026] Figure 12 is a schematic diagram of an example embodiment of a therapy system in accordance with this specification.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0027] The following description of example embodiments provides information that enables a person skilled in the art to make and use the subject matter set forth in the appended claims, but it may omit certain details already well-known in the art. The following detailed description is, therefore, to be taken as illustrative and not limiting.

[0028] Figure 1 is an exploded view of an example embodiment of a dressing 100 for application to a tissue site. The dressing 100 may include a cover layer, such as a drape 102, a pressure sensitive layer, such as a pressure indicating layer 104, a moisture retaining layer, such as an absorbent layer 106, a lateral fluid transport layer, such as a wicking layer 108, and a tissue or wound contact layer, such as contact layer 110. The drape 102 may include 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 polymide copolymers. Such materials are commercially available as, for example, Tegaderm® drape, commercially available from 3M Company, Minneapolis Minnesota; polyurethane (PU) drape, commercially available from Avery Dennison Corporation, Pasadena, California; polyether block polyamide copolymer (PEBAX), for example, from Arkema S.A., Colombes, France; and Inspire 2301 and Inspire 2327 polyurethane films, commercially available from Transcontinental Advanced Coatings, Wrexham, United Kingdom. For particular applications, the drape 102 may be Inspire 2301 material having an MVTR (according to the upright cup technique) of 2600 g/m²/24 hours and have a thickness of about 30 micrometers. The drape 102 may have a high MVTR, for example, at least 250 g/m² 24 hours. An MVTR in a range of about 250 g/m²/24 hours to about 5,000 g/m²/24 hours may be suitable for particular applications of the drape 102. The drape 102 may be substantially clear or optically transparent, permitting a user to see through the drape 102. The drape 102 may include a first side 112 opposite a second side 114, and include a periphery 116 at an outer perimeter of the drape 102. The drape 102 may be in a substantially sheet form such that the first side 112 and the second side 114 may be substantially planar surfaces.

[0029] The pressure indicating layer 104 may be a layer capable of providing a reversible visual indication of pressure applied to the pressure indicating layer 104. The pressure indicating layer 104 may include an elastomer layer or a colored elastomer layer. The colored elastomer layer may be formed from a hydrocarbon based gel, a polyurethane gel, a hydrogel, or a silicone based gel, and may have a Shore hardness on the Shore OOO, Shore OO, or Shore A scales. The colored elastomer layer may include a hydrocarbon based gel, such as a gel including a hydrocarbon and a copolymer. For example, the hydrocarbon based gel may include about 70% to about 98% hydrocarbon by weight, and up to about 30% copolymer by weight. The copolymer may be selected from one of a triblock, radial block, and multiblock copolymers. The copolymer may include from about 0%to about 10% by weight of a diblock copolymer. Examples of suitable copolymers may include styrene-ethylene/butylene- styrene (SEBS) copolymers and styrene-ethylene-propylene (SEP) copolymers. The colored elastomer layer may include an inorganic liquid, such as: mineral oil, isohexadecane, isododecane, hydrogenated polyisobutene, C12-C15 alkyl benzoate, isononyl isononanoate, isopropyl palminate, petrolatum, squalene, and/or hydrogenated poly(c6-12 olefin). The colored elastomer layer may also include a silicone-based polymer, such as the Silastic® range of silicone polymers commercially available from the Dow Inc., or the Elastosil® or Silpural® range of silicone polymers commercially available from Wacker Chemie AG. A portion of the colored elastomer layer may be colored with a suitable dye, which may be dissolved partially or fully in the elastomer. The elastomer layer may also be substantially transparent or optically clear, and may be associated with a colored backing sheet visible through the substantially transparent or optically clear elastomer layer. The colored elastomer layer may have a refractive index in a range of about 1.40 to about 1.60.

[0030] The pressure indicating layer 104 may further include an aperture layer adjacent to the colored elastomer layer as further described in the examples that follow. The aperture layer may include a single aperture or multiple substantially identical apertures. The aperture layer may have a thickness in a range of about 0.01 mm to about 5 mm. A thickness in a range of about 0.1 to about 2 mm may be suitable for particular applications of the aperture layer. The aperture layer may be a mesh layer, which may include a woven material, a non-woven material, a knitted material, or an aperture continuous material. Examples of suitable woven or knitted materials may include monofilament yams.

[0031] As will be described in the examples that follow, the pressure indicating layer 104 may include a lensing layer adjacent to the aperture layer opposite the colored elastomer layer. The lensing layer may be translucent, opalescent, semi-transparent, and/or semi -opaque, and may not transmit 100% of incident light from one face to the other. The lensing layer may return a portion of the incident light as scattered light or reflected light to the incident surface. The lensing layer may include a textured surface, which may include regular or irregular textures. Examples of textured materials with irregular surface textures which may be suitable for use as a lensing layer include: tissue paper, paper, nonwovens, woven fabrics, knitted fabric, open celled foams, and/or opacified polymer sheets (for example, polyvinylchloride sheets, polyethylene terephthalate, cellulose acetate, and/or Mylar A available from the 3M Company). The lensing layer may also include a plurality of regular structural features, such as hemispherical convex protrusions configured to scatter and/or reflect at least a portion of light incident to a surface of the lensing layer.

[0032] The lensing layer may be a lenticular lens array or microlens array. The lenticular lens array may be formed from a substantially transparent or optically clear material, and may have a thickness in a range of about 10 micrometers to about 5,000 micrometers. A thickness in a range of about 50 micrometers to about 1,000 micrometers may be suitable for particular applications of the lenticular lens array. The lenticular lens array may have a lens density in a range of about 10 lenses per linear inch to about 500 lenses per linear inch. A lens density in a range of about 50 lenses per linear inch to about 500 lenses per linear inch may be suitable for particular applications of the lenticular lens array. Each lens in the lenticular lens array may have a diameter in a range of about 10 micrometers to about 1,000 micrometers. Suitable examples of materials that the lenticular lens array may be formed from include: nylons, acrylic resins, polystyrene, polyethylene, polypropylene, polyethylene terephthalate (refractive index 1.636), poly(methyl methacrylate) (refractive index 1.49), polycarbonate (refractive index 1.58), polyvinylchloride (refractive index 1.60), cellulose (refractive index 1.54), or a blend or combination of materials. Commercially available examples of lenticular lens arrays are available from 0K3D International Group Limited, Film Optics Ltd, and Forward Optics.

[0033] The pressure indicating layer 104 may have a first side 118 opposite a second side 120. The first side 118 of the pressure indicating layer 104 may be a substantially planar surface. The second side 120 of the pressure indicating layer 104 may be a substantially planar surface. The pressure indicating layer 104 may also include a periphery 122 at an outer perimeter of the pressure indicating layer 104.

[0034] In example embodiments, a commercially available pressure indicating layer 104, such as the PressurePoint® product from Active Device Development Ltd may be used. [0035] The absorbent layer 106 may include a hydrophilic or an absorbent material adapted to absorb fluid, such as fluid from the tissue site or wound. The hydrophilic or absorbent material may hold, stabilize, and/or solidify fluids. The hydrophilic or absorbent material may be a hydrophilic foam material, and/or may be of the type of material referred to as “hydrogels,” “superabsorbents,” or “hydrocolloids.” The hydrophilic or absorbent material may include fibers or spheres, and may be capable of manifolding reduced pressure. The hydrophilic or absorbent material may be constructed or formed such that spaces between the fibers or spheres may allow a reduced pressure to be transferred within or through the hydrophilic or absorbent material. Examples of suitable hydrophilic or absorbent materials include: Absorbflex, Be Core, or Vortex, from Texsus s.p.a., Luquafleece® from BASF SE, Superabsorbent SAF™ fibers and fabrics from Technical Absorbents Limited, Gelok Laminates or TotalCare Airlaids from the Gelok International Corporation, sodium polyacrylate superabsorbents, cellulosics (carboxymethyl cellulose and salts such as sodium carboxymethyl cellulose), and/or alginates.

[0036] The absorbent layer 106 may also include a first wicking layer and a second wicking layer. The first wicking layer may have a grain structure adapted to wick fluid along a surface of the first wicking layer. Similarly, the second wicking layer may have a structure adapted to wick fluid along a surface of the second wicking layer. The first wicking layer and the second dressing wicking layer may wick or otherwise transport fluid in a lateral direction along the surfaces of the first wicking layer and the second wicking layer, respectively. The surface of the first wicking layer may be normal to the thickness of the first wicking layer, and the surface of the second wicking layer may be normal relative to the thickness of the second wicking layer. The wicking of fluid along the first wicking layer and the second wicking layer may enhance the distribution of fluid over a surface area of the hydrophilic or absorbent matenal, which may increase absorbent efficiency and resist fluid blockages by more evenly distributing fluid across the surface area of the hydrophilic or absorbent material. The first wicking layer may be coupled, laminated, adhered, or bonded to the second wicking layer at a periphery of the first wicking layer and the second wicking layer to form an envelope. The hydrophilic or absorbent material may be disposed within the envelope. The envelope may also contain the hydrophilic or absorbent material, and prevent the hydrophilic or absorbent material from migrating within the dressing 100. The absorbent layer 106 may have a first side 124 opposite a second side 126. The absorbent layer 106 may also include a periphery 128 at an outer perimeter of the absorbent layer 106.

[0037] The dressing 100 may also include the wicking layer 108, which may include a first side 130 opposite a second side 132, and include a periphery 134 at an outer perimeter of the wicking layer 108. The wicking layer 108 in a substantially sheet form such that the first side 130 and the second side 132 maybe substantially planar surfaces. The wicking layer 108 may have agrain structure adapted to wick fluid along the first side 130 and/or the second side 132 of the wicking layer 108. The wicking of fluid along the first side 130 and/or the second side 132 of the wicking layer 108 may wick or otherwise transport fluid in a lateral direction along the surfaces of the wicking layer 108, distributing fluid along the entirety ofthe wicking layer 108. The wicking layer 108 may include any material having a grain structure capable of wicking fluid as described, such as a nonwoven material. Nonwoven materials may be materials in which the majority of fibers in the fabric are neither woven nor knit together, and may be manufactured by placing fibers in a sheet or web structure, and binding the fibers together thermally (such as by spin bonding or flash spinning), with an adhesive, or mechanically (such as by mechanical interlocking). Materials suitable for the wicking layer 108 may include, without limitation, nonwoven materials such as Libeltex TDL2 or Libeltex TL4, having a material density in a range of about 80 grams per square meter to about 150 grams per square meter.

[0038] The contact layer 110 may be formed from an adhesive, such as a bonding or sealing adhesive. The bonding adhesive may be a high bond strength acrylic adhesive, high-tack silicone adhesive, or a polyurethane adhesive. The bond strength of the bonding adhesive may have a peel adhesion or resistance to being peeled from a stainless steel material between about 6 N/25 mm to about 10 N/25 mm on stainless steel substrate at 23° C at 50% relative humidity based on the American Society for Testing and Materials (“ASTM”) standard ASTM D3330. An acrylic bonding adhesive with a coating weight in a range of about 15 grams per square meter to about 70 grams per square meter may be suitable for particular applications. The sealing adhesive may be an adhesive having a low to medium tackiness, such as a silicone polymer, polyurethane, or an additional acrylic adhesive. The bond strength of the sealing adhesive may have a peel adhesion or resistance to being peeled from a stainless steel material between about 0.5 N/25 mm to about 1.5 N/25 mm on stainless steel substrate at 23° C at 50% relative humidity based on ASTM D3330. The sealing adhesive may have a tackiness such that the sealing adhesive may achieve the bond strength above after a contact time of less than 60 seconds. Tackiness may be considered a bond strength of an adhesive after a very low contact time between the adhesive and a substrate. The contact layer 110 may include a first side 136 opposite a second side 138, and include a periphery 140 at an outer perimeter of the contact layer 110. The contact layer 110 may include a plurality of perforations 142 formed through the contact layer 110. The perforations 142 may extend from the first side 136 of the contact layer 110 through the contact layer 110 and to the second side 138 of the contact layer 110. Fluid may flow from the first side 136 of the contact layer 110 through the thickness of the contact layer 110 and exit the contact layer 110 at the second side 138 of the contact layer 110. Fluid may flow in reverse from the second side 138 of the contact layer 110 through the thickness of the contact layer 110 and exit the contact layer 110 at the first side 136 of the contact layer 110. The perforations 142 may bring the first side 136 of the contact layer 110 into fluid communication with the second side 138 of the contact layer 110.

[0039] Figure 2 is an isometric view of an assembled example of dressing 100 of Figure 1, with the drape 102, pressure indicating layer 104, absorbent layer 106, wicking layer 108, and contact layer 110 in assembled form. The periphery 116 of the drape 102, the periphery 134 of the wicking layer 108, and the periphery 140 of the contact layer 110 may be substantially coextensive. The periphery 128 of the absorbent layer 106 may be substantially contained within the periphery 134 of the wicking layer 108. The region of the dressing 100 between the periphery 128 of the absorbent layer 106 and the periphery 140 of the contact layer 110, the periphery 128 of the absorbent layer 106 and the periphery 134 ofthe wicking layer 108, and/or the periphery 128 ofthe absorbent layer 106 and the periphery 116 of the drape 102 may be referred to as the moisture transport region 202. The region of the dressing 100 between the periphery 122 ofthe pressure indicating layer 104 and the periphery 128 of the absorbent layer 106 may be referred to as a border region 204. The size, area, or surface area of the moisture transport region 202 may be increased in order to increase the overall moisture vapor transmission rate (MVTR) ofthe dressing 100, and decreased in order to reduce the overall MVTR of the dressing 100. Generally, reducing the size of the border region 204 by selecting the periphery 122 ofthe pressure indicating layer 104 to be as extensive with the periphery 128 ofthe absorbent layer 106 as possible allows the pressure indicating layer 104 to provide pressure sensing and indicating capabilities for as much of the area covered by the absorbent layer 106 as possible . Generally, increasing the size of the border region 204 increases the overall MVTR of the dressing 100. The periphery 122 of the pressure indicating layer 104 may bound an area covering about 90% to about 95% of the area bounded by the periphery 128 of the absorbent layer 106 in particular applications. The pressure indicating layer 104, the absorbent layer 106, and the wicking layer 108 may be visible through the substantially clear or optically transparent drape 102.

[0040] Figure 3 is a cross-sectional view ofthe example dressing 100 of Figure 2, taken at line 3-3, and applied to an example tissue site, such as tissue site 302. The dressing 100 may be configured to interface with the tissue site 302. The dressing 100 may be generally configured to be positioned adjacent to the tissue site 302 and/or in contact with a portion of the tissue site 302, substantially all of the tissue site 302, the tissue site 302 in its entirety, or the tissue around the tissue site 302. The tissue site 302 may include a defect or targeted treatment site, such as a wound, that may be partially or completely filled or covered by the dressing 100. In various embodiments, the dressing 100 may take many forms, and may have many sizes, shapes, or thicknesses depending on a variety of factors, such as the type of treatment being implemented or the nature and size of the tissue site 302. For example, the size and shape of the dressing 100 may be adapted to the contours of deep and irregularly shaped tissue sites and/or may be configured to be adapted to a given shape or contour. In some embodiments, the tissue site 302 may comprise a wound 304 that extends through the epidermis 306 and into dermis 308. In some examples, as shown in Figure 3, the tissue site 302 may comprise a wound 304 which extends through the epidermis 306, the dermis 308, and into a subcutaneous tissue 310.

[0041] The contact layer 110 of the dressing 100 may be placed on the tissue site 302 such that at least a portion of the second side 138 of the contact layer 110 may be in contact with at least a portion of the tissue site 302. For example, at least a portion of the second side 138 of the contact layer 110 may be in contact with and/or adhered, coupled, or bonded to at least a portion of the wound 304 and/or the epidermis 306. In examples of the dressing 100 in which the contact layer 110 is formed from a silicone adhesive, the portion of the second side 138 of the contact layer 110 may not be adhered, coupled, or bonded to at least a portion of the wound 304, or may be adhered, coupled, or bonded to at least a portion of the wound 304 with reduced tack or strength if the portion of the wound 304 is moist or wet. The wicking layer 108 may be disposed on the contact layer 110 such that at least a portion of the second side 132 ofthe wicking layer 108 maybe in contact with and/or adhered, coupled, or bonded to at least a portion of the first side 136 of the contact layer 110. An adhesive layer 312, such as an acrylic adhesive, may be disposed on at least a portion of the second side 114 of the drape 102. In example embodiments, the adhesive layer 312 may be coated on the second side 114 of the drape 102 in a pattern, increasing the MVTR of the dressing 100 by increasing the uncoated surface area of the drape 102. The adhesive layer 312 may adhere, couple, or bond at least a portion of the drape 102 to at least a portion of the first side 130 of the wicking layer 108. For example, the adhesive layer 312 may adhere, couple, or bond the portion of the drape 102 at the moisture transport region 202 of the dressing 100 to the wicking layer 108 to define an interior space 314 of the dressing 100. The adhesive layer 312 may cover the entirety of the second side 114 of the drape 102, or cover only a portion of the second side 114 of the drape 102 in a suitable pattern. The absorbent layer 106 may be disposed within the interior space 314 such that at least a portion of the second side 126 of the absorbent layer 106 may be in contact with and/or adhered, coupled, or bonded to at least a portion of the first side 136 of the contact layer 110. The pressure indicating layer 104 may be disposed within the interior space 314 such that at least a portion of the second side 120 of the pressure indicating layer 104 may be in contact with and/or adhered, coupled, or bonded to at least a portion of the first side 124 of the absorbent layer 106. At least a portion of the first side 118 of the pressure indicating layer 104 may be in contact with and/or adhered, coupled, or bonded to at least a portion of the adhesive layer 312 or the second side 114 of the drape 102.

[0042] Moisture, fluid, and/or exudate from the wound 304 may travel through the perforations 142 in the contact layer 110 and into the wicking layer 108. The moisture, fluid, and/or exudate may be wicked laterally across at least a portion of the wicking layer 108. For example, some of the moisture, fluid, and/or exudate may be wicked laterally from the perforations 142 in the contact layer 110 to the moisture transport region 202 in the wicking layer 108, and exit the dressing 100 into the external environment through the first side 112 of the drape 102. Some of the moisture, fluid, and/or exudate may be transported from the portion of the first side 130 of the wicking layer 108 in contact with the portion of the second side 126 of the absorbent layer 106 and be absorbed by the absorbent layer 106. Some of the moisture, fluid, and/or exudate may be transported from the portion of the first side 130 of the wicking layer 108 in contact with the adhesive 312 and/or the second side 114 of the drape 102 across the drape 102 to exit into the external environment through the first side 112 of the drape 102. Some of the moisture, fluid, and/or exudate may be transported from the absorbent layer 106 (for example, from the periphery 128 of the absorbent layer 106 or from the border region 204) into the interior space 314 of the dressing 100, and across the drape 102 to exit into the external environment through the first side 112 of the drape 102. In embodiments where the drape 102 may be in contact with and/or adhered, coupled, or bonded to at least a portion of the absorbent layer 106 by the adhesive layer 312 (for example, at a portion of the periphery 128 of the absorbent layer 106 or at the border region 204), some of the moisture, fluid, and/or exudate may be transported from the absorbent layer 106 across the drape 102 to exit into the external environment through the first side 112 of the drape 102. Generally, increasing the size of the moisture transport region 202 and/or increasing the size of the border region 204 may increase the overall MVTR of the dressing 100. Conversely, reducing the size of the moisture transport region 202 and/or reducing the size of the border region 204 may reduce the overall MVTR of the dressing 100.

[0043] Figure 4 is a detail view, taken at reference FIG. 4 in Figure 3, illustrating details that may be associated with some example embodiments of the example dressing 100 of Figure 3. As described previously, the pressure indicating layer 104 may include a colored elastomer layer such as elastomer layer 402, an aperture layer such as aperture layer 404, and a lensing layer such as lensing layer 406. A side of the elastomer layer 402 may form the second side 120 of the pressure indicating layer 104. The aperture layer 404 may be disposed adjacent to the elastomer layer 404 opposite the second side 120 of the pressure indicating layer 104 such that at least a portion of the aperture layer 404 is in contact with at least a portion of the elastomer layer 402. A side of the lensing layer 406 may form the first side 118 of the pressure indicating layer 104. The lensing layer 406 may be disposed adjacent to the aperture layer 404 opposite the elastomer layer 402 such that at least a portion of the lensing layer 406 opposite the first side 118 of the pressure indicating layer 104 is in contact with at least a portion of the aperture layer 404. The lensing layer 406 may include a plurality of lenticular lenses 408, for example on the side of the lensing layer 406 opposite the first side 118 of the pressure indicating layer 104. As shown in the example of Figure 4, if a force is not applied to the first side 112 of the drape 102, the lensing layer 406 may not be received within the aperture 410, the aperture layer 404 may not be depressed into the elastomer layer 402, and the lenticular lenses 408 may not be in contact with the elastomer layer 402.

[0044] Figure 5 illustrates additional details that may be associated with the detail view of Figure 4 in some embodiments of the dressing 100 of Figure 3. Upon application of a force 502 to the first side 112 of the drape 102, a portion of the lensing layer 406 may be received in aperture 410, and/or the force 502 may be transmitted through the drape 102 and the lensing layer 406, pushing at least a portion of the aperture layer 404 into the elastomer layer 402, resulting in at least some of the plurality of lenticular lenses 408 being brought into contact with a portion of the elastomer layer 402. Generally, a higher level of optical clarity may be achieved when the refractive index is constant through a lensing material in the viewing direction. In the example embodiment of Figure 4, where an air gap is present in the aperture 410 between the lensing layer 406 and the colored elastomer layer 402, the optical clarity of the colored elastomer layer 402 viewed through the lensing layer 406 and the air gap in the aperture 410 may be reduced as a result of the difference in the refractive index of the air gap in the aperture 410 from the refractive index of the lensing layer 406. In the example embodiment of Figure 5, where the air gap is eliminated between the lenticular lenses 408 of the lensing layer 406 and the colored elastomer layer 402, then the optical clarity of the colored elastomer layer 402 viewed through the lenticular lenses 408, which are in contact with the colored elastomer layer 402, may be improved. For example, the color of the elastomer layer 402 may appear to be more vivid when viewed through the drape 102 and the lensing layer 406 at portions of the dressing 100 where the force 502 causes the lenticular lenses 408 to come into contact with the colored elastomer layer 402. The amount of force 502 required to bring the lenticular lenses 408 into contact with the elastomer layer 402 may vary depending on the thickness, geometry, and/or stiffness of the elastomer layer 402, the aperture layer 404, and/or the lensing layer 406.

[0045] Figure 6 illustrates additional details that may be associated with the detail view of Figure 4 in some embodiments of the dressing 100 of Figure 3. As described previously, in some embodiments, the aperture layer 404 of Figure 4 may be replaced by a mesh layer 602, with the apertures 410 defined as the spaces between the fibers 604 of the mesh layer 602.

[0046] Figure 7 illustrates additional details that may be associated with the detail view of Figure 6 in some embodiments of the dressing 100 of Figure 3. In the example of Figure 7, the force 502 may cause the lenticular lenses 408 into contact with the elastomer layer 402 through the apertures 410 between the fibers 604 of the mesh layer 602. For example, the force 502 may be transmitted to at least some of the fibers 604, pushing the fibers 604 into the elastomer layer 402, eliminating the air gap between the lenticular lenses 408 and the elastomer layer 402 at apertures 410. The amount of force 502 required to bring the lenticular lenses 408 into contact with the elastomer layer 402 may vary depending on the thickness, geometry, and/or stiffness of the elastomer layer 402, the mesh fibers 604 of the mesh layer 602, and/or the lensing layer 406.

[0047] Figure 8 is an exploded view of an example embodiment of the dressing 100 of Figure 1 illustrating additional and optional features that may be associated with the dressing 100. As illustrated in Figure 8, the pressure indicating layer 104 may be perforated, for example, with a plurality of perforations 802, through the pressure indicating layer 104. Each of the perforations 802 may be formed through the thickness of the pressure indicating layer 104, and extend from the first side 118 of the pressure indicating layer 104 through the pressure indicating layer 104 and to the second side 120 of the pressure indicating layer 104. Fluid may flow from the first side 118 of the pressure indicating layer 104 through the perforations 802 and exit the pressure indicating layer 104 at the second side 120 of the pressure indicating layer 110. Similarly, fluid may flow in reverse from the second side 120 of the pressure indicating layer 104 through the thickness of the pressure indicating layer 104 and exit the pressure indicating layer 104 at the first side 118 of the pressure indicating layer 104. The perforations 802 may bring the first side 118 of the pressure indicating layer 104 into fluid communication with the second side 120 of the pressure indicating layer 104. The perforations 802 may be any suitable shape, for example, circles, ovals, triangles, squares, rectangles, pentagons, hexagons, heptagons, octagons, nonagons, decagons, or any combination of suitable regular or irregular shapes. Circular perforations 802 with a diameter in a range of about 1 mm to about 4 mm may be suitable for particular applications. For example, diameters in a range of about 1 mm to about 2 mm may be suitable for some applications, while diameters in a range of about 3 mm to about 4 mm may be suitable for other applications. In example embodiments, the plurality of circular perforations 802 may be arranged in a pattern such that each of the perforations 802 is spaced a distance about 5 mm center to center from any other adjacent perforation 802. In illustrative embodiments, the plurality of circular perforations 802 may be arranged in a pattern such that each of the perforations 802 is spaced a distance about 5 mm measured as the shortest distance from edge to edge from any other adjacent perforation 802. In embodiments of the dressing 100 where the pressure indicating layer 104 includes perforations 802, the wicking layer 108 may optionally be omitted.

[0048] As illustrated in the example of Figure 8, the absorbent layer 106 may include a plurality of moisture indicators 804 at the border region 204 near the periphery 128 of the absorbent layer 106. Each of the moisture indicators 804 may include atop layer configured to transition from an opaque state in a dry state to a substantially clear or optically transparent state when exposed to fluid in a wet state. The top layer may have a refractive index in a range of about 1.0 to about 1.5 in the wet state. A refractive index in a range of about 1.25 to about 1.4 may be suitable for some applications of the top layer, while a refractive index of about 1.33 may be suitable for particular applications. Examples of suitable materials for the top layer of the moisture indicator 804 may include polyvinyl diflyroide membranes, such as the Durapore® membrane commercially available from Merck KGaA. Other flexible, breathable materials which may be configured to transition from an opaque state to a substantially clear or optically transparent state when exposed to fluid may also be used for the top layer of the moisture indicator 804.

[0049] The top layer of the moisture indicator 804 may be formed as a porous hydrophilic structure of fibers such that the top layer includes a plurality of air filled spaces when the top layer is in a dry state. In the dry state, the difference between the refractive index of the fibers and the refractive index of the air may cause light to be dispersed, resulting in the top layer appearing opaque. In the wet state, the spaces between the fibers in the top layer may be occupied by fluid. In the wet state, the higher refractive index of fluid results in less light being dispersed by the top layer, resulting in an increased clarity or optical transparency for the top layer. The fibers of the top layer may be selected to have a refractive index similar to the refractive index of the fluid within the top layer to increase the clarity or optical transparency of the top layer in the wet state. In some embodiments, the fibers may be formed so as to have a refractive index similar to the refractive index of water, for example, about 1.33.

[0050] The moisture indicator 804 may include an indicator layer configured to absorb fluids from the absorbent layer 106 of the dressing 100. The indicator layer may be formed from a hydrophilic porous material which provides a sufficiently high degree of wicking to allow fluid absorbed from the absorbent layer 106 to be transferred through the thickness of the indicator layer, and distributed to the top layer of the moisture indicator 804. For example, the indicator layer may be formed from a cellulose material with a low refractive index. In illustrative embodiments, the indicator layer may include a Whatman® Nylon Membranes filter member with about a 0.45 pore size. In example embodiments, the indicator layer may be formed from blotting paper. The indicator layer may act as a fdter for the fluid absorbed from the absorbent layer 106, reducing the exposure of the top layer of the moisture indicator 804 to any colored components of the fluid absorbed from the absorbent layer 106. One or more markings may be formed on the indicator layer, such as text, numbers, images, icons, symbols, logos, or any other indicia. The indicator layer may also be colored.

[0051] In assembled format, a surface of the top layer of the moisture indicator 804 may abut a surface of the indicator layer of the moisture indicator 804. For example, the surface of the top layer may be in contact with and substantially coextensive with the surface of the indicator layer. The indicator layer may be in contact with the first side 124 of the absorbent layer 106 on a surface of the indicator layer opposite the top layer. The indicator layer of the moisture indicator 804 may absorb fluid from the first side 124 of the absorbent layer 106, and wick the fluid through the thickness of the indicator layer, transporting the fluid to be in contact with the surface of the top layer in contact with the indicator layer. The fluid may be wicked throughout the top layer, causing the top layer to change from the opaque state dry state to the substantially clear or optically transparent wet state, allowing the user to see through the top layer and to the indicator layer. For example, when the moisture indicator 804 is sufficiently saturated with fluid, the one or more markings formed on the indicator layer and/or the color of the indicator layer may be visible to the user, providing visual indication that the moisture indicator 804 is in a fluid saturated state. In embodiments where the moisture indicators 804 are in contact with the first side 124 of the absorbent layer 106, the moisture indicators 804 may provide a visual indication or alert to the user that the absorbent layer 106 may be saturated with fluid.

[0052] Figure 9 is an isometric view of an assembled example of the dressing 100 of Figure 8, with the drape 102, pressure indicating layer 104, absorbent layer 106, optional wicking layer 108, contact layer 110, and moisture indicators 804 in assembled form. As illustrated in Figure 9, the moisture indicators 804 may be visible to the user through the substantially clear or optically transparent drape 102, providing the user a visual indication that the absorbent layer 106 may be saturated with fluid. The perforations 802 in the pressure indicating layer 104 may also be visible through the substantially clear or optically transparent drape 102. The perforations 802 may increase the overall MVTR through the dressing 100 by forming a pathway for fluid and/or moisture to travel from the absorbent layer 106 through the pressure indicating layer 104 and through the drape 102. By adding the perforations 802, the wicking layer 108 may be eliminated, and/or the moisture transport region 202 may be reduced or eliminated.

[0053] Figure 10 is a cross-sectional view of the example dressing 100 of Figure 9, taken at line 10-10, and applied to tissue site 302. Figure 10 illustrates an example of the dressing 100 with perforations 802 in the pressure indicating layer 104, moisture indicators 804 disposed on the first side 124 of the absorbent layer 106, and with the optional wicking layer 108. In illustrative embodiments of the dressing 100 with the perforations 802 and the optional wicking layer 108, an additional fluid path for the moisture, fluid, and/or exudate from the wound 304 is available through the perforations 802. Moisture, fluid, and/or exudate from the wound 304 may travel through the perforations 142 in the contact layer 110 and into the wicking layer 108. The moisture, fluid, and/or exudate may be wicked laterally across at least a portion of the wicking layer 108. Some of the moisture, fluid, and/or exudate may be transported from the portion of the first side 130 of the wicking layer 108 in contact with the portion of the second side 126 of the absorbent layer 106 and be absorbed by the absorbent layer 106. Some of the moisture, fluid, and/or exudate may be transported from the second side 126 of the absorbent layer 106, across the thickness of the absorbent layer 106 to the first side 124 of the absorbent layer 106, and into one or more of the perforations 802 in the pressure indicating layer 104. The moisture, fluid, and/or exudate may then exit the dressing 100 from the one or more of the perforations 802 by being transported across the drape 102 to exit the dressing 100 into the external environment through the first side 112 of the drape 102.

[0054] In examples of the dressing 100 with the perforations 802 and without the optional wicking layer 108, moisture, fluid, and/or exudate from the wound 304 may travel through the perforations 142 in the contact layer 110 and into the second side 126 of the absorbent layer 106. The moisture, fluid, and/or exudate may be absorbed by the absorbent layer 106. Some of the moisture, fluid, and/or exudate may be transported from the second side 126, across the thickness of the absorbent layer 106 to the first side 124 of the absorbent layer 106, and into one or more of the perforations 802 in the pressure indicating layer 104. The moisture, fluid, and/or exudate may be transported across the drape 102 to exit the dressing 100 into the external environment through the first side 112 of the drape 102.

[0055] Figure 11 is a block diagram of an example embodiment of a therapy system, such as therapy system 1100, that can provide negative-pressure treatment and instillation treatment. The therapy system 1100 may include a source or supply of negative pressure, such as a negative-pressure source 1102, and one or more distribution components. A distribution component is preferably detachable and may be disposable, reusable, or recyclable. A dressing, such as the dressing 100, and a fluid container, such as a container 1106, are examples of distribution components that may be associated with some examples of the therapy system 1100. As illustrated in the example of Figure 11, the dressing 100 may optionally be deployed as a cover over a tissue interface 1108 in some embodiments.

[0056] A fluid conductor is another illustrative example of a distribution component. A “fluid conductor,” in this context, broadly includes a tube, pipe, hose, conduit, or other structure with one or more lumina or open pathways adapted to convey a fluid between two ends. Typically, a tube is an elongated, cylindrical structure with some flexibility, but the geometry and rigidity may vary. Moreover, some fluid conductors may be molded into or otherwise integrally combined with other components. Distribution components may also include or comprise interfaces or fluid ports to facilitate coupling and de-coupling other components. In some embodiments, for example, a dressing interface or connector may facilitate coupling a fluid conductor to the dressing 100. For example, such a dressing interface may be a SENSAT.R.A.C.™ Pad available from Kinetic Concepts, Inc. of San Antonio, Texas.

[0057] The therapy system 1100 may also include a regulator or controller, such as a controller 1110. Additionally, the therapy system 1100 may include sensors to measure operating parameters and provide feedback signals to the controller 1110 indicative of the operating parameters. As illustrated in Figure 11, for example, the therapy system 1100 may include a first sensor 1112 and a second sensor 1114 coupled to the controller 1110.

[0058] The therapy system 1100 may also include a source of instillation solution. For example, a solution source 1116 may be fluidly coupled to the dressing 100, as illustrated in the example embodiment of Figure 11. The solution source 1116 may be fluidly coupled to a positive-pressure source such as a positive-pressure source 1118, a negative-pressure source such as the negative-pressure source 1102, or both in some embodiments. A regulator, such as an instillation regulator 1120, may also be fluidly coupled to the solution source 1116 and the dressing 100 to ensure proper dosage of instillation solution (e.g. saline) to a tissue site. For example, the instillation regulator 1120 may comprise a piston that can be pneumatically actuated by the negative-pressure source 1102 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 1110 may be coupled to the negative-pressure source 1102, the positive-pressure source 1118, or both, to control dosage of instillation solution to a tissue site. In some embodiments, the instillation regulator 1120 may also be fluidly coupled to the negative-pressure source 1102 through the dressing 100, as illustrated in the example of Figure 11.

[0059] Some components of the therapy system 1100 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 1102 may be combined with the controller 1110, the solution source 1116, and other components into a therapy unit.

[0060] In general, components of the therapy system 1100 may be coupled directly or indirectly. For example, the negative-pressure source 1102 may be directly coupled to the container 1106 and may be indirectly coupled to the dressing 100 through the container 1106. Coupling may include fluid, mechanical, thermal, electrical, or chemical coupling (such as a chemical bond), or some combination of coupling in some contexts. For example, the negative-pressure source 1102 may be electrically coupled to the controller 1110 and may be fluidly coupled to one or more distribution components to provide a fluid path to a tissue site. In some embodiments, components may also be coupled by virtue of physical proximity, being integral to a single structure, or being formed from the same piece of material. [0061] A negative-pressure supply, such as the negative-pressure source 1102, 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 micropump, for example. “Negative pressure” or “reduced 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 1102 may vary according to therapeutic requirements, the pressure is generally a low vacuum, also commonly referred to as a rough vacuum, between -5 mm Hg (-667 Pa) and -500 mm Hg (-66.7 kPa). Common therapeutic ranges are between -50 mm Hg (-6.7 kPa) and -300 mm Hg (-39.9 kPa).

[0062] The container 1106 is representative of a container, canister, pouch, or other storage component, which can be used to manage exudates and other fluids withdrawn from a tissue site. In many environments, a rigid container may be preferred or required for collecting, storing, and disposing of fluids. In other environments, fluids may be properly disposed of without rigid container storage, and a re-usable container could reduce waste and costs associated with negative-pressure therapy.

[0063] A controller, such as the controller 1110, may be a microprocessor or computer programmed to operate one or more components of the therapy system 1100, such as the negativepressure source 1102. In some embodiments, for example, the controller 1110 may be a microcontroller, which generally comprises an integrated circuit containing a processor core and a memory programmed to directly or indirectly control one or more operating parameters of the therapy system 1100. Operating parameters may include the power applied to the negative-pressure source 1102, the pressure generated by the negative-pressure source 1102, or the pressure distributed to the tissue interface 1108, for example. The controller 1110 is also preferably configured to receive one or more input signals, such as a feedback signal, and programmed to modify one or more operating parameters based on the input signals.

[0064] Sensors, such as the first sensor 1112 and the second sensor 1114, are generally known in the art as any apparatus operable to detect or measure a physical phenomenon or property, and generally provide a signal indicative of the phenomenon or property that is detected or measured. For example, the first sensor 1112 and the second sensor 1114 may be configured to measure one or more operating parameters of the therapy system 1100. In some embodiments, the first sensor 1112 may be a transducer configured to measure pressure in a pneumatic pathway and convert the measurement to a signal indicative of the pressure measured. In some embodiments, for example, the first sensor 1112 may be a piezo-resistive strain gauge. The second sensor 1114 may optionally measure operating parameters of the negative-pressure source 1102, such as a voltage or current, in some embodiments. Preferably, the signals from the first sensor 1112 and the second sensor 1114 are suitable as an input signal to the controller 1110, but some signal conditioning may be appropriate in some embodiments. For example, the signal may need to be filtered or amplified before it can be processed by the controller 1110. Typically, the signal is an electrical signal, but may be represented in other forms, such as an optical signal.

[0065] The tissue interface 1108 can be generally adapted to partially or folly contact a tissue site. In some embodiments, the tissue interface 1108 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 1108 underpressure. For example, a manifold may be adapted to receive negative pressure from a source and distribute negative pressure across the tissue interface 1108, 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.

[0066] In some embodiments, the cover or the dressing 100, may provide a bacterial barrier and protection from physical trauma. The cover or the dressing 100, 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 or the dressing 100, 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 or the dressing 100, may be substantially clear or optically transparent. The cover or the dressing 100, may have a high moisture-vapor transmission rate (MVTR) in some applications. For example, the MVTR may be at least 250 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 38°C and 10% relative humidity (RH). In some embodiments, an MVTR up to 5,000 grams per square meter per twenty-four hours may provide effective breathability and mechanical properties.

[0067] An attachment device may be used to attach the cover or the dressing 100, 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, pressuresensitive adhesive configured to bond the cover or the dressing 100, to epidermis around a tissue site. In some embodiments, for example, some or all of the cover or the dressing 100, may be coated with an adhesive, such as an acrylic adhesive, which may have a coating weight of about 25-65 grams per square meter (g.s.m.). In illustrative embodiments, the adhesive may be substantially clear or optically transparent. Thicker adhesives, or combinations of adhesives, may be applied in some embodiments to improve the seal and reduce leaks. Example embodiments of an attachment device may include a double-sided tape, paste, hydrocolloid, hydrogel, silicone gel, or organogel. [0068] The solution source 1116 may also be representative of a container, canister, pouch, bag, or other storage component, which can provide a solution for instillation therapy. Compositions of solutions may vary according to a prescribed therapy, but examples of solutions that may be suitable for some prescriptions include hypochlorite-based solutions, silver nitrate (0.5%), sulfur-based solutions, biguanides, cationic solutions, and isotonic solutions.

[0069] In operation, the tissue interface 1108 may be placed within, over, on, or otherwise proximate to a tissue site. If the tissue site is a wound, for example, the tissue interface 1108 may partially or completely fill the wound, or it may be placed over the wound. The cover or the dressing 100, may be placed over the tissue interface 1108 and sealed to an attachment surface near a tissue site . For example, the cover or the dressing 100, may be sealed to undamaged epidermis peripheral to a tissue site. Thus, the dressing 100 can provide a sealed therapeutic environment proximate to a tissue site, substantially isolated from the external environment, and the negative-pressure source 1102 can reduce pressure in the sealed therapeutic environment.

[0070] 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.

[0071] Negative pressure applied across the tissue site through the tissue interface 1108 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 1106.

[0072] In some embodiments, the controller 1110 may receive and process data from one or more sensors, such as the first sensor 1112. The controller 1110 may also control the operation of one or more components of the therapy system 1100 to manage the pressure delivered to the tissue interface 1108. In some embodiments, controller 1110 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 1108. 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 1110. 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 1110 can operate the negative-pressure source 1102 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 1108.

[0073] In some embodiments, the controller 1110 may have a continuous pressure mode, in which the negative-pressure source 1102 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 1110 can operate the negative-pressure source 1102 to cycle between a target pressure and atmospheric pressure. For example, the target pressure may be set at a value of 135 mmHg for a specified period of time (e g., 5 min), followed by a specified period of time (e.g., 2 min) of deactivation. The cycle can be repeated by activating the negative-pressure source 1102, which can form a square wave pattern between the target pressure and atmospheric pressure.

[0074] 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 1102 and the dressing 100 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, the initial rise time for one therapy system may be in a range of about 20-30 mmHg/second and in a range of about 5-10 mmHg/second for another therapy system. If the therapy system 1100 is operating in an intermittent mode, the repeating rise time may be a value substantially equal to the initial rise time.

[0075] 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 50 and 135 mmHg with a rise time set at a rate of +25 mmHg/min. and a descent time set at -25 mmHg/min. In other embodiments of the therapy system 1100, the triangular waveform may vary between negative pressure of 25 and 135 mmHg with a rise time set at a rate of +30 mmHg/min and a descent time set at -30 mmHg/min.

[0076] In some embodiments, the controller 1110 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 1110, 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.

[0077] In some embodiments, the controller 1110 may receive and process data, such as data related to 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 10 and 500 mL, and the dwell time may be between one second to 30 minutes. The controller 1110 may also control the operation of one or more components of the therapy system 1100 to instill solution. For example, the controller 1110 may manage fluid distributed from the solution source 1116 to the tissue interface 1108. In some embodiments, fluid may be instilled to a tissue site by applying a negative pressure from the negative-pressure source 1102 to reduce the pressure at the tissue site, drawing solution into the tissue interface 1108. In some embodiments, solution may be instilled to a tissue site by applying a positive pressure from the positive-pressure source 1118 to move solution from the solution source 1116 to the tissue interface 1108. Additionally or alternatively, the solution source 1116 may be elevated to a height sufficient to allow gravity to move solution into the tissue interface 1108.

[0078] The controller 1110 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 1108, 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 1108. 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 1110 may be utilized to select a mode of operation and the duration of the negative pressure treatment before commencing another instillation cycle.

[0079] Figure 12 is a schematic diagram of an example embodiment of a therapy system 1100 illustrating details that may be associated with some embodiments of the dressing 100 configured to treat a tissue site, such as tissue site 1202 with negative pressure. In operation, the tissue interface 1108 may be placed within, over, on, against, or otherwise proximate to the tissue site 1202, such as within wound 1204. The dressing 100 may be sealed to undamaged epidermis 306 peripheral to the tissue site 1202 by the contact layer 110, which may form an adhesive or sealing bond with the epidermis 306 at the second side 138 of the contact layer 110. As shown in Figure 12, the wicking layer 108 may be omitted from some embodiments of the dressing 100. Accordingly, the drape 102 may be bonded to the first side 136 of the contact layer 110 by adhesive 312 at an outer region 1206 of the dressing 100 (analogous to the moisture transport region 202 in location on the dressing 100) to define the interior space 314 ofthe dressing 100. Thus, the drape 102, adhesive 312, and contact layer 110 of the dressing 100 may provide a sealed therapeutic environment 1208 proximate to the tissue site 1202. The sealed therapeutic environment 1208 may be substantially isolated from the external environment, and the negative-pressure source 1102 may be fluidly coupled to the sealed therapeutic environment 1208. For example, the connector 1210 may be received through an aperture 1212 formed in the drape 102 and/or an aperture 1214 formed in the adhesive 312. The connector 1210 may form a fluid seal against aperture 1212 and/or aperture 1214, and be in fluid communication with the negative-pressure source 1102 by a fluid conduit, such as a tube 1216. The sealed therapeutic environment 1208 may be in fluid communication with the interior space 314 of the dressing 100 via the perforations 142 in the contact layer 110, and the interior space 314 of the dressing 100 may be in fluid communication with the negative-pressure source 1102 via the connector 1210. Negative pressure applied across the wound 1204 through the tissue interface 1108 disposed in the sealed therapeutic environment 1208 can induce macrostrain and microstrain at the wound 1204, and reduces exudates and other fluids from the wound 1204. The removed exudates and other fluids can be stored in the absorbent layer 106 and/or removed from the wound 1204 and dressing 100 and collected in a container 1106 fluidly coupled to the connector 1210 and the negative-pressure source 1102 and disposed of properly.

[0080] When negative pressure is applied to the system 1100, the sealed therapeutic environment 1208 and the interior space 314 of the dressing 100 may be at a pressure less than the ambient pressure external to the dressing 100 Accordingly, a pressure differential may be created across the drape 102, with resultant force vectors 1218 forming normal to the first side 112 of the drape 102 and in a direction from the first side 112 towards the second side 114. The resultant force vector 1218 may be transmitted to the first side 118 of the pressure indicating layer 104, causing at least some of the lenticular lenses 408 to come into contact with the colored elastomer layer 402, providing the user with a visual indication that the interior space 314 of the dressing 100 is under negative pressure. As the pressure within the interior space 314 of the dressing 100 may be normalized to the pressure within the sealed therapeutic environment 1208 through the perforations 142 in the contact layer 110, the pressure indicating layer 104 may provide a visual indication that the sealed therapeutic environment 1208 is under negative pressure.

[0081] The systems, apparatuses, and methods described herein may provide significant advantages. For example, the pressure indicating layer 104 will provide a visual indication by changing color when a specific level of force has been applied to an area (i.e., pressure) of the dressing 100 with the pressure indicating layer 104 by changing color in that area. When the dressing 100 is applied to a tissue site 302 on a patient, the pressure indicating layer 104 is therefore able to provide a visual indication for the user as to which areas of the pressure indicating layer 104 and dressing 100 are under pressure, allowing the user to identify areas which may be vulnerable to forming pressure sores or pressure ulcers. For example, the user may mark on the drape 102 the areas of the dressing 100 which are under pressure at a first time . The user may then reposition the patient so that a different area of the dressing 100 is under pressure at a second time t₂ after the first time preventing or reducing the incidence of pressure sore or pressure ulcer formation on the patient. Furthermore, the pressure indicating layer 104 may provide a visual indication to a user of the therapy system 1100 that negative pressure is provided to the sealed therapeutic environment 1208. For example, the pressure indicating layer 104 may change color when negative pressure is present in the sealed therapeutic environment 1208. Furthermore, the addition of the wicking layer 108 extending to the moisture transport region 202 may increase the overall MVTR of the dressing 100. Similarly, the addition of perforations 802 in the pressure indicating layer 104, particularly in examples of the pressure indicating layer including a colored elastomer layer 402 formed from a liquid and moisture occlusive material such as silicone, may increase the overall MVTR of the dressing 100. Increasing the overall MVTR of the dressing 100 may reduce maceration at the tissue site that the dressing 100 is applied to, and improve wound healing.

[0082] 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 100, the container 1106, tissue interface 1108, or any combination of components may be eliminated or separated from other components for manufacture or sale. In other example configurations, the controller 1110 may also be manufactured, configured, assembled, or sold independently of other components. Further features, elements, and aspects described in the context of some embodiments may also be omitted, combined, or replaced by alternative features serving the same, equivalent, or similar purpose without departing from the scope of the invention defined by the appended claims.

Claims

25

What is claimed is:

1. A dressing comprising: a drape coupled to a contact layer at an outer region of the dressing to define an interior space; a pressure indicating layer disposed within the interior space, the pressure indicating layer having a plurality of perforations; and an absorbent layer disposed within the interior space.

2. The dressing of claim 1, wherein the pressure indicating layer is disposed in the interior space adjacent to the drape.

3. The dressing of claim 2, wherein the absorbent layer is disposed in the interior space adjacent to the contact layer.

4. The dressing of claim 1, wherein the pressure indicating layer comprises: an aperture layer between a colored elastomer layer and a lensing layer, the aperture layer having one or more apertures; wherein the colored elastomer layer configured to contact the lensing layer through one or more of the apertures in response to a pressure applied to a surface of the pressure indicating layer.

5. The dressing of claim 1, wherein each perforation is a circle.

6. The dressing of claim 5, wherein each perforation comprises a diameter in a range of about 1 mm to about 4 mm.

7. The dressing of claim 5, wherein each perforation is spaced a distance about 5 mm center to center from any adjacent perforation.

8. The dressing of claim 5, wherein an edge of each perforation is spaced a distance of about 5 mm from an edge of any adjacent perforation.

9. The dressing of claim 1, wherein the absorbent layer comprises a hydrophilic foam.

10. The dressing of claim 1, wherein the absorbent layer comprises: a first wicking layer coupled to a second wicking layer at a periphery of the first wicking layer to form an envelope; and a superabsorbent material disposed inside the envelope.

11. A method for providing a visual indication of pressure comprising: providing a dressing; applying a pressure to a first area on a surface of the dressing; and observing a color change of the dressing through a surface of the dressing.

12. The method of claim 11, further comprising: applying the dressing to a tissue site on a patient; marking an area of the dressing with a color change at a first time //; repositioning the patient so pressure is applied to a second area on the surface of the dressing, the second area different from the first area. The method of claim 11, wherein the dressing comprises: a drape coupled to a contact layer at an outer region of the dressing to define an interior space; a pressure indicating layer disposed within the interior space adjacent to the drape, the pressure indicating layer having a plurality of perforations; and an absorbent layer disposed within the interior space adjacent to the contact layer. The method of claim 13, wherein the pressure indicating layer comprises: an aperture layer between a colored elastomer layer and a lensing layer, the aperture layer having one or more apertures; wherein the colored elastomer layer configured to contact the lensing layer through one or more of the apertures in response to the pressure applied to the surface of the dressing. The method of claim 14, wherein the step of observing a color change of the dressing through a surface of the dressing comprises observing the colored elastomer layer through the lensing layer and the drape. A system for treating a tissue site with negative pressure, comprising: a manifold configured to be positioned adjacent to the tissue site; a dressing configured to be positioned over the tissue site and the manifold and seal to tissue adjacent to the tissue site to form a sealed space, the dressing comprising: a drape coupled to a contact layer at an outer region of the dressing to define an interior space, a pressure indicating layer disposed within the interior space, the pressure indicating layer having a first plurality of perforations, and an absorbent layer disposed within the interior space; and a negative -pressure source configured to provide negative pressure to the sealed space. The system of claim 16, wherein the pressure indicating layer is disposed in the interior space adjacent to the drape, and wherein the pressure indicating layer is disposed in the interior space adjacent to the pressure indicating layer. The system of claim 16, wherein the pressure indicating layer comprises: an aperture layer between a colored elastomer layer and a lensing layer, the aperture layer having one or more apertures; wherein the colored elastomer layer configured to contact the lensing layer through one or more of the apertures in response to a pressure applied to a surface of the pressure indicating layer. The system of claim 16, wherein each perforation is a circle.

20. The system of claim 19, wherein each perforation comprises a diameter in a range of about 1 mm to about 4 mm.

21. A dressing comprising: a cover coupled to a wicking layer near a periphery of the wicking layer to define an interior space; a pressure indicating layer disposed within the interior space adjacent to the cover; and a moisture retaining layer disposed within the interior space adjacent to the wicking layer;

22. The dressing of claim 21, further comprising a contact layer coupled to the wicking layer opposite the cover.

23. The dressing of claim 22, wherein the contact layer comprises a plurality of perforations.

24. The dressing of claim 22, wherein the contact layer comprises a silicone adhesive.

25. The dressing of claim 22, wherein a periphery of the contact layer is substantially coextensive with a periphery of the wicking layer.

26. The dressing of claim 22, wherein a periphery of the contact layer is substantially coextensive with a periphery of the cover.

27. The dressing of claim 21, wherein the wicking layer is configured to wick fluid laterally across at least a portion of the wicking layer.

28. The dressing of claim 23, further comprising a moisture transport region on the wicking layer between a periphery of the wicking layer and a periphery of the moisture retaining layer.

29. The dressing of claim 28, wherein the wicking layer is configured to wick fluid from at least one of the plurality of perforations across the wicking layer to the moisture transport region.

30. The dressing of claim 21, wherein the cover comprises a polyurethane material.

31. The dressing of claim 21, wherein the cover comprises a thickness of about 30 micrometers.

32. The dressing of claim 21, wherein the cover comprises an MVTR in a range of about 250 g/m²/24 hours to about 5,000 g/m²/24 hours.

33. The dressing of claim 21, wherein the cover is optically transparent.

34. The dressing of claim 21, wherein the moisture retaining layer comprises a hydrophilic foam.

35. The dressing of claim 21, wherein the moisture retaining layer comprises: a first wicking layer coupled to a second wicking layer at a periphery of the first wicking layer to form an envelope; and an absorbent material disposed within the envelope.

36. The dressing of claim 35, wherein the absorbent material comprises a superabsorbent.

37. The dressing of claim 21, wherein the pressure indicating layer comprises: an aperture layer having one or more apertures; an elastomer layer adjacent to the aperture layer; and a lensing layer adjacent to the aperture layer opposite the elastomer layer.

38. The dressing of claim 37, wherein the aperture layer comprises a single aperture. 28

39. The dressing of claim 37, wherein the aperture layer comprises multiple apertures.

40. The dressing of claim 39, wherein the multiple apertures are substantially identical.

41. The dressing of claim 37, wherein the aperture layer comprises a mesh layer.

42. The dressing of claim 37, wherein the aperture layer comprises a thickness in a range of about

0.01 mm to about 5 mm.

43. The dressing of claim 37, wherein the elastomer layer comprises a colored silicone material.

44. The dressing of claim 37, wherein the elastomer layer exhibits a hardness on a Shore OOO scale.

45. The dressing of claim 37, wherein the elastomer layer exhibits a hardness on a Shore OO scale.

46. The dressing of claim 37, wherein the elastomer layer exhibits a hardness on a Shore A scale.

47. The dressing of claim 37, wherein the lensing layer comprises a lenticular lens array.

48. The dressing of claim 47, wherein the lenticular lens array exhibits a lens density in a range of about 10 lenses per linear inch to about 500 lenses per linear inch.

49. The dressing of claim 47, wherein the lenticular lens array is formed from material having a refractive index in a range of about 1.49 to about 1.636.

50. The dressing of claim 21, further comprising a border region on the moisture retaining layer layer between a periphery of the moisture retaining layer and a periphery of the pressure indicating layer.

51. The dressing of claim 50, wherein the periphery of the pressure indicating layer bounds an area covering about 90% to about 95% of an area bounded by the periphery of the moisture retaining layer.

52. The dressing of claim 50, further comprising a plurality of moisture indicators disposed on the border region of the moisture retaining layer.

53. The dressing of claim 52, wherein each moisture indicator comprises: a top layer configured to transition from an opaque state in a dry state to an optically transparent state in a wet state; and an indicator layer adjacent to the top layer.

54. The dressing of claim 53, wherein the top layer exhibits a refractive index in a range of about 1.0 to about 1.5 in the wet state.

55. The dressing of claim 53, wherein the top layer comprises a plurality of fibers forming a porous structure.

56. The dressing of claim 55, wherein each of the fibers exhibits a refractive index of about 1.33.

57. The dressing of claim 53, wherein the indicator layer comprises a wicking material.

58. The dressing of claim 53, wherein the indicator layer is marked with a symbol.

59. The dressing of claim 53, wherein the indicator layer comprises a color.

60. The systems, apparatuses, and methods substantially as described herein.