WO2005067988A1

WO2005067988A1 - Huckaback woven wound dressing

Info

Publication number: WO2005067988A1
Application number: PCT/IN2004/000012
Authority: WO
Inventors: Subhash Chander Anand; Kanwal Narain Seth
Original assignee: Datt Mediproducts Limited
Priority date: 2004-01-19
Filing date: 2004-01-19
Publication date: 2005-07-28

Abstract

The invention provides for a wound dressing which uses a single layer fabric woven using dense huckaback weave. The dense weave pattern used makes the wound dressing highly absorbent. The said fabric is treated in a solution of a non-ionic flocculent and a softening agent. One side of the fabric is laminated to a hydrophobic film to prevent seepage. The non-ionic flocculent reacts with exudate to form a film of gel between the dressing and the wound and thereby prevents the dressing from sticking to the wound.

Description

HUCKABACK WOVEN WOUND DRESSING

The present invention relates to a wound dressing and more particularly to a wound dressing that is non-adherent and high absorbent and a method of producing the same. BACKGROUND OF INVENTION: Commonly used wound dressings comprise gauze, foams, sponges, cotton wadding or other fibrous materials. Gauze and other fibrous materials absorb fluids by capillary action with the disadvantage that when new tissue is formed as part of the healing process, it engulfs the fibres and is torn when the material is removed causing wound injury. Traditional gauzes are thin loosely woven pieces of cloth used for dressings and swabs. Commonly available swabs comprise a number of layers of such gauze material and are of a predetermined shape. Such swabs absorb the fluids secreted from the wound in the many layers. On drying up, the swab tends to stick to the wound and loose fibers often get caught in the wounds. This causes irritation, trauma and even further injury when the dressing is changed. Further, it is medically known that for quick healing the wound must be kept moist and the commonly available swabs and dressings once dry offer no such moist environment. Various patents describe wound dressings that are non- adherent and are hydrogel based. However these dressings are not very absorbent. Some wound dressings use alginate fibres that are expensive and extremely difficult to process in woven structures. Furthermore, a number of layers are required to achieve the desirable levels of absorption. Publication W095/91795 of Bristol Myers Squibb describes a wound dressing comprising of textile fibres and gel forming fibres, which is inexpensive and non-adherent. The dressings disclosed are non-woven structures, the fibres being carded together to form a felt. These fabrics generally have less tensile strength in both wet and dry states than woven fabrics. These non-woven dressings have little integrity once used on the wound to remove intact. EP Patent No. 0925 396 discloses a wound dressing comprising a mixture of textile fibres and gel forming fibres wherein the dressing is a knitted fabric comprising support yarn and in-laid yarn, the support yarn is free of gel forming fibres. EP Patent No. 1 003 563 relates to a multi-layered wound dressing which includes a gelling polymer. US 4884563 and 5722943 relates of a non-stretching wound dressing, which contains urethane with adhesive on one side. US patent 6471982 provides for a wound dressing comprising a mixture of textile fibers and gel forming fibers. The wound dressing as described offers the advantage of being non- adherent and absorbent. US patent 4538603 also describes a wound dressing skin contacting layer that comprises of 35% to 50% by weight of low molecular weight polyisobutylenes and from about 45% to 60% by weight of one or more water dispensable hydrocolloids. The dressing disclosed is however adhesive and consists of an intermediate layer of semi-open cell polymeric foam. US Patent Nos. 5489262 and 5423737 relates to a multi- layered wound dressing with a removable tab and release line hydrogel adhesive. Thus there is a need for a wound dressing that is non- adherent and utilizes a single layer of fabric while being absorbent.

SUMMARY OF INVENTION: In order to overcome the above limitations, the present invention provides for a wound dressing that has an improved absorption capacity and is non-adherent. It is yet another purpose of the present invention to provide a wound dressing that uses a single layer of fabric as opposed to 8-12 layers being used in a conventional wound dressing. It is still another purpose of the invention to provide a wound dressing that forms a gel by flocculation on contact with any fluid. Yet another purpose of the invention to provide a wound dressing that does not have loose fibers, which get caught, in the wound. Yet still another purpose of the invention is to maintain a moist environment at and around the wound area to promote wound healing. To meet the aforementioned purposes and to overcome the drawbacks of the prior art, the present invention provides for a wound dressing which uses a single layered fabric woven using dense huckaback weave. The said fabric is treated in a solution of a non-ionic flocculent and a softening agent. On one side of the fabric a laminated hydrophobic film is coated to prevent seepage. The non-ionic flocculent reacts with exudates to form a film of gel between the dressing and the wound and thereby prevents the dressing from sticking to the wound. The hydrophobic film such as polyethylene or polyester prevents strike through of exudates and hinders the ingress of liquid. The textile fibre used in the weave can be any natural fibre such as cotton, wool, flex and silk. . The ratio of non-ionic flocculent to softening agent is in the range of 1:3 to 1:6 per litre of water. The softening agent is a fatty acid amide derivative and the flocculent is polyacrylamide The present invention also relates to a method of preparing a wound dressing comprising the steps of: bleaching the fabric and passing the said bleached fabric through unwinder rollers to give tension and straighten the fabric and again passing it through another set of rollers where the bleached fabric is dipped in a trough containing non-ionic flocculent and softening agent in a predetermined proportion, squeezing excess of fluid and drying the fabric by passing it through a stenter at a predetermined temperature and applying a coat of a laminated hydrophobic film to one side of the fabric to prevent seepage through the dressing BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS: The accompanying drawings illustrate the preferred embodiments of the invention and together with the following detailed description serve to explain the principles of the invention. Figure 1 shows the weave pattern used in ordinary gauze. Figure 2 shows the ordinary gauze swabs comprising a number of layers. Figure 3 shows a wound dressing in accordance with the present invention. Figure 4 shows the weave pattern of the wound dressing in accordance with the present invention. Figure 5 shows a schematic view of an embodiment of a method in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION: It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof. Throughout the patent specification, a convention employed is that in the appended drawings, like numerals denote like components. At the outset, it is appropriate to mention that a weave consists of a weft and a warp. The warp being the thread used lengthwise and the weft a thread used widthwise. Further, a weave construction is defined by the numerals X x T, where X' denotes the number of warps per inch or 'ends', Υ denotes the number of weft per inch or 'picks'. Referring to figure 1 there is shown ordinary gauze of the prior art. As can be seen from the figure a simple conventional weave is used with the warp (1) and weft (2) following a set pattern. The gauze formed with such a weave pattern lacks in strength. Loose fibres commonly separate out and these fibres get stuck with the wound. At the time of changing the dressing separation of these fibres from the wound causes pain, trauma and often results in a further injury at the wound. This is especially true in the case of a granulating wound. Ordinary gauze is by and large made of 100 percent cotton yarn. The fabric is woven using conventional two shafts with the warps and wefts following a set pattern. A number of fabric layers as shown in figure 2 are clubbed together to form a swab. Conventional swabs have between 8 to 12 such layers. These layers absorb any secretion from the wound. On drying up the swab tends to stick to the wound and the area around it. The absorbed liquid, however, is dissipated from the gauze upon the application of pressure to the wound. Referring to figures 3 and 4, a wound dressing in accordance with the present invention is shown. The dressing uses a single layer of cloth woven in a manner as depicted in figure 4. This kind of weave is commonly known as the huckaback weave and is denser and has certain strands above and certain below. The huckaback weave for the wound dressing has the following specification: Construction range: 50 x 46 to 80 x 16. The preferred construction is 70x26. Whereas 50 denotes number of warp yarn per inch and 46 denoted number of weft yarn per inch. Similar is the case of 80 x 16 & 70 x 26. Warp: 16_s to 40_s (Single yarn or double yarn). The preferred value is 24„. Weft: 8_g to 30_s (Single yarn or double yarn). The preferred value is 8_S. The fabric made of such a weave has a greater absorption capability. Further, such fabric has greater strength and tendency to shed loose fibers is rare. The use of this unique weave for gauzes allows the use of a single layer in place of eight to twelve layers as is conventionally used. The number denotes the fineness of yarn. Higher the value, finer is the yarn. The above fabric in accordance with this invention is treated with non-ionic flocculants and softening compounds. The flocculent in the fabric when comes in contact with any secretion from the wound forms a gel that results in a film between the wound and the fabric. This film prevents the fabric from sticking to the wound and gives the fabric a non-adherent quality. Further, the gel formation also results in the wound area remaining moist and thereby promotes wound healing. A softening agent such as an amphoteric fatty acid amide derivative is also applied to the fabric along with the flocculent.

The softening agent serves to soften the fabric and also increases the absorption capacity of the wound dressing. The flocculent and the softening agent are applied in ratio ranging from 1: 3 to 1:6 per liter of water The treated fabric is coated with a layer of hydrophobic film on one side to prevent seepage of fluid. The wound dressing in accordance with the invention is soft and easy to handle. There is no gelling in the dry state. The wound dressing can also be used on dry wounds unlike alginate dressings. Referring to figure 5 a schematic diagram depicting the method of preparation of a wound dressing in accordance with the present invention is shown. ' The roll of fabric first undergoes pre-treatment that includes the bleaching and scouring. Bleaching is carried out using compounds such as sodium hydroxide, sodium silicate, and hydrogen peroxide in a specified concentration. The fabric then undergoes a neutralization and washing step using compounds such as ethylene diamine tetracetic acid and a detergent. The pre-treatment is carried out for about 60 minutes at a temperature in the range of 80 to 120 degrees. The pre-treated roll of the fabric thus prepared and with a weave as shown is run through a series of rollers and dipped into a trough containing the non-ionic flocculent and a softening agent such as an amphoteric, fatty acid amide derivative. The fabric is then run through another set of rollers that squeeze out the excess chemicals before sending it further for drying. At the drying stage in a stenter, the fabric undergoes drying at a temperature between 80 to 120 degrees. The dried fabric is then coated with a layer of hydrophobic film to prevent seepage. The roll of fabric is then cut out into a predetermined size to form the wound dressings. It will be readily appreciated by those skilled in the art that the present invention is not limited to the specific embodiments herein shown. Thus variations may be made within the scope and spirit of the accompanying claims without sacrificing the principal advantages of the invention.

Claims

We claim:

1. A wound dressing characterized by a single layer densely woven fabric of the huckaback weave.

2. A wound dressing of claim 1 characterized in that the textile fibre used in the weave is of natural origin.

3. A wound dressing of claim 1 characterized in that the textile fibre used is hundred percent cotton yarn.

4. A wound dressing of claim 1.characterized in that the construction of the fabric is in the range of (50 x 46) to (80 x 16).

5. A wound dressing of claim 4 characterized in that the construction of the fabric is 70 x 26.

6. A wound dressing comprising: a single layer densely woven fabric of the huckaback weave treated in a solution of non-ionic flocculent and a softening agent and a coating of a lamination hydrophobic film on one surface to prevent seepage through the dressing.

7. A wound dressing of claim 6 characterized in that the textile fibre used in the fabric can be of natural origin.

8. A wound dressing of claim 6 characterized in that the textile fibre used is hundred percent cotton yarn.

9. A wound dressing of claim 6 characterized in that the construction of the fabric is in the range of (50 x 46) to (80 x 16).

10. A wound dressing of claim 6 characterized in that the construction of the fabric is 70 x 26. ,5

11. A wound dressing of claim 6 characterized in that the ratio of non-ionic flocculent to softening agent is in the range of 1:3 to 1:6 per litre of water.

12. A wound dressing of claim 6 characterized in that the softening agent is a fatty acid amide derivative.0

13. A wound dressing of claim 6 or 11 characterized in that the flocculent is polyacrylamide

14. A wound dressing of claim 12 characterized in that the softening agent is selected from polyglycol ether, siloxane or wax 5

15. A wound dressing of claim 6 characterized in that the laminated hydrophobic film is of polyethylene, polypropylene, polyurethane, polyester etc.

16. A method of preparing a wound dressing comprising the steps of: 0 - bleaching the fabric and passing the said bleached fabric through an unwinder to give tension and straighten the fiber and again passing it through another set of rollers characterized in that said bleached fabric is dipped in a trough containing 5 non-ionic flocculent and softening agent in a predetermined proportion squeezing excess of fluid and drying the fabric by passing it through a stenter at a predetermined temperature

30 - applying a coat of a laminated hydrophobic film to one side of the fabric to prevent seepage through the dressing

17. A method of claim 16 characterized in that the fabric is dried for about 60 minutes and at a temperature in the range of 80 to 120 degrees.

18. A method of claim 16 characterized in that the ratio of non- ionic flocculent to softening agent is in the range of 1:3 to 1:6 per liter of water.

19. A method of claim 16 characterized in that the softening agent is selected from polyglycol ether, siloxane or wax

20. A method of claim 16 characterized in that the laminated hydrophobic film is of polyethylene or polyester, polyurethane or polypropylene.