US20110066123A1 - Medical dressings, systems, and methods employing sealants - Google Patents

Abstract

According to an illustrative embodiment, a system for treating a wound at a tissue site of a patient comprising a reduced-pressure source to supply reduced pressure, a drape adhering to the tissue site to cover the wound where possible leak passages between the drape and the tissue site may occur, and a seal disposed between the drape and the tissue site, is disclosed. The seal is adapted to react with a fluid to form a sealant substantially filling the passages in response to air leaking through the passages from outside the drape when reduced pressure is applied to the wound. According to another illustrative embodiment, a method for sealing a drape to a tissue site for treating a wound at the tissue site comprising applying the drape to cover the tissue site whereby passages are formed between the drape and the tissue site, positioning a seal between the drape and the tissue site wherein the seal is adapted to react with a fluid to form a sealant for substantially filling the passages, is also disclosed.

Description

RELATED APPLICATION
• The present invention claims the benefit, under 35 USC §119(e), of the filing of U.S. Provisional Patent Application Ser. No. 61/242,488, entitled “System and Method for Sealing a Wound,” filed Sep. 15, 2009, which is incorporated herein by reference for all purposes.
BACKGROUND
• The present invention relates generally to medical treatment systems, and more particularly, medical dressings, systems, and methods employing sealants.
• Clinical studies and practice have shown that providing a reduced pressure in proximity to a tissue site augments and accelerates the growth of new tissue at the tissue site. The applications of this phenomenon are numerous, but application of reduced pressure has been particularly successful in treating wounds. This treatment (frequently referred to in the medical community as “negative pressure wound therapy,” “reduced pressure therapy,” or “vacuum therapy”) provides a number of benefits, which may include faster healing and increased formulation of granulation tissue. Unless otherwise indicated, as used herein, “or” does not require mutual exclusivity.
SUMMARY
• According to an illustrative embodiment, a system for treating a wound at a tissue site of a patient comprising a reduced-pressure source to supply reduced pressure, a drape adhering to the tissue site to cover the wound where possible leak passages between the drape and tissue site may occur, and a seal disposed between the drape and the tissue site, is disclosed. The seal is adapted to react with a fluid to form a sealant substantially filling the passages in response to air leaking through the passages from outside the drape when reduced pressure is applied to the wound.
• According to another illustrative embodiment, an apparatus includes a seal having a first side and a second, tissue-facing side. The seal is adapted for placement adjacent the tissue site and is operable to expand in a presence of a fluid to form a substantially sealed space at the tissue site. The apparatus also includes a drape for covering the sealant and further forming the substantially sealed space.
• According to another illustrative embodiment, a method for sealing a drape to a tissue site for treating a wound at the tissue site comprising applying the drape to cover the tissue site whereby passages are formed between the drape and the tissue site, positioning a seal between the drape and the tissue site wherein the seal is adapted to react with a fluid to form a sealant for substantially filling the passages, is also disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a schematic, cross-sectional view of a reduced-pressure treatment system including dressing that utilizes a sealant according to one illustrative embodiment;
• FIG. 2 is a schematic, plan view of the sealant and the wound shown in the embodiment ofFIG. 1;
• FIG. 3 is a schematic, cross-sectional view of the dressing and the sealant shown inFIG. 1 after the sealant has transformed to a gelatinous or liquid state;
• FIG. 4 is a schematic, cross-sectional view of another embodiment of dressing that utilizes a sealant in the reduced-pressure treatment system ofFIG. 1; and
• FIG. 5 is a schematic, perspective view of a drape, sealant, and release liner for use with dressing ofFIG. 4 according to one illustrative embodiment.
DETAILED DESCRIPTION
• In the following detailed description of the illustrative embodiments, reference is made to the accompanying drawings that form a part hereof. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is understood that other embodiments may be utilized and that logical structural, mechanical, electrical, and chemical changes may be made without departing from the spirit or scope of the invention. To avoid detail not necessary to enable those skilled in the art to practice the embodiments described herein, the description may omit certain information known to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the illustrative embodiments are defined only by the appended claims.
• The term “reduced pressure” as used herein generally refers to a pressure less than the ambient pressure at a tissue site that is being subjected to treatment. In most cases, this reduced pressure will be less than the atmospheric pressure at which the patient is located. Alternatively, the reduced pressure may be less than a hydrostatic pressure associated with tissue at the tissue site. Although the terms “vacuum” and “negative pressure” may be used to describe the pressure applied to the tissue site, the actual pressure reduction applied to the tissue site may be significantly less than the pressure reduction normally associated with a complete vacuum. Reduced pressure may initially generate fluid flow in the area of the tissue site. As the hydrostatic pressure around the tissue site approaches the desired reduced pressure, the flow may subside, and the reduced pressure is then maintained. Unless otherwise indicated, values of pressure stated herein are gauge pressures. Similarly, references to increases in reduced pressure typically refer to a decrease in absolute pressure, while decreases in reduced pressure typically refer to an increase in absolute pressure.
• The term “tissue site” as used herein includes, without limitation, a wound or defect located on or within any tissue, including but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. The term “tissue site” may further refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it is desired to add or promote the growth of additional tissue. For example, reduced pressure tissue treatment may be used in certain tissue areas to grow additional tissue that may be harvested and transplanted to another tissue location. The tissue may be that of any mammal, such as a mouse, rat, rabbit, cat, dog, or primate, including humans, that are being treated as patients. Also, the wound at the tissue site may be due to a variety of causes, including trauma, surgery, degeneration, and other causes.
• Referring toFIGS. 1 and 2, a reducedpressure treatment system100 for applying a reduced pressure to atissue site101 of a patient according to an illustrative embodiment where thetissue site101 includes awound102 surrounded by healthy tissue including, without limitation, anepidermis103 of such tissue. Thesystem100 comprises acanister104 having a filter (not shown) contained within thecanister104 and afluid supply106 for delivering afluid105 to thetissue site101. Thecanister104 is positioned in fluid communication with a reducedpressure source108 and a reducedpressure dressing110 that is positioned at thetissue site101. The reducedpressure dressing110 is fluidly connected to thecanister104 by aconduit112. Theconduit112 may fluidly communicate with the reducedpressure dressing110 through atubing adapter114. Asecond conduit116 fluidly connects thecanister104 with the reducedpressure source108.
• Thecanister104 may be a fluid reservoir, or collection member, to filter or hold exudates and other fluids removed from thetissue site101. In one embodiment, thecanister104 and the reducedpressure source108 are integrated into a single housing structure. Thefluid supply106 is fluidly connected to the reducedpressure dressing110 by athird conduit118 that may be connected directly to the reduced pressure dressing110 (not shown) or indirectly via theconduit112 which requiresvalves122 and124 for controlling the delivery of reduced pressure from the reducedpressure source108 and/or thefluid105 from thefluid supply106, respectively. Thefluid105 may be any gas or liquid, and may contain growth factors, healing factors, or other substances to treat thewound102 at thetissue site101. For example, thefluid105 may be air, water, saline, or dye saline.
• In the embodiment illustrated inFIG. 1, the reducedpressure source108 is an electrically-driven vacuum pump. In another implementation, the reducedpressure source108 may instead be a manually-actuated or manually-charged pump that does not require electrical power. The reducedpressure source108 instead may be any other type of reduced pressure pump, or alternatively a wall suction port such as those available in hospitals and other medical facilities. The reducedpressure source108 may be housed within or used in conjunction with a reducedpressure treatment unit128, which may also contain sensors, processing units, alarm indicators, memory, databases, software, display unites, and user interfaces that further facilitate the application of reduced pressure treatment to thetissue site101. In one example, a sensor or switch (not shown) may be disposed at or near the reducedpressure source108 to determine a source pressure generated by the reducedpressure source108. The sensor may communicate with a processing unit that monitors and controls the reduced pressure that is delivered by the reducedpressure source108.
• The reducedpressure dressing110 includes adistribution manifold130 adapted to be positioned at thetissue site101, and adrape132 that covers thedistribution manifold130 to maintain reduced pressure beneath thedrape132 at thetissue site101. Thedrape132 includes anaperture134 through which thetubing adapter114 extends to provide fluid communication between theconduit112 and thedistribution manifold130. Thedrape132 further includes aperiphery portion136 that may extend beyond a perimeter of thetissue site101 and may include an adhesive or bonding agent (not shown) to secure thedrape132 to tissue adjacent thetissue site101. In one embodiment, the adhesive disposed on thedrape132 may be used to provide a seal between theepidermis103 and thedrape132 to prevent leakage of reduced pressure from thetissue site101. In another embodiment, a seal layer (not shown) such as, for example, a hydrogel or other material may be disposed between thedrape132 and theepidermis103 to augment or substitute for the sealing properties of the adhesive.
• Thedistribution manifold130 of the reducedpressure dressing110 is adapted to contact thetissue site101. Thedistribution manifold130 may be partially or fully in contact with thetissue site101 being treated by the reducedpressure dressing110. When thedistribution manifold130 is in contact with thewound102 at thetissue site101, thedistribution manifold130 may partially or fully fill thewound102. Thedistribution manifold130 may be any size, shape, or thickness depending on a variety of factors, such as the type of treatment being implemented or the nature and size of thetissue site101 or thewound102. For example, the size and shape of thedistribution manifold130 may be customized by a user to cover a particular portion of thetissue site101, or to fill or partially fill thetissue site101 or thewound102. Thedistribution manifold130 may have, for example, a square shape, or may be shaped as a circle, oval, polygon, an irregular shape, or any other shape. Thedistribution manifold130 may further promote granulation at thetissue site101 when a reduced pressure is applied through the reduced pressure dressing110. For example, any or all of the surfaces of thedistribution manifold130 may have an uneven, coarse, or jagged profile that causes microstrains and stresses at thetissue site101 when reduced pressure is applied through thedistribution manifold130. These microstrains and stresses have been shown to increase new tissue growth.
• In one illustrative embodiment, thedistribution manifold130 is a foam material that distributes reduced pressure to thetissue site101 when thedistribution manifold130 is in contact with or near thetissue site101. The foam material may be either hydrophobic or hydrophilic. In one non-limiting example, thedistribution manifold130 is an open-cell, reticulated polyurethane foam such as GranuFoam® dressing available from Kinetic Concepts, Inc. of San Antonio, Tex. In the example in which thedistribution manifold130 is made from a hydrophilic material, thedistribution manifold130 also functions to wick fluid away from thetissue site101, while continuing to provide reduced pressure to thetissue site101 as a manifold. The wicking properties of thedistribution manifold130 draw fluid away from thetissue site101 by capillary flow or other wicking mechanisms. An example of a hydrophilic foam is a polyvinyl alcohol, open-cell foam such as V.A.C. WhiteFoam® dressing available from Kinetic Concepts, Inc. of San Antonio, Tex. Other hydrophilic foams may include those made from polyether. Other foams that may exhibit hydrophilic characteristics include hydrophobic foams that have been treated or coated to provide hydrophilicity.
• In one embodiment, thedistribution manifold130 may be constructed from bioresorbable materials that do not have to be removed from a patient's body following use of the reduced pressure dressing110. Suitable bioresorbable materials may include, without limitation, a polymeric blend of polylactic acid (PLA) and polyglycolic acid (PGA). The polymeric blend may also include, without limitation, polycarbonates, polyfumarates, and capralactones. Thedistribution manifold130 may further serve as a scaffold for new cell-growth, or a scaffold material may be used in conjunction with thedistribution manifold130 to promote cell-growth. A scaffold is a substance or structure used to enhance or promote the growth of cells or formation of tissue, such as a three-dimensional porous structure that provides a template for cell growth. Illustrative examples of scaffold materials include calcium phosphate, collagen, PLA/PGA, coral hydroxy apatites, carbonates, or processed allograft materials.
• Thedrape132 may be any material that provides a pneumatic or fluid seal. Thedrape132 may, for example, be an impermeable or semi-permeable, elastomeric material.
• “Elastomeric” means having the properties of an elastomer, and generally refers to a polymeric material that has rubber-like properties. More specifically, most elastomers have elongation rates greater than 100% and a significant amount of resilience. The resilience of a material refers to the material's ability to recover from an elastic deformation. Examples of elastomers may include, but are not limited to, natural rubbers, polyisoprene, styrene butadiene rubber, chloroprene rubber, polybutadiene, nitrile rubber, butyl rubber, ethylene propylene rubber, ethylene propylene diene monomer, chlorosulfonated polyethylene, polysulfide rubber, polyurethane, EVA film, co-polyester, and silicones. Specific examples of drape materials include a silicone drape, 3M Tegaderm® drape, acrylic drape such as one available from Avery Dennison, or an incise drape.
• The reduced pressure dressing110 further includes aseal140 that is generally annular in shape and disposed between thetissue site101 and thedrape132 thereby having a tissue-facingside142 and a drape-facingside144 when positioned on thetissue site101. Thedrape132 covers theseal140 such that theperiphery portion136 of thedrape132 extends beyond theseal140 so that the adhesive portion of thedrape132 adheres to the tissue surrounding thewound102 at thetissue site101. Theseal140 is substantially solid in form and substantially surrounds thewound102 so that the tissue-facingside142 is positioned adjacent theepidermis103 of thetissue site101. Even though theperiphery portion136 of thedrape132 functions as an adhesive with some sealing capability as described above, theepidermis103 may have recesses and cracks or other discontinuities on the surface, i.e.,epidermal discontinuities150, extending beyond theperiphery portion136. Theseepidermal discontinuities150form passages152 through which air from outside the reduced pressure dressing110 (“external air”) may leak into thetissue site101 when reduced pressure is delivered to thedistribution manifold130. Additionally, when thedrape132 is positioned on thetissue site101, folds or buckles in thedrape132, i.e., drapediscontinuities154, may also form thepassages152 through which external air may leak into thetissue site101 when reduced pressure is delivered to thedistribution manifold130.
• Referring toFIGS. 1 and 3, theseal140 is initially solid in form that is made from material adapted to react with fluid such as, for example, the flow of external air as indicated byarrows155. This reaction transforms theseal140 from solid phase to either liquid or gel which flows or expands to fill thepassages152 created by theepidermal discontinuities150 and/or thedrape discontinuities154. Consequently, the transformedseal140 forms asealant160 that fills thepassages152 and prevents the external air from leaking into thetissue site101 when reduced pressure is delivered to thedistribution manifold130. Thesealant160 substantially blocks thepassages152 to prevent the external air from being drawn into thewound102 by the reduced pressure, thereby maintaining the level of reduced pressure being delivered by thedistribution manifold130 to thetissue site101.
• Theseal140 may be fabricated from a material containing isocyanate that reacts with water vapor content of the external air to create carbon dioxide gas within the material causing the material to expand and fill thepassages152 forming thesealant160 that plugs thepassages152 created by theepidermal discontinuities150 and thedrape discontinuities154. Water-sensitive polymers may also be used to form theseal140. For example, theseal140 may be formed from an uncrosslinked water-sensitive polymer to liquify when exposed to moisture. Theseal140 may also be formed from a crosslinked water-sensitive polymer to swell when exposed to moisture. Water-sensitive polymers include polyacrylates, polyvinylpyrrolidone, polyvinyl alcohol, alginates, and carboxymethyl cellulose. In another example, theseal140 may be formed from water-sensitive materials that liberate gases such as metal hydrides and carbides. Further, hygroscopic materials, such as anhydrides, may be used to form theseal140 some of which may also increase in volume as moisture is absorbed. The transformation of a water-sensitive seal140 to form thesealant160 may be initiated or accelerated by first using a sponge or other application device to wet the surfaces of theseal140 with water. Further transformation results when the water vapor content of the external air reacts with the water-sensitive material being utilized for theseal140.
• In another embodiment, thefluid supply106 may provide the fluid105 to thetissue site101 via thedistribution manifold130 as described above and further indicated byarrows164 wherein the fluid105 includes an agent that facilitates the transformation of theseal140 into thesealant160 when exposed to the leakage of external air that comes in contact with theseal140. In another embodiment, thefluid supply106 may provide the fluid105 to thetissue site101 via thedistribution manifold130 as described above and further indicated by thearrows164 wherein the fluid105 includes an agent that causes the transformation of theseal140 into thesealant160 without being exposed to the leakage of external air that comes in contact with theseal140. For example, solvents may be introduced as solutions that cause theseal140 to liquefy or swell. As described above, the transformation of a water-sensitive seal140 to form thesealant160 may be initiated or accelerated by first using a sponge or other application device to wet the surfaces of theseal140 with either water or the solvent.
• Examples of solvents that may be used include alcohols, glycols, polyethylene glycols, and glycerine that react with aseal140 that is fabricated from materials such as modified polyurethanes, acrylics, and acetates. Other solvents, incompatible with water, may also be used and introduced as emulsions or dispersions that are absorbed by theseal140 which liquefies or swells as a result of the reaction. Examples of these water-incompatible solvents include esters, phthalates, trimellitates, citrates, and vegetable oils. Theseal140 may also be formed from polyurethane that contains an active substance that expands upon contact with thefluid105. The polyurethane may also function as an adhesive so that thesealant160 adheres more tightly to thedrape132 and the patient'sepidermis103.
• In another embodiment, theseal140 may also include isocyanate, tartaric acid and sodium bicarbonate, super absorbent fiber that expands when exposed to a fluid, or water-absorbing polymers that swell when exposed to a fluid. In the example in which theseal140 is formed from a fiber, the fiber may form a mesh such that the fibers are oriented along at least two directions and intersect with one another. In one embodiment, the expansion of theseal140 may be caused by the formation of bubbles within theseal140 after it transforms into thesealant160. These bubbles may be caused by the release of carbon dioxide upon contact between theseal140 and thefluid105. The specific material used for theseal140 may depend upon the manner in which the expansion of theseal140 is activated. Also, the shape of theseal140 can vary depending on the manner in which theseal140 is used or applied.
• The expansion of theseal140 can be activated using any of a variety of mechanisms depending on the embodiment employed, and several non-limiting examples follow. In one example, as discussed above, theseal140 expands in the presence of the fluid105 delivered from thefluid supply106 via thedistribution manifold130 as indicated by thearrows164 inFIG. 3. The fluid105 flows through thedistribution manifold130 and contacts theseal140 causing it to expand to fill thepassages152 created by theepidermal discontinuities150 and thedrape discontinuities154 as described above. The fluid105 may continue to be supplied to thesealant160 after the expansion of theseal140 to provide therapy to thewound102.
• The fluid used to activate and expand theseal140 may originate from sources other than thefluid supply106. In one embodiment, the fluid supplied to theseal140 may be exudate from thewound102. In this example, the exudate flows to theseal140 as indicated byexudate flow arrows157. In another example, fluid may be supplied to theseal140 by pre-applying the fluid to thetissue site101 with a sponge or other application device and, more specifically, the surface layer of theepidermis103, before applying the reduced pressure dressing110 to thetissue site101. This pre-applied fluid may be a gel or liquid sufficient to activate the expansion of theseal140. In yet another example, a fluid may be applied to theseal140 from under theperiphery portion136 of thedrape132 after the reduced pressure dressing110 has been applied to thetissue site101. In this example the fluid may be sprayed, injected, or otherwise applied onto or into theseal140 by a care giver, including the patient. Although the care giver may desire to expose all or a substantial portion of theseal140 to the fluid, the care giver may also apply the fluid to targeted regions of theseal140 based on an assessment of the areas in the reduced pressure dressing110 where thepassages152 are detected. Using this technique, a care giver may determine the areas at which a fluid lead exists in the reduced pressure dressing110, and apply the fluid to those portions of theseal140 that are adjacent thepassages152.
• In another example of a mechanism by which theseal140 may be exposed to a fluid, reduced pressure may be applied to thedistribution manifold130 so that the external air is drawn to theseal140 from the outside of the reduced pressure dressing110 through thepassages152 as described above and as indicated by thearrows155. When contacting theseal140, the vapor or humidity within the air reacts with theseal140 as described above. Theseal140 may be formed from material that reacts with the air or component thereof. For example, theseal140 may react with oxygen, carbon dioxide, or other component of the gas to cause the expansion of theseal140. In another embodiment, theseal140 may be formed from material that reacts to gases other than air that may be externally injected into thepassages152 causing theseal140 to expand. Examples of materials that increase in volume when absorbing a gas include iron that reacts with oxygen to form iron oxide (Fe₂O₃), and zinc oxide that reacts with carbon dioxide to form zinc carbonate. Amines and alcohol amines may also be used in theseal140 to absorb carbon dioxide.
• In yet another example, reduced pressure can be applied to thedistribution manifold130 to create a pressure differential under thedrape132 of sufficient magnitude to cause the expansion of theseal140. In this example, theseal140 is formed from a material that expands when a pressure drop exists across the length of the material. In one embodiment, theseal140 may be a composition comprising a material containing polymer spheres or bubbles (e.g., Expancel® from Akzo Nobel N.V. located at Strawinskylaan 2555, 1077 ZZ Amsterdam, Postbus 75730) that are filled with low boiling point liquids. Upon heating, the polymer softens and the spheres expand so that theseal140 fills any of thepassages152. Alternatively, the polymer spheres may soften into an elastic state without a significant change in the internal pressure or the corresponding size of the spheres. When a reduced pressure is applied to theseal140, however, the elastic spheres are subjected to a pressure differential causing them to expand so that theseal140 fills thepassages152. The pressure differential may be increased further causing the spheres to expand and ultimately rupture releasing their contents, such as gels or adhesives, to fill any of thepassages152 and bind the spheres together to form a tighter seal. Also, the exposed contents may be oxygen sensitive and harden over a period of time to increase the stability of the seal.
• Theseal140 and thedrape132 may be applied to thetissue site101 as a unit, or a care giver can cover theseal140 with thedrape132 after theseal140 has been applied. In another embodiment, the care giver may insert all or a portion of theseal140 under theperiphery portion136 of thedrape132 after thedrape132 has been applied to thetissue site101. By inserting theseal140 to the reduced pressure dressing110 after the reduced pressure dressing110 has been applied to thetissue site101, theseal140 may be used in conjunction with existing wound dressings.
• Referring now toFIGS. 4 and 5, a reduced pressure dressing210 is shown that includes thedrape132, a seal240 (as shown inFIG. 5) and thedistribution manifold130. Thedrape132 includes afirst side250 and a second, tissue-facingside252. Theseal240 is different from theseal140 ofFIG. 1 only in shape which covers a substantial portion of the second, tissue-facingside252 of thedrape132. When theseal240 transforms to a gelatinous or liquid state to form asealant260 as shown inFIG. 4, thesealant260 covers a larger surface area of theepidermis103 to plug more of the passages152 (not shown) resulting from theepidermal discontinuities150 and drape discontinuities (not shown) as described above. Using a sealant that covers a larger area of contact between thedrape132 and theepidermis103 may further reduce the number and severity of thepassages152 caused by both discontinuities.
• Arelease liner254 as shown inFIG. 5 may be utilized to cover a tissue-facingside212 of theseal240, prior to application of the reduced pressure dressing210 to thetissue site101. Therelease liner254 preserves the adhesiveness of theseal240 prior to the seal's240 contact with theepidermis103. Therelease liner254 also prevents fluid from contacting theseal240 prior to application of the reduced pressure dressing210 to thetissue site101. Therelease liner254 may be formed from any gas or liquid impermeable material to prevent theseal240 from being contaminated or from transforming to a gelatinous or liquid state before being applied to thetissue site101. Therelease liner254 may also have tabs (not shown) so that a care giver can easily peel therelease liner254 from theseal240 when desired.
• In an alternative embodiment, theseal240 may be inserted in separate pieces between thedrape132 and theepidermis103 after the reduced pressure dressing110 is applied to thetissue site101. Thedrape132 may be applied to thetissue site101 and held in place by an adhesive (not shown) that may also function as a sealant. The peripheral portion of thedrape132 is free from adhesive to leave a space for inserting pieces of theseal240 between thedrape132 and theepidermis103 to plug any of thepassages152 that may be detected after reduced pressure is applied to thewound102. The separate pieces of theseal240 do not need to be annular in shape as shown inFIGS. 1 and 4, but rather may be whatever shape necessary to plug thepassages152 that is detected. The separate piece or pieces ofseal240 are inserted under thedrape132 at the desired location and then exposed to any of the stimuli described above, e.g., reduced pressure or fluids, to transform the seal to thesealant160,260 as shown inFIGS. 3 and 4, respectively.
• Although the present invention and its advantages have been disclosed in the context of certain illustrative, non-limiting embodiments, it should be understood that various changes, substitutions, permutations, and alterations can be made without departing from the scope of the invention as defined by the appended claims.

Claims (29)

1. A system for treating a wound at a tissue site, the system comprising:

a pressure source to supply reduced pressure;

a manifold in fluid communication with said pressure source to provide reduced pressure to the wound;

a drape adhering to the tissue site to cover the wound and said manifold, there being passages between said drape and the tissue site; and,

a seal disposed between said drape and the tissue site, said seal adapted to react with a fluid to form a sealant substantially filling the passages in response to air leaking through the passages from outside said drape when said manifold provides reduced pressure to the wound.

2. The system ofclaim 1, wherein said seal contains an isocyanate material and the fluid is water vapor contained in the air that leaks from outside said drape to contact said seal.

3. The system ofclaim 1, wherein said seal is a water-sensitive polymer and the fluid is water vapor contained in the air that leaks from outside said drape to contact said seal.

4. The system ofclaim 3, wherein the water-sensitive polymer is polyacrylate, polyvinylpyrrolidone, polyvinyl alcohol, alginates, or carboxymethyl cellulose.

5. The system ofclaim 1, wherein said seal is a water-sensitive polymer and the fluid is exudates from the wound that contact said seal.

6. The system ofclaim 1, wherein said seal is a water-sensitive polymer and the fluid is water applied to said seal.

7. The system ofclaim 1, wherein said seal is a water-sensitive material that liberates gases to form the sealant and the fluid is water vapor contained in the air that leaks from outside said drape to contact said seal.

8. The system ofclaim 7, wherein the water-sensitive material is a metal hydride or a metal carbide.

9. The system ofclaim 1, further comprising a fluid supply for providing the fluid to the tissue site.

10. The system ofclaim 9, wherein the seal is polyurethane, acrylic, or acetate and the fluid is a solvent.

11. The system ofclaim 10, wherein the solvent is alcohol, glycol, polyethylene glycol, or glycerine.

12. The system ofclaim 1, wherein the fluid is a gas drawn into said manifold in response to application of reduced pressure to the tissue site, wherein the gas reacts with said seal to expand said seal to form the sealant.

13. The system ofclaim 1, wherein the fluid is pre-applied to the tissue site.

14. The system ofclaim 1, wherein said seal is a material comprising polymer spheres responsive to reduced pressure and expanding in response to a pressure differential provided by said pressure source to form the sealant.

15. The system ofclaim 1, wherein said seal has a first side and a second side facing the tissue site, further comprising:

a release liner covering at least one of the first side and the second side of the seal, the release liner adapted to prevent said seal from forming the sealant prior to application of the seal and the drape to the tissue site.

16. The system ofclaim 1, wherein said seal expands to form the sealant for filling the passages.

17. The system ofclaim 1, wherein the sealant at least partially fills the passages formed by a fold in said drape to substantially seal the passages.

18. The system ofclaim 1, wherein the seal forms an annulus at least partially surrounding the wound at the tissue site.

19. The system ofclaim 1, wherein said drape has a first side and a second side facing the tissue site, and wherein said seal substantially covers the second side of said drape.

20. The system ofclaim 1, wherein the sealant is adhesive and operable to cause said drape to adhere to the tissue site.

21. An apparatus for treating a wound at a tissue site, the apparatus comprising:

a manifold adapted to provide reduced pressure to the wound;

a drape having an adhesive surface for adhering to the tissue site to cover the wound and said manifold, there being passages between said drape and the tissue site; and,

a seal adjacent the adhesive surface of said drape, said seal disposed between said drape and the tissue site when applied to the tissue site and transformable to form a sealant substantially filling the passages between said drape and the tissue site when said manifold provides reduced pressure to the wound;

whereby air leaks from outside said drape are reduced when said manifold provides reduced pressure to the wound.

22. The apparatus ofclaim 21, wherein said seal contains an isocyanate material reactive with water vapor and transforms to form the sealant in response to water vapor contained in air when air leaks from outside said drape and contacts said seal.

23. The apparatus ofclaim 21, wherein said seal is a water-sensitive polymer that transforms to form the sealant in response to water vapor contained in air when air leaks from outside said drape and contacts said seal.

24. The apparatus ofclaim 23, wherein the water-sensitive polymer is polyacrylate, polyvinylpyrrolidone, polyvinyl alcohol, alginates, or carboxymethyl cellulose.

25-40. (canceled)

41. A method for sealing a drape to a tissue site for treating a wound at the tissue site, the method comprising:

applying the drape to cover the tissue site whereby passages are formed between the drape and the tissue site;

positioning a seal between the drape and the tissue site wherein the seal is adapted to react with a fluid to form a sealant for substantially filling the passages;

applying reduced pressure to the tissue site; and,

applying the fluid to the seal to form the sealant, whereby the sealant substantially fills the passages and reduces air leaking from outside said drape when reduced pressure is applied to the tissue site.

42-50. (canceled)

51. A method for treating a tissue site of a patient, the method comprising:

applying a dressing to the tissue site, the dressing comprising:

a seal having a first side and a second, tissue-facing side, the seal adapted for placement adjacent the tissue site, the seal operable to expand in a presence of a fluid to form a substantially sealed space at the tissue site; and

a drape for covering the seal and further forming the substantially sealed space.

52-58. (canceled)

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