Ultrasound patch heals venous ulcers in human trial

 

Posted on August 1, 2013 by Stone Hearth News

In a small clinical study, researchers administered a new method for treating chronic wounds using a novel ultrasound applicator that can be worn like a band-aid. The applicator delivers low-frequency, low-intensity ultrasound directly to wounds, and was found to significantly accelerate healing in five patients with venous ulcers. Venous ulcers are caused when valves in the veins malfunction, causing blood to pool in the leg instead of returning to the heart. This pooling, called venous stasis, can cause proteins and cells in the vein to leak into the surrounding tissue leading to inflammation and formation of an ulcer.
The technology was developed by researchers at Drexel University, Philadelphia, with funding from the National Institute of Biomedical Imaging and Bioengineering (NIBIB), part of the National Institutes of Health.
Venous ulcers account for 80 percent of all chronic wounds found on lower extremities and affect approximately 500,000 U.S. patients annually, a number that’s expected to increase as obesity rates climb. It’s estimated that treatment for venous ulcers costs the U.S. healthcare system over $1 billion dollars per year.
Standard treatment for venous ulcers involves controlling swelling, taking care of the wound by keeping it moist, preventing infection, and compression therapy — a technique in which patients wear elastic socks that squeeze the leg to prevent blood from flowing backwards. Despite these measures, wounds often take months and occasionally years to heal.

“Right now, we rely mostly on passive treatments,” said Michael Weingarten, M.D., chief of vascular surgery at Drexel Medicine and a researcher in the study. “With the exception of expensive skin grafting surgeries, there are very few technologies that actively stimulate healing of these ulcers.”
In an article to be published in the Journal of the Acoustical Society of America, the Drexel researchers report that patients who received low-frequency, low-intensity ultrasound treatment during their weekly check-up (in addition to standard compression therapy), showed a net reduction in wound size after just four weeks (Fig. 3a,3b). In contrast, patients who didn’t receive ultrasound treatment had an average increase in wound size during the same time period (Fig. 2a,2b).
“There have been studies on the therapeutic benefits of ultrasound for wound healing, but most of the previous research was performed at much higher frequencies, around 1-3 megahertz (MHz),” said Peter A. Lewin, Ph.D., Richard B. Beard Professor of Biomedical Engineering at Drexel, and the primary investigator on this project. “We had an idea that if we went down to the range of 20 to 100 kilohertz (kHz), which is at least an order of magnitude lower, we might see more profound changes; that’s exactly what happened.”
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