Venous ulcers are nasty things, often found on the lower extremities of elderly or inactive people. They occur when high blood pressure causes the skin adjacent to the affected veins to break down, leaving open wounds that take months or even years to heal. Standard treatments include compression bandages, infection control and standard wound dressings, although these approaches don't work in all cases. Now, however, scientists are getting good results using band-aid-like patches that emit ultrasound into the ulcers.
It's been suspected for some time that ultrasound could have a curative effect on the ulcers, although most studies have investigated the use of fairly high frequencies – around 1 to 3 megahertz. Instead, a group of scientists from Philadelphia's Drexel University tried using frequencies that were considerably lower.
Test subject patients were divided into four groups, each group receiving either 20 kHz for 15 minutes, 20 kHz for 45 minutes, 100 kHz for 15 minutes, or 15 minutes of a placebo. It was the first group that ultimately came out best, with all five participants completely healed as of their fourth session. By contrast, the ulcers on the placebo group actually got worse over the same time period.
It's still not exactly clear why a longer exposure to the ultrasound doesn't work even better, but the scientists did achieve similar results when they tested the affects of ultrasound on mouse fibroblasts (cells that are involved in wound healing).
Although the treatment certainly shows promise, standard ultrasound transducers can be big and bulky, and need to be plugged into an AC outlet ... which is why the patch was created. In its current form, it weighs 100 grams and runs off two rechargeable AA batteries. It's designed to be worn over the ulcer while the patient is at home, delivering controlled pulses of ultrasound to the wound. It also features a monitoring component, that uses near infrared spectroscopy to assess how well the ulcer is healing.
Before it can see widespread use, however, larger-scale studies of its efficacy and safety need to be conducted. One such trial is currently under way, in which 20 patients are being treated with the patches.
The research is being led by Dr. Peter A. Lewin, and has received funding from the National Institute of Biomedical Imaging and Bioengineering (NIBIB), which is part of the National Institutes of Health.
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