HK1133404A

HK1133404A - Biocompatible wound dressing

Info

Publication number: HK1133404A
Application number: HK10100437.9A
Authority: HK
Inventors: 阿切尔‧安布罗休; R‧W‧约翰森
Original assignee: 凯希特许有限公司
Priority date: 2007-01-25
Filing date: 2008-01-17
Publication date: 2010-03-26

Abstract

A multi-layer reduced pressure delivery apparatus is provided for applying reduced pressure tissue treatment to a tissue site. The multi-layer apparatus includes a tissue contact layer, a release layer, and a manifold layer. The tissue contact layer includes a scaffold adapted to contact the tissue site, the release layer includes a hydrogel-forming material and a plurality of flow channels, and the manifold layer includes a distribution manifold. The release layer is positioned between the tissue contact layer and the manifold layer to allow easy release of the manifold layer from the tissue contact layer following the administration of reduced pressure tissue treatment.

Description

Biocompatible wound dressing

Background

1. Field of the invention

The present invention relates generally to a system or method for promoting tissue growth, and more particularly to a multilayer wound dressing having a tissue growth medium for enhancing tissue growth when exposed to reduced pressure.

2. Description of related Art

Vacuum induced healing of open wounds has recently been provided by Kinetic Concepts, inc.And (5) production line popularization. The vacuum induced healing process has been described in the following commonly assigned patents: U.S. patent No. 4,969,880 issued on 13.11.1990 to zaierowski and continuation and partial continuation patents thereof, namely U.S. patent No. 5,100,396 issued on 31.3.1992, U.S. patent No. 5,261,893 issued on 16.11.1993 and U.S. patent No. 5,527,293 issued on 18.6.1996, the disclosures of which are incorporated herein by reference. Further improvements and improved vacuum induced healing methods are also described in the following patents: U.S. patent No. 6,071,267 to zaierowski at 6/2000 and U.S. patent nos. 5,636,643 and 5,645,081 to argentia et al at 6/10/1997 and 7/8/1997, respectively, the disclosures of which are incorporated by reference as if fully set forth herein.

Major work involving the formation of bioabsorbable and includable cell growth enhancing matrices, lattices or scaffolds has also been undertaken. Exemplary U.S. patents known to the applicant include U.S. patent No. 5,256,418 to Kemp et al issued on 10/26/1993; U.S. patent No. 5,449,383 to Chatelier et al, granted on 12.9.1995; bennett et al, 5,578,662, granted on 11, 26, 1996; and two patents to Yasukawa et al-U.S. patent No. 5,629,186 issued on 5/13/1997 and U.S. patent No. 5,780,281 issued on 7/14/1998, both from a common parent application; the disclosures of these patents are incorporated herein by reference.

As is well known to those of ordinary skill in the art, surface wound closure involves inward migration (inward migration) of epithelial and subcutaneous tissue in the vicinity of the wound. This migration is often accompanied by an inflammatory process whereby blood flow is increased and various functional cell types are activated. As a result of the inflammatory process, blood flow through damaged or diseased blood vessels is stopped by capillary level occlusion; after which purge and rebuild operations begin. Unfortunately, this process is prevented when the wound is large or has become infected. In such wounds, a zone of stasis (i.e., an area in which local elevations of tissue restrict blood flow to the tissue) forms near the surface of the wound.

Without sufficient blood flow, the epithelial and subcutaneous tissues surrounding the wound not only acquire reduced oxygen and nutrients, but are also less successful at resisting bacterial infection and are therefore less able to close the wound naturally. This difficult wound was only treated by using sutures or staples (staple) before vacuum-induced therapy appeared. Although such mechanical closure techniques are still widely practiced and generally effective, they have the major disadvantage that they cause tightening of the skin tissue in the vicinity of the wound. In particular, the tension required to achieve closure using sutures or staples can create very high localized stresses at the suture or staple insertion point (insertion point). These stresses often result in tissue disruption at the insertion point, which can ultimately cause wound dehiscence and additional tissue sloughing.

Furthermore, because of infection, some wounds harden and inflame to the extent that closure by stapling or suturing is not feasible. Wounds that cannot be repaired by suturing or stapling often require long-term hospitalization with attendant high costs and major surgical procedures, such as transplantation of surrounding tissue. Examples of wounds that are not easily treated with staples or sutures include large, deep open wounds; bedsores; ulcers caused by chronic osteomyelitis; and partial cortical burns, which subsequently develop into full cortical burns.

In view of these and other drawbacks of mechanical closure devices, a device for applying continuous negative pressure has been developedMethods and devices for draining a wound. It has been found that such negative pressure, when applied to a sufficient area of the wound, promotes the migration of epithelial and subcutaneous tissue to the wound. In practice, under the name "Vacuum Assisted Closure" (or "v.a.c.) by the assignee or its parent (its parent).") the application of negative gauge pressure to a wound under therapy, which is commercialized, typically involves mechanical contraction of the wound while removing excess fluid. In this way, v.a.c.Treatment increases the body's natural inflammatory process while alleviating many of the known inherent side effects, such as the production of edema caused by increased blood flow in the absence of the vascular structure required for proper venous return.

Despite v.a.c.Treatment has been very successful in promoting wound closure, but difficulties remain in healing many wounds previously largely considered untreatable. As v.a.c.The very nature of the treatment requires a constant pressure seal of the wound site, so the treatment must often be performed in a wound treatment mode that excludes other advantageous and therefore desirable wound treatment modes. To date, one of these modes of elimination is to promote cell growth by providing an in situ cell growth-enhancing matrix.

There are still additional difficulties in frequently changing wound dressings. With the wound closed, binding of the cellular tissue to the wound dressing may occur. Conventional v.a.c. was used.Treatment requires regular dressing changes. If cellular tissue has overgrown into the dressing, a light dressing change may result in some tissue damage at the wound site.

Brief description of the invention

The systems and methods of the present invention solve problems with existing tissue dressings. In accordance with one embodiment of the present invention, a reduced pressure delivery system for applying reduced pressure tissue treatment to a tissue site is provided. The reduced pressure delivery system includes a multi-layer reduced pressure delivery apparatus having a tissue contact layer, a release layer, and a manifold layer. The tissue contacting layer includes a scaffold adapted to contact the tissue site. The release layer includes a hydrogel-forming material (hydrogel-forming material) and a plurality of flow channels, and the manifold layer includes a distribution manifold. The release layer is positioned between the tissue contact layer and the manifold layer, and the hydrogel-forming material of the release layer is bonded to at least one of the tissue contact layer and the manifold layer. A reduced pressure delivery tube is fluidly connected to the manifold layer to deliver reduced pressure to the tissue site.

In accordance with another embodiment of the present invention, a multi-layer reduced pressure delivery apparatus includes a first layer having a scaffold adapted to contact a tissue site and a second layer having a hydrogel-forming material and a plurality of flow channels. The hydrogel-forming material is in contact with the scaffold. The reduced pressure delivery apparatus further includes a third layer having a distribution manifold in contact with the hydrogel-forming material.

In yet another embodiment of the present invention, a multi-layer reduced pressure delivery apparatus includes a tissue contact layer, a manifold layer, and a release layer. The tissue contacting layer includes a scaffold adapted to contact the tissue site to obtain ingrowth of new tissue from the tissue site. The tissue contact layer further includes a first plurality of flow channels. The manifold layer includes a porous material capable of distributing reduced pressure to the tissue site and a third plurality of flow channels. The release layer is positioned between the tissue contact layer and the manifold layer and includes a hydrogel-forming material coupled to at least one of the tissue contact layer and the manifold layer. The hydrogel-forming material is adapted to form a hydrogel upon absorption of a fluid to release at least one of the tissue contact layer and the manifold layer. The release layer further includes a second plurality of flow channels in fluid communication with the first plurality of flow channels and the third plurality of flow channels.

In accordance with yet another embodiment of the present invention, a reduced pressure delivery apparatus for applying reduced pressure tissue treatment to a tissue site is provided. The reduced pressure delivery apparatus includes a scaffold adapted to contact a tissue site to obtain ingrowth of new tissue from the tissue site, a distribution manifold adapted to distribute reduced pressure through the scaffold to the tissue site, and a release material positioned between and in contact with the scaffold and the distribution manifold to substantially prevent contact between the scaffold and the distribution manifold in an area where the release material is disposed.

Still further in accordance with the present invention, another embodiment of a reduced pressure delivery system includes a reduced pressure delivery apparatus having a distribution manifold, a scaffold, and a hydrogel-forming material. The distribution manifold distributes the reduced pressure, and the scaffold promotes in-growth of new tissue from the tissue site. The distribution manifold and the scaffold are joined together by a hydrogel-forming material located between the distribution manifold and the scaffold. The system further includes a reduced-pressure delivery tube having a distal end fluidly connected to the distribution manifold to deliver reduced pressure to the tissue site through the distribution manifold and the scaffold.

According to another embodiment of the present invention, a tissue growth kit (tissue growth kit) for promoting new tissue growth at a tissue site is provided. The tissue growth kit comprises: a scaffold having a first face and a second face, the first face adapted to contact a tissue site; a hydrogel-forming material adapted to contact the second side of the scaffold; and a distribution manifold adapted to contact the hydrogel-forming material to distribute reduced pressure through the scaffold to the tissue site.

In yet another embodiment of the present invention, a method for promoting new tissue growth at a tissue site includes placing a scaffold in contact with the tissue site, placing a hydrogel-forming material in contact with the scaffold, and placing a manifold in contact with the hydrogel-forming material. Reduced pressure is applied to the tissue site through the manifold and scaffold.

In yet another embodiment of the present invention, a method for promoting new tissue growth at a tissue site includes placing a multi-layer reduced pressure delivery apparatus in contact with the tissue site. The multi-layer reduced pressure delivery apparatus includes a tissue contact layer having a scaffold adapted to contact a tissue site and a manifold layer having a distribution manifold. The reduced pressure delivery apparatus further includes a release layer having a hydrogel-forming material and a plurality of flow channels. The release layer is positioned between the tissue contact layer and the manifold layer, and the hydrogel-forming material of the release layer is bonded to at least one of the tissue contact layer and the manifold layer. The multi-layer reduced pressure delivery apparatus is positioned such that the tissue contacting layer contacts the tissue site. Reduced pressure is applied to the tissue site through the distribution manifold, the flow channels, and the scaffold.

In another embodiment of the present invention, a method for promoting new tissue growth at a tissue site includes placing a multi-layer reduced pressure delivery apparatus in contact with the tissue site. The multi-layer reduced pressure delivery apparatus includes a first layer having a scaffold adapted to contact a tissue site and a second layer having a hydrogel-forming material and a plurality of flow channels. The hydrogel-forming material contacts the scaffold. The third layer with the distribution manifold contacts the hydrogel-forming material. The multi-layer reduced pressure delivery apparatus is positioned such that the tissue contacting layer contacts the tissue site and reduced pressure is applied to the tissue site through the distribution manifold, the flow channels, and the scaffold.

In accordance with yet another embodiment of the present invention, a method for promoting new tissue growth at a tissue site includes placing a scaffold in contact with the tissue site, placing a hydrogel-forming material in contact with the scaffold, and placing a distribution manifold in contact with the hydrogel-forming material. Reduced pressure is applied to the tissue site through the distribution manifold and the scaffold to stimulate new tissue growth at the tissue site.

Other objects, features and advantages of the present invention will become apparent with reference to the drawings and detailed description that follow.

Brief Description of Drawings

FIG. 1 illustrates a perspective view, partially in section, of a wound dressing according to an embodiment of the invention, showing the wound dressing being applied to a tissue site;

FIG. 2 depicts a cross-sectional side view of a reduced pressure delivery system including a reduced pressure delivery apparatus having a tissue contact layer, a release layer, and a manifold layer, according to an embodiment of the present invention;

FIG. 3 illustrates a cross-sectional side view of a reduced pressure delivery system including a reduced pressure delivery apparatus having a tissue contact layer, a release layer, and a manifold layer in accordance with an embodiment of the present invention;

FIG. 4 depicts a top view of one embodiment of the release layer of FIGS. 2 and 3 taken at 4-4;

FIG. 5 illustrates a top view of another embodiment of the release layer of FIGS. 2 and 3 taken at 5-5;

FIG. 6 depicts a top view of yet another embodiment of the release layer of FIGS. 2 and 3 taken at 6-6;

FIG. 7 illustrates a method of promoting new tissue growth at a tissue site, according to one embodiment of the invention;

FIG. 8 depicts a method of promoting new tissue growth at a tissue site according to another embodiment of the invention; and

fig. 9 illustrates a front view of a tissue growth kit according to an embodiment of the present invention.

Detailed description of the preferred embodiments

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific preferred embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be 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 present invention. To avoid detail not necessary to enable those skilled in the art to practice the invention, 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 present invention is defined only by the appended claims.

As used herein, the term "manifold" generally refers to a substance or structure configured to facilitate the application of reduced pressure to, the delivery of fluids to, or the removal of fluids from a tissue site. The manifold typically includes a plurality of flow channels or pathways that are interconnected to facilitate distribution of fluids provided to and removed from the tissue region surrounding the manifold. Examples of manifolds may include, but are not limited to, devices having structural elements arranged to form flow channels, porous foams such as open-cell foams, porous tissue collections, and liquids, gels, and foams that include or are treated to include flow channels.

As used herein, the term "reduced pressure" generally refers to a pressure that is lower than the ambient pressure at the tissue site being treated. In most cases, this reduced pressure will be below the atmospheric pressure at which the patient is located. Although the terms "vacuum" and "negative pressure" may be used to describe the pressure applied to the tissue site, the actual pressure applied to the tissue site may be significantly lower than the pressure normally associated with a complete vacuum. The reduced pressure may begin to generate fluid flow in the tube and the tissue site area. When the pressure around the tissue site reaches the desired reduced pressure, the flow may be stopped, and the reduced pressure is then maintained. Unless otherwise stated, the pressure values described herein are gauge pressures.

As used herein, the term "scaffold" refers to a substance or structure used to enhance or promote cell growth and/or tissue formation. Scaffolds are generally three-dimensional porous structures that provide a template for cell growth. The scaffold may be infused, coated or constructed with cells, growth factors, extracellular matrix components, nutrients, integrins or other substances that promote cell growth. The scaffold may be used as a manifold according to embodiments described herein to administer reduced pressure tissue treatment to a tissue site.

As used herein, the term "tissue site" refers to a wound or defect located on or in any tissue, including but not limited to: bone tissue, adipose tissue, muscle tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. The term "tissue site" may further refer to any tissue region that is not necessarily wounded or defective, but rather is a replacement region where additional tissue growth needs to be added or promoted. For example, reduced pressure tissue treatment may be used in certain tissue regions to grow additional tissue that may be harvested and transplanted to another tissue location.

The present invention is a biocompatible wound dressing for negative pressure therapy. As used herein, the term "wound" may include burns, incisional wounds, excisional wounds, ulcers, traumatic wounds, and chronic open wounds. As used herein, the term "pad" refers to foam, screens, other porous-like materials. The term "conventional mat" refers to a mat commonly used for v.a.c.Therapeutic Polyurethane (PU) or polyvinyl alcohol (PVA) foams. As used herein, the term "v.a.c.Treatment "refers to negative pressure wound therapy commercialized by the assignee or its parent company and further described in the previously mentioned patents and patent applications.

Referring now to the drawings, the present invention 10 is shown to generally include a foam pad 11 for substantial insertion into a wound site 12 and a wound drape (outlet dra) for sealing around the foam pad 11 at the wound site 12pe) 13. In accordance with the present invention, the foam pad 11 is modified to include a cell growth enhancing matrix or lattice 14 whereby a desired highly porous cell growth enhancing substrate may be directed toward and toward the wound site 12. After insertion into the wound site 12 and sealing with the wound drape 13, the foam pad 11 is placed in fluid communication with a vacuum source, as known to those of ordinary skill in the art, to facilitate fluid drainage. The foam cushion 11 is modified from prior art cushions in that the cushion 11 includes a matrix 14, the matrix 14 being known as v.a.c.The treatment is not harmful and therefore no modification thereof is required.

According to a preferred embodiment of the present invention, the foam pad 11, wound drape 13 and vacuum source are provided as known in the art, in addition to those modifications to the foam pad 11 as further detailed herein. Each of these components is described in detail in U.S. patent application No. 08/951,832 filed on 16/10/1997, which is a continuation of U.S. patent application No. 08/517,901 filed on 22/8/1995, and U.S. patent application No. 08/517,901 is a continuation-in-part of U.S. patent application No. 08/293,854 filed on 22/8/1994. By this reference, the entire specification of U.S. patent application No. 08/951,832 ("the' 832 application"), including the claims and drawings, is incorporated as if fully set forth herein.

As detailed in the' 832 application, the foam pad 11 preferably comprises a highly reticulated, open-cell polyurethane or polyether foam for good permeability of wound fluid under suction. As also detailed in the' 832 application, the foam pad 11 is preferably in fluid communication with a vacuum source via a hose 15 of plastic or similar material, the vacuum source preferably including a canister that is safely placed under vacuum by being in fluid communication with a vacuum pump via an intermediate hydrophobic membrane filter. Finally, the' 832 application also details a wound drape 13, which preferably includes an elastomeric material covered at least peripherally with a pressure sensitive acrylic adhesive for sealing application over the wound site 12.

In accordance with the preferred method of the present invention, components such as those described in the' 832 application are generally used as known in the art, except that a foam pad 11 having a matrix 14 is provided. The matrix 14 is shown to include a porous material 16 that has been formed into a plurality of sections 17. The material 16 is implanted into the foam pad 11 at the bottom 18 of the foam pad 11. As the foam pad 11 needs to be trimmed ready for use in v.a.c.For wound treatment of therapy, the material 16 is preferably placed in the central portion of the pad 11. The applicant does not intend to limit itself to a regular or symmetrical arrangement of material 16 or portions 17 by using the term "matrix".

Alternatively, or in addition to the preferred embodiment, the foam pad may be composed of bioabsorbable branched polymers alone (not shown) or in combination with the matrix 14.

When the pad 11 is placed, a wound drape 13 is applied to the pad to form an air seal over the wound site, the pad 11 having a matrix 14 embedded therein and/or projecting therefrom and/or comprised of a bioabsorbable branched polymer. In use, v.a.c. was performed as known.Treatment, and if desired, cell growth enhancement therapy, is increased by simply providing a matrix 14 containing material 16. In this manner, cell growth enhancing treatments can be conveniently compared to existing v.a.c.Treatment combination without loss of v.a.c.Efficacy of treatment without inconvenience or unduly increased expense.

Example I

The open-cell foam described above is formed into a cushion. The structure overlying the bottom of the pad is formed following the general principles set forth in column 5, lines 5-42 of U.S. patent No. 5,795,584 to Totakura et al, 8, 18, 1998. The pores are disposed in those portions of the non-bioabsorbable substrate that are relatively distant from the bioabsorbable cell growth enhancing matrix substrate. The matrix covers a portion of the pad that is located within the boundaries of the wound being treated. Then v.a.c. was used.Standard practice for treatment is to completely cover the pad with an airtight drape and subject the pad to sub-atmospheric pressure. The matrix is absorbed during the expected useful life of the pad, so that when the pad is removed, the matrix is already absorbed and does not interfere with the growing cells. If necessary, the pad is replaced with a conventional pad or with a pad containing a matrix, as required by the treatment.

Example II

A conventional pad is selected. The collagen cell growth matrix is applied to a portion of the bottom of the conventional mat. V.a.c. was followed.General principles of treatment and replacement of conventional pads with pads containing a matrix. During the expected duty cycle of the pad, the collagen matrix is absorbed by the growing cells, so that when the pad is removed, the matrix is already absorbed and does not interfere with the growing cells. If necessary, the pad is replaced with a conventional pad or with a pad containing a matrix, as required by the treatment.

Example III

The procedure set forth in example II was followed. However, an ultra-low density fused fiber ceramic, sometimes referred to as a ceramic under the trademark p.r.i.m.m., was substituted for the collagen matrix in example II. V.a.c. was followed.General principles of treatment. In thatDuring the expected duty cycle of the pad, the ultra-low density fused fiber ceramic is absorbed by the growing cells, so that when the pad is removed, the ultra-low density fused fiber ceramic has been absorbed and does not interfere with the growing cells. If necessary, the pad is replaced with a conventional pad or with a pad containing a matrix, as required by the treatment.

Example IV

Many suitable bioabsorbable materials have been used as sutures, surgical instruments, and the like. A small sample of these materials is listed in the following U.S. patents: U.S. patent No. 5,997,568 issued to Lin on 7.12.1999 and the following patents issued to Roby et al in 1999: U.S. patent No. 5,914,387; 5,902,874, and 5,902,875. Selected ones or more of these or similar materials are placed on a conventional pad. V.a.c. was followed.General principles of treatment. The bioabsorbable material is absorbed by the growing cells during the expected duty cycle of the pad, so that when the pad is removed, the bioabsorbable material has been absorbed and does not interfere with the growing cells. If necessary, the pad is replaced with a conventional pad or with a pad containing a matrix, as required by the treatment.

Example V

Bioabsorbable branched polymers form the pad, similar to those described in U.S. Pat. No. 5,578,662 to Bennet et al. V.a.c. was followed.General principles of treatment and replacement of conventional pads with bioabsorbable branched polymer pads. During the expected duty cycle of the pad, the pad is absorbed by the growing cells so that the pad does not need to be replaced and does not interfere with the wound site. If further treatment is deemed necessary, a conventional pad or an additional matrix-containing pad or an additional bioabsorbable branched polymer pad can be placed in the wound site, andv.a.c. was continued.And (6) treating.

Referring to fig. 2 and 3, a reduced pressure delivery system 211 according to an embodiment of the invention includes a biocompatible wound or tissue dressing or reduced pressure delivery apparatus 213, a reduced pressure delivery tube 217, and a reduced pressure source 219. The reduced pressure delivery system 211 is configured to administer reduced pressure tissue treatment to a tissue site 221 of a person. The tissue site may include a burn or other wound, or alternatively, may be healthy tissue on which it is desired to promote new tissue growth. A reduced pressure source 219 is fluidly connected to the distal end of the reduced pressure delivery tube 217, and the reduced pressure delivery apparatus 213 is fluidly connected to the proximal end of the reduced pressure delivery tube 217. In fig. 2, the reduced pressure delivery tube 217 is fluidly connected to the reduced pressure delivery apparatus 213 via a conduit fitting 220 similar to the conduit fitting (piping connector) illustrated in fig. 1. In fig. 3, the reduced-pressure delivery tube 217 is positioned directly within or adjacent to the reduced-pressure delivery apparatus 213 and may include a plurality of apertures (apertures) 222 to communicate with the reduced-pressure delivery apparatus 213. The reduced-pressure source delivers reduced pressure to the reduced-pressure delivery apparatus 213 through the reduced-pressure delivery tube 217, and the reduced-pressure delivery apparatus 213 distributes the reduced pressure to the tissue site 221. The membrane 224 is placed over the reduced pressure delivery apparatus 213 and sealingly attached to the tissue surrounding the tissue site 221. The membrane 224 reduces contamination of the tissue site 221 and assists in maintaining reduced pressure at the tissue site 221.

The reduced pressure delivery apparatus 213 is a multi-layer apparatus having a first or tissue contacting layer 223, a second or release layer 225, and a third or manifold layer 227. The first layer 223 includes a scaffold 233 and a first plurality of flow channels 234. The second layer 225 includes a release material 235, such as a hydrogel-forming material or a water-soluble polymer. The second layer 225 further includes a second plurality of flow channels 236. The third layer 227 includes a distribution manifold 237 and a third plurality of flow channels 238. The three layers are arranged such that the second layer 225 is located between the first layer 223 and the third layer 227, the first layer 223 abutting the second layer 225, the second layer 225 abutting the first layer 223 and the third layer 227, and the third layer 227 abutting the second layer 225.

In one embodiment, each of the layers 223, 225, 227 is connected to the adjoining layer by any connection means appropriate to the type of material in each layer. For example, the third layer 227 may be bonded to the second layer 225, or the first layer 223 may be bonded to the second layer 225, or all three layers 223, 225, 227 may be bonded together. Bonding may be accomplished by heating the interface of one, two, or all of the layers and applying force to press the layers into a bonded connection. Alternatively, adhesive or mechanical fasteners may be used to attach the layers to one another so long as the fastening or bonding means does not substantially affect and does not negatively affect the distribution of pressure through the layers. In another embodiment, the layers 223, 225, 227 may not be interconnected, but rather, the layers 223, 225, 227 may simply be placed in contact with one another prior to and/or during the application of the reduced pressure tissue treatment. Alternatively, two of the layers may be bonded to each other and a third of the layers is placed in contact with one of the two bonded layers. For example, the second layer 225 may be connected to the third layer 227 in the manner previously described, and the first layer 223 may be placed in contact with the second layer 225, but not connected to the second layer 225. Alternatively, the second layer 225 may be connected to the first layer 223, and the second layer 225 may be placed in contact with the third layer 227, but not connected to the third layer 227.

A first plurality of flow channels 234, a second plurality of flow channels 236, and a third plurality of flow channels 238 are disposed in the first layer 223, the second layer 225, and the third layer 227, respectively, to allow distribution of reduced pressure within the reduced pressure delivery apparatus 213 and to the tissue site 221. The flow channels provided in each layer may be an inherent feature of the material provided in that layer (e.g., a naturally porous material), or the flow channels may be chemically, mechanically, or otherwise formed in the material before or after assembly of the three layers 223, 225, 227. The placement of the layers 223, 225, 227 adjacent to each other allows the flow channels in one layer to be in fluid communication with the flow channels in an adjacent layer. For example, the relative positioning or attachment of the layers as described above allows the first plurality of flow channels 234 to be in fluid communication with the second plurality of flow channels 236, while the second plurality of flow channels 236 can be in fluid communication with the third plurality of flow channels 238.

The scaffold 233 of the first layer or tissue contact layer 223 promotes new tissue growth and accepts new tissue ingrowth from the tissue site 221. The scaffold 223 can be any porous bioabsorbable material capable of accepting and/or incorporating new tissue growth into the scaffold. The pores (holes) of the scaffold 233 are preferably interconnected to define a first plurality of flow channels 234, but additional flow channels may be provided by mechanically, chemically, or otherwise forming flow channels in the scaffold. Suitable scaffold materials may include, but are not limited to: polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone, polyhydroxybutyrate, polyhydroxyvalerate, polydioxanone, polyorthoesters, polyphosphazene, polyurethanes, collagen, hyaluronic acid, chitosan, and copolymers, terpolymers, or mixtures of these materials. Additional materials that may be used with hard tissue applications include, but are not limited to: ceramics such as hydroxyapatite, coral apatite, calcium phosphate, calcium sulfate, calcium carbonate or other carbonates, bioglass, allografts (allografts), autografts, and composites of these ceramics with previously listed polymeric materials. The scaffold material may further comprise PLA, PGA, polycarbonate, polyfumarate (polyfumarate), caprolactone (capralactone), and/or a polymeric blend of any of the above-mentioned materials. The scaffold 233 can be manufactured by any of the following processes: salt leaching (salt leaching), freeze drying, phase separation, weaving fibers, bonding non-woven fibers, foaming, or any other suitable manufacturing method of the selected material.

The pore size associated with the scaffold 233 is typically between about 50 microns and 500 microns, and more preferably between about 100 microns and 400 microns. Pore sizes below 50 microns tend to inhibit or prevent tissue growth. In one embodiment, the preferred average pore size of the pores within the scaffold is about 100 microns.

The support may be provided as a sheet or pad of material. When the reduced pressure delivery apparatus is placed adjacent to the tissue site, the thickness of the scaffold is measured in a direction perpendicular to the tissue site. The thickness of the material can vary, but in one embodiment the thickness of the stent is about 1mm to 4 mm. The dimensions of the sheet or pad of scaffold material in a plane perpendicular to the thickness dimension may vary depending on the size of the tissue site to be treated. A pad or sheet of material may be provided in a large size and then trimmed to fit the tissue site.

The release material 235 of the second or release layer 225 minimizes the contact point between the first layer 223 and the third layer 227. In one embodiment, the release material 235 will prevent any contact between the first layer 223 and the third layer 227. By minimizing contact between the first layer 223 and the third layer 227, the release material 235 acts as a barrier to tissue ingrowth from the scaffold 233 into the distribution manifold 237 of the third layer 227.

The release material 235 also acts as an adhesive and release agent for the first layer 223 and the third layer 227. The release material 235 may be used to bond the first and third layers as previously described before and during reduced pressure tissue treatment. The release material 235 is preferably a hydrogel-forming material or a water-soluble polymer.

In the case of a hydrogel-forming material, the release material 235 is capable of forming a liquid and/or gel upon exposure to water or other fluid. The hydrogel-forming material is preferably in a solid "non-hydrated" state during initial application of the reduced pressure delivery apparatus 213 to the tissue site and during administration of the reduced pressure tissue treatment. In other words, the hydrogel-forming material has not been converted to a liquid and/or gel-like state. When reduced pressure tissue treatment is administered, the hydrogel-forming material may be exposed to wound exudate and other fluids that flow from or are applied to the tissue site, but compression of the first, second, and third layers under the influence of the reduced pressure preferably reduces or eliminates absorption of fluids by the hydrogel-forming material. This leaves the hydrogel-forming material in a solid state until reduced pressure delivery is stopped. After the reduced pressure treatment is discontinued, the hydrogel-forming material may be hydrated by applying water, saline solution, or other fluid to the hydrogel-forming material, or by allowing wound exudate to hydrate the hydrogel-forming material. When the hydrogel-forming material hydrates, the material transforms into a liquid and/or gel state, which allows the third layer 227 to be easily released from the first layer 223.

The hydrogel-forming material may be any suitable material that is capable of accepting and/or forming a liquid or gel-like substance after exposure to water or other fluid for a specified period of time. Hydrogel-forming materials are typically crosslinked polymers; however, the material need not be crosslinked. Suitable hydrogel-forming materials may include, but are not limited to: cross-linked polyethylene glycols, hydrophilic polyethers, polyvinyl alcohols, polyvinyl acetates, polyacrylates, polysulfonates, polyphosphazene hydrogels, collagen, gelatin, hyaluronic acid, glycosaminoglycans, chitosan and alginates. Uncrosslinked polymers having hydrophobic and hydrophilic portions, such as copolymers of ethylene glycol and lactic acid, or polyurethanes having very long hydrophilic soft segments, may also be used.

The release material 235 may also be a water soluble polymer. When a water soluble polymer, the release material 235 is capable of dissolving in the presence of water or other liquid. The water-soluble polymer is preferably in a "non-hydrated" form during initial application of the reduced pressure delivery apparatus 213 to the tissue site and during administration of reduced pressure tissue treatment. In other words, the polymer has not absorbed water or other liquids. When reduced pressure tissue treatment is performed, the water-soluble polymer may be exposed to wound exudate and other fluids exuded from or applied to the tissue site, but compression of the first, second, and third layers under the influence of the reduced pressure preferably reduces the solubility of the water-soluble polymer, which prevents premature dissolution of the water-soluble polymer. This leaves the water-soluble polymer in a solid state until reduced pressure delivery is stopped. After cessation of reduced pressure treatment, the water-soluble polymer may be hydrated by applying a fluid to the polymer, or by allowing wound exudate to hydrate the polymer. When the water-soluble polymer is hydrated, the polymer dissolves into the hydration liquid, which allows the third layer 227 to be easily released from the first layer 223.

Water soluble polymers may include, but are not limited to: non-crosslinked polyethylene glycol, hydrophilic polyethers, polyvinyl alcohol, polyvinyl acetate, polyacrylates, polysulfonates, polyphosphazenes, collagen, hyaluronic acid, glycosaminoglycans, chitosan, and deoxyribonucleic acid (DNA).

The presence of the second plurality of flow channels 236 in the second layer 225 allows for the distribution of reduced pressure from the distribution manifold 237 to the scaffold 233. The second plurality of flow channels 236 further allows for the passage of any fluid that is provided to or removed from the tissue site 221. While the second plurality of flow channels 236 may be an inherent feature of the release material 235 (i.e., interconnected pores or other flow channels in the material itself), it is more likely that the second plurality of flow channels 236 are mechanically, chemically, or otherwise formed in the release material 235. For example, referring to fig. 4, the second plurality of flow channels 236 may be defined by voids between adjacent strands of release material 235 arranged in a grid-like manner. Alternatively, referring to fig. 5, the release material 235 may be applied as beads of material between the first layer 223 and the third layer 227. In this particular configuration, the second plurality of flow channels 236 is defined by voids between adjacent beads of release material 235. In yet another configuration, referring to fig. 6, a sheet of release material 235 may be provided with slits formed in the sheet to define a second plurality of flow channels 236. The shape, size, and positioning of the apertures and voids described above may vary and, in one embodiment, may be random.

Whether pores, voids, gaps, or some combination thereof are used to define the second plurality of flow channels 236, the porosity of the second layer 225 may be less than the porosity of the scaffold 233 to minimize tissue ingrowth into the second layer 225. The porosity of the second layer 225 may be controlled by limiting the size of the pores, voids, or interstices located in the second layer 225, or by controlling the number (i.e., density) of such pores, voids, or interstices. However, the porosity of the second layer 225 must be maintained high enough to allow for distribution of reduced pressure and for fluid flow through the second layer 225.

Similar to the scaffold 233, the release material 235 may be provided as a sheet or pad of material (see fig. 6). Alternatively, the release material 235 may be provided as a grid of strands, dots, or other individual pieces of material (see fig. 4 and 5). The shape, size, and distribution of these individual pieces of material can vary, and in some cases, the shape, size, and distribution can be random. When the reduced pressure delivery apparatus is placed adjacent to the tissue site, the thickness of the release material 235 is measured in a direction perpendicular to the tissue site. Although not required, the thickness of the release material 235 is typically less than the thickness of the stent to save material costs. In one embodiment, the release material 235 has a thickness of about 200 microns to about 500 microns before absorbing fluid. After hydration of the release material, the thickness can expand to about 500 microns to 1 mm. The dimensions of the sheet or pad of release material in a plane perpendicular to the thickness dimension may vary depending on the size of the tissue site to be treated, but will generally have approximately the same dimensions in length and width as the dimensions of the stent. A pad or sheet of material may be provided in a large size and then trimmed to fit the tissue site.

The distribution manifold 237 of the third or manifold layer 227 helps distribute the reduced pressure received from the reduced pressure delivery tube 217. The manifold may further be used to distribute fluids introduced to the tissue site, or to direct (manifest) wound exudate and other fluids collected from the tissue site. The manifold 237 may be any porous material capable of accomplishing these tasks, and in one embodiment, the manifold is formed from a porous material such as an open cell foam. The material preferably comprises a hole fluidly connected to an adjacent hole. The third plurality of flow channels 238 are formed by and between the "open cells" of the porous material. The flow channels allow fluid communication throughout the portion of the porous material having open pores. The apertures and flow channels may be uniform in shape and size, or may include patterned or random variations in shape and size. Variations in the shape and size of the pores of the porous material result in variations in the third plurality of flow channels 238, and such characteristics may be used to change the flow characteristics of the fluid through the porous material. The porous material may further comprise a portion comprising "closed cells". The closed-cell portion of these porous materials contains a plurality of pores, most of which are non-fluidly connected to adjacent pores. The closed cell portions of the porous material may be selectively combined with the open cell portions to prevent the transmission of fluid through selected portions of the manifold 237.

In one embodiment, the manifold 237 is made from an open-celled reticulated polyether polyurethane foam having a cell size range of about 400-600 microns. Examples of such foams may include GranuFoam, manufactured by KineticConcepts, inc. The manifold 237 may also be a polyurethane foam, a polyvinyl alcohol foam, a polyethylene foam, an expanded polytetrafluoroethylene, a silicone foam, a loofah sponge, a sponge, gauze, a felted mat, or any other biocompatible material capable of providing fluid communication in a plurality of three-dimensional flow channels.

Similar to the scaffold 233 and release material 235, the manifold 237 may be formed from a sheet or pad of material. The thickness of the manifold 237 can vary, but in one embodiment, the thickness will be at least as great as the thickness of the scaffold 233. The dimensions of the manifold in a plane perpendicular to the thickness dimension may also vary depending on the size of the tissue site being treated. A pad or sheet of manifold material may be provided in large size and then trimmed to fit the tissue site.

In operation, the reduced pressure delivery apparatus 213 is trimmed as necessary to match the shape and size of the tissue site 221. In many cases, the tissue site 221 may be an open wound, a burn, or other damaged tissue, but the tissue site 221 may likewise be a site containing healthy tissue on which additional tissue needs to grow. The reduced pressure delivery apparatus 213 is placed adjacent to the tissue site 221 such that the first layer 223 is in contact with the tissue site 221. As previously described, the multiple layers of the reduced pressure delivery apparatus 213 may be laminated, bonded, or otherwise connected, but the layers may also be separate from one another. If some of the layers are not connected to each other, the different layers may be placed individually such that the first layer 223 is in contact with the tissue site, the second layer 225 is in contact with the first layer 223, and the third layer 227 is in contact with the second layer 225.

After positioning the reduced pressure delivery apparatus 213, reduced pressure is delivered from the reduced pressure source 219 through the reduced pressure delivery tube 217 to the manifold 237 of the first layer 227. The reduced pressure is distributed through the third plurality of flow channels 238 associated with the manifold 237 to the second plurality of flow channels 236 associated with the second layer 225. The reduced pressure is then distributed to the first plurality of flow channels 234 associated with the scaffold 233 of the first layer 223. When reduced pressure reaches the tissue site 221, fluids, such as wound exudate, at the tissue site 221 may be drawn through the first, second, and third plurality of flow channels 234, 236, 238 and removed from the reduced pressure delivery apparatus 213. A reservoir (not shown) and various filters may be disposed between the reduced pressure delivery apparatus 213 and the reduced pressure source 219 to collect exudates and protect the reduced pressure source 219. In addition to allowing the reduced pressure to be distributed and fluids to be drained from the tissue site 221, the first, second, and third pluralities of flow channels 234, 236, 238 may be used to distribute fluids, such as irrigation fluids, drugs, antimicrobial agents, antiviral agents, and growth factors, to the tissue site 221.

Application of reduced pressure to the tissue site 211 induces new tissue growth. Some of the mechanisms that promote new tissue growth include micro-deformation of the tissue, epithelial migration, and improved blood flow. These factors accelerate the growth of granulation tissue at the tissue site, which causes new tissue growth. While the discussion of providing reduced pressure tissue treatment is directed to "delivering" reduced pressure to a tissue site, the delivery of reduced pressure generally involves creating a pressure differential between the reduced pressure source 219 and the tissue site 221, as should be apparent to one of ordinary skill in the art. The pressure differential (the pressure at the reduced pressure source 219 being lower than the pressure at the tissue site 221) creates an initial flow of fluid from the tissue site 221 to the reduced pressure source 219. Once the pressure at the tissue site 221 approaches or equals the pressure at the reduced pressure source 219, the reduced pressure at the tissue site may be maintained due to the fluid connection with the reduced pressure source 219 and the sealing function of the membrane 224.

When new tissue forms under the influence of reduced pressure, the new tissue is allowed to grow into the scaffold 233. The material selected for use as scaffold 233 preferably supports and promotes new tissue growth. Because the scaffold will remain at the tissue site after the reduced pressure tissue treatment is applied, it is preferred that new tissue penetrate the scaffold as far as possible. It has been observed that under the influence of reduced pressure, new tissue can penetrate up to 1mm (thickness) of the scaffold in a period of 2 days. In some embodiments, because the scaffold 233 may be only about 1mm to 4mm thick, it may be necessary to remove the second layer 225 and the third layer 227 of the reduced pressure delivery apparatus 213 and replace the two layers with a new dressing containing the first layer 223, the second layer 225, and the third layer 227. In other words, after the second layer 225 and the third layer 227 are removed, a new scaffold 233 can be placed on top of the old scaffold 233. By removing only a portion of the reduced pressure delivery apparatus 213 and leaving the scaffold 233, new tissue growth may be gradually added to the tissue site 221 because the new scaffold 233 is deposited onto the previously inserted scaffold 233 into which the new tissue growth has penetrated.

The release of the second layer 225 and the third layer 227 from the first layer 223 is simplified due to the presence of the release material 235. During the application of reduced pressure and removal of fluid from the tissue site 221, the release material 235 preferably remains in a solid state, thereby allowing the second plurality of flow channels 236 to remain open. Although the release material will typically convert to a liquid or gel, or will dissolve, upon absorption of water or other fluid, this change is significantly reduced during application of reduced pressure to the reduced pressure delivery apparatus 213. The reduced pressure causes the reduced pressure delivery apparatus 213 to compress, which reduces the surface area of the release material exposed to the fluid flowing through the first, second, and third pluralities of flow channels 234, 236, 238. Thus, absorption of fluid by the release material 235 is minimized until reduced pressure delivery ceases.

The release material preferably minimizes contact between the first layer 223 and the third layer 227, or prevents contact between the first layer 223 and the third layer 227 during application of reduced pressure. By this separation between the scaffold 233 and the manifold 237, and by the release material 235 itself, the growth of new tissue to the scaffold 233 interferes with the growth of new tissue to the manifold 237. While tissue growth into the manifold 237 may still occur, such growth is minimized, which reduces pain to the patient when the manifold 237 is removed.

After the reduced pressure is applied for a selected period of time, the release material may be hydrated by soaking the reduced pressure delivery apparatus 213 with water, saline solution, or other fluid. Alternatively, the reduced pressure delivery apparatus 213 may be allowed to rest until the body fluids from the tissue site hydrate the release material 235. If the release material 235 is a hydrogel-forming material, the release material 235 transforms into a gel-like state and typically expands as it hydrates. This makes the manifold 237 easier to remove from the scaffold 233. After removal of the manifold 237, any hydrogel-forming material (or hydrogel) remaining may be manually removed or dissolved by introducing additional fluid. Alternatively, if the release material 235 is a water-soluble polymer, it will be dissolved as it absorbs water or other fluid, thus releasing the third layer 227 from the first layer 223.

Referring to fig. 7, a method 711 of promoting tissue growth at a tissue site according to an embodiment of the present invention is illustrated. The method 711 includes placing 715 the multi-layer reduced pressure delivery apparatus in contact with the tissue site. The reduced pressure delivery apparatus includes a scaffold, a release material, and a manifold. At 719, the device is positioned such that the scaffold is in contact with the tissue site. At 723, reduced pressure is applied to the tissue site through the manifold and scaffold.

Referring to fig. 8, a method 811 of promoting new tissue growth at a tissue site according to an embodiment of the invention is illustrated. The method 811 includes placing the scaffold in contact with the tissue site, placing a release material in contact with the scaffold, and placing the manifold in contact with the release material at 815. At 819, new tissue growth is stimulated at the tissue site by applying reduced pressure to the tissue site through the manifold and scaffold.

Referring to fig. 9, a tissue growth kit 911 for promoting new tissue growth at a tissue site according to an embodiment of the present invention includes a scaffold 913, a release material 915, and a distribution manifold 917. The scaffold 913 includes a first side and a second side, the first side of the scaffold 913 being adapted to contact the tissue site. The scaffold 913 is similar to the scaffold 233 previously described with reference to fig. 2 and 3. The release material 915 is adapted to contact the second side of the scaffold 913 and is similar to the release material 235 previously described with reference to fig. 2 and 3. The distribution manifold 917 is adapted to contact the release material 915 to distribute reduced pressure to the tissue site through the scaffold 913. The distribution manifold 917 is similar to the manifold 237 described previously with reference to fig. 2 and 3. The tissue growth kit 911 may further include a container 921 for housing the scaffold 913, the release material 915, and the distribution manifold 917 prior to use of the components. The container 921 may be a flexible bag, box, or any other container suitable for storing the scaffold 913, the release material 915, and the distribution manifold 917.

While the multi-layer reduced pressure delivery apparatus disclosed herein is used in conjunction with a reduced pressure delivery source to provide reduced pressure tissue treatment to a tissue site, the reduced pressure delivery apparatus may also be used alone as an advanced tissue dressing in the absence of reduced pressure application. The same materials, relative positioning and connectivity between layers can be used for advanced tissue dressings. Similar to the reduced pressure delivery apparatus described herein, advanced tissue dressings may include a first layer that promotes and accepts new tissue growth, a third layer that helps direct fluid away from the tissue site, and a second layer that promotes removal of the third layer from the first layer at selected times. The third layer of the advanced tissue dressing, instead of having a "manifold," can be considered to include a fluid reservoir for collecting and containing fluids exuded by the wound. Materials described herein as suitable distribution manifold materials are similar to suitable materials for the reservoirs of the third layer. The only requirement of the reservoir is that it be made of a material capable of storing fluid generated by or present at the tissue site.

While the systems and methods of the present invention have been described with reference to tissue growth and healing in human patients, it will be appreciated that these systems and methods for applying reduced pressure tissue treatment may be used in any living body where it is desirable to promote tissue growth or healing. Similarly, the systems and methods of the present invention may be applied to any tissue, including but not limited to: bone tissue, adipose tissue, muscle tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. Although healing of tissue may be one of the central points of application of the reduced pressure tissue treatments described herein, the application of reduced pressure tissue treatments may also be used to induce tissue growth in non-diseased, defect-free, or undamaged tissue. For example, it may be desirable to apply reduced pressure tissue treatment to grow additional tissue at a tissue site that may subsequently be harvested. The harvested tissue may be transplanted to another tissue site to replace diseased or damaged tissue, or alternatively, the harvested tissue may be transplanted to another patient.

It is apparent from the above description that the present invention has been provided with significant advantages. While the invention is shown in only a few of its forms, it is not just limited to those forms but is susceptible to various changes and modifications without departing from the spirit thereof.

Claims

1. A reduced pressure delivery system for applying reduced pressure tissue treatment to a tissue site, comprising:

a multi-layer reduced pressure delivery apparatus having a tissue contact layer comprising a scaffold adapted to contact a tissue site, a release layer comprising a hydrogel-forming material and a plurality of flow channels, and a manifold layer comprising a distribution manifold, the release layer being positioned between the tissue contact layer and the manifold layer, the hydrogel-forming material of the release layer being bound to at least one of the tissue contact layer and the manifold layer; and

a reduced-pressure delivery tube fluidly connected to the manifold layer to deliver reduced pressure to the tissue site.

2. The reduced pressure delivery system according to claim 1, wherein the hydrogel-forming material is positioned between the scaffold and the distribution manifold to substantially prevent contact between the scaffold and the distribution manifold at an area where the hydrogel-forming material is positioned.

3. The reduced pressure delivery system according to claim 2, wherein the distribution manifold is in contact with the scaffold at areas where the hydrogel-forming material is not disposed during application of reduced pressure.

4. The reduced pressure delivery system according to claim 1, wherein the tissue contact layer has a thickness of from about 1mm to about 4 mm.

5. The reduced pressure delivery system according to claim 1, wherein a thickness of the release layer is less than a thickness of the tissue contact layer.

6. The reduced pressure delivery system according to claim 1, wherein the plurality of flow channels of the release layer are provided by apertures in the sheet of hydrogel-forming material.

7. The reduced pressure delivery system according to claim 6, wherein the pores in the release layer have a pore size that is smaller than the pore size of the pores in the scaffold.

8. The reduced pressure delivery system according to claim 1, wherein:

the hydrogel-forming material is arranged in a grid such that strands of the hydrogel-forming material are arranged in rows and columns; and is

The plurality of flow channels are formed by voids arranged between rows and columns of the hydrogel-forming material.

9. The reduced pressure delivery system according to claim 1, wherein:

the hydrogel-forming material is provided as a plurality of individual beads, each bead being spaced apart from an adjacent bead by a void; and is

The plurality of flow channels are formed by voids disposed between beads of the hydrogel-forming material.

10. The reduced pressure delivery system according to claim 9, wherein a porosity provided by the voids is less than a porosity provided by the scaffold.

11. The reduced pressure delivery system according to claim 1, wherein the distribution manifold is an open-cell, reticulated polyether polyurethane foam.

12. The reduced pressure delivery system according to claim 1, wherein the hydrogel-forming material is a barrier to tissue penetration.

13. The reduced pressure delivery system according to claim 1, wherein the scaffold is composed of at least one material selected from the group of materials consisting of: polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxybutyrate, polyhydroxyvalerate, polydioxanone, polyorthoesters, polyphosphazene, polyurethane, collagen, hyaluronic acid, chitosan, hydroxyapatite, coral apatite, calcium phosphate, calcium sulfate, calcium carbonate, bioglass, allograft and autograft.

14. The reduced pressure delivery system according to claim 1, wherein the hydrogel-forming material is comprised of at least one material selected from the group of: polyethylene glycol, hydrophilic polyethers, polyvinyl alcohol, polyvinyl acetate, polyacrylates, polysulfonates, polyphosphazene hydrogels, collagen, gelatin, hyaluronic acid, glycosaminoglycans, chitosan, alginates, and non-crosslinked copolymers of ethylene glycol and lactic acid.

15. The reduced pressure delivery system according to claim 1, wherein the distribution manifold is comprised of at least one material selected from the group of: polyurethane foam, polyvinyl alcohol foam, polyethylene foam, expanded polytetrafluoroethylene, silicone foam, loofah sponge, gauze, and felted pads.

16. The reduced pressure delivery system according to claim 1, further comprising:

a reduced-pressure source fluidly connected to a proximal end of the reduced-pressure delivery tube.

17. A multi-layer reduced pressure delivery apparatus for applying reduced pressure tissue treatment to a tissue site, comprising:

a first layer having a scaffold adapted to contact a tissue site;

a second layer having a hydrogel-forming material and a plurality of flow channels, the hydrogel-forming material in contact with the scaffold; and

a third layer having a distribution manifold contacting the hydrogel-forming material.

18. The reduced pressure delivery apparatus according to claim 17, wherein the hydrogel-forming material is positioned between the first layer and the third layer and is coupled to at least one of the scaffold and the distribution manifold.

19. The reduced pressure delivery apparatus according to claim 17, further comprising:

a reduced-pressure delivery tube fluidly connected to the third layer to deliver reduced pressure to the tissue site.

20. The reduced pressure delivery apparatus according to claim 17, wherein the hydrogel-forming material is positioned between the scaffold and the distribution manifold to substantially prevent contact between the scaffold and the distribution manifold at an area where the hydrogel-forming material is positioned.

21. The reduced pressure delivery apparatus according to claim 17, wherein the distribution manifold is in contact with the scaffold at areas where the hydrogel-forming material is not disposed during application of reduced pressure.

22. The reduced pressure delivery apparatus according to claim 17, wherein reduced pressure is delivered to a tissue site through the distribution manifold, the plurality of flow channels, and the scaffold.

23. The reduced pressure delivery apparatus according to claim 17, wherein the flow channel is capable of transmitting fluid from the scaffold to the distribution manifold during application of reduced pressure.

24. The reduced pressure delivery apparatus according to claim 23, wherein the fluid is wound exudate from the tissue site.

25. The reduced pressure delivery apparatus according to claim 17, wherein the first layer has a thickness from about 1mm to about 4 mm.

26. The reduced pressure delivery apparatus according to claim 17, wherein a thickness of the second layer in a dehydrated state is less than a thickness of the first layer.

27. The reduced pressure delivery apparatus according to claim 17, wherein the scaffold includes pores having pore sizes ranging from about 50 microns to about 500 microns in diameter.

28. The reduced pressure delivery apparatus according to claim 17, wherein the scaffold includes pores having pore sizes ranging from about 100 microns to about 400 microns in diameter.

29. The reduced pressure delivery apparatus according to claim 17, wherein the plurality of flow channels of the second layer are provided by apertures in the sheet of hydrogel-forming material.

30. The reduced pressure delivery apparatus according to claim 29, wherein the pores in the second layer have a pore size that is smaller than the pore size of the pores in the scaffold.

31. The reduced pressure delivery apparatus according to claim 17, wherein:

32. The reduced pressure delivery apparatus according to claim 17, wherein:

33. The reduced pressure delivery apparatus according to claim 32, wherein a porosity provided by the voids is less than a porosity provided by the scaffold.

34. The reduced pressure delivery apparatus according to claim 17, wherein the distribution manifold is a cellular foam.

35. The reduced pressure delivery apparatus according to claim 17, wherein the distribution manifold is an open-cell, reticulated polyether polyurethane foam.

36. The reduced pressure delivery apparatus according to claim 17, wherein the distribution manifold includes a pore size ranging from about 400 microns to about 600 microns in diameter.

37. The reduced pressure delivery apparatus according to claim 17, wherein the third layer includes an antimicrobial agent.

38. The reduced pressure delivery apparatus according to claim 17, wherein the hydrogel-forming material is bioabsorbable.

39. The reduced pressure delivery apparatus according to claim 17, wherein the hydrogel-forming material is a barrier to tissue penetration.

40. The reduced pressure delivery apparatus according to claim 17, wherein the tissue site is comprised of tissue selected from the group of adipose tissue, bone tissue, cartilage, connective tissue, dermal tissue, ligaments, muscle tissue, tendons, and vascular tissue.

41. The reduced pressure delivery apparatus according to claim 17, wherein the scaffold is composed of at least one material selected from the group of materials consisting of: polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxybutyrate, polyhydroxyvalerate, polydioxanone, polyorthoesters, polyphosphazene, polyurethane, collagen, hyaluronic acid, chitosan, hydroxyapatite, coral apatite, calcium phosphate, calcium sulfate, calcium carbonate, bioglass, allograft and autograft.

42. The reduced pressure delivery apparatus according to claim 17, wherein the hydrogel-forming material is comprised of at least one material selected from the group of: polyethylene glycol, hydrophilic polyethers, polyvinyl alcohol, polyvinyl acetate, polyacrylates, polysulfonates, polyphosphazene hydrogels, collagen, gelatin, hyaluronic acid, glycosaminoglycans, chitosan, alginates, and non-crosslinked copolymers of ethylene glycol and lactic acid.

43. The reduced pressure delivery apparatus according to claim 17, wherein the porous material is comprised of at least one material selected from the group of: polyurethane foam, polyvinyl alcohol foam, polyethylene foam, expanded polytetrafluoroethylene, silicone foam, loofah sponge, gauze, and felted pads.

44. The reduced pressure delivery apparatus according to claim 17, wherein the porous material is selected from the group of woven porous pads, non-woven porous pads, loofah, and sponges.

45. A multi-layer reduced pressure delivery apparatus for applying reduced pressure tissue treatment to a tissue site, comprising:

a tissue contact layer having a scaffold adapted to contact a tissue site to obtain ingrowth of new tissue from the tissue site, the tissue contact layer further having a first plurality of flow channels;

a manifold layer having a porous material to distribute reduced pressure to a tissue site, the manifold layer further having a third plurality of flow channels; and

a release layer positioned between the tissue contact layer and the manifold layer, the release layer comprising a hydrogel-forming material coupled to at least one of the tissue contact layer and the manifold layer, the hydrogel-forming material adapted to form a hydrogel upon absorption of a fluid to release the at least one of the tissue contact layer and the manifold layer, the release layer further having a second plurality of flow channels in fluid communication with the first plurality of flow channels and the third plurality of flow channels.

46. The reduced pressure delivery apparatus according to claim 45, further comprising a reduced pressure delivery tube fluidly connected to the manifold layer to deliver reduced pressure to a tissue site through the third plurality of flow channels, the second plurality of flow channels, and the first plurality of flow channels.

47. The reduced pressure delivery apparatus according to claim 45, wherein:

the hydrogel-forming material substantially prevents contact between the scaffold and the porous material at the region where the hydrogel-forming material is placed; and is

The porous material is in contact with the scaffold at areas where the hydrogel-forming material is not disposed during application of reduced pressure.

48. The reduced pressure delivery apparatus according to claim 45, wherein the tissue contact layer has a thickness of from about 1mm to about 4 mm.

49. The reduced pressure delivery apparatus according to claim 45, wherein a thickness of the release layer is less than a thickness of the tissue contact layer.

50. The reduced pressure delivery apparatus according to claim 45, wherein the scaffold includes pores having pore sizes ranging from about 50 microns to about 500 microns in diameter.

51. The reduced pressure delivery apparatus according to claim 45, wherein the second plurality of flow channels of the release layer are provided by apertures in the sheet of hydrogel-forming material.

52. The reduced pressure delivery apparatus according to claim 51, wherein the pores in the release layer have a pore size that is smaller than the pore size of the pores in the scaffold.

53. The reduced pressure delivery apparatus according to claim 45, wherein:

The second plurality of flow channels are formed by voids arranged between rows and columns of the hydrogel-forming material.

54. The reduced pressure delivery apparatus according to claim 45, wherein:

The second plurality of flow channels are formed by voids disposed between beads of the hydrogel-forming material.

55. The reduced pressure delivery apparatus according to claim 54, wherein a porosity provided by the voids is less than a porosity provided by the scaffold.

56. The reduced pressure delivery apparatus according to claim 45, wherein the porous material is an open-cell, reticulated polyether polyurethane foam.

57. The reduced pressure delivery apparatus according to claim 45, wherein the hydrogel-forming material is a barrier to tissue penetration.

58. The reduced pressure delivery apparatus according to claim 45, wherein the scaffold is composed of at least one material selected from the group of: polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxybutyrate, polyhydroxyvalerate, polydioxanone, polyorthoesters, polyphosphazene, polyurethane, collagen, hyaluronic acid, chitosan, hydroxyapatite, coral apatite, calcium phosphate, calcium sulfate, calcium carbonate, bioglass, allograft and autograft.

59. The reduced pressure delivery apparatus according to claim 45, wherein the hydrogel-forming material is comprised of at least one material selected from the group of: polyethylene glycol, hydrophilic polyethers, polyvinyl alcohol, polyvinyl acetate, polyacrylates, polysulfonates, polyphosphazene hydrogels, collagen, gelatin, hyaluronic acid, glycosaminoglycans, chitosan, alginates, and non-crosslinked copolymers of ethylene glycol and lactic acid.

60. The reduced pressure delivery apparatus according to claim 45, wherein the porous material is comprised of at least one material selected from the group of: polyurethane foam, polyvinyl alcohol foam, polyethylene foam, expanded polytetrafluoroethylene, silicone foam, loofah sponge, gauze, and felted pads.

61. A reduced pressure delivery apparatus for applying reduced pressure tissue treatment to a tissue site, comprising:

a scaffold adapted to contact a tissue site to obtain ingrowth of new tissue from the tissue site;

a distribution manifold adapted to distribute reduced pressure through the scaffold to a tissue site; and

a release material positioned between and in contact with the support and the distribution manifold to substantially prevent contact between the support and the distribution manifold in an area where the release material is disposed.

62. The reduced pressure delivery apparatus according to claim 61, wherein the release material is coupled to at least one of the scaffold and the distribution manifold.

63. The reduced pressure delivery apparatus according to claim 61, further comprising:

a reduced-pressure delivery tube having a distal end fluidly connected to the distribution manifold to deliver reduced pressure to the distribution manifold.

64. The reduced pressure delivery apparatus according to claim 61, wherein the distribution manifold is in contact with an area of the scaffold in which the release material is not disposed during application of reduced pressure.

65. The reduced pressure delivery apparatus according to claim 61, further comprising:

a plurality of flow channels between the support and the distribution manifold to allow fluid communication between the support and the distribution manifold.

66. The reduced pressure delivery apparatus according to claim 61, wherein the scaffold has a thickness from about 1mm to about 4 mm.

67. The reduced pressure delivery apparatus according to claim 61, wherein the release material has a thickness that is less than a thickness of the scaffold.

68. The reduced pressure delivery apparatus according to claim 61, wherein the scaffold includes pores having pore sizes ranging from about 50 microns to about 500 microns in diameter.

69. The reduced pressure delivery apparatus according to claim 61, wherein the scaffold includes pores having pore sizes ranging from about 100 microns to about 400 microns in diameter.

70. The reduced pressure delivery apparatus according to claim 61, further comprising:

a plurality of flow channels between the support and the distribution manifold to allow fluid communication between the support and the distribution manifold; and is

Wherein the plurality of flow channels are provided by apertures in the sheet of release material.

71. The reduced pressure delivery apparatus according to claim 70, wherein the aperture size of the apertures in the sheet of release material is smaller than the aperture size of the apertures in the scaffold.

72. The reduced pressure delivery apparatus according to claim 61, further comprising:

a plurality of flow channels between the support and the distribution manifold to allow fluid communication between the support and the distribution manifold;

wherein the release material is arranged in a grid such that strands of the release material are arranged in rows and columns; and is

Wherein the plurality of flow channels are formed by voids arranged between rows and columns of the release material.

73. The reduced pressure delivery apparatus according to claim 61, further comprising:

the release material is provided as a plurality of individual beads, each bead being spaced apart from an adjacent bead by a void; and is

The plurality of flow channels are formed by voids disposed between beads of the release material.

74. The reduced pressure delivery apparatus according to claim 73, wherein a porosity provided by the voids is less than a porosity provided by the scaffold.

75. The reduced pressure delivery apparatus according to claim 61, wherein the distribution manifold is a cellular foam.

76. The reduced pressure delivery apparatus according to claim 61, wherein the distribution manifold is an open-cell, reticulated polyether polyurethane foam.

77. The reduced pressure delivery apparatus according to claim 61, wherein the distribution manifold comprises pore sizes ranging from about 400 microns to about 600 microns in diameter.

78. The reduced pressure delivery apparatus according to claim 61, wherein the distribution manifold is impregnated with an antimicrobial agent.

79. The reduced pressure delivery apparatus according to claim 61, wherein the release material is bioabsorbable.

80. The reduced pressure delivery apparatus according to claim 61, wherein the release material is a barrier to tissue penetration.

81. The reduced pressure delivery apparatus according to claim 61, wherein the tissue site is comprised of tissue selected from the group of adipose tissue, bone tissue, cartilage, connective tissue, dermal tissue, ligaments, muscle tissue, tendons, and vascular tissue.

82. The reduced pressure delivery apparatus according to claim 61, wherein the scaffold is composed of at least one material selected from the group of: polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxybutyrate, polyhydroxyvalerate, polydioxanone, polyorthoesters, polyphosphazene, polyurethane, collagen, hyaluronic acid, chitosan, hydroxyapatite, coral apatite, calcium phosphate, calcium sulfate, calcium carbonate, bioglass, allograft and autograft.

83. The reduced pressure delivery apparatus according to claim 61, wherein the release material is comprised of at least one material selected from the group of: polyethylene glycol, hydrophilic polyethers, polyvinyl alcohol, polyvinyl acetate, polyacrylates, polysulfonates, polyphosphazene hydrogels, collagen, gelatin, hyaluronic acid, glycosaminoglycans, chitosan, alginates, deoxyribonucleic acids, and non-crosslinked copolymers of ethylene glycol and lactic acid.

84. The reduced pressure delivery apparatus according to claim 61, wherein the distribution manifold is comprised of at least one material selected from the group of: polyurethane foam, polyvinyl alcohol foam, polyethylene foam, expanded polytetrafluoroethylene, silicone foam, loofah sponge, gauze, and felted pads.

85. The reduced pressure delivery apparatus according to claim 61, wherein the distribution manifold is selected from the group of woven porous pads, non-woven porous pads, loofah, and sponges.

86. A reduced pressure delivery system for applying reduced pressure tissue treatment to a tissue site, comprising:

a reduced pressure delivery apparatus having a distribution manifold that distributes reduced pressure and a scaffold that promotes in-growth of new tissue from a tissue site, the distribution manifold and the scaffold being joined together by a hydrogel-forming material located between the distribution manifold and the scaffold;

a reduced-pressure delivery tube having a distal end fluidly connected to the distribution manifold to deliver reduced pressure to a tissue site through the distribution manifold and the scaffold.

87. The reduced pressure delivery system according to claim 86, wherein the hydrogel-forming material substantially prevents contact between the scaffold and the distribution manifold at the area where the hydrogel-forming material is disposed.

88. The reduced pressure delivery system according to claim 86, wherein the distribution manifold contacts the scaffold at areas where the hydrogel-forming material is not disposed during application of reduced pressure.

89. The reduced pressure delivery system according to claim 86, further comprising:

90. The reduced pressure delivery system according to claim 86, wherein the scaffold has a thickness of from about 1mm to about 4 mm.

91. The reduced pressure delivery system according to claim 86, wherein the hydrogel-forming material has a thickness that is less than a thickness of the scaffold.

92. The reduced pressure delivery system according to claim 86, further comprising:

Wherein the plurality of flow channels are provided by apertures in the sheet of hydrogel-forming material.

93. The reduced pressure delivery system according to claim 92, wherein the pores in the sheet of hydrogel-forming material have a pore size that is smaller than the pore size of the pores in the scaffold.

94. The reduced pressure delivery system according to claim 86, further comprising:

wherein the hydrogel-forming material is arranged in a grid such that strands of the hydrogel-forming material are arranged in rows and columns; and is

Wherein the plurality of flow channels are formed by voids arranged between rows and columns of the hydrogel-forming material.

95. The reduced pressure delivery system according to claim 86, further comprising:

96. The reduced pressure delivery system according to claim 95, wherein a porosity provided by the voids is less than a porosity provided by the scaffold.

97. The reduced pressure delivery system according to claim 86, wherein the distribution manifold is an open-cell, reticulated polyether polyurethane foam.

98. The reduced pressure delivery system according to claim 86, wherein the hydrogel-forming material is a barrier to tissue penetration.

99. The reduced pressure delivery system according to claim 86, wherein the scaffold is composed of at least one material selected from the group of materials consisting of: polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxybutyrate, polyhydroxyvalerate, polydioxanone, polyorthoesters, polyphosphazene, polyurethane, collagen, hyaluronic acid, chitosan, hydroxyapatite, coral apatite, calcium phosphate, calcium sulfate, calcium carbonate, bioglass, allograft and autograft.

100. The reduced pressure delivery system according to claim 86, wherein the hydrogel-forming material is comprised of at least one material selected from the group of: polyethylene glycol, hydrophilic polyethers, polyvinyl alcohol, polyvinyl acetate, polyacrylates, polysulfonates, polyphosphazene hydrogels, collagen, gelatin, hyaluronic acid, glycosaminoglycans, chitosan, alginates, and non-crosslinked copolymers of ethylene glycol and lactic acid.

101. The reduced pressure delivery system according to claim 86, wherein the distribution manifold is comprised of at least one material selected from the group of: polyurethane foam, polyvinyl alcohol foam, polyethylene foam, expanded polytetrafluoroethylene, silicone foam, loofah sponge, gauze, and felted pads.

102. The reduced pressure delivery system according to claim 86, further comprising:

103. A tissue growth kit for promoting new tissue growth at a tissue site, comprising:

a scaffold having a first face and a second face, the first face adapted to contact a tissue site;

a hydrogel-forming material adapted to contact the second side of the scaffold; and

a distribution manifold adapted to contact the hydrogel-forming material to distribute reduced pressure through the scaffold to a tissue site.

104. A method for promoting new tissue growth at a tissue site, comprising:

placing the scaffold in contact with the tissue site;

placing a hydrogel-forming material in contact with the scaffold;

placing a manifold in contact with the hydrogel-forming material; and

applying reduced pressure to the tissue site through the manifold and the scaffold.

105. The method of claim 104, further comprising:

drawing exudate through the scaffold and the manifold.

106. The method of claim 104, further comprising:

stopping application of reduced pressure to the manifold;

hydrating the hydrogel-forming material into a gel form; and

removing the manifold from the hydrogel-forming material.

107. The method of claim 106, further comprising removing the hydrogel-forming material from the scaffold.

108. The method of claim 106, wherein the step of hydrating the hydrogel-forming material further comprises:

delivering a fluid to the hydrogel-forming material through the manifold.

109. The method of claim 106, further comprising:

placing a second support in contact with the first support after removing the manifold;

placing a second hydrogel-forming material in contact with the second scaffold;

placing a second manifold in contact with the second hydrogel-forming material; and

applying reduced pressure to the second manifold.

110. The method of claim 104, wherein the tissue site is comprised of tissue selected from the group of adipose tissue, bone tissue, muscle tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, and ligaments.

111. A method for promoting new tissue growth at a tissue site, comprising:

placing a multi-layer reduced pressure delivery apparatus in contact with a tissue site, the multi-layer reduced pressure delivery apparatus comprising:

a tissue contact layer having a scaffold adapted to contact a tissue site;

a manifold layer having a distribution manifold; and

a release layer having a plurality of flow channels and a hydrogel-forming material, the release layer being located between the tissue contact layer and the manifold layer, the hydrogel-forming material of the release layer being bound to at least one of the tissue contact layer and the manifold layer;

positioning the multi-layer reduced pressure delivery apparatus such that the tissue contacting layer contacts the tissue site; and

applying reduced pressure to the tissue site through the distribution manifold, the flow channel, and the scaffold.

112. The method of claim 111, further comprising:

drawing exudate through the scaffold, the flow channel, and the distribution manifold.

113. The method of claim 111, further comprising:

stopping the application of reduced pressure;

hydrating the hydrogel-forming material into a gel form; and

removing the distribution manifold from the hydrogel-forming material.

114. The method of claim 113, further comprising:

after removing the distribution manifold, placing a second multi-layer reduced pressure delivery apparatus in contact with the first support; and is

Applying reduced pressure to the second multi-layer reduced pressure delivery apparatus.

115. A method for promoting new tissue growth at a tissue site, comprising:

a first layer having a scaffold adapted to contact a tissue site;

a third layer having a distribution manifold in contact with the hydrogel-forming material;

116. A method for promoting new tissue growth at a tissue site, comprising:

placing a scaffold in contact with a tissue site, placing a hydrogel-forming material in contact with the scaffold, and placing a distribution manifold in contact with the hydrogel-forming material; and

applying reduced pressure to the tissue site through the distribution manifold and the scaffold to stimulate new tissue growth at the tissue site.