A Closer Look At Ultrasonic Debridement

Martin E. Wendelken, DPM, RN, Lee Markowitz, DPM, and Oscar M. Alvarez, PhD

Can ultrasonic debridement facilitate improved wound healing? Sharing insights from their clinical experience as well as the literature, these authors discuss the mechanism of ultrasonic debridement, how it compares to other debridement methods and offer perspectives on the advantages and weaknesses of ultrasonic debridement.

   Ultrasound in medicine continues to help the clinician treat and evaluate numerous conditions and pathologies. Diagnostic ultrasound at frequencies of 5 to 12 MHz provides the ability to view the musculoskeletal system for pathology in addition to evaluating arterial and venous blood flow. Therapeutic ultrasound for physical therapy uses frequencies ranging from 0.7 to 3.3 MHz. This treatment provides the benefits of both thermal and non-thermal effects on soft tissue.1

   Low-intensity pulsed ultrasound (at 1 kHz) provides a mechanical stimulus that helps bones heal as in the case of both traumatic and surgical nonunions.2 Low-frequency ultrasound (22 kHz to 35 kHz) has also found a home in wound care. One may utilize this modality to remove devitalized tissue as a selective method of wound debridement.

   Debridement of non-viable tissues is necessary for wound improvement and healing, and is considered a cornerstone of acute or chronic wound management. Research has shown that removing non-viable tissues decreases the incidence of infection and accelerates the rate of closure.3,4

Reviewing The Different Methods Of Debridement

Methods of debridement include sharp debridement, mechanical debridement, autolytic debridement, biosurgical debridement and chemical (enzymatic) debridement.
The term surgical or sharp debridement does not necessarily imply aggressive debridement. The level of invasiveness defines aggressive debridement. Sharp debridement describes the use of surgical instruments such as scissors, scalpels, curettes or other sharp blades to remove devitalized tissue.

   Sharp debridement can be invasive (aggressive) or non-invasive (conservative). For example, removing eschar from a pressure ulcer that you have clearly differentiated from viable tissue is considered conservative even if you use a blade or scissor. Sharp debridement, if the physician performs it conservatively, does not require anesthesia or hemostasis. This is the fastest type of debridement.

   Autolytic debridement is a form of chemical debridement but does not involve treating the wound with a therapeutic agent. It is the process by which the wound bed clears itself of devitalized tissue and cellular debris via phagocytic cells and endogenous proteolytic enzymes present in the wound or in wound fluid.

   Autolytic debridement usually requires the use of a moist, hypoxic environment provided by an occlusive dressing. The debridement by autolysis of deep pressure ulcers or diabetic neuropathic foot ulcers is not as predictable as with venous ulcers or more superficial pressure ulcers, and may take a longer time.5

   Chemical debridement involves the application of topical agents (enzymatic or non-enzymatic) that chemically disrupt or digest devitalized extracellular proteins present in the wound. Most of the research work in the field of chemical debridement has dealt with the use of enzymes with proteolytic action.6

   Biosurgical debridement involves myiasitic maggots, which feed on dead tissue, resulting in the cleaning of the wound bed.7

   Mechanical debridement may be aggressive or conservative. Mechanical debridement methods include hydrosurgery, forceful irrigation (high-pressure saline debridement), therapeutic ultrasound hydrotherapy and the use of wet-to-dry gauze dressings. The difference between mechanical debridement and other methods is that mechanical debridement does not discriminate between viable and nonviable tissues.

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