EFFECT OF INTERFERENCE CURRENT ON FOREARM VASCULAR-RESISTANCE IN ASYMPTOMATIC HUMANS

Background and Purpose. Several case reports suggest that transcutaneo us application of interference current (IC) produces physical blockade of sympathetic vasoconstrictor fibers in peripheral nerves. To test t his theory we studied the effects of IC on forearm vascular resistance in asymptomatic humans. Subjects. One man and four women, aged 21 to 44 years ((X) over bar= 33, SD= 12), served as subjects. Methods. We m easured forearm blood flow during IC applications over the left stella te ganglion. Forearm vascular resistance was calculated by dividing me an arterial pressure by forearm blood flow. Results. Interference curr ent did not alter flow ((X) over bar= 5.6 [SD= 1.0] versus 6.2 [SD= 1. 1] mL/100 mL/min min) or resistance ((X) over bar= 15.4 [SD= 3.1] vers us 13.8 [SD= 2.4] units). When sym pathetic outflow was augmented usin g lower-body suction, IC again failed to alter flow or resistance. Con clusion and Discussion. interference current applied over the stellate ganglion does not alter forearm hemodynamics in asymptomatic individu als. These findings challenge the concept that IC can block sympatheti c vasoconstrictor impulses in peripheral, nerves. [Indergand HJ, Morga n BJ. Effect of interference current on forearm vascular resistance in asymptomatic humans. Phys Ther. 1995;75:306-312.]