REPRODUCIBILITY OF THE COLD-INDUCED VASODILATION RESPONSE

Abstract

Performance during cold-weather activities may be affected by decreased manual dexterity and risk of frostbite. A strong cold-induced vasodilation (CIVD) response may limit those detrimental effects; therefore, identification of methods for enhancing CIVD is important. Detection of such a method may be hampered by the large variability in CIVD. How much this variability can be reduced by controlling for factors that alter CIVD, such as changes in core or mean skin temperature, is not known. PURPOSE To quantify day-to-day variability in finger skin temperature response to cold-water immersion (CWI). METHODS 20 volunteers resting in a controlled environment (27°C, 50% rh) immersed their middle finger in warm water (42°C) for 15 min to standardize initial finger temperature, then in cold water (4°C) for 30 min on five occasions, each a week apart. Finger nailbed (Tnb) and pad (Tpad), mean skin (Tsk), and core (Tre) temperatures were measured, and CIVD parameters of nadir temperature (Tmin), onset time (tmin) and maximum temperature (Tmax) were identified. RESULTS Within-subject standard deviation and coefficient of variation for average temperatures during CWI: Tre 0.1 °C, 0.3%; Tsk 0.3 °C, 0.8%; Tnb 0.7, 10%; Tpad 2.1 °C, 15%; and for CIVD parameters Tmin: nb 0.5 °C, 9%; pad 2.0 °C, 21%; tmin: nb 0.7 min, 19%; pad 0.8 min, 20%; and Tmax: nb 1.0 °C, 12%; pad 2.4 °C, 13%. CONCLUSION These data identify the expected standard deviations for CIVD parameters during cold-water finger immersion under controlled conditions, and demonstrate that variability is less in the nailbed than in the pad. It is suggested that a meaningful treatment effect may be ascribed to a method that alters a CIVD parameter by twice the standard deviation.