Wound dressing

Abstract

The present invention relates to a wound dressing composition for use as or in a wound dressing and to methods of making the wound dressing composition. The wound dressing composition comprises an absorbent material, an adhesive material and an anchor material attached to the absorbent material and the adhesive material. The anchor material is operable to maintain a link between the absorbent material and the adhesive material when the wound dressing composition is wet.

Claims

1. A wound dressing composition comprising: a first layer of an absorbent material, wherein the absorbent material comprises a foam configured to directly contact a wound, a second layer of a superabsorbent polymer in the form of a powder or granules, wherein the superabsorbent polymer is mixed with an adhesive material, and a third layer of a superabsorbent material, wherein the superabsorbent material in the third layer is in the form of fibres comprising a material selected from starch, poly(vinyl alcohol), poly(ethylene oxide), poly(acrylic acid), a polymeric material obtained by graft polymerisation of acrylic acid onto a chain of carboxymethyl cellulose, and a blend of chitosan fibres with a material that has an acid associated therewith, or a derivative of any of the above, wherein the second layer is positioned between the first layer and the third layer and bonds the first layer of the absorbent material and the third layer of the superabsorbent material together.

2. The wound dressing composition according to claim 1, wherein the superabsorbent material in the third layer comprises poly(acrylic acid) or a derivative thereof.

3. The wound dressing composition according to claim 1, wherein the superabsorbent polymer is mixed with a hot meltable adhesive to bond the first layer of the absorbent material and the third layer of the superabsorbent material together.

4. The wound dressing composition according to claim 3, wherein the hot meltable adhesive comprises a pressure-sensitive adhesive.

5. The wound dressing composition according to claim 3, wherein the hot meltable adhesive is selected from acrylic adhesives and polyurethane adhesives.

6. The wound dressing composition according to claim 1, wherein the fibres form a non-woven layer.

7. The wound dressing composition according to claim 1, further comprising a backing layer that is highly breathable.

8. A method of absorbing fluid discharged from a physiological target, or in stemming a flow of a fluid discharged from a physiological target site, the method comprising use of the wound dressing composition according to claim 1.

9. The wound dressing composition according to claim 1, wherein the second layer comprises a cured mixture of the superabsorbent polymer and the adhesive material.

10. The wound dressing composition according to claim 9, wherein the adhesive material is in the form of a hot melt adhesive powder.

11. The wound dressing composition according to claim 1, wherein the third layer is gelling or semi-gelling upon contact with water or body fluid(s).

12. A method of manufacturing a wound dressing composition according to claim 1, comprising the steps of: (a) providing a first layer of an absorbent material wherein the absorbent material comprises a foam configured to directly contact a wound, a second layer of a superabsorbent polymer in the form of a powder or granules, wherein the superabsorbent polymer is mixed with an adhesive material, and a third layer of a superabsorbent material, wherein the superabsorbent material is in the form of fibres comprising a material selected from starch, poly(vinyl alcohol), poly(ethylene oxide), poly(acrylic acid), a polymeric material obtained by graft polymerisation of acrylic acid onto the chain of carboxymethyl cellulose, and a blend of chitosan fibres with a material that has an acid associated therewith, or a derivative of any of the above; and (b) attaching the second layer either to the first layer or to the third layer, either simultaneously or sequentially, whereby the second layer is positioned between the first layer and the third layer.

13. The method according to claim 12, wherein the second layer is attached to the first layer before it is attached to the third layer.

14. The method according to claim 12, wherein the superabsorbent polymer is blended with an adhesive material prior to carrying out step (b).

15. The method according to claim 12, further comprising placing the third layer of the superabsorbent material layer above the second layer of superabsorbent polymer prior to heating and subsequent cooling, wherein the cooling cures the second layer and bonds the first layer of the absorbent material and the third layer of the superabsorbent material together.

16. A wound dressing comprising a wound dressing composition, the wound dressing composition comprising a first layer of an absorbent material wherein the absorbent material comprises a foam configured to directly contact a wound, a second layer of a superabsorbent polymer in the form of a powder or granules, and a third layer of a superabsorbent material, wherein the superabsorbent material is in the form of fibres comprising a material selected from starch, poly(vinyl alcohol), poly(ethylene oxide), poly(acrylic acid), a polymeric material obtained by graft polymerisation of acrylic acid onto a chain of carboxymethyl cellulose, and a blend of chitosan fibres with a material that has an acid associated therewith, or a derivative of any of the above, wherein the second layer is positioned between the first layer and the third layer and bonds the first layer of the absorbent material and the third layer of the superabsorbent material together.

17. A method of absorbing fluid discharged from a physiological target, or in stemming a flow of a fluid discharged from a physiological target site, the method comprising use of the wound dressing according to claim 16.

Description

(1) Embodiments of the present invention will now be further described with reference to the following non-limiting examples and accompanying figures in which:

(2) FIG. 1: is a cross-sectional representation of a wound dressing composition according to an embodiment of the present invention;

(3) FIG. 2: is a cross-sectional representation of an alternative wound dressing composition of the present invention;

(4) FIG. 3: is a cross-sectional representation of a wound dressing composition of the present invention comprising a skin protection layer;

(5) FIG. 4: is a cross-sectional representation of a further alternative wound dressing composition of the present invention comprising a skin protection layer;

(6) FIG. 5: is a cross-sectional representation of a further alternative wound dressing composition of the present invention comprising a skin protection layer;

(7) FIG. 6: is a cross-sectional representation of a further alternative wound dressing composition of the present invention;

(8) FIG. 7: is a cross-sectional representation of the wound dressing composition of FIG. 6 further comprising a skin protection layer;

(9) Referring to FIGS. 1 and 2, there is shown a wound dressing composition (1) comprising a layer of wound contact absorbent material as a first layer (2), a blend layer of superabsorbent polymer and meltable adhesive as a second layer (3), a layer of superabsorbent material as a third layer (4), a layer of anchor material (5), a layer of adhesive material (6), and a backing layer (7). FIG. 2 also has two layers around the border comprising of a carrier layer (8) and a skin friendly adhesive layer (9).

(10) The wound contact absorbent material (2) is adjacent to the wound site and will come into direct contact with the wound upon application of the wound dressing composition (1) to a wound. The superabsorbent material (4) has a wound facing surface (4a) and a non-wound facing surface (4b). The wound contact absorbent material (2) is attached to the superabsorbent polymer (3) by a meltable adhesive. The wound contact absorbent layer (2) also serves to prevent or reduce the leaching of material from the blend layer of superabsorbent polymer, and meltable adhesive (3).

(11) The superabsorbent polymer blended with the meltable adhesive (3) is positioned between the absorbent wound contact layer (2) and the superabsorbent material layer (4). In FIGS. 1 and 2, the bond created between these layers is such that it will not break when the respective materials get wet with wound fluid during use.

(12) The anchor material (5) is attached to the non-wound facing surface (4b) of the superabsorbent material (4). Typically, the anchor material (5) is heat-bonded to the superabsorbent material (4). As described herein, the bond created between the anchor material (5) and the superabsorbent material (4) is such that it will not break when the respective materials get wet with wound fluid during use.

(13) The adhesive layer (6) has a backing layer (7) attached to its non-wound facing surface. As with the anchor material (5), the backing layer (7) can be attached to the adhesive layer (6) by contacting the two materials together and applying pressure.

(14) As can be seen in both FIGS. 1 and 2, the adhesive layer (6) and the backing layer (7) have a greater cross-sectional area than the anchor material (5), the superabsorbent material (4) and the wound contact material (2), creating a border portion (8). The wound facing surface of the backing layer (7) in the border portion (8) is, in use, applied directly to the patient's skin surrounding the wound site with the use of an adhesive (10). Thus, the adhesive layer (10) has the dual purpose of adhering to the anchor layer (5) and the skin of the patient.

(15) FIG. 3 is an alternative design, whereby a perforated layer, comprising of a carrier layer (8), a layer of a pressure sensitive adhesive (10) proximal to the superabsorbent layer and a silicone adhesive layer proximal to the wound is used to envelope the fluid absorbing portion of the dressing. In doing so there is no requirement for the anchor layer. FIGS. 4 and 5 are alternatives to the embodiments in FIGS. 1 and 2, whereby the adhesive portion of the dressing that is used to secure it to the skin or wound of a person overlaps the wound contact layer, but not fully across this layer. This layer can be perforated or non-perforated.

(16) FIGS. 6 and 7 each show a non-bordered version with and without an adhesive face. In using the combination of the superabsorbent polymer, absorbent layer and superabsorbent material, this reduces the risk of superabsorbent polymer leaching from the wound dressing edges.

(17) In use, the wound dressing composition (1) of the present invention is applied to a wound by contacting the wound contact layer and/or the silicone layer with the wound site. The wound dressing composition (1) can be affixed to the patient's skin by applying downward pressure to the border portion or the non-bordered part where no border is present, or by means of a secondary securement device. Wound exudates from the wound will be absorbed by the absorbent wound contact layer (2) and drawn through to the superabsorbent layers (3, 4). This has the effect of drawing fluid away from the wound bed, creating a moisture level at the wound bed that is more conducive to healing.

EXAMPLES

(18) The wound dressing compositions of the present invention do not delaminate, maintain a level of moisture and do not harden when the composition is exposed to fluid, such as wound exudate and then allowed to dry. To test this, the following experiment was followed.

(19) Test Methodology

(20) An island wound dressing as shown in FIG. 3 was prepared. The wound dressing was made up of a superabsorbent layer of polyacrylate fibres gsm 200, an a pattern coated adhesive layer of a pressure-sensitive acrylic adhesive 20 gsm, a backing layer of a highly breathable polyurethane film, 30 micron thickness and an absorbent wound contact layer of a polyurethane foam, 1.5 mm thickness and a superabsorbent polymer/dry hot meltable adhesive layer at 0.49 g per 100 cm.sup.2. A second dressing was constructed as the control made up of a superabsorbent layer of polyacrylate fibres gsm 250, an a pattern coated adhesive layer of a pressure-sensitive acrylic adhesive 20 gsm, a backing layer of a highly breathable polyurethane film, 30 micron thickness and an absorbent wound contact layer of a polyurethane foam, 1.5 mm thickness and a dry hot meltable adhesive layer at 0.49 g per 100 cm.sup.2.

(21) Three wound dressings had the central absorbent pad area semi-saturated with solution A to half their absorbency potential. The absorbency potential was comparable for both dressing types. The dressings were then subjected to an incubator at 37 C. and assessed at different time intervals.

(22) In the tests, Solution A is 142 mmol sodium ions and 2.5 mmol calcium ions as the chloride salt, Solution B is saline and Solution C is simulated wound fluid (50% peptone water and 50% fetal bovine serum).

(23) The wound dressings were then inspected for softness and conformability. After 24 hrs the dressing with no superabsorbent polymer had lost some of its conformability and had dry hard sections within the central absorbent pad. This was not observed for the invention dressing. After 48 hrs, the dressing with no superabsorbent polymer has lost most of its conformability and felt very rigid and hard to the touch. This dressing did not arch under its own weight. The invention dressing still felt soft and confirmable and arch under its own weight. After 7 days, the invention dressing still maintained its conformability.

(24) Further testing on fluid handling using the BS EN 13726-1:2002 test methodology gave the following results:

(25) TABLE-US-00001 Fluid Total Fluid MVTR absorbed Full Dressing Handling (g/10 cm2/ (g/10 cm2/ Absorption (g) (g/10 cm2/24 hr) 24 hr) 24 hr) Control 28 8.8 6.2 2.5 dressing Invention 29 8.0 4.0 4.1

(26) The above result show comparable absorbency and total fluid handling results for the two dressings, the control and the invention. The use of the superabsorbent polymers retains more fluid within the dressing structure of the invention, reducing the breathability and as such minimising the risk of drying out.

(27) It is of course to be understood that the present invention is not intended to be restricted to the foregoing examples which are described by way of example only.