Noncontact Low-Frequency Ultrasound * for Efficient Gentle Debridement and Bioburden Control in Complex Wounds: A Case Series

Purpose: Debridement of necrotic tissue and bioburden is required to prevent disruption of the wound healing process.¹ Noncontact low-frequency ultrasound (NLFU)*, which is indicated for maintenance debridement of slough, fibrin, and bacteria, has been reported to accelerate healing in chronic lower-extremity wounds.^2-5

Case Series: NLFU was administered to three patients to painlessly debride lower-extremity wounds and reduce wound bioburden. An 89-year-old woman with peripheral vascular disease and venous insufficiency developed full-thickness ulcers of the left-lower leg. Treatment consisted of twice weekly NLFU and sharp debridement (first 4 weeks) with skin prep and hydrofiber, clear absorbant dressing. All three wounds (proximal 12.25 cm², 80% slough; distal 0.54 cm², 100% fibrin; medial 4.9 cm², 90% slough) progressed to closure in 6 weeks despite pitting edema and inability to tolerate compression therapy. A 58-year-old diabetic woman had chronic, recurrent (2 years) bilateral ankle ulcerations related to varicose veins and venous insufficiency.  The right ankle wound (reported here) measured 10 cm² with 50% slough. Treatment consisted of oral antibiotic, NLFU and sharp debridement 2-3 times weekly with dressings of zinc, silver, foam, and compression stockings. The wound was fully (100%) granulated at 1.5 weeks and completely closed at 6 weeks. A 71-year-old man with chronic renal insufficiency presented with a crush injury of the left femur and a large, necrotic left thigh wound (308 cm²). Treatment consisted of oral antibiotic, NLFU 2-3 times weekly with moisture retentive/absorptive dressings, including silver for final 2 weeks. After 6 weeks, the wound had progressed from 95% thick leathery slough to 90% granulation, and successful split-thickness graft was performed. All three patients reported decreased pain after NLFU initiation.

Discussion: NLFU provided efficient, painless debridement of heavily necrotic wounds, thus reducing bioburden, preventing severe debilitating infection, and resulting in complete wound healing or preparation for planned skin graft.