Wound dressing

Abstract

A wound dressing including a layer in the form of a strip and including gel-forming fibers, the strip having longitudinal lines of stitches formed from a thread and transverse lines of stitches formed from a thread. In certain forms, the wound dressing includes at least one stitch free column.

Claims

1. A wound dressing having a non-woven web of gel-forming fibers, the wound dressing comprising: longitudinal lines of stitches formed from thread; transverse lines of stitches formed from thread extending between at least two of the longitudinal lines of stitches to form a stitched column; and at least one stitch free column; wherein at least two stitched columns are formed and separated by the at least one stitch free column; wherein two of the transverse lines of stitches are offset from one another in a longitudinal direction by an offset distance; and wherein a longitudinal length of the at least one stitch free column is greater than the offset distance.

2. The wound dressing as claimed in claim 1, wherein the longitudinal lines of stitches are from 1 mm to 10 mm apart and are parallel to a long edge of the wound dressing.

3. The wound dressing as claimed in claim 1, wherein the transverse lines of stitches are stitched through the wound dressing.

4. The wound dressing as claimed in claim 1, wherein the gel-forming fibers comprise one or more of cellulose fibers, chemically modified cellulosic fibers, pectin fibers, alginate fibers, chitosan fibers, hyaluronic acid fibers, polysaccharide fibers and fibers derived from gums.

5. The wound dressing as claimed in claim 1, wherein the thread comprises one or more of nylon, polyolefin, polyurethane, polyester, cellulosic, and modified cellulosic.

6. The wound dressing as claimed in claim 1, wherein the transverse lines of stitches are in the form of a continuous zig-zag.

7. The wound dressing as claimed in claim 1, wherein the wound dressing has a slit in a longitudinal direction in the at least one stitch free column, and wherein the slit is configured to remove any loose thread from the transverse lines of stitches at longitudinal edges.

8. The wound dressing as claimed in claim 1, wherein the transverse lines of stitches are in the form of a castellated pattern.

9. The wound dressing as claimed in claim 1, wherein the wound dressing forms a strip.

10. A method of manufacturing a wound dressing, the method comprising: forming a first roll of fabric comprising a non woven web of gel-forming fibers; forming a first stitched column formed by longitudinal lines of stitches having transverse lines of stitching formed from thread extending between the longitudinal lines of stitches, wherein two of the transverse lines of stitching are offset from one another in a longitudinal direction by an offset distance; and forming a second stitched column spaced from the first stitched column to create a stitch-free column between the first stitched column and the second stitched column; wherein a longitudinal length of the stitch-free column is greater than the offset distance.

11. The method as claimed in claim 10, wherein the first roll of fabric is formed by knitting a roll of gel-forming fibers.

12. The method as claimed in claim 10, wherein the nonwoven web is made by hydroentangling a web of lyocell fibers and carboxymethylating the web.

13. The method as claimed in claim 10, wherein the method comprises the further step of treating the dressing with a source of silver.

14. The method as claimed in claim 10, wherein the dressing has no loose thread from the transverse lines of stitching at longitudinal edges.

15. The method as claimed in claim 10, further comprising superposing a second roll of fabric comprising a non woven web of gel-forming fibers on the first roll of fabric and stitching the first and second roll together.

16. A wound dressing, comprising: a non woven web of gel-forming fibers; transverse lines of stitches extending between longitudinal lines of stitches to form columns; wherein the transverse lines of stitches are finished at an edge of at least two longitudinal lines of stitches, and wherein the transverse lines of stitches are stitched through the wound dressing.

17. The wound dressing as claimed in claim 16, wherein the gel-forming fibers comprise one or more of spun cellulose fibers, chemically modified cellulosic fibers, pectin fibers, alginate fibers, chitosan fibers, hyaluronic acid fibers, other polysaccharide fibers and fibers derived from gums.

18. The wound dressing as claimed in claim 16, wherein the stitches are formed of thread, and wherein the thread comprises one or more of nylon, polyolefin, polyurethane, polyester, cellulosic, or modified cellulosic.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view of a layer of gel-forming fibers in the form of a roll (1) with longitudinal lines of stitching (2) joined by transverse lines of stitching (4) in the form of an angular zig-zag (6) prior to slitting.

(2) FIG. 2 is a view of a layer of gel-forming fibers in the form of a roll with longitudinal lines of stitching (2) and transverse lines of stitching (4) in the form of a castellated pattern (12) prior to slitting.

(3) FIG. 3 illustrates a first fabric roll (51) and a second fabric roll (52) superposed on the first fabric roll (51), with the rolls (51, 52) being joined by stitching (53).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) FIG. 1 shows a nonwoven roll (1) of gel-forming fibers made by a needle felting carding technique to form a web. Optionally, the roll (1) can have an antimicrobial material incorporated into it and, in particular, silver by the method described in WO 02/43743. The roll is stitched in the longitudinal direction with lines of stitching in Tencel® yarn. The longitudinal lines of stitches (2) are supplemented by transverse lines of stitching (4) in the form of continuous, angular zig-zags (6) which extend between adjacent longitudinal lines of stitches. In this way stitch free gaps (8) are left between columns (10) of longitudinal stitching. The roll is slit in the longitudinal direction in the stitch free gaps (8) to form ribbons. The roll (1) includes a long edge (3) and longitudinal slits (7).

(5) FIG. 2 shows a nonwoven roll (1) similar to that shown in FIG. 1 except that the continuous zig-zag of transverse stitches (4) is made in a castellated pattern (12) between the longitudinal lines of stitches (2) and joins them together. The roll is slit in the longitudinal direction in the stitch free gaps (8) to form ribbons. The roll (1) includes a long edge (3) and longitudinal slits (7).

(6) Preferred embodiments of the invention will now be described with reference to the following examples:

Example 1

(7) Dressing A

(8) A wound dressing was made from a roll of gel-forming fibers as described for the dressing of FIG. 1. The roll had lines of longitudinal stitching spaced 5 mm apart. The column width was 2.5 cm. Ribbons were cut from each roll by slitting in a longitudinal direction at the gaps between the columns in the transverse stitching.

(9) Dressing B

(10) An alternative wound dressing was made by superposing two rolls of gel-forming fibers as described for Dressing A and stitching as described for Dressing A.

(11) Dressing C

(12) An alternative wound dressing was made by eliminating the transverse stitching of Dressing A.

(13) Dressing D

(14) Dressing D was formed from 100 gsm Aquacel® a nonwoven dressing made from fibers of carboxymethyl cellulose manufactured by ConvaTec Inc.

(15) Test samples were cut from the stitched rolls to have the dimensions 25 mm wide by 100 mm long for the wet samples and 25 mm wide by 75 mm long for the dry samples. The tensile strength of the gelled and dry samples were measured in the longitudinal and transverse direction in the following manner.

(16) Dry Tensile Testing

(17) Samples were conditioned at 20° C.±2° C. and 65%±4% relative humidity for a minimum period of 24 hours. The samples were secured in the pneumatic jaws of a Zwicke fitted with a 100N load cell. The sample was elongated at a speed of 100 mmimin until a 75% reduction in the sample's maximum force was measured.

(18) Wet Tensile Testing

(19) Samples were conditioned at 20° C.±2° C. and 65%±4% relative humidity for a minimum period of 24 hours. 2 ml of a sodium and calcium chloride solution BP (British Pharmacopeia) was dispensed via a pipette onto the center of the sample and left for a period of 1 minute. The sample was secured within the pneumatic jaws of a Zwick® U.T.M. fitted with a 100N load cell. The sample was elongated at a speed of 100 mmimin until a 75% reduction in the sample's maximum force was measured.

(20) The results are given below where MD=Machine Direction and TD=Transverse Direction.

(21) TABLE-US-00001 Property Dry Tensile Wet Tensile Measurement MD N/cm TD N/cm MD N/cm TD N/cm Dressing D 5.33 16.19 0.16 0.42 Dressing B 8.04 20.82 4.51 4.39 Dressing C 13.51 15.75 8.00 0.44 Dressing A 12.19 30.78 8.05 4.45

(22) These results show the improvement in tensile strength in transverse stitched samples.

Example 2

(23) Dressing A was used to pack a tracking wound. On removal from the wound the ribbon dressing was fully hydrated with wound fluid yet had maintained its structure. The dressing was easily removed from the wound in one piece.