ABSORBENT PADS FOR WOUND DRESSINGS

Abstract

The present invention concerns extensible absorbent pads for wound dressings. The absorbent pad has a plurality of fenestrations therein, wherein the fenestrations are arranged in a pattern about a central point. The pattern comprises one or more fenestrations having symmetry about a cardinal axis and one or more fenestrations having symmetry about an intercardinal axis, wherein the cardinal and intercardinal axes cross at the central point. The absorbent pads of the present invention can be used in advanced wound care dressing applications where additional stretch and extensibility of the dressing will assist clinicians in applying the dressing to difficult to dress anatomical areas.

Claims

1. An absorbent pad for a wound dressing, the pad having a plurality of fenestrations therein, wherein the fenestrations are arranged in a pattern about a central point, wherein the pattern comprises one or more fenestrations having symmetry about a cardinal axis and one or more fenestrations having symmetry about an intercardinal axis, the cardinal and intercardinal axes crossing at the central point.

2. An absorbent pad as claimed in claim 1, wherein one or more of the fenestrations has an arc shape that faces towards the central point.

3. An absorbent pad as claimed in claim 1, wherein the fenestrations are present in two or more different geometrical shapes and/or two or more different sizes.

4. An absorbent pad as claimed in claim 1, wherein the pattern comprises a plurality of fenestrations having symmetry about one or both cardinal axes.

5. An absorbent pad as claimed in claim 1, wherein the pattern comprises a plurality of fenestrations having symmetry about one or both intercardinal axes.

6. An absorbent pad as claimed in claim 1, wherein the pattern comprises a plurality of fenestrations having symmetry about one or more of the secondary intercardinal axes; or wherein the pattern comprises one or more fenestrations in one or more of the secondary intercardinal regions.

7. An absorbent pad as claimed in claim 1, wherein the pattern of fenestrations is radiating outwardly from the central point.

8. An absorbent pad as claimed in claim 7, wherein the fenestrations radiate outwardly from the central point along the cardinal and intercardinal axes; and optionally wherein additional fenestrations are located within the secondary intercardinal regions.

9. An absorbent pad as claimed in claim 8, wherein the number of fenestrations located on the cardinal and intercardinal axes in one direction from the central point is equal to the number of fenestrations located on the same cardinal and intercardinal axes in the opposite direction.

10. An absorbent pad as claimed in claim 1, wherein the pattern of fenestrations is symmetrical about at least one of the cardinal, intercardinal or secondary intercardinal axes.

11. An absorbent pad as claimed in claim 10, wherein the pattern of fenestrations is symmetrical about the cardinal axes and the intercardinal axes.

12. An absorbent pad as claimed in claim 1, wherein one or more fenestrations have a cross shape.

13. An absorbent pad as claimed in claim 1, further comprising a central fenestration located at or near to the central point.

14. An absorbent pad as claimed claim 13, wherein the fenestrations comprise slits; the pad comprises a central fenestration located at the central point; and wherein the fenestrations are present in two or more different geometrical shapes and/or two or more different sizes.

15. An absorbent pad as claimed in claim 13, wherein the central fenestration has rotational symmetry.

16. An absorbent pad as claimed in claim 13, wherein the central fenestration has n-fold rotational symmetry, wherein n is an integer from 2 to 10.

17. An absorbent pad as claimed in claim 13, wherein the central fenestration has the same shape as the fenestrations arranged about the central point.

18. An absorbent pad as claimed in claim 13, wherein the central fenestration has a different shape to the fenestrations arranged about the central point.

19. An absorbent pad as claimed in claim 13, wherein the central fenestration is larger than the fenestrations arranged about the central point.

20. An absorbent pad as claimed in claim 13, wherein the central fenestration has a triskelion shape or a tetraskelion shape.

21. An absorbent pad as claimed in claim 13, wherein the central fenestration has a cross shape comprising two intersecting slits or comprises two opposing arcs.

22. An absorbent pad as claimed in claim 21, wherein central fenestration comprises a cross shape and the one or more fenestrations having symmetry about a cardinal axis and one or more fenestrations having symmetry about an intercardinal axis have an arc shape.

23. An absorbent pad as claimed in claim 1, having a laminate structure.

24. An absorbent pad as claimed in claim 23, wherein the laminate structure comprises two layers.

25. An absorbent pad as claimed in claim 1, wherein the fenestrations penetrate through the entire thickness of the absorbent pad; or wherein the fenestrations penetrate partially through the thickness of the absorbent pad.

26. A wound dressing comprising an absorbent pad as claimed in claim 1.

27. A method of manufacturing an article, said method comprising applying a plurality of fenestrations to an absorbent pad, wherein the fenestrations are arranged in a pattern about a central point, wherein the pattern comprises one or more fenestrations having symmetry about a cardinal axis and one or more fenestrations having symmetry about an intercardinal axis, the cardinal and intercardinal axes crossing at the central point.

28. An absorbent pad as claimed in claim 1 for use in absorbing fluid discharged from a physiological target, or for use in stemming a flow of a fluid discharged from a physiological target site.

29. A wound dressing as claimed in claim 26 for use in absorbing fluid discharged from a physiological target, or for use in stemming a flow of a fluid discharged from a physiological target site.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0117] In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0118] FIG. 1 is a plan view of a first embodiment of a wound dressing comprising an absorbent pad;

[0119] FIG. 2 is a perspective view of the embodiment of FIG. 1;

[0120] FIG. 3 is a side view of the embodiment of FIG. 1;

[0121] FIG. 4 is a plan view of a second embodiment of a wound dressing comprising an absorbent pad;

[0122] FIG. 5 is a plan view of a third embodiment of a wound dressing comprising an absorbent pad;

[0123] FIG. 6 is a plan view of a fourth embodiment of a wound dressing comprising an absorbent pad;

[0124] FIG. 7 is a plan view of nine different embodiments of fenestration patterns in an absorbent pad;

[0125] FIG. 8 is a graphical representation showing the extensibility of the nine embodiments shown in FIG. 7 and a control sample.

[0126] Referring to FIGS. 1-3, there is shown a wound dressing 1 comprising a backing layer 2 and an absorbent pad 3. The absorbent pad 3 comprises a plurality of fenestrations 4. Each of the fenestrations 4 has an arc shape. The majority of the fenestrations 4 have a semi-circular arc shape. The fenestrations 4 all face towards a central fenestration 5 which is located at a central point 6.

[0127] The central fenestration 5 has a cross-shape, having two intersecting slits 7, 8. The intersecting slits 7, 8 create two pairs of opposite angles α, β and γ, δ. Each pair of opposite angles adds to 180°.

[0128] The absorbent pad 3 is in the shape of a rounded-edge square and has a wound facing surface 9 into which the fenestrations 4 are cut. The fenestrations 4 are arranged in a radiating pattern that extends outwardly away from the central point 6.

[0129] FIG. 1 shows two cardinal axes A-A and B-B and two intercardinal axes C-C and D-D, all intersecting at the central point 6. The pattern of fenestrations 4 contains fenestrations 10 having symmetry at least about cardinal axes A-A and B-B and fenestrations 11 having symmetry at least about intercardinal axes C-C and D-D. The pattern of fenestrations 4 further includes eight fenestrations 12 that are located in the secondary intercardinal regions. A fenestration 12 in one secondary intercardinal region has symmetry with another fenestration 12 in another secondary intercardinal region at least about the cardinal and intercardinal axes A-A, B-B, C-C and D-D.

[0130] The absorbent pad 3 has a laminate structure, in this embodiment comprising two layers 13, 14. The wound facing layer 13 is formed from a polyurethane foam and the second layer 14 is formed from a superabsorbent material.

[0131] The backing layer 2 has a border portion 16 that extends beyond the edges of the absorbent pad 3. The wound facing surface 17 of the border portion 16 is coated with an adhesive (not shown) to facilitate the adhesion of the wound dressing 1 to the wound-surrounding skin of a patient (not shown).

[0132] The backing layer 2 has a removable protecting layer 15 adhered to the distal surface of the backing layer 2. The removable protecting layer 15 comprises two removable parts 18, 19 which can be peeled off through pulling the tabs 20, 21.

[0133] In use, when a human or animal suffers a penetrating wound, the removable protecting layer 15 is removed from the wound dressing 1. The wound dressing 1 is then applied to the wound, with the wound facing surface 9 of the absorbent pad 3 being placed in direct contact with the wound. Upon application to a wound, the pattern of fenestrations 4 enables the absorbent pad 3 to stretch and readily conform to the contours of the anatomical area to which the wound dressing 1 is being applied. Once in place, force can be applied to the wound dressing 1 as necessary.

[0134] Turning to FIG. 4, there is shown an alternative pattern of fenestrations 104 in an absorbent pad 103. In this embodiment, the absorbent pad 103 comprises a plurality of fenestrations 104. Each of the fenestrations 104 has an arc shape. The majority of the fenestrations 104 have a semi-circular arc shape.

[0135] The absorbent pad 103 is in the shape of a rounded-edge square and has a wound facing surface 109 into which the fenestrations 104 are cut. The fenestrations 104 are arranged in a radiating pattern that extends outwardly from the central point 106.

[0136] In this embodiment, there is not a central fenestration located at a central point 106. Fenestrations 110 are located along the cardinal axes A-A and B-B and have symmetry at least about the cardinal axes A-A and B -B. The fenestrations 110 face away from the central point 106. Fenestrations 111 are located along the intercardinal axes C-C and D-D and have symmetry at least about the intercardinal axes C-C and D-D. Fenestrations 111 all face towards the central point 106. The pattern of fenestrations 104 further includes a plurality of fenestrations 112 located in the secondary intercardinal regions, wherein fenestrations in one secondary intercardinal region may have symmetry with fenestrations located in another secondary intercardinal region. For example, fenestrations 112a located in one secondary intercardinal region have symmetry with fenestrations 112b, 112c, 112d, 112e located in other secondary intercardinal regions at least about the cardinal and intercardinal axes A-A, B-B, C-C and D-D.

[0137] Turning to FIG. 5, there is shown an alternative pattern of fenestrations 204 in an absorbent pad 203. In this embodiment, the absorbent pad 203 comprises a plurality of fenestrations 204. Each of the fenestrations 204 has a cross shape. The cross shape is formed from a pair of slits intersecting at the midpoint of each slit, wherein each of the pairs of opposite angles add to 180°.

[0138] The absorbent pad 203 is in the shape of a rounded-edge square and has a wound facing surface 209 into which the fenestrations 204 are cut. The fenestrations 204 are arranged in a radiating pattern that extends outwardly from the central point 206.

[0139] A central fenestration 205 is located at a central point 206. The central fenestration 205 has a cross-shape, having two intersecting slits 207, 208. The intersecting slits 207, 208 create two pairs of opposite angles α, β and γ, δ. Each pair of opposite angles adds to 180°.

[0140] In this embodiment, there are no fenestrations located along the cardinal axes A-A and B-B. Fenestrations 210 are located within secondary intercardinal regions and have symmetry at least about the cardinal axes A-A and B-B. Fenestrations 211 are also located within secondary intercardinal regions and have symmetry at least about the intercardinal axes C-C and D-D. The pattern of fenestrations 204 further contains fenestrations 222 which are the substantially equivalent in size to the central fenestration 205. The fenestrations 222 are located in the corners of the absorbent pad 203.

[0141] Turning to FIG. 6, there is shown a plan view of a wound dressing 301 that is shaped for use on the heel and ankle of a patient. The wound dressing 301 has a trilobal shape. The wound dressing 301 comprises a trilobal shaped backing layer 302 and an absorbent pad 303. The absorbent pad 303 is shaped to substantially follow the contours of the trilobal backing layer 302.

[0142] The backing layer 302 has a border portion 316 that extends beyond the edges of the absorbent pad 303. The wound facing surface 317 of the border portion 316 is coated with an adhesive (not shown) to facilitate the adhesion of the wound dressing 301 to the wound-surrounding skin of a patient (not shown).

[0143] The absorbent pad 303 comprises a plurality of fenestrations 304. The fenestrations are located in two of the lobes 323, 324 of the absorbent pad 303. Each of the fenestrations 304 has an arc shape. The majority of the fenestrations 304 have a shallow arc shape.

[0144] The absorbent pad 303 has a wound facing surface 309 into which the fenestrations 304 are cut. The fenestrations 304 within each lobe 323, 324 are arranged in a radiating pattern that extends outwardly from the central points 306, 325.

[0145] In this embodiment, there is not a central fenestration located at either central point 306, 325. Fenestrations 310 are located along the cardinal axes A-A and B-B and have symmetry at least about the cardinal axes A-A and B-B. The fenestrations 310 face away from the central point 306. Fenestrations 311 are located along the intercardinal axes C-C and D-D and have symmetry at least about the intercardinal axes C-C and D-D. Fenestrations 311 all face towards the central point 306. Correspondingly, Fenestrations 326 are located along the cardinal axes AA-AA and BB-BB and have symmetry at least about the cardinal axes AA-AA and BB-BB. The fenestrations 326 face away from the central point 325. Fenestrations 327 are located along the intercardinal axes CC-CC and DD-DD and have symmetry at least about the intercardinal axes CC-CC and DD-DD. Fenestrations 327 all face towards the central point 325.

EXAMPLES

[0146] In order to evaluate the extensibility of absorbent pads according to the present invention, nine different fenestration patterns were tested according to the test method set out below. The nine different fenestration patterns are shown in FIG. 7. The nine fenestration patterns were tested against an absorbent pad having no fenestration pattern as a control.

[0147] Each of the test articles comprised a polyurethane backing film, an absorbent pad having the fenestration pattern cut therein and a perforated wound contact layer. The absorbent pad was adhered to the backing film using an acrylic adhesive. The acrylic adhesive was pattern coated onto the surface of the backing film. The absorbent pad was adhered to the wound contact layer using a silicone adhesive.

[0148] The absorbent pad formed a central island, comprising a superabsorbent air-laid material laminated with a polyurethane foam. The central island had a thickness of approximately 3-4.5 mm.

[0149] The extensibility and conformability test assess the extensibility and permanent set conformability of an absorbent pad.

Test Method

[0150] (1) Cut out a 25 mm (±0.5) wide specimen for the sample material;

[0151] (2) After removing the specimen from the roll or backing film, allow it to relax for a minimum of 300 seconds

[0152] (3) Place two parallel marks on the specimen 100 mm (±10) apart, such that the marks are at equal distance from the two ends. Measure the distance between the two marks to the nearest 0.5 mm (L1) using a calibrated ruler;

[0153] (4) Clamp the specimen outside the marks into the jaws of a tensile testing machine and extend the specimen by 20% using an extension rate of 300 mm/min (±10). Record the maximum load (ML) to the nearest 0.1N;

[0154] (5) Hold the specimen at this extension for 60 seconds (±1) then remove the specimen from the jaws and allow it to relax for 300 seconds (±15);

[0155] (6) Re-measure the distance between the two marks on the specimen (L2) using a calibrated ruler.

The extensibility of each sample was calculated using the formula:

Extensibility (N.Math.cm.sup.1)=ML/2.5

[0156] The results of the extensibility testing for the absorbent pads is displayed in Table 1.

TABLE-US-00001 Extensibility (N/cm) Pad Wound dressing Control 7.58 3.16 A 4.49 2.97 B 2.41 2.93 C 2.24 2.95 D 2.81 3.06 E 2.32 2.97 F 1.97 2.71 G 2.27 2.81 H 3.03 2.85 I 2.95 2.86

[0157] All of the tested samples A-I showed significantly increased extensibility over the control in both the absorbent pad and the wound dressing comprising the absorbent pad. The results in Table 1 have been graphed and can be seen in FIG. 8. The graph shows the significant improvement in extensibility of the Samples A-I of the present invention compared to the control sample having no fenestrations.

[0158] The various different fenestration patterns of Samples A-I were developed to better understand the contribution of design aspects such as increasing number of fenestrations (e.g. Sample B vs Sample A), the inclusion of a central fenestration (Sample C), having the arc fenestrations all facing towards the central point (Sample D), having the fenestration pattern extend to the edge of the absorbent pad (Sample E), combining several of these aspects (Sample F) and changing the shape of the fenestrations (Sample G). Lastly, Samples H and I were developed based on the good results observed for Samples F and G, respectively.

[0159] The good results observed for Sample F indicate that increasing the number of fenestrations, extending the fenestrations to the edge of the absorbent pad and introducing a central fenestration are all important factors to improving the extensibility of the absorbent pad and subsequent wound dressing. Of particular note are the comparatively beneficial results obtained where the pattern of fenestrations comprises a central fenestration having a different shape to the fenestrations radiating outwardly from the central point, such as in Sample F. In combination, the aforementioned design elements provide the best stretch and conformability of the designs tested.

[0160] The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.