Cath Lab Digest

A n important aspect of preparing wound beds for healing is debridement - removal of non-viable or necrotic tissue until only healthy tissue is exposed. Wounds with necrosis have high levels of bacteria and toxins¹ and are more likely to have a prolonged inflammatory response and healing process with increased risk for development of acute or chronic infection.^2-6 This may increase the potential for development of a slow or nonhealing, recalcitrant wound.^4,5,7,8 Debriding necrotic tissue removes a large source of bacteria,¹ which helps diminish the inflammatory response, decrease toxin production, and move the wound into the proliferative phase more rapidly. In addition, complete debridement allows clinicians to stage or grade the wound and evaluate the healing progress. Debridement may be completed early in wound care and/or throughout the entire wound healing process. Clean wounds without necrotic tissue create the best possible local environment for healing.

Debridement can be non-selective or selective. Non-selective methods, such as mechanical, include wet-to-dry gauze, whirlpool, and surgical debridement.⁷ Wet-to-dry gauze dressings are often applied incorrectly, making them less effective for debridement.⁹ They allow wound bed tissues to dry out, potentially prolonging the healing process. The non-selective debridement facilitated by wet-to-dry gauze dressings delays healing by adhering to and removing living tissue and is quite painful. Wet-to-dry dressings should be changed several times daily to be most effective, making the method labor intensive, costly, and complex. Thus, considering wet-to-dry gauze dressings a standard of care may be erroneous.¹⁰

Selective methods include autolytic, conservative sharp, and enzymatic debridement. To achieve a clean wound using some of these traditional methods of debridement may take weeks or even months. Autolytic debridement is accomplished by keeping wounds continually moist, allowing the host's own white blood cells and enzymes to liquify the necrotic tissue. People with ineffective inflammatory responses or large amounts of necrotic tissue will not have effective debridement with this method alone. Conservative sharp debridement is effective and rapid, but access to qualified and certified personnel may be limited. Sharp debridement methods do not remove all necrotic tissue; thus, adjunctive methods are required.

Many clinicians use enzyme agents for debridement. Enzyme preparations exert their selective debridement activity by denaturing and digesting proteins. Enzymes may have variable effectiveness based on the pH of the wound and type of necrosis.^8,11 However, as a practical matter, clinicians do not test wounds for pH. The effectiveness of enzymes depends on the skill of the caregiver to appropriately apply and cleanse the enzyme and debris from the wound.⁵ Further, not all enzymes are indicated for infected wounds, as they are not reported to have a direct effect on bacteria.

In addition to these methods, specific types of polymers - polyacrylates - may enhance selective autolytic debridement. Moisture-activated polyacrylate dressing pads selectively debride by attracting and permanently removing proteins from necrotic tissue, as well as by attracting and retaining toxins and bacteria.^12,13 Removal of these proteins breaks down the structure of the necrotic tissue. An activated polyacrylate dressing is indicated for use in any kind of wound where moist wound therapy is desired.