Method for dressing a wound

Abstract

A method for dressing a wound is provided including providing a wound dressing pad of hydrophobic fabric that is treated to bind microorganisms; placing the hydrophobic fabric so that it faces the wound; and applying negative pressure therapy to the wound dressing so that microorganisms in the wound surface adhere to the dressing through hydrophobic interaction. The negative pressure therapy may be alternated with hyperbaric oxygen treatments of the wound dressing.

Claims

1. A method of treating a wound, comprising: a) providing a wound dressing consisting of a hydrophobic fabric that is treated to bind microorganisms through hydrophobic interaction, wherein the hydrophobic fabric is a cellulose acetate gauze treated with a compound containing hydrophobic groups selected from the group consisting of dialkyl carbamoyl chloride, dioctadecyl carbamoyl chloride and alkyl ketene dimers, and wherein the wound dressing does not contain an antimicrobial substance; b) placing the hydrophobic fabric so that it faces the wound; and c) applying negative pressure therapy to the wound dressing, thereby treating the wound.

2. The method of claim 1, further comprising alternating the negative pressure therapy with hyperbaric oxygen treatments of the wound dressing.

3. The method of claim 1, further comprising providing a drain line configured for attachment to a negative pressure source and for removing exudate from the wound; a supply line configured for attachment to a fluid source and for supplying fluid to the wound; and a controller configured to cause negative pressure therapy to be administered to the wound via the drain line.

4. The method of claim 3, wherein the controller is further configured to cause hyperbaric fluid therapy to be administered to the wound via the supply line.

5. The method of claim 4, wherein the controller is further configured to cause hyperbaric fluid therapy to be administered to the wound at an absolute pressure of at least approximately 1.5 atmospheres via the supply line.

6. The method of claim 4, wherein the hyperbaric fluid therapy utilizes oxygen.

7. The method of claim 4, wherein the controller is further configured to control the administration of negative pressure therapy and hyperbaric fluid therapy such that the administration of negative pressure therapy and hyperbaric fluid therapy is cyclical and the hyperbaric fluid therapy alone or together is administered to the wound for no more than 30 minutes during each cycle.

8. The method of claim 4, wherein the negative pressure therapy and hyperbaric fluid therapy are administered intermittently.

9. The method of claim 4, wherein the fluid source is configured to supply a constant flow of fluid such that the administration of negative pressure therapy is accomplished by activating the negative pressure source and the administration of hyperbaric fluid therapy is accomplished by deactivating the negative pressure source.

10. The method of claim 4, wherein the administration of negative pressure therapy is accomplished by activating the negative pressure source and reducing the flow of fluid from the fluid source.

11. The method of claim 4, wherein the administration of negative pressure therapy is accomplished by not having any flow from the fluid source.

12. The method of claim 4, wherein the administration of hyperbaric fluid therapy is accomplished by deactivating the negative pressure source and increasing the flow of fluid from the hyperbaric fluid source.

13. The method of claim 4, wherein the negative pressure and fluids are supplied by a portable unit.

14. The method of claim 1, wherein negative pressure therapy is administered for about 20-180 seconds followed by hyperbaric fluid therapy, or negative pressure therapy is followed by non-therapy to provide intermittent negative pressure therapy.

15. The method of claim 1, wherein negative pressure therapy is administered for about 10-60 seconds followed by hyperbaric fluid therapy, or negative pressure therapy is followed by non-therapy to provide intermittent negative pressure therapy.

16. The method of claim 1, wherein the administration of negative pressure therapy comprises exposing the wound pressures ranging from about 60-160 mm Hg.

17. The method of claim 1, wherein applying negative pressure therapy to the wound dressing increases the binding of microorganisms to the hydrophobic fabric.

18. The method of claim 1, further comprising placing a sealing material on top of the wound dressing and optionally over a drain line and a supply line.

19. The method of claim 1, wherein the hydrophobic fabric is treated with dioctadecyl carbamoyl chloride or alkyl ketene dimers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an overview of the treated wound site according to the invention herein.

(2) FIG. 2 shows a schematic set-up of a system of the invention herein.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF

(3) The product of the invention is ideal for treatment of wounds. It protects the wound, removes exudate and reduces the number of pathogenic microorganisms, without using antimicrobial substances. In the method of the invention, the wound is treated with vacuum and possibly alternating hyperbaric oxygen treatments using a wound dressing based on the Sorbact principle discussed above, for example, products such as the Sorbact pad consist of folded acetate gauze and cotton gauze treated with the fatty acid ester DACC (dialkyl carbamoyl chloride) or dioctadecyl-carbamoyl chloride or an alkyl ketene dimer (AKD) so that the Sorbact pads have a strong hydrophobic property and pathogenic microorganisms in the wound surface adhere to the pad through hydrophobic interaction. The pad can optionally be rendered cation active. Such pads have possibly two primary components, the first of which has one or more liquid permeable layers of a hydrophobic and possible cationic, bacteria-adsorbing, physiologically innocuous material containing a woven or nonwoven hydrophilic fabric. The fabric has been rendered hydrophobic by chemical treatment with a compound containing hydrophobic groups. The optional second component consists of one or more layers of a hydrophilic, liquid absorbing, physiologically innocuous material. The hydrophilic liquid-absorbing material effects a liquid flow by suction of exudate from the wound. If the microorganisms exhibit hydrophobic surface structures they will accompany this flow of liquid and come in contact with the hydrophobic component and bind.

(4) In its basic embodiment the wound dressing used in the invention herein is a bacteria-adsorbing composition in water-insoluble form which includes a first component comprising one or more liquid permeable layers of a powerfully hydrophobic, bacteria adsorbing, physiologically innocuous material comprising a woven or non-woven hydrophilic fabric, which has been rendered hydrophobic by chemical treatment with a compound containing hydrophobic groups, and a second component comprising one or more layers of a hydrophilic, liquid absorbing, physiologically innocuous material, at least one layer of hydrophilic material being located externally of at least part of the hydrophobic material as viewed from the surface to be treated, as set forth in U.S. Pat. No. 4,617,326, the disclosure of which is incorporated herein, used together with vacuum or alternating vacuum and hyperbaric oxygen treatments of the wound dressing supplied from an apparatus for the treatment of a wound on a patient. The apparatus includes a drain line configured for attachment to a negative pressure source and for removing exudate from the wound; a supply line configured for attachment to a fluid source and for supplying fluid to the wound; and a controller. The controller is configured to cause negative pressure therapy to be administered to the wound via the drain line. The controller is further configured to optionally cause hyperbaric fluid therapy, for example using oxygen, to be administered to the wound via the supply line. The controller is further configured to cause hyperbaric fluid therapy to be administered to the wound at an absolute pressure of at least approximately 1.5 atmospheres via the supply line.

(5) A wound treatment apparatus that includes a drain line configured for attachment to a negative pressure source and for removing exudates from the wound, for example the system disclosed in WO 2007/062024 or a similar system, can be used. The apparatus further includes a supply line configured for attachment to a fluid source and for supplying fluid to the wound and a controller. The controller is configured to cause negative pressure therapy to be administered to the wound for a first time period via the drain line, and cause hyperbaric fluid therapy to be administered to the wound for a second time period via the supply line, wherein the first time period is approximately two to three times as long as the second time period. The apparatus further includes a controller that is configured to cause negative pressure therapy to be administered to the wound via the drain line, and optionally to cause hyperbaric fluid therapy to be administered to the wound at via the supply line. The controller is further configured to control the administration of negative pressure therapy and hyperbaric fluid therapy such that the administration of negative pressure therapy and hyperbaric fluid therapy is cyclical and the hyperbaric fluid therapy alone or together is administered to the wound for no more than 30 minutes during each cycle. The negative pressure therapy and hyperbaric fluid therapy may be administered intermittently. The fluid source may be configured to supply a constant flow of fluid such that the administration of negative pressure therapy is accomplished by activating the negative pressure source and the administration of hyperbaric fluid therapy is accomplished by deactivating the negative pressure source.

(6) The administration of negative pressure therapy may also be accomplished by activating the negative pressure source and reducing the flow of fluid from the fluid source, or by not having any flow from a fluid source. Similarly, the administration of hyperbaric fluid therapy may be accomplished by deactivating the negative pressure source and increasing the flow of fluid from the hyperbaric fluid source. While each of the negative pressure therapy and the hyperbaric fluid therapy could potentially be administered to the wound 2 for hours before alternating to the other therapy, it is presently preferred that the controller 9 cause negative pressure therapy to be administered to the wound 2 for relatively short periods of time. For example, negative pressure therapy may be administered for approximately 20-180 seconds before moving on to hyperbaric fluid therapy or to non-therapy in the event that the apparatus is set to intermittently apply only negative pressure therapy. Similarly, the controller 9 may cause hyperbaric fluid therapy to be administered to the wound 2 for approximately 10-60 seconds before moving on to negative pressure therapy or to non-therapy in the event that the apparatus is set to intermittently apply only hyperbaric pressure therapy.

(7) As will be understood by those of skill in the art, the administration of negative pressure therapy generally involves exposing the wound 2 to pressures of less than 1 atmosphere. The pressures employed during negative pressure therapy may include absolute pressures ranging from approximately 0 mm Hg to approximately 300 mm Hg. Preferably, the absolute pressure ranges from approximately 60 mm Hg to approximately 160 mm Hg during the administration of negative pressure therapy.

(8) FIG. 1 shows an example overview of the treated wound site according to the invention herein, where: the skin 1 of a patient, has a wound 2, to be treated by the invention herein, using the woven Sorbact pad 6, on top of the wound 2, and a drain line 4 on top of the Sorbact pad 6, and an optional drain device 5 fixed to the end of the drain line 4, and an optional supply line 3 on top and everything under a sealing material 7 to make the negative pressure and hyperbaric treatment possible.

(9) The system for supplying the negative pressure and fluids can be a portable unit as disclosed above or fixed bedside installations for suction and oxygen in hospitals can be used together with a controller and tubing according to FIG. 2, where the wound 2 is dressed according to FIG. 1 and connected to the fluid-source 10, via the supply-line 3 and to the negative pressure source 8, via the drain-line 4 and the negative pressure source 8 and fluid source 10 are controlled by the controller 9.

(10) Other objects and features of the inventions will be more fully apparent from the following examples and appended claims.

Example 1

Manufacture of Wound Dressing Product

(11) In this example, a standard wound dressing is manufactured based on the invention in the following manner:

(12) Materials: (From Inside-Out)

(13) TABLE-US-00001 COMMERCIAL LAYER PRODUCT NAME MANUFACTURER 1. Hydrophobic layer Green Cellulose Acetate ABIGO Medical AB woven prepared according Sweden to U.S. Pat. No. 4,617,326 2. Optional Adhesive National 505E National Starch & Chemical Ltd., United Kingdom 3. Optional Absorbent (Airlaid) Concert Concert GmbH, material MH080.104.P000 Falkenhagen, Germany

(14) A. The hydrophobic layer is preferably produced according to U.S. Pat. No. 4,617,326 by applying to a cellulose acetate fabric an amount of dioctadecyl carbamoyl chloride DACC or AKD as disclosed in this patent making a covalent bond between the materials. The acetate fabric is on rolls of 50 m length and at a width of 1 m, and taken as such to the next step.

(15) B. The optional bonding of the hydrophobic layer with the absorbent layer is made in a machine for the purpose, having a suitable applicator for the hot-melt, a slot applier, and heated rolls for the bonding of the two materials, so called nip rolls, as is known in the art. In order to minimize the risk for the adhesive to bleed through the surface layer it is preferable to put the hot melt layer on the absorbent layer. In prior test runs it was found that the risk for the adhesive to bleed through the hydrophobic cellulose acetate layer increases dramatically if the amount of adhesive is >10 g/m.sup.2. Decreasing the amount of adhesive, however, reduces the lamination strength. The ideal amount of adhesive is between 7-10 g/m.sup.2. In our prior test runs we found a hot melt temperature of 150 degrees C. to work well together with pre heated nip rolls.

(16) Test of Lamination Strength:

(17) The test sample is placed in water solution with 0.9% NaCl or defibrillated sheep blood for one hour. The layers are separated from each other and the lamination strength is measured. If possible it should be at least 10 gram/cm, but preferably >20 gram/cm width Because it can sometimes be difficult to get hold of the layers in order to separate them, a knife or tweezers with sharp edges may be used, or the sample may be prepared prior to the water test by separating the layers from each other by leaving flaps to grab.

(18) Other Tests:

(19) Adhesive bleeding through the green cellulose acetate woven fabric is tested by pressing samples of the laminated material surface layer (green woven material) hard against each other. Only a minor sticking is acceptable.

(20) Blood clotting is tested by application of 0.3 ml of defibrillated sheep blood on top of the lamination. The blood should easily pass through the green cellulose acetate woven layer and leave only small amounts of blood on the surface.

(21) After the bonding process of the hydrophobic acetate layer and the absorbing layer, the now bonded materials are still in a roll form, which is taken to the cutting step.

Example 2

Use of the New Dressing Product to Bind Pathogens in a Liquid Drench Without Applying Vacuum

(22) Material: Wound dressing as described in Example 1 Bacterial strains: Staphylococcus aureus Newman, Pseudomonas aeruginosa 510, Enterococcus faecalis, Candida albicans

(23) Isolates were cultured on agar with 5% horse erythrocytes in 5% CO.sub.2 atmosphere at 37 C. Suspensions were made in phosphate-buffered saline (PBS, 0.02 M sodium phosphate and 0.15 M sodium chloride, pH 7.2) at 10.sup.9 bacterial cells/ml, 10.sup.7 fungal cells/ml or indicated concentration.

(24) The dressing was cut in 1 cm.sup.2 pieces. Incubation was made in 24 well polymer plates. 1 ml of suspension was added to each dressing. The plates were placed on a rotary shaker at very low speed. Incubation was performed at room temperature for the indicated time. After incubation, dressings were rinsed in PBS several times, and then put in 2.5% TCA (tricarboxylic acid).

(25) The ATP content was measured in a luminometer (LKB Wallac). Controls: the number of adhered bacteria (CFU/ATP) was normalized against the number of total added bacteria (CFU/ATP), and the blank (no bacteria, only EDTA-Tris buffer) was the ATP value control.

(26) Results:

(27) S. aureus >10.sup.5 cells adhered during 30 sec, 1, 5 and 10 minutes, and then increased to 10.sup.6 cells after 2 hrs. Some multiplication occurred during the following 24 hrs to reach 510.sup.6 cells/cm.sup.2. P. aeruginosa Around 10.sup.6 cells adhered during 30 s, 1, 5 and 10 min, and then increased during 30 and 60 min incubation to reach 10.sup.7 cells/cm.sup.2 after 2 hrs incubation. No multiplication of adhered bacteria occurred during the following 24 hrs.

(28) The maximal adsorption was when 510.sup.9 cells of S. aureus were added and 10.sup.8 cells adhered; for P. aeruginosa, 10.sup.8 cells adhered out of 10.sup.9.5 added; and for E. faecalis, 810.sup.6 out of 510.sup.10 added. For C. albicans the slope levels off, and 10.sup.5 cells adhered out of 10.sup.7.5 added.

(29) Conclusion: Under ideal conditions, the test dressing with the hydrophobic layer, such as this liquid drench, is a good adsorber of different important and potential pathogens in wound healing.

Example 3

Test of the New Dressing on a Rough Surface Without Applying Vacuum

(30) A standardized pig wound model is used (BMC Surg. 2008; 8: 5. Hirsch et al; Enhanced susceptibility to infections in a diabetic wound healing model) and the experimental protocol of Example 2. The maximal adsorption to the Sorbact is measured after 2 hours. When 10.sup.9 cells of S. aureus are added, 10.sup.6 cells adhere, for P. aeruginosa 10.sup.5 cells adhere out of 10.sup.9.5, and for E. faecalis 110.sup.5 cells out of 510.sup.10 adhere. For C. albicans, 10.sup.3 cells adhere out of 10.sup.7 added.

Example 4

Application of Vacuum/Suction and Hyperbaric Pressure

(31) The application of vacuum/suction to the wound dressing discussed above is preferably according to WO 2007/062024 (published May 31, 2007), the disclosure of which is incorporated herein, or methods known in the art that accomplish the same result(s). In particular, the apparatus used therefore preferably includes a drain line that attaches to a negative pressure source, giving 40 mmHg to approximately 120 mmHg negative pressure so that exudates may be removed from a wound. The vacuum level should never be painful, if the patient report discomfort, reduce the under-pressure. An example of one such portable pump is the PROSPERA PRO-I (Prospera Inc, 2831 Bledsoe Street Fort Worth, Tex. 76107, U.S.A.) A controller of this pump, or comparable thereto, controls the administration of the negative pressure therapy.

Example 5

Test of the New Dressing and Vacuum on a Rough Surface

(32) The same experimental set up as in example 3 is used but now combining the Sorbact pad with vacuum as in example 4. The maximal adsorption to the Sorbact pad is measured after 2 hours. When 510.sup.9 cells of S. aureus are added, 10.sup.8 cells adhere, for P. aeruginosa 10.sup.7 cells adhere out of 10.sup.9.5, and for E. faecalis 10.sup.7 out of 10.sup.10. For C. albicans, 10.sup.6 cells adhere out of 10.sup.7 added.

(33) While the invention has been described with reference to specific embodiments, it will be appreciated that numerous variations, modifications, and embodiments are possible, and accordingly, all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of the invention.