MXPA98010047A - Aposito for heri - Google Patents

Abstract

A wound dressing (10; 110; 210) is described for covering a wound (2; 102; 202) on a tissue structure of a human or animal living body, comprising a lower section (1; 101; 201) which , when the wound dressing covers the wound it is placed adjacent to the wound, the lower section being fluid permeable and comprises a bioresorbable material, which promotes the healing process in the wound, and an upper section (3; 103; 203 ) which, when the dressing covers the wound overlaps the lower section, the upper section being vapor permeable and impermeable to bacteria. The wound dressing can be an integrally formed structure, an integrated structure or formed when the wound is covered.

Description

WOUND APOSITO DESCRIPTION OF THE INVENTION The present invention relates to wound dressings or bandages, for bandaging wounds on internal or external structures of human or animal living bodies. Existing dressings or bandages for wounds have a number of advantages. Conveniently, gauze dressings have been used for the treatment of wounds such as burns, cuts, abrasions and other disorders. Such dressings, however, need to be changed frequently and the application and subsequent removal of a dressing for replacement with a fresh one can be painful for the patient. In fact, some dressings are so inconvenient that they can immobilize the patient. In European Patent EP-A-0349505 (Astra Meditec AB) it is shown that the healing of soft tissue in mammals including man, can be improved by the use of a flexible sheet per leaf of a bioresorbable polymer free of proteins having a Liner size that allows the passage of water and salts through it, but which secures the cells and other tissue particles. It is described REF: 28917 that the leaf causes a specific stimulating effect on the formation of macrophages in the soft tissue, the macrophages releasing a growth factor that stimulates tissue healing. Suitable polymeric materials mentioned in European Patent EP-A-0349505 for the sheet are those based on polyglycolic acids, copolymers of glycolic acid and lactic acids, copolymers of lactic acid and e-aminocaproic acid, polymers of lactide, polydeoxazon, poly ( 3-hydroxybutyrate), copolymers of poly (3-hydroxybutyrate) and 3-hydroxyvalerate, polyesters of succinic acid and cross-linked hyaluronic acid. European Patent EP-A-03495Q5 makes known the formation of a non-woven sheet of poly (3-hydroxybutyrate) having the required properties by pressing together the spun fibers in solution of the poly (3-hydroxybutyrate) manufactured according to the Patent North American US-A-4603070 (Steel et al.). Since the size of the pores in the sheet of European Patent EP-A-0349505 is sufficient to allow the passage of water through them, there is a possibility that the bacteria will pass through the sheet to the wound. While this can not be so problematic for the case where the blade is for internal use, that is, to be placed inside a human or animal body to cover an internal wound, this can be problematic in the case of external wounds such like wounds on the skin. British Patent GB-A-2166354 (Imperial Chemical Industries Pie) discloses a wound dressing comprising a poly (3-hydroxybutyrate) polymer dissolved or swollen with a volatile solvent such as chloroform, preferably copolymerized with 3-hydroxyvalerate units. The material is painted on the wound as a gel solution to give a thin film of polymer in intimate contact with the treated area. It is stated that the poly (3-hydroxybutyrate) is hydrophilic, making obvious the need for an external hydrophilic layer. It is established that the dressing is particularly suitable for the rapid protection of a site injured by temporary coverage. The thin layer of the hydrophilic poly (3-hydroxybutyrate) described in British Patent GB-A-2166354 has a number of disadvantages as a wound dressing. To begin with, there is no provision for excess fluid withdrawal since the poly (3-hydroxybutyrate) layer is not particularly absorbent and exudate from the wound will not pass through it. In addition, it may be difficult to remove the dressing from an open wound, and the volatile solvent in it tends to be toxic to the cells and could cause irritation to the wound site. In addition, the pore size distribution created in the poly (3-hydroxybutyrate) layer could be such that the size of the pores closest to the wound, it could be smaller than the size of the pores remote from the wound. There is therefore the possibility of infection of the wound through the entry of bacteria into the dressing. In summary, the prior art has not faced the problem of providing a convenient dressing for wounds, for use during gradual healing of wounds that can be conveniently applied and, where necessary, removed, which provides thermal insulation to maintain body temperature in the vicinity of the wound surface, and maintains the moisture of the wound allowing even the removal of excessive fluid from the wound. The present invention proposes to improve this situation. According to the present invention, a wound dressing is provided for bandaging a wound on a tissue structure of a living human or animal body, when the wound dressing kit has a lower outer surface positioned adjacent to the wound, a surface outer upper separated from the lower outer surface, a lower section permeable to fluid which has the lower outer surface and comprises a bioresorbable material which promotes the process of wound healing, and a porous upper section overlapping the lower section, the As the upper outer surface is present, the pore size of the pores in the upper porous section is less than about 0.25 μm, whereby the upper section is vapor permeable and impermeable to bacteria. The dressing is relatively simple to manufacture. In addition, the dressing is easy to apply and can be adapted to facilitate easy removal. The dressing thus provides thermal cooling to maintain body temperature in the vicinity of the wound surface and maintains the moisture of the wound, while at the same time retaining excessive fluid from the wound. Assuring that the upper section is essentially impermeable to bacteria also means that a barrier is present to prevent the formation of the infection. Transport of the exudate away from the wound could be prevented if the exudate had no means to escape after it has accumulated on the upper surface of the lower section away from the wound. The provision of an upper section which is permeable to steam solves this problem by allowing the exudate to be slowly dispersed by evaporation. In addition, steam from the wound surrounding the wound will also be able to pass through the upper section. Extracting the exudate from the wound to the lower section and the subsequent evaporation of excess moisture creates a flow of material in the direction away from the wound into the atmosphere. This flow also prevents the passage of bacteria in the opposite direction, and thus prevents an infection from occurring. The wound dressing of the invention can be left in place for a relatively long period. This means that minor changes to the dressing are necessary than those needed to date, thus avoiding the disturbance of the healing process with less pain for the patient. The use of a superior section that is vapor permeable ensures that the wound is kept moist, regardless of how effective the removal of excessive fluid from the wound may be. Preventing the wound from drying out results in pain being controlled. In a first form of the invention, the wound dressing is an integral structure. In a second form of the invention, the wound dressing is formed with an integrated structure. For example, the upper and lower sections may be presented respectively by the upper and lower layers of wound dressing, which are coupled to each other before bandaging the wound. In a third form of the invention the wound dressing is formed once the wound is bandaged, for example the upper and lower section are respectively presented by the upper and lower layers of the wound dressing, which are applied to the wound separately. Having the lower section of the wound dressing as a lower layer of the wound dressing, for example a sheet, means that it can be easily put into position and used as a barrier facilitating the transport of the exudate from the wound and retaining it away from the wound. the wound . In an embodiment of the invention according to its various forms, the wound dressing further comprises an intermediate section between the upper and lower section, which is adapted to absorb liquids. This is particularly advantageous where a large amount of exudate is found. For the second and third forms the intermediate section may be of any suitable material, for example treated cellulose fibers or polyacrylic acids. However, a hydrocolloid is particularly suitable. A hydrocolloid is normally capable of absorbing four to six times its own volume of fluid, and it has been reported that the new hydrocolloids absorb twenty times its own volume. The hydrocolloids are adhesive to the skin, so that the hydrocolloid can perform the double function of intermediate absorbent layer and adhesive edge for the dressing. The intermediate section of the second and third forms of the invention may be in the form of an intermediate layer of the wound dressing or may be part of the upper and lower layer of the wound dressing. In one embodiment of the first form of the invention, the wound dressing consists of the upper and lower sections, which comprise the bioresorbable material. The bioresorbable material may be in particulate or fiber form. For example, the wound dressing may comprise particles or fibers of the bioresorbable material in a matrix material such as a gel matrix of hyaluronic acid or the like. On the other hand, the wound dressing can be a fiber sheet of the bioresorbable material, for example a sheet of non-woven fibers. In one embodiment of the invention according to the second and third forms, one or more of the layers of the wound dressing are in the form of one or more wound dressing sheets. In one embodiment of the second form of the invention, the wound dressing consists of the upper and lower layers of the wound dressing, with the lower layer of the dressing being adhered to a lower surface of the upper layer of the wound dressing. Alternatively, where the wound dressing comprises the middle layer of the wound dressing, the upper and lower layers of the wound dressing are respectively adhered to the upper and inner surfaces of the intermediate wound dressing layer. In one embodiment of the second form of the invention, the lower layer of the wound layer is releasably secured to the rest of the wound dressing. For example, the lower layer of the wound dressing can be releasably secured to the lower surface of the upper layer of the wound dressing to the lower surface of the intermediate layer of the wound dressing. In a preferred embodiment of the invention according to its various forms, the lower section of the wound dressing is substantially free of volatile solvent. In an embodiment of the second and third forms of the invention, the lower layer of the wound dressing is presented by a particle layer of the bioresorbable material. The particles can be supported in a matrix material, for example a skin matrix comprising hyaluronic acid. In an embodiment of the second form of the invention, the particularly bioresorbable material of the lower layer of the wound dressing is adhered to the inner surface of the upper or intermediate layer of the wound dressing, by mixing the particles in a solvent, coating the mixture to the lower surface and then evaporating the solvent. The chloroform can be mentioned as a suitable solvent. In one embodiment of the invention according to its third form, when the wound dressing covers the wound the lower section is presented by a layer of loose particles or fibers of the bio-resorbable material placed on the wound. Alternatively, the lower layer of the wound dressing may be a gel comprising a bioresorbable material coated on the wound or one or more lower sheets of the wound dressing, placed on the wound. In an embodiment of the second and third forms of the invention, the bioresorbable material of the lower layer of the wound dressing is in the form of a row, for example supported on a matrix such as a gel matrix formed from acid and hyaluronic acid. . Alternatively, the lower layer of the wound dressing can take the form of one or more sheets of wound dressing fibers, for example formed from non-woven fibers and in which case the lower surface of the lower layer of the wound dressing can advantageously be roughened to expose the ends of the fibers. In one embodiment of the various forms of the invention, the bioresorbable material of the lower section is a polymer. For example, the polymer is free of proteins, examples of which are poly (3-hydroxybutyrate) (PHB), polylactic acids, polyglycolic acid, glycolic acid and lactic acid copolymers and e-aminocaproic acid, lactide polymers, polydeoxazon, copolymers of poly (3-hydroxybutyrate) and 3-hydroxyvalerate, polyesters of succinic acid and cross-linked hyaluronic acid. The use of a bioresorbable polymer free of protein in the inner section, seems to stimulate healing during degradation, by stimulating the macrophages, by forming a barrier against the surroundings and working as a scaffold for the development of the cells. The invasion of macrophages caused by protein-free polymers covers the wound with tissue and effectively controls the pain of the wound in the first or second day. Vascularization and microcirculation occur, again stimulated by the polymer. In addition, the degradation of certain protein-free polymers such as PHB has a bacterial, fungal and fungal effect, and facilitates the healing of the skin wound. Invasive macrophages also have a bactericidal effect. The wound message can be left in place for a longer period of time due to the bacteriostatic and fungistatic properties and the wound healing environment created below the dressing. Minor dressing changes mean less disturbance of the healing process and less pain for the patient. Poly (3-hydroxybutyrate) is the preferred material for the lower section, because the Applicant has found that the PHB has the ability to attract macrophages to the site of the wound at a higher rate than other tested polymers. PHB also appears to lead to increased vascularization, perhaps through a macrophage effect promoted by PHB. In addition, the dressing period is also improved with the PHB being used due to the fact that the bacteriostatic and fungistatic properties are increased over time, with the degradation of the PHB. Further, in the case where the lower section is formed as a fibrous PHB sheet, for example a non-woven sheet, having hydrophobic fibers, the nature of the PHB fibers is such that the sheet has a capillary capacity which helps the Exudate is extracted away from the wound and retained in the region between the leaf and the upper section. In addition, a nonwoven PHB fiber sheet will swell during the first; ten days approximately by the addition of blood components and cells from the surrounding tissue, due to its construction, a. Although the fibers are hydrophobic. In conclusion, the PHB fiber sheet as the lower section of the wound dressing will allow the wound to "breathe" and make it possible to transport the vapor, leaving it to the patient. surface of the wound with adequate moisture. Where the poly (3-hydroxybutyrate) is selected -j the oligo (3-hydroxybutyrate), for example, having 3 to 10 monomer units, it may also be included in the lower section or it may constitute the lower section. A wide range of other materials may be adequate for the function of the lower section which could easily be for an expert reader in the. technique, with non-limiting examples being polysaccharides such as chitosan, collagen and proteins. In one embodiment of the various forms of the invention, the wound dressing is flexible, which makes it possible for the dressing to follow the contour of the wound, for example a recessed wound. In an embodiment of the second and third forms of the invention, the lower part of the wound dressing is adapted to follow the contour of the wound, for example by being flexible. To assist the wound healing process the lower section of the various forms of wound dressing according to the invention, can support one or more growth factors. In an embodiment of the second and third forms of the invention, the top layer of the wound dressing comprises a polymeric material. The polymeric material can be a bioresorbable one and can also be protein free. As an example, the upper section may comprise poly (3-hydroxybutyrate). Alternatively, the upper section may comprise a material. non-bioresorbable, non-biodegradable, being non-limiting examples of the polymer and the polyurethane and the polytetrafluoroethylene. Where the upper and lower sections are both porous, the pore size according to the pores of the upper section will be smaller than the pore size of the lower section. In one embodiment of the invention according to its various forms, the wound dressing has an adhesive edge for releasable adherence to a surface of the tissue structure adjacent to the wound. This facilitates the application and removal of the dressing or the top of it. In an embodiment of the second and third forms of the invention, the upper layer of the wound dressing has the adhesive edge, in which case the upper layer of the wound dressing can completely surround the lower layer of the wound dressing. An ideal overlap range is approximately 10 to 15 mm. Where the top layer of the wound dressing includes the intermediate section, the adhesive edge can be presented by the middle section of the top layer of the wound dressing. In an embodiment of the second and third forms of the invention, the intermediate layer of the wound dressing has the adhesive edge.

According to the invention there is also provided a method for the treatment of a wound on a structure of a living human or animal body, comprising the steps of applying a wound dressing according to the invention to the wound. The embodiments of the invention will now be described by way of example with reference to the accompanying Figures of the drawings, in which: Figure 1 is a cross-sectional side view of a first wound dressing according to the present invention; Figure 2 is a cross-sectional side view of a second wound dressing according to the present invention; Y Figure 3 is a cross-sectional side view of a third wound dressing according to the present invention; As you can see from the Figure 1, a wound dressing 10 according to the present invention comprises a layer 1 of a bioresorbable material which promotes the processes of wound healing, in this case the poly (3-hydroxybutyrate) (hereinafter. "PHB" ), applied to a wound 2 of the skin in the form of a nonwoven, fibrous sheet, substantially free of volatile solvent, and a microporous, outer layer 3 of a polyurethane polymer. The pores of the outer polymer layer 3 have a pore size of less than 0.22 μm. This makes the layer 3 permeable to vapor and gases, while keeping the layer 3 essentially impermeable to bacteria. The dressing 10 can be conventionally applied and removed, and further provides thermal insulation to maintain body temperature in the vicinity of the wound surface, by virtue of the outer polymeric layer 3. The dressing 10 also keeps the wound 2 moist, by being permeable to moisture vapor, making it possible to remove excess fluid from the wound 2. This prevents the nerve terminals in the wound from drying out and concomitantly being a cause of pain for the patient. To facilitate the application and removal of the dressing 10 the outer polymeric layer 3 has an adhesive edge 4. The PHB fibers in the dressing 10 show hydrophobic properties. The nature of the PHB fibers is such that the exudate is removed from the wound 2 and retained in the PHB 1 layer and the space between the PHB 1 layer and the outer polymeric layer 3. The wound dressing 10 can be left in place. site for a relatively long period. This means that minor changes to the dressing are needed than with the proposed dressings to date. This avoids disturbing the healing process with less pain for the patient. One possibility when changing the dressing 10 could be to remove the outer layer of the polymer 3 and the excess exudate only, then putting a fresh outer layer 3 in place without disturbing the layer of PHB 1. Alternatively, most of the PHB 1 layer can also be removed and replaced with a fresh piece of PHB, with PHB fibers that adhere to the wound 2 that is left behind. In Figure 2 there is shown a second wound dressing 110 according to the present invention, which counting the PHB layer 101 applied to a wound 102 on the skin in the form of a fibrous nonwoven sheet, substantially free of volatile solvent and an outer microporous layer 103 of a polyurethane polymer. The PHB layer 101 is in the form of a patch completely surrounded by the outer polymeric layer 103 with a range of 10 to 15 mm (m) of the outer polymeric layer 103 around the patch of PHB 101 that is left. The size of the patch of PHB 101 therein may vary according to the size of the wound 102. In addition, an intermediate absorbent layer 105 of a hydrocolloid material is provided. This absorbs the exudate that is transported away from the wound 102 by the PHB 101 patch, and promotes transport away from the additional exudate. The microporpsity of the outer layer of polyurethane 103 means that the exudate can be slowly dispersed while still maintaining the wound 102 and thereby excluding the bacteria. Steam from the skin surrounding the wound 102 will also be able to pass through the outer polymeric layer 103. The outer polymeric layer 103 has an adhesive edge 104 to facilitate the application and removal of the dressing 110. Returning now the Figure 3, a third wound dressing 210 according to the present invention, comprises the PHB layer 201 applied to a wound 202 on the skin, in the form of a nonwoven fibrous sheet substantially free of volatile solvent, and an outer microporous layer 203 of a polyurethane polymer. The PHB is again in the form of a patch completely surrounded by the outer polymer layer 203 with a 10 to 15 mm (-zn) margin of the polymer left around the PHB patch. An intermediate absorbent layer 205 of a hydrocolloid material is again provided, but in this case the hydrocolloid layer 205 is made integral with the outer polymeric layer 203. Since the hydrocolloid material is adhesive to the skin, it can be adhered to the skin by its edge 204. In this way, the hydrocolloid performs the double function of intermediate absorbent layer and adhesive edge to outer layer 203. A person skilled in the art will readily appreciate that the invention is not restricted to specific examples of wound dressings. described hereinabove with reference to the accompanying drawings, but the invention may take many forms or modalities within the scope of the claims. The applicant has observed that wound dressings must meet the following objectives: • Thermal insulation must maintain the body temperature of the wound surface. • The wound should be kept moist, but excess fluid should be removed. • The dressing must be permeable to vapor impermeable to bacteria. • The dressing must be absorbent and breathable. • The pain must be controlled. • The dressing should be easy to apply and, where necessary, remove. • The dressing should stimulate the healed. • The dressing must comply with other treatments, for example allowing an outer compression dressing to be provided and allowing the desquamation of the dead skin to occur. • The dressing must be compatible and non-toxic. • The dressing should not immobilize the patient. The wound dressings described hereinabove with reference to the attached Figures of the drawings satisfy these objectives in a simple and inexpensive manner. In a comparative test a wound dressing according to the invention and a wound dressing comprising a polyurethane sheet (Tagerderm ™) were used to bandage a wound on the skin of the body of a mammal. The dressing according to the invention consisted of a lower section in the form of a sheet of nonwoven fibers of PHB and an upper section of a sheet of polyurethane. The wound dressing of the invention produced a healed wound, improved compared to the polyurethane sheet wound dressing. This was characterized by the healed wound covered by the wound dressing of the invention, which has a thicker layer and better quality of hepitelial cells in the regenerated tissue, than in the healed wound covered by the wound dressing of polyurethane sheet .

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (42)

1. A wound dressing for bandaging a wound on a tissue structure of a living human or animal body, characterized in that when the wound dressing covers the wound, it has a lower external surface positioned adjacent to the wound, an external upper surface separated from the wound. upper external surface, a lower section permeable to the fluid which presents the lower external surface, and comprises a bioresorbable material which promotes the process of wound healing and a porous upper section that overlaps the inner section, which presents the external surface above, wherein the pore size of the pores in the porous upper section is less than about 0.25 μm whereby the upper section is vapor permeable and impermeable to bacteria.

2. A wound dressing according to claim 1, characterized in that the lower section is permeable to liquid.

• A wound dressing according to claim 1 or 2, characterized in that the lower section of the wound dressing is substantially free of volatile solvent.

4. A wound dressing according to any of claims 1 to 3, characterized in that the bioresorbable material is in particulate or fiber form.

5. A wound dressing according to claim 4, characterized in that the particles or fibers of bioresorbable material are in a matrix material.

6. A wound dressing according to claim 5, characterized in that the matrix is a gel matrix.

7. A wound dressing according to claim 6, characterized in that the gel matrix is hyaluronic acid.

8. A wound dressing according to any of claims 1 to 7, characterized in that the bioresorbable material of the lower section comprises a polymer.

9. A wound dressing according to claim 8, characterized in that the polymer is free of proteins.

10. A wound dressing according to claim 9, characterized in that the polymer is poly (3-hydroxybutyrate), a polylactic acid, polyglycolic acid, a glycolic acid and lactic acid copolymer, a copolymer of lactic acid and acid, e- aminocaproic acid, a polymer of lactide, polydeoxazone, a copolymer of poly (3-hydroxybutyrate) and 3-hydroxyvalerate, a polyester of succinic acid or cross-linked hyaluronic acid.

11. A wound dressing according to claim 1, characterized in that the lower section comprises poly (3-hydroxybutyrate) and oligo (3-hydroxybutyrate).

12. A wound dressing according to any of claims 1 to 7, characterized in that the bioresorbable material of the lower section comprises a polysaccharide-such as a lipopolysaccharide, chitosan, collagen or a protein.

13. A wound dressing according to any of claims 1 to 12, characterized in that the lower section is porous.

14. A wound dressing according to claim 13, characterized in that the pore size of the pores of the upper section is smaller than the pore size of the pores of the lower section.

15. A wound dressing according to any of claims 1 to 12, characterized in that the lower section is perforated.

16. A wound dressing according to any of the preceding claims, characterized in that the lower section supports one or more growth factors.

17. A wound dressing according to any of claims 1 to 16, characterized in that the upper section comprises a non-bioresorbable material.

18. A wound dressing according to claim 17, characterized in that the upper section comprises a polymeric non-bioresorbable material.

19. A wound dressing according to claim 18, characterized in that the polymeric material is polyurethane or polytetrafluoroethylene.

20. A wound dressing according to any of claims 1 to 19, characterized in that the wound dressing further comprises an intermediate section between the upper and lower section, which is adapted to absorb liquid.

21. A wound dressing according to claim 20, characterized in that the intermediate section comprises a hydrocolloid.

22. A dressing for wounds according to any of claims 1 to 21, characterized in that the wound dressing is a ruc

23. A wound dressing according to claim 22 when dependent on any of claims 1 to 19, characterized in that the wound dressing consists of the upper and lower sections, with the upper and lower sections comprising the iorresorbable material.

24. A wound dressing according to claim 22 or claim 23, characterized in that the wound dressing is in the form of a sheet.

25. A wound dressing according to claim 23, characterized in that the wound dressing is a fiber sheet of the bioresorbable material.

26. A dressing according to claim 25, characterized in that the wound dressing is a sheet of non-woven fiber.

27. A wound dressing according to claim 25 or 26, characterized in that the lower surface of the wound dressing is roughened to expose ends of the fibers.

28. A wound dressing according to any of claims 22 to 27, characterized in that the wound dressing is flexible, whereby it is possible for the dressing to follow the contour of the wound such as a recessed wound.

29. A wound dressing according to any of claims 1 to 21, characterized in that the wound dressing is formed as an integrated structure.

30. A wound dressing according to claim 29, characterized in that the upper and lower sections are respectively presented by the upper and lower layers of the wound dressing, which are coupled to each other before covering the wound.

31. A wound dressing according to any one of claims 1 to 21, characterized in that the wound dressing is formed once the wound is covered.

32. A wound dressing according to claim 31, characterized in that the upper and lower section are respectively presented by the upper and lower layers of the wound dressing, which are applied to the wound separately.

33. A wound dressing according to claim 31, characterized in that when the wound dressing covers the wound, the lower section is presented by a layer of loose particles or fibrils of the bioresorbable material placed on the wound.

34. A wound dressing according to claim 32, characterized in that when the wound dressing covers the wound, the lower layer of the wound dressing is a gel comprising the bioresorbable material coated on the wound.

35. A wound dressing according to any of claims 30 or 32 when dependent on one of claims 20 or 21, characterized in that the intermediate section is in the form of an intermediate layer of the wound dressing.

36. A wound dressing according to claims 30, 32, or 35, characterized in that one or more of the layers of the wound dressing are in the form of one or more sheets of the wound dressing.

37. A wound dressing according to claims 30, 32, .35 or 36, characterized in that the lower layer of wound dressing is adapted to follow the contour of the wound.

38. A wound dressing according to claim 37, characterized in that the lower layer of the wound dressing is flexible.

39. A wound dressing according to any of claims 30, 32 or 34 to 38, characterized in that the upper layer of the wound dressing of the wound dressing comprises a polymeric material.

40. A wound dressing according to claim 39, characterized in that the polymeric material is bioresorbable.

41. A wound dressing according to claim 40, characterized in that the polymeric material is free of proteins.

42. A wound dressing according to claim 41, characterized in that the upper section comprises poly (3-hydroxybutyrate).