Therapeutic ultrasound: the effects upon cutaneous blood flow in humans

The premise of the current crossover, randomised, double-blinded and controlled study was to ascertain the physiologic effects of pulsed and continuous ultrasound (US) upon cutaneous blood flow in humans as measured by laser Doppler flowmetry. Ten healthy volunteers (5 male, 5 female; aged 18 to 36 y) were assigned to undergo four experimental conditions in a predetermined random order: (i) control, (ii) placebo, (iii) pulsed US and (iv) continuous US. US was applied at a frequency of 3 MHz at an intensity of 1 W/cm(2) for a total of 6 min over the lateral aspect of the forearm. Ambient and skin temperatures were measured concomitantly. Statistical analysis indicated that there were significant differences in blood perfusion units between pulsed US and continuous application of US compared with the control condition for cutaneous blood flow at 2 min (p < or = 0.05), 4 min (p < or = 0.03) and 6 min (p < or = 0.05). Additionally, the placebo group was found only significantly to be different from the control condition at 6 min (p = 0.02), indicating that the movement of the transducer head can produce an additional massage effect. There were no significant differences found for ambient or skin temperature recordings. These findings suggest that active US produces significant increases in cutaneous blood flow.