Ultrasound Patch Accelerates Venous Wound Healing

In order to determine the optimal US frequency as well as treatment duration, the researchers treated five patients with either 15 minutes of 20 kHz US, 45 minutes of 20 kHz US, 15 minutes of 100 kHz US, or 15 minutes of a sham (placebo) US.

The researchers found that the group receiving 15 minutes of 20 kHz US showed the greatest improvement, with all five patients experiencing complete healing by the fourth treatment. The clinical findings were corroborated by an in vitro study in which mouse fibroblasts experienced on average a 32% increase in cell metabolism and a 40% increase in cell proliferation compared with control cells 24 hours after receiving 20 kHz ultrasound for 15 minutes.

The battery-powered patch incorporates a transducer that produces medically relevant energy levels using minimum voltage and weighs just 100 grams, connected to two lithium ion batteries, which are fully rechargeable. The design gives patients the option of using the transducer in a home environment, while still wearing compression socks. It also prevents the need for a doctor’s visit, which can be a difficult task for patients with chronic wounds. The study describing the new US patch was published in the August 2013 issue of the Journal of the Acoustical Society of America.

“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,” said lead author professor of biomedical engineering Peter Lewin, PhD. “We had an idea that if we went down to the range of 20 to 100 kilohertz, which is at least an order of magnitude lower, we might see more profound changes; that’s exactly what happened.”

The researchers anticipate that patients with other types of chronic wounds such as diabetic or pressure ulcers may also benefit from therapeutic US. As a result, they have developed and are currently testing a diagnostic monitoring component that uses near infrared spectroscopy (NIRS) to noninvasively assess changes in the wound bed, which could reveal whether a treatment is working in its earliest stages, when healing is difficult to detect with the naked eye.

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