Characterization of the cutaneous blood flow‐local temperature response through its entire range

Abstract

Thermal provocation of the skin circulation has been used to assess resistance vessel function, yet the response to dose‐dependent changes in local skin temperature (Tsk) has not been examined across the range from full vasoconstriction (VC) to full vasodilation (VD). Skin blood flow responses were assessed in 6 young healthy subjects (3 men, 3 women) using laser Doppler flowmetry (LDF) during two different heating and cooling protocols. 3 sites on the ventral forearm were randomly assigned to cooling (34°C–17°C), heating (31°C–41°C), or thermoneutral. R was a continuous ramp (0.6°C•min−1); S used stepwise heating/cooling at 0.33°C•min−1. Cutaneous vascular conductance (CVC) was calculated as LDF/MAP. Both protocols elicited highly reproducible CVC‐Tsk function curves, whether expressed as absolute or normalized CVC. There were no significant differences in thresholds for VD (R: 36.0 ± 0.6°C, S: 36.6 ± 0.7°C, p=0.37) and VC (R: 30.9 ± 0.8°C, S: 32.3 ± 0.8°C, p=0.12), the max (R: 2.15 ± 0.26, S: 2.23 ± 0.20, p=0.81), min (R: 0.04 ± 0.01, S: 0.04 ± 0.01, p=0.85), or range (R: 2.08 ± 0.29, S: 2.17 ± 0.19, p=0.79) of CVC between protocols. Only R elicited both an axon reflex and cold‐induced VD. Standardized thermal provocation elicits highly reproducible changes in skin blood flow and may provide a means to noninvasively assess changes in resistance vessel function across the entire response range in health and disease.