HK1020857A - A permanently deformable dressing - Google Patents

Description

Permanent deformation dressing

The present invention relates to dressings, in particular to dressings for covering parts of anatomical surfaces of a living body, to a method of preparing such dressings, to the use of a film capable of adhering to the skin to form such dressings, and to a method of treating parts of anatomical surfaces of a living body, in particular projecting or recessed parts of the body.

Conventional dressings for treating or preventing wounds or tenderness or even unbroken skin are substantially flat dressings, sufficiently shaped to be applied over flat or slightly curved areas of the body. Such flat dressings are less suitable for use on protruding parts of the body or parts of the body such as elbow joints, the heel or especially the fingers or toes or parts of the body with very pronounced curvatures such as the area between the fingers (toes), as they often wrinkle and stress concentrations on the dressing often cause slippage of the adhesive and inadvertent detachment of the dressing.

Published european patent application EP0676183a1 discloses conformable adhesive bandages which are said to be very conformable and also sufficiently resilient to retain their shape after a user is forced by movement. Furthermore, it is stated that the recovery energy of the bandage disclosed in EP0676183a1 should be relatively high in order to ensure that the bandage does not become permanently deformed during use. Such recovery energy stored in the dressing or bandage will inevitably attempt to return to its original shape if stretched and put the skin under the harsh stresses experienced by the user during use.

The pressure sensitive adhesive sheet disclosed in US4,436,700 is said to be conformable and to have visco-elastic properties similar to human skin. Also known as such, materials exhibit stress relaxation over time, which when fully relaxed can restore them to a length close to their original unstressed length.

Published european patent application EP0457977a1 discloses a wound dressing comprising a soft polyurethane foam pad (a surface layer of which is hydrophilic and a backing layer of which is hydrophobic) and a soft comfortable sheet or strip of polyether foam having adhesive on one surface thereof. The dressing exhibits sufficient elasticity to easily conform to difficult areas such as elbow and knee joints for longer periods of time.

US1,741,949 discloses polyetherester elastic nonwoven webs formed from melt blown fibers composed of polyester.

Liquid plasters are known under the trade name Nobecutan in the form of a solution of a polymer in ethyl acetate^Such a patch will naturally fit the area to which it is applied, but is highly unsuitable for use on damaged or inflamed skin, because the presence of ethyl acetate can cause severe local irritation.

No documents have hitherto disclosed a dressing capable of adhering to the skin, being soft and formable to fit the contours of a body covering site, adhering to the skin and being able to adapt to and follow joint movements such as finger joints without placing the skin under great stress after application, and being applicable directly to broken or inflamed skin without unpleasant sensation.

It is an object of the present invention to provide a flexible dressing which can be shaped so as to conform to the contours of a covered part of the body, which dressing adheres to the skin and can adapt to or follow the movements of the skin or joints such as the knuckles. Such a dressing would be suitable, for example, as a fingertip or toe tip dressing, or as a dressing suitable for use with a joint, even in the interphalangeal combination area of the hand or foot.

It is a further object of the present invention to provide a dressing that can be protected against, for example, wear or abrasion (e.g., heel or elbow), which provides a surface that can be adapted to the environment, wherein the dressing used provides a longer effective use time between dressing changes.

It is a further object of the present invention to provide a dressing comprising an emollient or active ingredient (e.g., a retinoid) to treat or prevent the development of psoriasis, eczema, callous skin, corns, insect bites, acne or water sores.

It is a further object of the present invention to provide a method of making such a dressing.

The present invention relates to a dressing for covering a portion of an anatomical surface of a living body, which dressing is capable of adhering to the skin, mucous membranes and/or wounds of any part of the living body and which dressing is formable so as to be able to conform to the contours of the covered portion of the body.

Furthermore, the invention relates to the use of a film that can be adhered to the skin to form a dressing covering a biopsy surface, the film exhibiting permanent deformations that occur before or during use of the dressing.

The invention also relates to a method of treating a portion of a living anatomical surface comprising applying a dressing capable of adhering to the skin, the dressing being formable so as to conform to the contours of a covered portion of the body.

The invention will now be described in more detail with reference to the accompanying drawings.

Figure 1 shows a stress-strain curve of 100% deformation followed by stress removal applied to a dressing of the invention with a predetermined load.

FIG. 2 shows a conventional dressing (Tegaderm)^Clear dressing) of the strain.

It has now surprisingly been found that the objects of the invention can be achieved with the dressing according to the invention.

The present invention relates to a dressing for covering a surface portion of a living body, which can be adhered to the skin, mucosa and/or wound of any part of the living body.

The dressing of the invention is characterized in that it adheres to the skin, mucous membranes and/or wounds in any part of the living body without being subjected to great stress after use, and in that the dressing exhibits permanent deformations before and during use. The dressing may optionally also be partially or wholly covered with one or more release liners or cover films which may be peeled away before or during use.

When the dressing is applied to a protruding or substantially flat part of the body, the dressing of the invention surprisingly gives it a stretch to fit the size of the body part to be covered, after which the dressing fits rather tightly to the contour of the body part to be covered and adheres thereto without the skin being subjected to great stresses after application of the dressing. The dressing will adhere to the skin and follow a subsequent movement like a "second skin", which will ensure that the dressing does not tighten the skin or contract the part of the body. Reduced stress will give long wear times and the dressing of the invention will only need to be replaced when there is a "technical need", avoiding multiple replacements due to slippage.

Such a dressing allows for a sufficiently deformable expansion to cover a protruding part of the body, such as a finger, after which the dressing quickly conforms to and adheres to the protruding part of the body. The dressing of the invention may be wrapped around a tip such as a finger or extended to cover, for example, a fingertip or toe, or may be extended to a substantially flat area prior to application to adapt the dressing to the actual area of the body to be covered. The dressing of the invention is therefore well suited for covering inter-digital areas, and also for application to "irregular" areas suffering from e.g. psoriasis.

According to the invention, the stress required to produce 100% elongation is preferably less than 15N/25mm, preferably less than 10N/25mm, more preferably at most 8N/25 mm. This feature makes the dressing easily adaptable to the area to be covered and ensures that the body part enclosed in the dressing does not need to be taped.

Thickness is not considered a critical dressing feature, and therefore the components of the dressing and the dressing of the invention may have a greater thickness to allow the dressing to meet the requirements described herein.

The elongation at break of the dressing is preferably at least 100%, preferably at least 200%, so that it can be adapted to the size of the dressing when the dressing is used, in particular when the dressing is applied or stretched to cover a fingertip or toe tip.

To ensure a sufficiently low stress after application, the dressing preferably exhibits a permanent set of at least 60% after being subjected to 100% elongation. Preferably at least 75% permanent set after being subjected to 100% elongation, suitably at least 80% set after being subjected to 100% elongation.

Under normal conditions, the dressing preferably does not exhibit near 100% permanent deformation after being subjected to 100% elongation, since it is preferred to retain some elasticity that allows the dressing to fully conform to the site to be applied after use due to small elastic recoil.

In one embodiment of the invention, the film is inherently adhesive and may be used as is.

In another embodiment of the invention, a layer of adhesive is applied to at least one side of the film to impart tack to the film to adhere to the area to be covered.

In a particular embodiment of the invention, the dressing has at least one area that is different from the remaining area of the dressing. This area can serve as a marker, for example, to indicate its placement in the area of the body that needs to be covered. This ensures that the protruding part of the body (e.g. a fingertip) is correctly positioned before the dressing is stretched to fit the part and prevents the dressing from deforming beyond the elongation at break. The indicia may be a visual indication in the form of indicia or a distinctive planar or slightly solid portion, not necessarily as described above with respect to the stretchable nature of the dressing. The area may have a covering to eliminate pressure on the crush injury. Such a covering may be in the form of, for example, a layer of foam padding having a central portion that can be removed.

The present invention also relates to a method of making a dressing for covering a portion of a anatomical surface of a living body, the dressing being capable of adhering to the skin, mucosa and/or wound on any portion of the living body without subjecting the skin to substantial stress after use of the dressing, the method comprising combining an adhesive having a conformable backing layer and an optional release liner and an optional cover film. The combination can be carried out in a manner known per se. Care must be taken in combination that the conformable backing layer and the final product are not subjected to stresses that can cause elongation of the layer or the final product.

Another aspect of the invention relates to the use of a film exhibiting permanent deformation prior to or during use to form a dressing for covering a portion of an anatomical surface of a living body, the dressing being capable of adhering to the skin, mucosa and/or wounds in any part of the living body without subjecting the skin to substantial stress after use on the skin, the dressing being formable to conform to the contours of the protruding portion of the body to be covered. When the dressing of the present invention is used on a joint, the dressing may be applied in a joint extension position, after which the joint is flexed to extend the dressing. When the dressing is in the extended position it is relaxed and will adhere to the skin and following joint movement, like a "second skin".

The surface to be covered with the dressing may be a protruding or indented part of the body and the dressing is adapted to cover a hyperboloid part of the body, for example the interphalangeal area of a hand or foot or a joint such as a wrist, elbow, heel or knee.

It is advantageous if the dressing of the invention comprises an indicator of wound healing, a soft pad or similar means to treat or prevent the formation of wounds and/or skin allergies. This opens up a convenient and contamination-free application of additional medical treatment and active ingredients to wounds, for example, active ingredients of growth hormones such as cytophones or polypeptide growth factors or retinoids, which are combined in the wound in a form suitable for topical application, wherein the medicament may act on the wound. Other agents, such as bacteriostatic or bactericidal compounds (e.g., iodine, iodopovidone complex, chloramines, chlorohexidine, silver salts, zinc or salts thereof, 2-methyl-5-nitro-1-imidazolyl-ethanol, sulfonamides, and penicillins), tissue recovery enhancers (e.g., RGD tripeptides and the like), enzymes that cleanse wounds (e.g., pepsin, trypsin, and the like), cytotoxic agents and diffusion inhibitors for surgical inserts of products such as cancer tissue, and/or other therapeutic agents that may be selectively topically applied, analgesics, retinoids, or sedatives are also considered to be within the scope of the present invention.

Growth hormone in this context means any growth hormone which may be used according to the invention, such as human, bovine, ovine, porcine, equine, salmon or tuna growth hormone or analogues or derivatives thereof such as growth hormones of reduced or prolonged potency (e.g. methionyl growth hormone). The preferred growth hormone is human growth hormone.

The wound-healing related indicator may be, for example, a pH indicator, O₂A partial pressure indicator, a temperature indicator, a radical mechanism indicator, or a biotechnological assay indicator (e.g., indicating collagen formation).

In addition, the invention relates to the use of a "blank" dressing in the form of a film or dressing capable of adhering to the skin, mucosa and/or any part of a wound of a living body, to form a permanent "deformed" dressing of different size and at least one direction greater than the blank, suitable for the specific area to be covered.

A third aspect of the invention relates to a method of treating a portion of a surface of a living anatomy comprising applying to a covering portion of the living anatomy before, during or after application a dressing which shows permanent deformation, the dressing being capable of adhering to the skin, mucosa and/or a wound on any part of the living body, while the skin is not subjected to significant stress after application, and the dressing being optionally covered in part or in whole by one or more release liners or cover films which are removable before use, the dressing being applied by placing it in position and stretching it so as to cover the body part, after which the dressing is left and adhered to the skin.

The dressings of the present invention are generally in the form of a laminate comprising a backing layer, an adhesive layer and optionally covered in part or in whole by one or more release liners or cover films which may be removed prior to use. The dressing may also include a top layer that can be removed prior to use.

The backing layer may be any film or combination of films or layers that, in combination with an adhesive, exhibit the desired characteristics described above. The film may be produced from a polyolefin material or a polyurethane material. Suitable films are, for example, those sold under the trademark Parafilm^The commercially available film of (1).

The backing layer may be, for example, a combination or laminate of one or more films and/or optionally fibrous layers such as woven or non-woven or knitted layers. The backsheet film may also comprise a fibrous layer, such as a woven or non-woven or knitted layer, onto which the polymer material is applied in a manner known per se. Such coatings may be present on one or both sides of the film.

One skilled in the art will be able to establish a suitable combination of film and adhesive using routine experimentation based on knowledge of the elastic and plastic characteristics of the material.

The adhesive of the dressing of the invention may be any adhesive known to have affinity for skin and which is capable of adhering to the skin, mucous membranes and/or wounds on any part of the living body, preferably an adhesive comprising a hydrocolloid, suitable adhesives being hydrocolloid-containing absorbent materials such as those disclosed in US4,367,732. The adhesive may also comprise a skin-friendly acrylate adhesive containing hydrophilic areas. The adhesive may be substantially uniform or of different composition over a particular area, such as the adhesives disclosed in WO89/05619 or WO 94/15562.

The binder may comprise fibers, which reinforce the binder. The hydrocolloid may be in the form of granules or fibres.

The living body may be an animal, such as a domestic animal (e.g. horse, cow, pig) or a pet such as cat, dog, preferably a human. The top layer may be, for example, a layer of paper or plastic film. Any layer, film or the like conventionally used as a top layer of dressings is suitable, as the characteristics of such a top layer or film are not critical to the dressing of the invention, it being intended to be removed before use.

The top or back layer of the dressing of the invention may provide, for example, a surface that exhibits abrasion resistance to give a dressing that may be protected against, for example, wear or abrasion, such as a dressing for heels or elbows; or the top or back substrate of the dressing of the invention may provide a surface that exhibits hydrophobicity to provide a dressing that is suitable for use in a moisture resistant environment, resulting in longer effective use times between dressing changes.

Release liners suitable for use with the dressings of the present invention may be made from kraft papers, polyethylene, polypropylene, polyester or composites of these materials. The liner is preferably coated with an anti-blocking agent such as a fluorochemical agent or silicone. The release liner (if present) may be removed before or after application. If removed after application, the release liner may serve as a handle during application. Comparative testing of inventive dressings with conventional elastic dressings

Testing of physical Properties of the invention

The physical properties were recorded using the following stress-strain test procedure:

1. test samples of 25X 90mm were cut from the test dressings and the release liners were removed prior to testing. The samples were preconditioned at 23 ℃ and 50% RH for at least 30 minutes prior to testing.

2. The preconditioned test sample was placed between the jaws of a Lloyd LR 5K tester (model TG420 FH). The initial gap length was 40 mm.

3. The test piece was stretched to 100% strain at a rate of 5 mm/sec, and the maximum load (N) at this step was measured.

4. Immediately after the test piece reached 100% strain, it was allowed to retract at a rate of 5 mm/sec until the load was 0.1N. The permanent set is defined as the strain at that time.

This test is an indirect control with elongation at break greater than 100%.

Examples

Preparation of the dressing of the invention

100 grams of Vistanex were mixed in a Linden 0.25 laboratory mixer^LH-MH (PIB) was mixed with 100 g of Blankose 9HXF (CMC) at 130 ℃ for 30 minutes to prepare a pressure sensitive hydrocolloid adhesive (PSA).

Then prepared under hot pressing at 90 ℃ and 150 bar pressure with a standard Parafilm^(American Can), PSA and release liner (siliconized paper Sterapap, AC/KV 120, supplied by Jackstadt A/S). The laminate is cut to the desired dressing size.

Comparative testing of inventive dressings with conventional dressings

FIGS. 1 and 2 are a dressing of the invention and a conventional dressing (Tegaderm) as defined above^Transparent dressing, from 3M company). The curves show the results of three identical experiments.

As can be seen in fig. 1, the dressing of the present invention shows a sharp rise in stress initially followed by a drop in stress when further stretched to 100% strain. The dressing of the present invention showed a permanent set of about 83% after the swatches were retracted to a load of 0.1N.

As can be seen from fig. 2, the conventional dressing shows quite different strain curves. The stress is gradually increased when stretched to 100% strain and the dressing shows a better elastic behaviour and shows a permanent set of about 13%.

Stress relaxation test of backing film of dressing of the invention

Standard Parafilm is put^(American Can) to 20% elongation, and the stress relaxation after 1 minute was determined according to ASTM D882.

The stress relaxation is about 33 percent, which shows that the invention has the stress relaxation characteristic like the standard Parafilm^The dressing comprising the carrier film of (a) is a dressing capable of adhering to the skin, mucosa and/or wound of any part of the living body without subjecting the wound to a large stress after application, and the dressing shows a permanent deformation before or after application.

Practical testing of the dressing of the invention

Parafilm coated with hydrocolloid adhesive containing hydrocolloids^A blank sample was prepared. A panel of volunteers (9, with digital splinters or skin inflammation) was tested with a market-supplied bandage (composite)^Cuts&Grazes) were compared.

The reports are meaningful and consistent: all subjects agreed that the test product was extremely soft for the dressing to suit the particular injury, regardless of where the wound was. A further common assessment is "no pinching of the wound".

Market-supplied compact^Cuts&Grace does not show the same degree of softness and adaptability as the dressing of the invention.

Claims (13)

1. A dressing for covering a portion of an anatomical surface of a living body, the dressing being capable of adhering to the skin, mucosa and/or wound on any portion of the living body without subjecting the skin to substantial stress after application, the dressing exhibiting permanent deformation prior to or during application, and the dressing being optionally partially or fully covered with one or more release liners or cover films which are removed prior to or during application.

2. The dressing of claim 1 wherein the stress required to produce 100% elongation is less than 15N/inch.

3. The dressing of claim 2 wherein the stress required to produce 100% elongation is less than 10N/inch.

4. A dressing according to any of claims 1 to 3, characterized in that it has an elongation at break of at least 100%.

5. A dressing according to claim 4, characterized in that it has an elongation at break of at least 200%.

6. A dressing according to any of claims 1 to 5, wherein the dressing exhibits a permanent set of at least 60% after being subjected to an elongation of 100%.

7. A dressing according to claim 6, wherein the dressing exhibits a permanent set of at least 75% after being subjected to an elongation of 100%.

8. A dressing according to claim 7, wherein the dressing exhibits a permanent set of at least 85% after being subjected to an elongation of 100%.

9. A dressing according to any of claims 1 to 8, characterized in that the film is inherently adhesive.

10. A dressing according to any of claims 1 to 9, characterized in that at least one side of the film is coated with a layer of adhesive.

11. A dressing according to any one of claims 1 to 10, wherein the dressing has a different area to the remainder of the dressing.

12. A film exhibiting permanent deformation before or during application is used to form a dressing covering an anatomical surface portion of a living body, which dressing is capable of adhering to the skin, mucosa and/or wounds of any part of the living body without the skin being subjected to large stresses after application.

13. A method of treating an anatomical surface portion of a living body comprising applying a dressing exhibiting permanent deformation occurring prior to or during application to cover the anatomical surface portion of the living body, the dressing being capable of adhering to skin, mucosa and/or a wound on any part of the living body and not subjecting the skin to substantial stress after application, and the dressing being optionally covered with one or more release liners or cover films which are removed prior to or during application, the dressing being applied by being placed and stretched to cover a site of the body and thereafter left at the site and adhered to the skin.