ADHESIVE DRESSINGS

Abstract: An adhesive dressing (1) for covering a wound in skin or nails is provided comprising a protective backing layer (3), a first film layer (7) for application over the wound, and a second film layer (11), having tabs (13, 15) to hold the second film layer (11) and also the first film layer (7) during application of the first film layer (7) to the wound. The first film layer (7) may be provided with a strip of writing material (9), and the dressing (1) can be applied to skin or nails avoiding contact with the skin or nails during application.

Description: ADHESIVE DRESSINGS This invention relates to adhesive dressings which may be applied to skin or nails to cover a wound, cut, infection, skin disorders and the like to prevent or reduce the access of dirt particles, bacteria or other undesirable microorganisms. The invention therefore encompasses surgical dressings and wound dressings. Adhesive plasters, bandages and other dressings for such use are well known in the art. Among the known dressings are semi-permeable films such as those disclosed in GB-A-1280631. Such films are often thin and very pliable and, consequently, it is difficult to apply them to skin or nails evenly and without excessive hand contact by the person applying the dressing. In an attempt to solve this problem, various semi- permeable film dressings have been made available; the dressings comprise, in addition to the film, one or more extra layers supposedly to help with the application of the film. A known two-layer dressing is Smith & Nephew's OPSITE product, which comprises a semi-permeable adhesive film where the adhesive film that is to be applied to the wound is protected by a layer of protective paper and has removable "handles" at either end of the adhesive film so that the whole dressing may be peeled away from the protective paper before application to the wound and subsequent removal of the handles. A second similar known adhesive dressing is sold by Johnson & Johnson under the trade mark BIOCLUSIVE. It is similar to the OPSITE product in that it too comprises two layers, firstly a transparent adhesive film and a layer of protective paper. The adhesive film has "handles" at either end of the adhesive film. Another dressing of a similar type is 3M's TEGADERM product, which comprises three layers which include a layer of protective paper away from which the transparent dressing film may be peeled. The transparent dressing film is adhesive on one side only and this side faces and is protected by the protective paper. The adhesive layer is sandwiched between the protective paper and a backing layer which may also be made of paper. The backing layer may be pre-cut so that a central portion of the backing layer may be removed so that the combination of the backing layer remaining and the transparent dressing resembles a window, where the shape of the backing layer remaining attached to the transparent dressing film thus forms a paper frame. The transparent dressing film and paper frame are then put over the wound and the paper frame removed. In this specification the term "wound" includes burns, cuts, sores, blisters, rashes or any other lesion or area of troubled skin. These known dressings suffer from several disadvantages. In the case of the dressings that comprise two layers, namely the adhesive film and the protective paper, the protective paper is peeled away from the adhesive film so that the latter is ready for application to the skin. While holding the film by handles one edge of the adhesive film is placed against the skin while the protective paper is peeled away from the adhesive film. This exposes some of the adhesive surface of the film to be adhered to the skin. However, this process of covering the wound with the adhesive film should be conducted under conditions of minimum tension to the adhesive film and the adhesive film should not be stretched nor should creases be allowed to form. In practice this ideal situation can, however, be difficult to achieve. Due to the nature of the wound, the adhesive nature of the thin adhesive film and the relatively large area of the adhesive film (to ensure good adhesion and coverage around the wound) means that the adhesive film is often stretched so that part of the adhesive film becomes thinner and therefore weaker, particularly in the area which will eventually cover the wound. "Where creases form in the adhesive film this immediately offers a .channel of entry of bacteria and dirt particles to the wound under the adhesive film. Since the adhesive film is so thin and by its nature very adhesive, creases are extremely difficult to smooth out and in any case to do so may result in stretching the adhesive film. Clearly the amount of smoothing of the adhesive film (whether or not creases have developed) should be kept to a minimum as the wound and the surrounding area may already be inflamed and causing the patient pain. Another associated problem with the known types of dressings is that it is often extremely difficult, if not impossible, to avoid touching the wound or skin surrounding the wound while applying the dressing. Contact between the hands applying the dressing and the skin to which the dressing is to be applied is clearly undesirable both from the point of view -of hygiene in that contamination should be minimised and to reduce the amount of pain that the patient may endure during dressing of the wound. The previously mentioned types of dressings must either be applied one edge first and then progressively peeling off the protective paper while applying freshly revealed adhesive film to the wound, or a central portion of the adhesive film is applied to the wound while the portions of the adhesive film to the sides from the central portion are applied moving away from the wound. However, in the latter case this is almost impossible to achieve without at some stage touching the adhesive on the adhesive film itself. This removes some of the adhesive (in which case the adhesive film adheres to the skin less well) or there is the possibility that the adhesive film is contaminated by substances on the tips of the fingers while applying the adhesive film. Clearly, although hands may be washed so that they are essentially clean, hands cannot of course be completely sterile. Sterile gloves could be put on, but this would add to the time taken and the cost of materials. For these reasons, and because pressure on the skin surrounding the wound is likely to cause further pain to the patient, there is a need for an adhesive film dressing which can be applied to a wound which can eliminate almost all risk of or need for contact between the skin to which the adhesive film dressing is to be applied and the hands that effect this. Therefore, according to a first aspect of the present invention there is provided an adhesive dressing suitable for adhesion to skin or nails comprising a first film layer having one side substantially coated with a pressure sensitive adhesive and the other side substantially coated with a second layer of adhesive and backed by, and in use separable from, a second film layer having tab means for holding and applying the dressing to the skin or nails. Preferably the first film layer is also provided with tab means that is suitable for holding and applying the first film layer to the skin or nails. Both the first and second film layers may be transparent so that the wound can be seen through the dressing while applying it to the skin or nails. Preferably the first film layer is permeable to moisture vapour and impermeable to water. Advantageously the first and second film layers will be joined by a second layer of adhesive which will tend to be of an adhesive strength or tack less than the pressure sensitive adhesive. The first film layer will usually be in accordance with the teaching of GB-A- 1280631 and will therefore be a moisture vapour permeable pressure sensitive adhesive material for use on animal skin and nails, comprising a backing material having a pressure sensitive adhesive on at least substantially the whole of the body adhering portion of at least one surface of said backing material, both said backing material and said adhesive being moisture vapour permeable and unaffected by water and at least one of said backing material and said adhesive comprising a synthetic polymer and being continuous and non-permeable to liquid water, said adhesive material having a moisture vapour permeability of at least 300 g./sq. metre/24 hours/40°C./80 percent RH. Preferred thicknesses (dry) are from 15 _+ 2.25 microns. Usually the adhesive side of the first film layer will be substantially covered by a layer of protective material so as to prevent contamination of the first film layer, thereby to keep the adhesive side of the first film layer sterile and prevent removal of the adhesive. The protective material may impart a degree of rigidity to the dressing for ease of handling and to this end may itself be relatively rigid. It may, for example, be formed of paper or card and will if necessary have a suitable release surface which may be ~ - w a or silicone layer. Emulsion silicones are especially preferred since they resist the formation of free radicals during sterilisation by irradiation, which can interfere with the tack of the adhesives. The protective material usually covers the whole of the side of the first film layer that is coated with the pressure sensitive adhesive and is removed before the first film layer is applied to the wound. Thus, prior to use (and in a configuration suitable for packaging) the first film layer is sandwiched between the second film layer and protective material. It is advantageous that the tab means comprise one or more tabs each attached to an edge of the second, and optionally also the first, film layer. The first film layer may have a single tab ' at on edge of the first film layer. The second film layer may have two paper tabs at opposing ends of the second film layer. Each tab usually extends beyond a respective edge of the first and/or second film layer. Often the tab means will comprise one or two relatively rigid (eg paper or card) tabs, for example at opposing ends of the second film layer, since both the first and second film layer will preferably be rectangular in shape. In the case when the dressing has more than one tab then these may be of different colours. For example, if the tabs are colour-coded the person applying the dressing may know which tab to hold during the various steps of application of the dressing and thus which end of the second film layer is to be peeled away from the first film layer or the protective material. Appropriate instructions on the application of the dressing may be provided with the dressing. The first film layer tab means may extend beyond the area of the second film layer, or may be sandwiched between the second film layer or second film layer tab means and the protective material, depending on the relative sizes, shape and area of the tab means and first and second film layers and protective material. The first film layer tab means is preferably a strip of writing material, for example, near or adjacent to one edge of the first film layer. This may be used for writing, for example, dates or a patient's name, close to the site of the wound, to which the first film layer has been applied. Such a writing material is usually paper. The second film layer may be larger (i.e. of greater area) than the first film layer, so that the second film layer overlaps one, some or all of the edges of the first film layer. It is particularly preferred that the second film layer is larger than the first film layer so that it overlaps (and thus may border) the first film layer tab means, especially when the latter is a strip of writing material, to keep the strip clean. The second film layer is also preferably thicker than the first film layer, eg. 50 +_ 5 microns. Both the pressure sensitive adhesive and second adhesive layer are preferably solvent-soluble acrylic adhesives, the first of greater tack than the latter. Thus the adhesive tack of the pressure sensitive adhesive may be from 400-800 g/25mm, (both pre- and post-sterilisation), and for the second adhesive layer may be from 100-180 g/25mm post-sterilisation. According to a second aspect of the present invention there is provided a process for dressing skin or nails by the application of an adhesive dressing suitable for adhesion to the skin or nails, the process comprising adhering a first film layer substantially coated with a second layer of adhesive having one side substantially coated with a pressure sensitive adhesive to the skin or nails and separating from the other side of the first film layer substantially coated with a second layer of adhesive a second film layer having tab means for holding and applying the dressing to the skin or nails . The adhesive dressing used may be the adhesive dressing according to the first aspect of the present invention and preferred features are as the first aspect mutatis mutandis. To apply the first film layer of an adhesive dressing according to the present invention to the skin or nails to be dressed (for example in the case of dressing a wound) the protective material may be peeled away from the adhesive side of the first film layer. This is achieved by using the tab means of the second film layer. Where the second film layer has a first and second tab, preferably coloured, at opposing ends of the second film layer, only one tab (for example the first tab coloured yellow) need be held with one hand, while the protective material is held with the other hand. The protective material can then be discarded. The dressing is then bent or gently folded by bringing the two tabs of the second film layer towards each other so that the dressing becomes U-shaped. The central portion (or the bottom of the now U-shaped dressing) is applied to the wound and adjacent portions of the first film layer not already adhered to the skin or nails is allowed to contact and thus adhere to the skin or nails. This is continued so that the point of contact between the skin or nails and the first film layer moves away from the central portion so that eventually the whole first film layer is applied to the skin or nails. During this process the dressing is usually held by the first and second tabs and therefore contact between the skin or nails and the hands applying the dressing can thereby be avoided. Furthermore, because the first film layer is still backed by the second film layer during the application process the first film layer will tend not to stretch, bend or crease. The second film layer can be peeled away from the adhered first film layer by holding the second tab (for example coloured white) with one hand, where the strength or tack of adhesive between the skin or nails and first film layer is greater than that between the first and second film layers. However, where the first film layer is also provided with a tab means, this may be pressed to the skin or nails gently (avoiding contact with the skin or nails) to hold the first film layer in place with one hand while the other hand peels away the second film layer. In a further embodiment of the present invention the first film layer is provided with a wound contact pad, on the side coated with the pressure sensitive adhesive. The wound contact pad is usually smaller than the first film layer, so that the first film layer borders the wound contact pad providing means for the wound contact pad to be adhered to skin or nails. The wound contact pad may be any suitable material, but it is particularly preferred for the wound contact pad to comprise alginate. A non-woven, woven or knitted fabric of alginate fibres, such as mixed salt calcium/sodium alginate, is preferred. The invention will now be described by example with reference to the accompanying drawings in which:- FIGURE 1 is a perspective view of an adhesive dressing in accordance with the present invention; FIGURE 2 is an enlarged section along line II-II of an adhesive dressing as shown in Figure 1 ; and FIGURES 3 to 6 are successive section views of an adhesive dressing in accordance with the present invention being applied to a piece of skin or nail. In Figure 1 there is shown a dressing 1 which comprises a rectangular piece of protective paper 3 which protects an adhesive coated side 5 of a transparent first film 7. The first film 7 is also rectangular with the same width, but shorter, than the protective paper 3. The first film 7 is provided with tab means which is a paper strip 9 along one of its short edges. A second transparent film 11 backs and overlaps the first film 7 so that the first film 7 is sandwiched between the second film 11 and the protective paper 3. The second film 11 is provided with, at its two shorter edges, two different coloured tabs, one white tab 13 and one yellow tab 15, both which are of the same width as the protective paper 3 and are formed from portions of the transparent second film 11 (which overlap the first film 7) backed by paper. The first film 7 is considerably thinner than the second film. The first film 7 may in accordance with Example 1 of GB-A- 1280631,in accordance with that sold by DRG under the Trade Mark MEDIFIX 6013, or in accordance with the uncoated film sold by BAYER under the Trade Mark WALOPLAST PURE which is then coated with adhesive. In another embodiment the first film layer conforms to the Specification 37 of the UK Drug Tariff concerning Semipermeable Adhesive Film Dressing (10cm x 10cm adhesive area) published by HMSO. The first film layer is a sterile, extensible, waterproof polyurethane copolymer having a dry weight of 14 g/m 2 while the actual weight per unit area will usually be above 25 g/m . The dry density of the first film layer is about 1.13 _+ 0.17 g/cm , with a thickness, when dry, of about 15 +_ 2.25 microns. The film is permeable to water vapour with a permeability of at least 500 g/m 2 per 24 hours, but it preferably has an MVTR of 686 g/m 2 per 24 hours, (2500 g/m 2 per 24 hours when dry and uncoated) while at the same time being impermeable to water. The film is evenly coated with a solvent soluble acrylic adhesive, at a adhesive mass of at least 20 g/m 2 but more preferably 25-35 g/m 2 providing an adhesion that can be up to, or greater than 1.0 kg/25mm pre-irradiation and 0.47 g/m 2 post-irradiation, where the radiation is gamma radiation for sterilisation. However, the peel adhesion level of the first film layer (to steel) is preferably 450-700 g/25mm pre- sterilisation and (after storage of one year) remains within the same range post-sterilisation. The sterilisation, by 25kGy of gamma irradiation, has been found not to effect the adhesion of the first film layer. The coating weight of the adhesive is optionally about 33 .+ 4 g/m 2 . The first film layer is extensible by up to 600%, with an elastic modulus of 2.04 N/cm. Tensile strength is at least 0.2 kg/cm, preferably 0.38 kg/cm. The second film layer is preferably low density polyethylene, which is commercially available. It is preferably thicker than the first film layer, by an amount of at least 50%, and thicknesses of 50 _+ 5 microns are especially preferred. The second layer of adhesive, between the first and second film layers, is preferably the same as the pressure sensitive adhesive, namely a solvent-soluble acrylic adhesive. However, the adhesion or tack of the second adhesive layer is preferably less, for example by a factor of 2-3, than the pressure sensitive adhesive. Preferred adhesive levels of the second adhesive layer is 45-110 g/25mm, such as 50-100 g/25mm pre-sterilisation, and 90-200 g/25mm, such as 100-180 g/25mm, post-sterilisation. Although gamma radiation may increase the tack of the adhesive, the dressing may still be applied to the skin or nails successfully as long as the adhesion of the pressure sensitive adhesive is between 2-3 times greater than the adhesion between the first and second film layers. Measurement of adhesion values (either between films or with reference to, for example, a steel plate) can be made using a desk-top Instron type 4301 machine, the procedure being well known to those skilled in the art. The values quoted in this specification are, where appropriate, with reference to using a 180 grit finished steel plate. In use, the protective paper 3 is peeled away from the first film 7 thus exposing the adhesive side 5 of the first film 7 as shown in Figure 3. By bringing the two second film tabs 13 and 15 together (Figure 4) the dressing 1 can be made into a U-shape so that the bottom of the U-shape can be applied to the skin or nail 17 that is to be dressed. The adhesive coated side 5 of the first film 7 thus adheres to the skin or nail 17 and without contacting the skin or nail 17 the remainder of the first film 7 is adhered by moving the point of contact between the first film 7 and the skin or nail 17 away from the wound or along the arms of the U-shape. Once the whole of the adhesive side 5 of the first film 7 has adhered to the skin or nail 17 then the second film 11 may be peeled away (Figure 5), using the tabs 13 and 15. The paper strip 9 is held or pressed gently to the skin or nail 17 by one or more fingers of one hand while the yellow tab 15 is grasped in the other hand to peel away the second film 11 from the first film 7. The paper strip 9 can then be written on if desired. The area of skin or nail 17 to be dressed is thus covered by the first film 7 and the wound protected as shown in Figure

Claims: CLAIMS 1. An adhesive dressing (1) suitable for adhesion to skin or nails comprising a first film layer (7) having one side (5) substantially coated with a pressure sensitive adhesive and the other side substantially coated with a second layer of adhesive and backed by, and in use separable from, a second film layer (11) having tab means (13,15) for holding and applying the dressing to the skin or nails. 2. A dressing as claimed in claim 1 wherein the second layer of adhesive has ' an adhesive strength or tack less than the pressure sensitive adhesive. 3. A dressing as claimed in claim 1 wherein the second film layer (11) is thicker than the first film layer (7) . 4. A dressing as claimed in claim 1 wherein the first film layer (7) is provided with tab means (9) for holding and applying the first film layer to the skin or nails. 5. A dressing as claimed in claim 1 wherein both the first (7) and second (11) film layers are transparent. 6. A dressing as claimed in claim 1 wherein the first film layer (7) is permeable to moisture vapour and impermeable to water. 7. A dressing as claimed in claim 1 wherein the pressure sensitive adhesive is substantially covered by a layer of protective material (3) . 8. A dressing as claimed in claim 7 wherein the protective material (3) is paper. 9. A dressing as claimed in claim 4 wherein the tab means comprises one or more tabs each attached to an edge of the first and/or second film layer. 10. A dressing as claimed in claim 1 where the tab means comprise two paper tabs at opposing ends of the second film layer .and/or one tab at an edge of the first film layer. 11. A dressing as claimed in claim 4 wherein the first film layer tab means is a strip of writing material (9) near or adjacent to one edge of the first film layer. 12. A dressing as claimed in claim 11 wherein the writing material is paper. 13. A process for dressing skin or nails by the application of an adhesive dressing (1 ) suitable for adhesion to the skin or nails, the process comprising adhering a first film layer (7) having one side (5) substantially coated with a pressure sensitive adhesive to the skin or nails, separating from the other side of the first film layer substantially coated with a second layer of adhesive a second film layer (11) having tab means (13,15) for holding and applying the dressing to the skin or nails.

Inventors: KEYS ALLISON FRANCES, KEYS, ALLISON, FRANCES
Applicants: BRITCAIR LTD, BRITCAIR LIMITED
Application year: 1989
Main classification: A61F13
IPC codes: A61F13