Wound Management Recommendations

Ted Stashak, DVM, MS, Dipl. ACVS, emeritus professor of veterinary medicine and surgery at Colorado State University, and Laurie Goodrich, DVM, MS, Dipl. ACVS, of Cornell University, moderated a table topic on wound management at the 50th annual American Association of Equine Practitioners (AAEP) Convention, held Dec. 4-8, 2004 in Denver, Colo.

Stashak noted that for heavily contaminated and infected wounds, the wet-to-dry plain gauze or antimicrobial-impregnated gauze (Kerlix AMD antimicrobial dressing, Tyco Healthcare/Kendall, Mansfield, MA) dressing can be effective, but they are often used for too long a period. In general, the gauze is wetted with a sterile salt solution, excess fluid is squeezed out, and the dampened dressing is applied to the wound surface.

For plain gauze, a dilute 0.01% (1 mL/100 mL) povidone iodine or 0.05% (1:40 dilution) chlorhexidine or physiologic saline solution alone are most commonly used to wet the material.

If Kerlix is used, the gauze is moistened with saline alone. When applied to the wound surface, the moisture liquefies the wound exudate, allowing movement (egress) of fluid and bacteria through the gauze mesh. As the dressing dries, fibrin from the wound bed causes temporary bonding of the dressing to the wound bed. As the dressing is peeled off the wound, fibrin, debris, bacteria, and necrotic (dead) tissue are removed (debrided) from the wound surface. Since the debridement process is non-selective, and healthy newly formed tissue can be damaged, he recommended using them for one or two bandage changes only. Once the wound appears clean, another dressing type is indicated.

He also advised against using an occlusive dressing that promotes moist wound healing on an infected wound. It is better to use a dressing that "lifts and stores" the exudate (pus) away from the wound surface.

Stashak says many of the newer dressings are designed to create a moist wound healing environment, which allows the wound fluids to remain in contact with wound. A moist wound that is free of infection provides an environment rich in white blood cells, enzymes, and growth factors beneficial to wound healing. The enzymes released primarily from the white blood cells cause "autolytic debridement" of the wound (the wound cleans itself), which appears to be selective for necrotic (dead) tissue. Under these dressings, autolytic debridement usually occurs 72-96 hours after wounding, thus cleaning the wound in preparation for the repair phase. Wound healing is stimulated by growth factors present in the moist wound.

Goodrich said it is not necessary to scrub a wound to clean it. She said you can put toxic amounts of Betadine on a wound and hurt the healing at later phases if you continue to "clean" a wound after the initial debridement. She does think that with a contaminated wound, you should be aggressive in the beginning to debride it and get rid of the bacteria. That makes it easier to treat the wound on the second and third days, she added.

Stashak added that clinicians have the most influence on the debridement phase of wound healing, and he advises "sharp" debridement and low-pressure (10-15 PSI, or pounds per square inch, of pressure) lavage. He said bacteria on the surface of a wound can migrate into the tissue and begin to destroy it within three hours. If there is pus, then the superficial tissues are infected and you should get rid of cells where bacteria are replicating.

Stashak said he has no problem with using Betadine scrub to clean a heavily contaminated wound as long as the wound is thoroughly flushed/rinsed afterward.

One veterinarian from the audience asked about using a flap of skin in an avulsed (torn away) wound to cover exposed areas of a wound. Stashak said if he can temporarily suture a viable skin flap in place to prevent retraction (shrinking) of the skin flap and dehydration of the wound surface, he does. If the wound is contaminated, he debrides it, after which he will stabilize the skin flap in place with several strategically placed large diameter sutures (e.g. #1 or #2 monofilament Nylon) tied in a bow knot. Following this, the wound is bandaged, either with a "Stent" bandage for the upper body, which is stabilized with sutures, or a standard limb bandage for the distal extremities. If the wound needs further debridement after several days, the bandage is removed, the suture knots are untied to expose the wound bed, and the wound is debrided again. Once the wound is clean it can be sutured by delayed primary closure.

Another veterinarian asked about using hydrogen peroxide to clean a wound. Goodrich doesn't recommend it, and Stashak said, "There is no place for it." He said 3% hydrogen peroxide has a narrow (minimal) spectrum of antimicrobial activity, and it causes thrombosis (plugging) of the small vessels in the wound bed. The veterinarian countered that medical doctors use it. "They shouldn't," was Stashak's reply.

A question from the audience asked what was most "tissue friendly" to clean a wound. Goodrich said her primary response to a wound is to get rid of the bacteria, then use saline because it is the most "friendly" to the tissues.

Stashak said some wounds are huge and it takes a hose to clean them thoroughly, but there is a problem with cells absorbing water, which can lead to a problem if the wound is continually flushed during the repair phase. He prefers a spray bottle with saline and diluted (1/100mL) povidone iodine solution to lavage smaller wounds.

In discussing low-pressure lavage (10-15 PSI), Stashak mentioned the Stryker Interpulse battery-driven lavage machine (www.Stryker.com) that can be used in the field to give low-pressure (12-15 PSI) lavage. He said there is a huge amount of data on the value of low-pressure lavage for wound care.

Stashak said 10-15 PSI is the most effective to remove bacteria from the surface of a wound. One member of the audience said a clean 2-3 gallon garden sprayer filled with antiseptic (25 cc of salt to one gallon of water) can make an effective lavage in the field.

A question was raised about the controversy of shaving vs. clipping around a wound. Stashak said there is a huge amount of data that shows using a depilatory (chemical hair remover) such as Nair is better than shaving or compared to no hair removal. He said clipping or shaving can contaminate the wound with foreign bodies (hair fragments), which increases the wound's susceptibility to infection. Therefore, he recommends the wound be covered with a moistened towel or gauze and the hair surrounding the wound be wetted to prevent the clippings and shavings from contaminating the wound bed. Both clippers and razors can damage the skin; he noted studies have shown that clipping and shaving a surgical site for an elective surgery should be done after induction of anesthesia and very close to time of the surgery. Clipping four hours before an elective surgery can give a three-fold increase in the chance of infection, he explained. Stashak recommends using a guarded razor rather than a free blade such as a "Weck blade."

Goodrich also advised not to use products on wounds that contain petroleum, which has been found to impair wound healing.

A question from the audience asked about topical medications for sutured wounds. Stashak said he doesn't use them--he simply uses a sterile dressing over a sutured wound. He said if the veterinarian has done the job correctly by debriding, using antibiotics, and creating a "new" wound to heal properly, then topical medications shouldn't be needed for the sutured wound. He advised using double gloves and separate instruments for debriding a contaminated wound. Once the wound is debrided, the outer gloves are removed, the wound is redraped and new instruments are used to suture the wound.

Someone asked about the value of DMSO gel around a suture line, not on it; both Stashak and Goodrich said there were no data indicating that this was indicated or a good idea. DMSO gel should not be applied full strength around a wound underneath a bandage; the gel can cause blisters.

 The wound healing product Acell was discussed. Negatives and positives were presented. Stashak concluded that he thinks there is a place for Acell therapy in wound management, but that its use needs to be better defined.

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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