In a small clinical study, researchers found a new, wearable ultrasound patch significantly accelerated healing in five patients who had venous ulcers, according to a news release.
The ultrasound applicator, which can be worn like a bandage, delivers low-frequency, low-intensity ultrasound directly to wounds. It was developed by researchers at Drexel University in Philadelphia with funding from the National Institute of Biomedical Imaging and Bioengineering, part of the National Institutes of Health.
Venous ulcers, caused when valves in the veins improperly function and allow blood to pool in the leg, account for 80% of all chronic wounds found on lower extremities and affect about 500,000 U.S. patients each year, according to the release. That number is expected to increase as obesity rates climb. Treatment for venous ulcers costs the U.S. healthcare system more than $1 billion per year.
Standard treatment for venous ulcers involves controlling swelling, keeping the wound moist, preventing infection and using compression therapy. Despite these interventions, wounds often take months and occasionally years to heal.
Right now, we rely mostly on passive treatments, Michael Weingarten, MD, chief of vascular surgery at Drexel Medicine and one of the researchers, said in the release. With the exception of expensive skin grafting surgeries, there are very few technologies that actively stimulate healing of these ulcers.
In an article published in the Journal of the Acoustical Society of Americas August 2013 Special Issue on Therapeutic Ultrasound, the researchers found patients who received ultrasound treatment during their weekly visits and standard compression therapy showed a net reduction in wound size after just four weeks. In contrast, patients who did not receive ultrasound treatment had an average increase in wound size during the same time period.
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 to 3 megahertz, primary investigator Peter A. Lewin, PhD, the Richard B. Beard Professor of Biomedical Engineering at Drexel, said in the release. We had an idea that if we went down to the range of 20 to 100 kilohertz we might see more profound changes; thats exactly what happened.
To determine the optimal ultrasound frequency and duration, the researchers treated patients with either 15 minutes of 20 kHz ultrasound, 45 minutes of 20 kHz ultrasound, 15 minutes of 100 kHz ultrasound or 15 minutes of a sham ultrasound (placebo). Each group included five patients. The group receiving 15 minutes of 20 kHz ultrasound showed the greatest improvement, with all five patients wounds healing completely by the fourth treatment.
The ultrasound patch weighs 100 grams equivalent to a king-size candy bar and is connected to two rechargeable lithium ion batteries. Lewin said the design gives patients the option of using the transducer at home, while still wearing their compression socks.
Larger studies are needed to confirm the results and safety, but the technology is promising for future treatment of chronic wound patients, according to Hector Lopez, PhD, NIBIB program director for Diagnostic and Therapeutic Ultrasound.
Study abstract: http://asadl.org/jasa/resource/1/jasman/v134/i2/p1541_s1?isAuthorized=no