Effects of Low-power Pulsed Ultrasound on Second-intention Healing of Total Skin Injuries in Rats

We evaluated the effects of low-power pulsed ultrasound on skin injury healing at dorsal region of rats. Sixty male rats were used (Wistar, mean weight: 300 g) divided into two groups, namely: 1) simulated irradiation; 2) effective irradiation (basic rate of 1.5MHz, pulse cycle rate of 1KHz, pulse width of 200 μs, power of 30mW/cm2 –SATA, 10 minutes of application in alternate days). These were further divided into subgroups, according to the time of injury assessment, as 3, 7, and 14 days, and healing was assessed by planimetrical and histomorphometrical analysis. A significant increase (p<0.05) of the healing area was seen for Group 2 (141.88±18.50 mm2) compared to Group 1 (117.38±15.14 mm2), at the 14th day. There was a significant reduction of the number of inflammatory cells (p<0.05), associated to an increment of angiogenesis for Group 2 (2196.56 cel/mm2±234.93) in comparison to Group 1 (2611.68 cel/mm2±423.82), at the 3rd day. No significant differences were seen in collagen formation, or on dermis and epidermis area between groups. It was concluded that low-power pulsed ultrasound does not cause any deleterious effects and can moderately stimulate skin second-intention healing in experimental environments, showing a potential to clinical use in human beings.