Selective Thermal Stimulation Delays the Progression of Vasoconstriction During Body Cooling.

The objective of this study was to test the feasibility of selective thermal stimulation (STS) as a method to upregulate glabrous skin blood flow. STS is accomplished by mild surface heating along the spinal cord. Four healthy subjects were tested in this study. Each participated in a control experiment and an intervention experiment (STS). Both experiments included establishing a maximum level of vasodilation, considered unique to a subject on a test day, and then cooling to a maximum level of vasoconstriction. Perfusion was measured by a laser Doppler flow probe on the index fingertip. The percent of perfusion in the range of minimum to maximum was the primary outcome variable. The data were fit to a linear mixed effects model to determine if STS had a significant influence on perfusion during whole body cooling. STS had a statistically significant effect on perfusion and increased glabrous skin blood flow by 16.3% (P < 0.001, CI (13.1%, 19.5%)) as skin temperature was decreased. This study supports the theory that STS improves the heat exchanger efficiency of palmar and plantar surfaces by increasing the blood flow.