In the past, bloodletting was used to "cure" almost every disease.1 The procedure was recommended in ancient civilizations by the famous healers Papyrus in Egypt and Hippocrates in Greece. Before lower limb amputations, bloodletting included the removal of a quantity of blood equal to the amount perfusing the limb that was scheduled to be removed. Bloodletting was performed for many years by barbers (hence the red-striped pole) as an extension of their razor use; later this was undertaken by surgeons.2 The bloodletting procedure remained in Dr William Osler's classic book The Principles and Practice of Medicine until 1923.3 In modern medicine, bloodletting is still performed selectively when patients have overabundant red blood cells because of hematologic disorders.
As outlined in this month's continuing education article, several methods of modern debridement are available to wound care clinicians (biological, autolytic, mechanical, enzymatic, conservative and acute surgical) and some patients require more than one option. The most important step prior to debridement is to determine (1) if there is an adequate blood supply to heal and (2) if the cause of the wound has been corrected. If debridement is attempted surgically without first treating the cause of the wound, a larger wound is created that advantages bacterial tissue invasion and disadvantages host tissue.
Conservative surgical debridement removes slough/necrotic tissue, foreign material, and bacterial surface organisms including biofilms. A biofilm contains a protective glycocalyx that is difficult for topical antimicrobial agents to penetrate. Iodine is a small molecule and penetrates biofilm glycocalyx more efficiently than silver or other larger molecular weight antiseptic agents.4
Active surgical debridement (such as bloodletting) also removes viable cells, but it is a selective process adjacent to the wound surface, creating an acute wound within the chronic wound that accelerates wound healing. In a randomized controlled study, Steed et al5 found that wound bed preparation with regular active surgical debridement was more effective for healing diabetic neurotropic foot ulcers than conservative debridement. Further, the addition of adjunctive therapy (platelet-derived growth factor) was more effective when combined with regular active surgical debridement.5 The ability to perform active surgical debridement depends on the healthcare professional's scope of practice and expertise as well as institutional, state, or province regulations.
Mechanical debridement, which refers to tissue removal by an external force, can be performed by several methods, including running water in a jet stream, whirlpool bath, shower, or syringe/catheter. In this issue of Advances, Xu and colleagues report using negative-pressure wound therapy as a mechanical debridement procedure. This procedure lasted 3 months and the time to prepare for skin grafting may have been even shorter with active surgical debridement between dressing reapplications.
Sterile maggots from the green bottle fly (Lucilla sericata) ingest dead tissue, release antibacterial substances, and may eliminate antibiotic-resistant bacteria. They offer a useful alternative in the debridement toolkit if maggots can be obtained in a timely fashion and the cost is covered by the patient's healthcare system. There is an "ick" factor for many patients, and even some professionals, that may be partly addressed by containment in a mesh bag; however, debridement is slower in a containment device versus free range activity. Leeches have also been FDA-approved to pierce distal skin with their teeth, release anticoagulant saliva, and extract blood for 20 to 45 minutes (eg, to treat a patient's toe that has a diabetes-related microvascular clot).
Autolytic debridement from dressings is slower than biologic, mechanical, or surgical debridement methods. This process can be facilitated by any moisture exchanging, non-fluid-lock dressings including calcium alginates, foams, hydrocolloids, and films.
The sixth selective method of debridement is accomplished by applying an enzyme (eg, collagenase) to the wound bed. A prescription is required (enzymes are classified as drugs) and clinicians need to follow the FDA-approved product labeling regarding dosage, application, precautions, and contraindications. This method of debridement usually requires daily dressing changes and is an alternative option when methods requiring licensed clinical expertise are not available. When indicated, debridement methods are a key component of wound bed preparation.
R. Gary Sibbald, MD, MEd, FRCPC, FAAD, JM
Elizabeth A. Ayello, PhD, MS, RN, CWON, FAAN
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