WO2009047564A2

WO2009047564A2 - Wound dressing

Info

Publication number: WO2009047564A2
Application number: PCT/GB2008/050926
Authority: WO
Inventors: Stephen Cotton
Original assignee: Brightwake Limited
Priority date: 2007-10-09
Filing date: 2008-10-09
Publication date: 2009-04-16
Also published as: WO2009047564A3; GB0719683D0

Abstract

A wound dressing or the like comprises a layer of support material coated on one side thereof with a hydrophobic gel layer. The area of the support material that, in use, faces the skin is only partially coated with hydrophobic gel. The hydrophobic gel layer may be applied in a regular pattern that has openings in it, such that the layer is not continuous, eg a pattern of round openings arranged in a square or hexagonal array.

Description

Title - Wound dressing

Field of the Invention

The present invention relates to a wound dressing and its method of manufacture.

Background of the Invention

Different types of wound dressing are reguired to meet different clinical needs. However, there are several desirable characteristics that are common to all wound dressings. Pain-free removal and the ability to remove a dressing without trauma to the wound and the surrounding skin are two of the most important characteristics. The term "atraumatic dressing" is used in relation to products that, upon removal, do not cause trauma either to newly formed tissue or to the peri-wound skin.

In order to prevent pain and trauma, the facing layer of a wound dressing needs to maintain a moist layer over the wound to prevent adherence to the drying wound. However, to help to maintain the wound dressing in position and avoid infection, the facing layer must adhere to the peri-wound skin.

Biocompatible gels, in particular soft silicone gels, adhere readily to dry skin but do not stick to the surface of a moist wound and do not cause damage on removal. As well as satisfying these principal reguirements for use as the skin contact layer in atraumatic dressings, there are several other intrinsic properties of soft silicone that make it particularly advantageous for use in wound dressings. These properties are well-documented and include the fact that silicones are non-toxic, non-allergenic or sensitising, do not shed particles or fibres into the wound, feel soft on the skin and are conformable yet robust. Numerous published papers describe the properties of silicone and the use of soft silicone dressings. Indeed, there are different types of soft silicone dressings currently on the market, including atraumatic wound contact layers, absorbent dressings for exuding wounds and also a dressing for the treatment of hypertrophic scars and keloids.

EP-A-0633758 discloses a wound dressing comprising a layer of hydrophobic silicone gel, a layer of carrier material and an absorbent body, wherein the carrier material and gel layer have mutually coinciding penetrating perforations at least within the region of the absorbent body.

EP-A-0300620 describes a surgical dressing, particularly adapted to the treatment of burns, comprising a sheet of silicone gel having a wound-facing surface and, laminated to the other surface, a film of silicone elastomer.

EP-A-0633757 is concerned with methods by which a dressing comprising a perforated carrier coated with silicone can be manufactured. That method involves blowing cold air onto the underside of the carrier to prevent silicone clogging the perforations.

EP-A-0855921 relates to dressings comprising a layer of absorbent foam. The surface of the foam that is applied to the wound has a pattern of pores or holes and is coated with silicone gel such that the walls of the holes are coated with gel at those end parts of the holes that lie proximal to the wearer's skin when the dressing is worn. A first embodiment is described in which the gel extends slightly into the open pores of the foam material , without closing all the pores. However, it is acknowledged that some of the pores in the foam material that face towards the wound are closed by the gel layer, and it is clear that the absorbency of the dressing is compromised as a result. Indeed, the first embodiment is only intended for wounds from which fluid is exuded only slightly or in normal quantities and a second embodiment is recommended for use on wounds that exude fluid in normal to copious quantities. In the second embodiment a pattern of holes is cut into the foam and then the foam is coated with silicone gel, the gel layer extending slightly into the cut holes and also into the pores of the foam material.

The absorbency of the wound dressings described as the first embodiment in EP-A-0855921 is limited, a) because most of the pores of the foam may be closed by the gel layer, and b) because the pores that are not completely blocked by the silicone gel are subject to clogging with wound exudate. This will evidently lead to a build-up of fluid under the gel layer, which may eventually escape out of the side of the dressing. The build-up of fluid will reduce or remove adhesion between the dressing and the skin, and the dressing will no longer be able to perform its function as an aid to wound healing. Exudate must be effectively managed if the optimal moist environment necessary for wound healing is to be created. As well as causing maceration of the surrounding skin, and being messy and unpleasant for the patient, leaking exudate causes breaks in the seal around the edges of the dressing, increasing the risk of infection.

Wounds heal fastest when the dressing is left undisturbed for several days. However, in order to mitigate the above problems the dressing would need to be changed at more frequent intervals than is desirable for healing. Frequent re-dressing is also more costly, resource-intensive and may increase pain and trauma to the wound bed and peri-wound skin.

It is likely that a dressing with a continuous gel layer will not allow sufficient skin breathability, particularly if the pores of the foam are blocked.

Although the second embodiment described in EP-A-0855921 may have improved absorbency, the need to cut the foam layer complicates the manufacturing process, increasing production costs. There is also a risk that particles or fragments may be created upon cutting, and then become detached in the wound causing aggravation, a foreign body reaction or, in the worst case, the formation of an abscess.

There remains a need to provide an improved atraumatic dressing for exuding wounds that overcomes or substantially mitigates the above-mentioned and/or other disadvantages of the prior art. In particular, there remains a need to improve the absorbency of wound dressings having a gel facing layer.

Summary of the Invention

According to a first aspect of the invention, there is provided a wound dressing or the like comprising a layer of support material coated on one side thereof with a hydrophobic gel layer, characterised in that the area of the support material that, in use, faces the skin is only partially coated with hydrophobic gel.

Embodiments of the wound dressing according to the invention are advantageous they may exhibit some or all of the benefits associated with the use of a hydrophobic gel facing layer, but improved performance compared to the prior art with respect to absorbency and/or skin-breathability.

By a "wound dressing or the like" is meant in this context a flexible and conformable article that is suitable and intended for application to a patient's skin for medical purposes. Such articles may include articles that themselves have a therapeutic effect, as well as articles that do not themselves have a therapeutic effect but are intended to retain articles that do.

For the dressing of exuding wounds, the partial coating of hydrophobic gel is preferably applied to a layer of supporting material that is absorbent, eg an absorbent foam material. Thus according to a preferred embodiment of the invention, there is provided a wound dressing comprising a layer of absorbent foam material coated on one side thereof with a hydrophobic gel layer, characterised in that the area of the foam material that, in use, faces the skin is only partially coated with the hydrophobic gel.

The exudate is absorbed into the foam through the uncoated areas. Since the skin-facing area of the foam is not cut into during manufacture, there is no risk that particles or fragments of foam will fall into the wound bed and cause aggravation.

Preferably, the absorbent material carries on its other side a layer of liquid- impermeable material to act as a barrier and prevent fluid such as wound exudate from escaping from the dressing, thus keeping the outer surface of the dressing dry. Preferably, the liquid-impermeable layer covers the exposed foam material around the edges of the dressing, or else the edges are otherwise sealed, eg by compression and/or heat-sealing.

The wound dressings and the like of the present invention are advantageous, even for applications in which the absorption of fluids is not required. The principal benefit of only a partial coating of hydrophobic gel is that it facilitates the transmission of vapours, in particular water vapour, from the surface of the skin.

In a second embodiment of the invention, there is provided a wound dressing or the like comprising a layer of breathable material coated on one side thereof with a hydrophobic gel layer, characterised in that the area of the breathable material that, in use, faces the skin is only partially coated with the hydrophobic gel.

By 'breathable' is meant in the context of this invention that the material is vapour-permeable. The layer of breathable material is preferably a breathable film. In more preferred embodiments, the layer of breathable material is a breathable film that is waterproof, ie liquid-impermeable. Suitable materials include plastic films, eg polyurethane films.

For certain applications, it may also be preferable for liquid perspiration as well as water vapour to be directed away from the surface of the skin, in which case the layer of breathable material may be a fabric.

It is advantageous for wound dressings to have a high moisture vapour transmission rate, eg to avoid or minimise the risk of skin lesions caused by moisture accumulation, and the same advantages apply to similar devices that bond to the skin, for example medical tapes and footcare products.

Medical tapes are used for many different applications, for example covering and/or securing wound dressings, securing tubes and other medical devices, and strapping.

The main problems associated with the use of current medical tapes are skin stripping, adhesive transfer onto the skin, allergic response, and pain, eg as a result of skin stripping, wound disturbance and/or the removal of body hair. These problems are commonly due to the use of harsh pressure-sensitive adhesives against the skin. The problems are of course exacerbated when the medical tape is used on fragile or sensitive skin and when repeated tape applications are required over the same site.

It is advantageous to use a layer of hydrophobic gel, eg soft silicone gel, as the skin facing layer of a medical tape. The general benefits of using a hydrophobic gel, eg soft silicone, against the skin are described above. In particular, the hydrophobic gel allows the tape to be removed easily and gently, reducing pain and discomfort for the patient and avoiding the usual secondary problems associated with the use of medical tapes. If inspection and repositioning is necessary, a medical tape having a hydrophobic gel skin-facing layer can be lifted and re-applied with little or no loss of adherence.

Medical tapes having a soft silicone skin-facing layer are known in the art, eg soft silicone tapes sold under the trade name Mepitac® by Molnlycke

Healthcare. Mepitac® consists of a soft silicone layer, a knitted fabric and a breathable polyurethane film. The soft silicone layer is a continuous layer.

Thus, there still exists a need for a soft silicone tape that has improved breathability characteristics.

According to the further aspect of the invention, there is provided a medical tape comprising a layer of breathable material coated on one side thereof with a hydrophobic gel layer, characterised in that the area of the breathable material that, in use, faces the skin is only partially coated with the hydrophobic gel.

Hydrophobic gel layer It is a novel and inventive feature of the invention that the support material that, in use, faces the skin is only partially coated with hydrophobic gel.

The percentage of the surface area of the support material that is uncoated is generally at least 5%, preferably at least 10%, more preferably at least 20%, and most preferably at least 25%.

The percentage of the surface area of the support material that is uncoated is generally less than 90%, preferably less than 60%, more preferably less than 50%, and most preferably less than 40%.

Thus, the percentage of the surface area of the support material that is uncoated is generally 5% to 90%, preferably 10% to 60%, more preferably 20% to 50%, and most preferably 25% to 40%. In order to achieve partial coating, the gel layer is preferably applied in a regular pattern that has spaces or openings in it, such that the layer is not continuous. The openings may be of any shape, including round, square, rectangular, hexagonal, or any combination of shapes. Preferably, the gel layer has a pattern of round openings. Most preferably, the centres of the openings are arranged in a square or hexagonal array.

A pattern in which the centres of the openings are arranged in a hexagonal array is particularly preferred.

The thickness of the gel layer may typically be between 5μm and 10mm, more commonly between 20μm and 5mm.

The hydrophobic gel that is carried on the skin-facing side of the foam layer is most preferably a silicone gel (soft silicone).

The properties of silicone gels are well-documented. In particular, silicone gels exhibit excellent releasable adhesion to the skin, and this and other advantages and benefits of skin contact layers comprising layers of silicone gel are particularly well-documented for wound dressing applications. For example, silicone gels are soft, tactile and conformable. They exhibit good adhesion to dry skin and, particularly importantly, low adherence to an underlying wound. Thus, the dressing can be applied to a wound and subsequently removed without causing trauma to the wound. Silicone gels are adhesive but do not leave fibres, residue or tack on a surface/substrate when removed.

Most preferably, suitable silicone gels are formed by reaction between two components that are mixed immediately prior to application to the absorbent foam layer. Suitable components that are intended for such reaction to form a silicone gel are readily available commercially. Typically, the two components are a vinyl substituted silicone and a hydride-containing silicone.

Gels having different properties may be produced by varying the proportions and/or nature of the components used in the reaction. For example, the molecular weights of the various components and/or their degree of substitution by reactive groups may be different.

Suitable components for forming silicone gels for use in the wound dressing of the present invention are readily available.

Prior to use, the layer of hydrophobic gel is most preferably protected by a release liner that is removed to expose the hydrophobic gel immediately prior to use. The release liner is most preferably formed in such a way as to be readily grasped and removed, eg by having one or more projecting tabs.

Foam layer

In certain embodiments of the inventioin, the layer of support material is a layer of absorbent foam material.

The foam material is an absorbent foam, for instance a polyurethane foam.

Preferably, the surface of the foam layer is substantially flat, in that, apart from the open cells or pores of the foam, it does not include any holes, perforations or the like which open onto the side of the foam material that lies proximal to the wearer's skin in use.

The thickness of the foam layer may typically be between 1 mm and 10mm, more commonly between 2mm and 6mm, and preferably about 4mm.

Active ingredients may be incorporated into the foam layer and/or into the layer of hydrophobic gel, either during or after manufacture. Active agents may be used, for example, to facilitate and accelerate healing of the wound, to prevent or reduce malodour, to minimise pain, and/or to prevent or counteract infection. In particular, the foam may include an antimicrobial agent or active carbon.

The foam material may carry a layer of liquid-impermeable material on the side of the foam material that is opposite to the gel layer (distal to the skin in use). The liquid-impermeable material may conveniently comprise a liquid- impermeable, but vapour-permeable, plastic film, for example a polyurethane film.

The liquid-impermeable layer acts as a barrier to prevent escape of fluid such as wound exudate from the dressing, thus keeping the outer surface of the dressing dry.

Breathable layer

In other embodiments of the invention, the layer of support material is a layer of breathable material, preferably a breathable film. The layer of breathable material is preferably a liquid-impermeable, vapour-permeable, film of plastics material, eg a polyurethane film.

Form and manufacture

It is recommended that a wound dressing should overlap the wound margin by at least about 2cm. Wound dressings according to the invention may be supplied as a large sheet that can be cut to size by a patient or medical practitioner, depending on the size and shape of the wound. However, the wound dressings according to the invention will generally be pre-cut in a range of sizes intended for immediate application. If required, the pre-cut dressing may be further trimmed to a particular size or shape prior to application. The wound dressings according to the invention are generally packaged as individual units in envelopes that are bacteria-proof and which have been sterilised, most commonly using ethylene oxide or by irradiation with γ- radiation.

It may be desirable to use additional means, such as a bandage or adhesive tape, to keep the wound dressing of the invention in place.

The wound dressing according to the invention may be manufactured in various ways. A currently preferred method of manufacture comprises the steps of: a) providing a layer of support material; b) applying to the support material a partial coating of a curable hydrophobic gel precursor composition; and c) causing or allowing the gel precursor composition to cure, thereby forming a layer of hydrophobic gel.

Preferably a rotogravure-type process is used, in which the pattern of the hydrophobic gel layer is engraved onto a carrier, eg a cylinder. The cylinder is loaded with the curable hydrophobic gel precursor composition so that, as it rotates, composition is carried in the engraved recesses. The composition may be poured onto the cylinder, the quantity of composition being controlled by a suitably formed applicator, eg a blade. Alternatively, the cylinder may be partially immersed in the composition, so that the composition is picked up as the cylinder rotates. In any event, the thickness of the hydrophobic layer may be controlled by the depth of the engraved image and the composition of the hydrophobic gel.

The support material preferably travels between the rotating cylinder and a fixed support, which may be flat plate or a counter-rotating roller, that presses the support material into contact with the cylinder as it rotates, such that the curable gel precursor composition is transferred from the cylinder and applied to the support material.

The layers are then preferably transported through a dryer, preferably a series of infra-red heaters, in which curing takes place.

Where the hydrophobic gel is a silicone gel, the hydrophobic gel precursor composition is preferably prepared by mixing the relevant ingredients immediately prior to application to the support material. Typically, such a composition will comprise a vinyl substituted silicone and a hydride-containing silicone.

Embodiments of the invention will now be described in greater detail, by way of illustration only, with reference to the accompanying drawings, in which

Figure 1 is a cross-sectional view, schematic and not to scale, of a foam- based wound dressing according to the invention;

Figure 2 is a fragmentary view of the surface of the skin-contacting surface of the wound dressing of Figure 1 , showing the pattern of holes in the gel layer;

Figure 3 is a view similar to Figure 1 of a film dressing according to the invention;

Figure 4 is a partial cross-sectional view, schematic and not to scale, of a section of medical tape according to the invention;

Figure 5 is a perspective view of a roll of of the tape of Figure 4; and

Figure 6 is a perspective view, showing the removal of a piece of the tape of Figures 4 and 5 from a release liner. Referring first to Figure 1 , a wound dressing according to the invention is generally designated 1. The dressing is generally square in shape. However, it will be appreciated that the dressing 1 may be any shape, depending on the size and nature of the wound to which the dressing 1 is to be applied. The dressing 1 is composed of a layer of absorbent foam 2 carrying on its top surface a liquid-impermeable layer, preferably a polyurethane film 3. The opposite surface of the foam, that in use is applied to the wound, is coated with a layer of silicone gel 4. The silicone gel layer 4 is protected by a release liner 5, which comprises two sheets 5a, 5b of textured plastics film that cooperate to completely cover the contacting surface of the dressing 1 , and which are formed with tabs 6a, 6b by which the sheets 5a, 5b can be grasped and pulled away to expose the silicone gel layer 4 immediately prior to application.

The silicone layer 4 does not cover the whole surface of the foam 2, but is formed with a regular array of openings 7. The openings 7 in the silicone layer 4 may vary in size and shape, depending on the type of wound to be dressed and its position, but are typically circular (as in the illustrated embodiment), with a diameter of the order of a few millimetres, eg 4-1 Omm, though smaller or larger diameter openings may be appropriate in certain applications. Usually, the openings are all of the same shape and size, but different forms of opening may be present in the same product. Most commonly, the openings are arranged in a regular array, the separation between adjacent openings typically being comparable with, or greater than, the dimensions of the openings. However, an irregular or random distribution of openings may also be possible.

The silicone gel layer of the wound dressing of Figure 1 is applied with circular openings, the centres of which are arranged in a regular hexagonal array, as shown clearly in Figure 2. In this preferred embodiment the diameter of each of the openings is about 7mm, and about 45% of the surface of the foam is uncoated. The dressing 1 may be manufactured as follows.

A pre-formed laminate consisting of the foam layer 2 with the liquid- impermeable backing layer 3 is fed along a conveyor with the exposed foam surface uppermost. The conveyor preferably comprises one or more looped belts, eg of PTFE-coated glass fibre. Suction may be applied from beneath the belts to hold the pre-formed laminate flat during at least the initial stages of the manufacturing process.

The silicone gel layer is applied using a rotogravure-type printing process. A gravure cylinder engraved with the negative image of the desired pattern of openings contacts the upper surface of the foam layer 2. Precursor components of a hydrophobic gel are mixed and immediately applied to the rotating cylinder by a suitable applicator, eg a blade applicator. As the cylinder rotates the curable precursor composition is drawn into the engraved surface of the cylinder.

As the pre-formed laminate passes beneath the rotating cylinder, the hydrophobic gel precursor mixture is applied to the surface of the foam layer 2 in the desired pattern, and to the desired thickness.

After passing the rotating cylinder, the coated laminate passes through successive stations of a manufacturing line.

The coated laminate passes into a first curing stage where the laminate passes beneath a bank of medium wave infra-red heaters that operate continuously. The thermal energy from these heaters initiates curing of the silicone mixture, and in particular cures the upper surface of the mixture, which maintains the structural integrity of the silicone layer during passage of the laminate through a second, longer curing stage. In the second curing stage, the laminate passes beneath further medium wave infra-red heaters. Curing of the silicone mixture, to form a layer of gel of the desired thickness and other properties, is completed during passage of the laminate through the second curing stage. The operating parameters may be optimised to suit the particular dressing being manufactured. Variables that may be adjusted include the power of the infra-red heaters, the speed of passage through the various stages of the process, as well as the length of the curing stages. Typically, the time taken for the laminate to pass through the curing stages is between 5 and 15 minutes.

After completion of curing, the release liner is applied to the exposed surface of the silicone gel layer. This may be achieved by conventional means, involving the feeding of the two components of the release liner from rollers and passing the two components over suitable formers to introduce the fold into the first component 6a and to cause the two components 6a, 6b to overlap to the desired extent.

Finally, individual dressings cut from the assembled laminate, and packaged and sterilised in conventional manner.

Turning now to Figure 3, a second embodiment of a wound dressing according to the invention is generally designated 20 and has the form of a film dressing. The film dressing 20 comprises a layer of polyurethane film 22 that carries on one side thereof a silicone gel layer 24. As for the embodiment of Figure 1 , the silicone gel layer 24 is protected by a release liner 25, which comprises two sheets of textured plastics film that cooperate to completely cover the contacting surface of the dressing 20, and which are formed with tabs by which the sheets can be grasped and pulled away to expose the silicone gel layer 24 immediately prior to application.

Also as for the embodiment of Figure 1 , the silicone layer 24 does not cover the whole surface of the foam 22, but is formed with a regular array of openings 27. In the illustrated embodiment, the array of openings is similar in form to that of the embodiment of Figure 1 , and so Figure 2 is equally applicable to the embodiment of Figure 3, when the release liner 25 has been removed.

A further embodiment of the invention, this time in the form of a medical tape, is shown in Figures 4 to 6, and is generally designated 30. The tape 30 comprises a structural layer 32 in the form of a film of melt-blown polyurethane. The structural layer 32 is coated on one side (the underside as viewed in Figure 4) with a layer of soft silicone 34 (hydrophobic silicone gel).

The surface of the soft silicone layer 34 that adheres to the skin or other surfaces during use is protected by a release liner 35, which is typically formed from high density polyethylene (HDPE).

On the other side (the upper side as viewed in Figure 4), the structural layer 32 is coated with a layer of acrylic contact adhesive 38 which in turn carries a breathable and water-resistant polyurethane backing layer 39.

As can be seen in Figure 4, the coating of silicone 34 does not completely cover the underside of the structural layer 32, but is formed with a regular array of openings 36.

The tape 30 is conveniently supplied in the form of a roll, as shown in Figure 5. As can be seen from Figures 5 and 6, the release liner 35 is wider than the adhesive tape itself to facilitate removal prior to use. In use, an appropriate length of tape is torn or cut from the roll, and the tape peeled away from the release liner 35 to expose the layer of silicone gel 34 by which the tape can be affixed to a patient's skin. The openings 36 in the silicone gel 34 are visible in Figure 6.

Claims

1. A wound dressing or the like comprising a layer of support material coated on one side thereof with a hydrophobic gel layer, characterised in that the area of the support material that, in use, faces the skin is only partially coated with hydrophobic gel.

2. A wound dressing or the like as claimed in Claim 1 , wherein the support material is a layer of absorbent foam material.

3. A wound dressing or the like as claimed in Claim 1 , wherein the support material is a plastics film.

4. A wound dressing or the like as claimed in Claim 1 , which has the form of a tape.

5. A wound dressing as claimed in any preceding claim, wherein the percentage of the surface area of the support material that is uncoated is at least 5%, preferably at least 10%, more preferably at least 20%, and most preferably at least 25%.

6. A wound dressing or the like as claimed in any preceding claim, wherein the percentage of the surface area of the support material that is uncoated is less than 90%, preferably less than 60%, more preferably less than 50%, and most preferably less than 40%.

7. A wound dressing or the like as claimed in Claim 1 , wherein the percentage of the surface area of the support material that is uncoated is 5% to 90%, preferably 10% to 60%, more preferably 20% to 50%, and most preferably 25% to 40% .

8. A wound dressing or the like as claimed in any preceding claim, wherein the hydrophobic gel layer is applied in a regular pattern that has openings in it, such that the layer is not continuous.

9. A wound dressing or the like as claimed in Claim 8, wherein the hydrophobic gel layer has a pattern of round openings.

10. A wound dressing or the like as claimed in Claim 8 or Claim 9, wherein the centres of the openings are arranged in a square or hexagonal array.

11. A wound dressing or the like as claimed in any preceding claim, wherein the thickness of the hydrophobic gel layer is between 5μm and 10mm.

12. A wound dressing or the like as claimed in Claim 11 , wherein the thickness of the hydrophobic gel layer is between 20μm and 5mm.

13. A wound dressing or the like as claimed in any preceding claim, wherein the hydrophobic gel is a silicone gel.

14. A wound dressing or the like as claimed in Claim 2, wherein the foam layer comprises polyurethane foam.

15. A wound dressing or the like as claimed in Claim 2, wherein the thickness of the foam layer is between 1 mm and 10mm.

16. A wound dressing or the like as claimed in Claim 15, wherein the thickness of the foam layer is between 2mm and 6mm

17. A wound dressing or the like as claimed in Claim 16, wherein the thickness of the foam layer is about 4mm.

18. A wound dressing or the like as claimed in any preceding claim, wherein therapeutically active ingredients are incorporated into the support material and/or into the layer of hydrophobic gel.

19. A wound dressing or the like as claimed in any preceding claim, wherein the support material carries a layer of liquid-impermeable material on the side of the support material opposite to the gel layer.

20. A wound dressing or the like as claimed in Claim 19, wherein the liquid- impermeable material comprises a liquid-impermeable, vapour-permeable, plastic film.

21. A wound dressing or the like as claimed in Claim 20, wherein the plastic film is polyurethane film.

22. A method for manufacturing a wound dressing or the like as claimed in Claim 1 , comprising the steps of: a) providing a layer of support material; b) applying to the support material a partial coating of a curable hydrophobic gel precursor composition; and c) causing or allowing the gel precursor composition to cure, thereby forming a layer of hydrophobic gel.