HK1059207B - Method and manufacture of a wound dressing for covering an open wound - Google Patents

Description

Method of covering an open wound and manufacture of a wound dressing for covering an open wound

Technical Field

The present invention relates to a method of covering an open wound. The invention also relates to a method for producing a cellulose wound dressing which is sterilized and formed into a bandage.

Background

In the medical industry, wound dressings have been used for many years to help heal and protect open wounds. Cellulose bandages used in the medical industry are typically made from a knitted blank, which is an unbleached and unfinished cloth. The cloth is bleached to whiten the fabric and converted into a gauze bandage.

Ideally, a cellulosic wound dressing should have certain characteristics in order to assist in the proper healing of the wound. For example, U.S. patent No.5527271 to Shah et al discloses a thermoplastic hydrogel impregnated composite for use in a wound dressing. The hydrogel is coated on a cotton gauze wound dressing to prevent the wound dressing from sticking to the wound during the healing process.

Similarly, U.S. patent No.4838253 to missington et al discloses a silicone gel coated permeable wound dressing made by coating a non-crosslinked silicone material onto a sheet of perforated material and then crosslinking it. The wound dressing has increased absorption capacity while also having the property of preventing the wound dressing from sticking to the skin of the wound.

Furthermore, and more importantly, the wound dressing should have antimicrobial properties that kill airborne bacteria in contact with the dressing to prevent bacteria from entering and passing through the wound. Thus, efforts have been made in the past to treat cellulosic wound dressings with antimicrobial properties.

For example, U.S. patent No.4728323 to Matson discloses an antimicrobial wound dressing coated with an effective antimicrobial film of silver salt. The antimicrobial wound dressing is made by depositing a quantity of silver salt onto the surface of the wound dressing. However, the method of treating the wound dressing is rather time-consuming and complicated, since the antimicrobial treatment has to be carried out by a separate device, i.e. by a sputter coating device.

EP 0136900 and canadian patent No.1223208 disclose a nonwoven fabric having antimicrobial properties and being used to make surgical drapes. The nonwoven fabric is treated with an antimicrobial agent which has a broad spectrum of activity against Gram-negative and Gram-positive bacteria and which is not inactivated by serum. The antibacterial agent used was polyhalobenzoic acid (hereinafter referred to as "PHMB"). As described in the background section, PHMB is suggested for use as an antimicrobial in the treatment of textile materials. Us patent 2336605; 2990425, respectively; 4022836, respectively; 2863919 discloses such applications.

In addition, PHMB has been used in water treatment to control the growth of algae, as described in U.S. patent No.4014676 to Carter et al; treatment of dandruff, as described in U.S. patent No.4405645 to rotlisberger et al; and as contact lens preservatives, as described in U.S. patent No.4758595 to Ogunbiyi et al.

Recently, PHMB has been used to weave fabric materials, such as clothing. For example, GB2300200 discloses a cellulosic substrate treated with a biguanide and subsequently with an anti-tack agent to impart antimicrobial properties to the cellulosic substrate. The treated substrate has the additional effect of reducing the tendency of the substrate to yellow upon contact. The treated articles may be formed into shirts, undergarments, uniforms and socks, and are particularly suitable for articles that will become soiled and prone to microbial growth. It is important to note that the anti-adherent agent is used to help prevent the normal adverse effects of PHMB on the human body when it is used alone. When PHMB is used alone to treat items, it can cause skin discomfort, such as redness, tenderness, and measles.

W098/18330 discloses a non-leaching antimicrobial material that is capable of killing microorganisms by contact, but does not leach significant amounts of the antimicrobial material into the surrounding environment. The antimicrobial material includes a composite of a polycationic ligand compound and a metallic material, wherein the polycationic compound is a polymer. In a preferred embodiment, the polymeric material is PHMB and the cross-linking agent is non-methylenediglycidylaniline (hereinafter "MBDGA") and the metallic material is a silver salt, wherein the silver salt is transferred from the coating to the microorganisms and accumulates to toxic levels to kill the microorganisms. The antimicrobial composition can be used on a variety of substrates such as wood, metal, paper, clothing, glass, and ceramics. In addition, the material in powder form may be dispersed and dissolved in a carrier and used for topical sterilization, topical application to wounds, or for topical disinfection. However, the composition can only be added to a substrate as a surface coating. Thus, when the composition is used as a surface coating, it is able to prevent bacteria from passing through the wound dressing.

U.S. patent No.5019096 to Fox et al discloses an anti-infective composition for medical devices and surfaces and methods of making and using the anti-infective composition. The method comprises the following steps: combining an effective amount of the antimicrobial agent into a matrix comprising a polymer component, wherein the matrix is capable of causing controlled release of the antimicrobial agent upon contact with a fluid at a level sufficient to inhibit infection. The antimicrobial agent includes a synergistic amount of a silver salt and a biguanide. Preferably, the final coating comprises 10 to 70% by weight of the microbial agent. The composition acts only as a coating and does not prevent microorganisms from passing through the wound dressing.

Disclosure of Invention

The present invention provides a method of preparing a cellulose bandage, the method comprising: a step of applying an antibacterial dose of PHMB on the cellulose bandage.

The present invention also provides a method of manufacturing a wound dressing having antimicrobial properties, comprising the steps of: A) providing at least one bundle of rolled cellulosic material; B) inserting the bundle of material into a closed container; C) adding PHMB to a container, wherein the volume of PHMB added to the container is between 0.10% and 0.80% of the total volume of water; D) the PHMB is cycled for a predetermined time.

The invention also provides a cellulosic wound dressing consisting essentially of PHMB in an antimicrobial amount.

In one aspect, the present invention provides a method of covering and preventing microbial contamination of an open wound by dressing the wound with a cellulosic wound dressing having an antimicrobial dose of PHMB applied to the dressing.

In another important aspect, the present invention provides a method of dressing a wound by directly contacting the wound with a cellulosic wound dressing having an antimicrobial dose of PHMB applied to the bandage without an intermediate layer between the antimicrobial treatment bandage and the open wound.

In another aspect, the invention provides a wound dressing consisting essentially of PHMB.

In another aspect, the present invention provides a method of manufacturing a wound dressing having antimicrobial properties. The method comprises the following steps:

A) providing at least one bundle of rolled cellulosic material;

B) inserting the bundle of material into a closed container;

C) adding PHMB to a container;

D) the PHMB is cycled for a predetermined time.

In another aspect, the invention provides a method of manufacturing a wound dressing as claimed in.

Brief description of the drawings

Other features and characteristics of the present invention will be better understood by referring to the following detailed description of the drawings, which schematically illustrate the manufacturing process of the invention.

Detailed description of the invention

As mentioned above, one aspect of the present invention relates to a method of covering a wound with a cellulose bandage having a calculated dose of PHMB applied to the bandage. PHMB is known for its antibacterial properties, but has not been used as an ingredient to prevent bacterial infection of wounds. This is mainly because PHMB, when used alone and without combination with other substances, will irritate the skin of the human body and even have a stronger effect on the vulnerability of open wounds.

The present invention discloses that the PHMB can be used alone on a cellulosic fabric to cover a wound without irritating the skin or the wound, yet still provide a wound dressing with sufficiently strong antimicrobial properties. The cellulosic wound dressing of the invention substantially comprises PHMB in an antibacterial dose. The term "consisting essentially of is meant to exclude additional ingredients, such as anti-adherents, which have previously been used to prevent the normal adverse effects of PHMB on the human body. In addition, PHMB acts as the primary antimicrobial agent and does not require an intermediate layer between the antimicrobial treatment bandage and the open wound.

In particular, the antimicrobial dose of PHMB applied to the material, as determined by extraction, is preferably between 500-3000ppm, most preferably between 1500-2500 ppm. However, this dose can be reduced because it is still effective below 500ppm, the antimicrobial dose being defined as the dose of PHMB applied in the wound dressing required to provide sufficient antimicrobial properties without irritating the skin or open wound.

One manufacturer of PHMB is Avecia corporation, located in Wilmington, Delaware, which sells the product called COSMOCIL CQ^TMThe product of (1), which is an antibacterial article supplied in the form of PHMB at a concentration of 20% in water. The article is particularly suitable for mixing with cotton and for cosmetic use, such as medical devices, and overcomes adverse effects (counterapplication). However, it should be understood that other PHMB manufacturers and various formulations may be used with the present invention.

There are a variety of methods for applying manufactured PHMB articles to cellulosic wound dressings. For example, PHMB may be applied to a cellulosic wound dressing by spraying, or by placing PHMB in a pool of water and allowing the gauze to feed into the pool before drying. However, it is important to have the PHMB applied uniformly over the entire wound dressing, which is difficult to achieve by spraying the PHMB onto the wound dressing. Furthermore, it would be desirable to include the treatment of wound dressings by PHMB as part of the conventional manufacturing process for making cellulose bandages from an unfinished blank. Preferably, PHMB is added to the wound dressing in a bleaching process.

Referring to fig. 1, a typical bleaching process involves the use of a bleaching barrel 10 into which bleaching barrel 10 bundles of unfinished fabrics 12 are inserted. The tub 10 may be made of stainless steel, as is well known in the art. The tank 10 is a pressure vessel that allows fluid to circulate therein for treating materials placed therein.

The blank is rolled into a bundle 12 on a perforated, hollow drum 14. The construction of the hollow drum 14 is well known in the art, as described in U.S. patent No.3596481 to Wilcox, which is incorporated herein by reference. Further, a typical bale weighing approximately 950Ibs prior to bleaching is approximately 4 feet wide, with a radius of approximately 3 feet, and a length of approximately 40000 linear yards. Preferably, two cloths weighing about 1900Ibs are stacked in a container prior to bleaching. It will be appreciated, however, that any bundle of cloth may be prepared as is preferred, depending on the size of the bucket.

The wrapped blank 12 is inserted into the tub 10 by means of an overhead crane such that the fluid inlet conduit 20 is disposed and inserted into the hollow drum 14 to direct fluid into the inner surface of the hollow drum 14 and to cause the fluid to flow radially outwardly through the wrapped blank 12 in a manner well known in the art. Although the present invention discloses the use of only one perforated drum 14 per barrel 10, it should be understood that the barrel bleaching system may use multiple beams within a single barrel, as described in U.S. patent No.4032292 to Jones.

The fluid inlet conduit 20 is connected to a holding tank 22, which holding tank 22 holds the bleaching solution to be released in the bleaching cycle. A heat exchanger 24 is connected between the holding tank 22 and the fluid inlet conduit 20 to heat the bleaching solution before it is added to the tub 10. Heating the bleaching solution increases the rate of bleaching of the fabric.

To add bleaching solution to the vat 10, valves 25 and 26 are opened, which causes water from the fresh water source 27 to flush bleaching fluid from the holding tank 22 to the main valve 28. The main valve 28 is then opened to allow bleaching fluid to flow to the eductor 30. When the eductor valve 32 is open, fresh water causes bleaching fluid to flow from the holding tank 22 into the circulation system 33.

A pump 34 pumps bleaching fluid through the heat exchanger 24 and the fluid inlet conduit 20 into the pressure drum 10. The pump 34 also functions to recirculate the bleaching solution during the bleaching cycle. The wastewater of the system is released through fluid outlet line 40 and pumped into the plant wastewater system by pump 44. The bleaching process is a standard industrial process and is well known in the art.

When the bleaching operation is complete, the weight of the resultant cloth is reduced from about 1900Ibs to about 1690 Ibs. PHMB may now be added to the keg 10 by opening valve 50 and valve 25, and water from the fresh water source flushes PHMB from holding tank 52 by opening valve 50 and valve 25. The main valve 28 is then opened to allow PHMB to flow to the eductor 30. When the eductor valve 32 is open, fresh water causes PHMB to enter the circulation system 33 from the holding tank 52. The pump 34 causes the PHMB to be pumped into the pressure drum 10 through the heat exchanger 24 and the fluid inlet conduit 20.

All chemical additives and valves may be controlled by a computer connected to the system. The computer control unit controls the processing parameters of the bucket and may include a graph on the screen representing the current cycle.

Although many chemicals can be used in the bleaching cycle, hydrogen peroxide acts as an active chemical to bleach the cloth. The hydrogen peroxide will neutralize the PHMB. Therefore, chemical cleaning and water rinse cycles should be performed prior to the addition of PHMB.

The tub 10 will then be filled with ambient cleaning water from the fresh water source 54. When tub 10 is full of water, PHMB is then released from holding tank 52 by opening eductor valve 32 and valves 25, 50, and 28, which valves 25, 50, and 28 allow fresh water to flush PHMB from holding tank 52. The PHMB is circulated through the tub 10 by a recirculation pump 34.

Alternatively, the PHMB may be pumped directly into the tank 10 from the cylinder in which it is sold, or in any other manner known in the art. Preferably, PHMB is added to the tub 10 and the volume of PHMB introduced is measured so that the concentration in the tub 10 is between 0.10% and 0.80%, preferably 0.67%.

The PHMB should be thoroughly mixed within 5 minutes, and preferably the PHMB is cycled for 15-45 minutes, more preferably about 30 minutes. Furthermore, depending on the size of the tub, the size of the fabric, and the strength of the pump, the contact time may be longer. However, it should be appreciated that when the mixing time exceeds 45 minutes, the dosage of PHMB on the dressing may have a detrimental effect on the human tissue. The temperature of the PHMB circulated through the barrel 10 should be between 40F and 140F, and preferably about 80F. The pressure of the keg during the PHMB cycle should be between 5 and 40, preferably about 20. When the chemical cycle is complete, the waste water from the drum is again discharged by pump 44 into the waste water system of the plant.

The wet bundle of cloths 12 is removed from the tub 10, at which point bleaching and antimicrobial treatment is performed. The processing is distributed to a sorting station (range station) which processes multiple beams simultaneously. The sorting station unfolds, folds, curls and dries the cloth and feeds the cloth to a conveyor. The conveyors containing successive quantities of cloth advance to cutting, folding and packaging machines to form the shape of the final product, respectively.

Preferably, the cellulosic bandage has at least 50% cellulose, most preferably 100% cellulose. The greater the percentage of cellulose, the more effective the chemical bond between the dressing and PHMB. The shape of the final product may include sponges, bandage rolls, release dressings, and other wound dressings known in the art, such as wound tape, and the like. The gauze bandage roll typically comprises 6 layers, approximately 4.5 inches by 4.1 yards. The gauze sponge was approximately 6 inches by 6.75 inches in the diagonal direction. The resulting cellulosic wound dressing primarily includes PHMB in an antimicrobial amount, while eliminating the need for additional ingredients such as anti-adhesive or intermediate layers to prevent the normal effects of PHMB on the body. It should be understood, however, that other additives may be incorporated into the cellulosic bandage, as is preferred.

The bucket system used in the present invention may be manufactured by Gaston County Dyeing machine company, located in Stanley, North Caeolina.

The advantage of using PHMB on a cellulose bandage for covering an open wound is to prevent the growth of bacteria in the dressing, but also to prevent bacteria from passing through the dressing. Although PHMB is a broad spectrum agent, it is particularly effective against organisms contaminating acute and chronic wounds. In particular, PHMB is effective against a variety of bacteria including staphylococcus aureus and pseudomonas aeruginosa. In addition, PHMB may be used alone without other ingredients to effectively kill bacteria without irritating the patient's skin and, more importantly, without irritating and preventing infection of the patient's open wound.

The following example shows how the dose of the chemical agent contained in the cloth can be calculated. It is to be understood that the invention is defined by the appended claims and not by the specific details of this example.

Examples of the invention

A bundle of grey cloths was placed in a tub and subsequently bleached. When bleaching is complete, PHMB is added to the bucket to treat the cloth bundle. PHMB, available from Avecia Inc, for treating grey cloth, has 20% active agent. The volume of chemical introduced was measured to give a concentration of 0.67% in the barrel (5 gallons PHMB/743 gallons of water). The chemical agent is circulated for 30 minutes.

Extraction was performed to determine the dose of chemical agent adhered to the cloth (grams PHMB/gram of cloth). Extraction was performed by soaking the cloths overnight in 4% saline or IM acetic acid at 56 ℃. PHMB in the formed volume was determined by UV spectrophotometer or HPLC. This value is quantified by plotting against a standard dilution curve and forming a peak. The calculated PHMB loading amount is 1500-.

Although the present invention has been described with reference to certain preferred embodiments, it will be appreciated that variations and modifications thereof can be made by those skilled in the art without departing from the scope of the invention as defined by the following claims.

Claims (26)

1. A method of making a cellulosic bandage, the method comprising: a step of applying an antibacterial dose of PHMB on the cellulose bandage.

2. The method of claim 1, further comprising: the cellulosic bandage can be in direct contact with an open wound without the need for an intermediate layer.

3. The method of claim 1, wherein: the antibacterial dosage of PHMB applied to the bandage is 1500ppm to 2500 ppm.

4. The method of claim 1, wherein: the cellulose bandage is 50% to 100% cellulose.

5. The method of claim 1, wherein: the cellulose bandage is a barrier dressing.

6. The method of claim 1, wherein: the cellulose bandage is a sponge.

7. The method of claim 1, wherein: the cellulosic bandage is a bandage roll.

8. A method of manufacturing a wound dressing having antimicrobial properties, comprising the steps of:

A) providing at least one bundle of rolled cellulosic material;

B) inserting the bundle of material into a closed container;

C) adding PHMB to a container, wherein the volume of PHMB added to the container is between 0.10% and 0.80% of the total volume of water;

D) the PHMB is cycled for a predetermined time.

9. The method of claim 8, wherein: at least one bundle of material is wound on a perforated drum through which PHMB is added to the container.

10. The method of claim 9, further comprising: a step of bleaching the strands of material prior to adding PHMB to the container.

11. The method of claim 10, wherein: the bleaching step is accomplished by pumping the bleaching agent through a perforated drum into a container.

12. The method of claim 10, further comprising: a step of chemically cleaning the strands after said bleaching step and before said step of adding PHMB to the container.

13. The method of claim 12, further comprising: a step of filling the closed container with water after the washing step and before the step of adding PHMB to the container.

14. The method of claim 8, wherein: the cycling step is carried out for between 15 and 45 minutes.

15. The method of claim 14, wherein: the cycling step was performed for 30 minutes.

16. The method of claim 15, wherein: during the step of adding PHMB, the volume of PHMB added to the vessel was 0.67% of the total volume of water.

17. The method of claim 8, further comprising: a step of discharging the wastewater into a wastewater system of the plant.

18. The method of claim 8, further comprising the steps of:

A) removing the bundle of material from the closed container; and

B) the material is unrolled for further processing.

19. The method of claim 8, wherein: the step of circulating the PHMB is performed by directing the PHMB radially outward through a perforated drum.

20. A product made according to the method of claim 8.

21. A cellulosic wound dressing comprising only an antibacterial amount of PHMB.

22. A cellulosic wound dressing according to claim 21, wherein: the antimicrobial dose of PHMB applied to a cellulosic wound dressing is between 500-3000 ppm.

23. A cellulosic wound dressing according to claim 21, wherein: the cellulosic wound dressing is 50% to 100% cellulose.

24. A cellulosic wound dressing according to claim 21, wherein: the cellulosic wound dressing is a barrier dressing.

25. A cellulosic wound dressing according to claim 21, wherein: the cellulose wound dressing is a sponge.

26. A cellulosic wound dressing according to claim 21, wherein: the cellulose wound dressing is a bandage roll.