ESTIMATION OF REGIONAL CUTANEOUS COLD SENSITIVITY BY ANALYSIS OF THE GASPING RESPONSE

Regional cutaneous sensitivity to cooling was assessed in males by separately immersing four discrete skin regions in cold water (15-degrees-C) during head-out immersion. The response measured was gasping at the onset of immersion; the gasping response appears to be the result of a nonthermoregulatory neurogenic drive from cutaneous cold receptors. Subjects of similar body proportions wore a neoprene "dry" suit modified to allow exposure to the water of either the arms, upper torso, lower torso, or legs, while keeping the unexposed skin regions thermoneutral. Each subject was immersed to the sternal notch in all four conditions of partial exposure plus one condition of whole body exposure. The five cold water conditions were matched by control immersions in lukewarm (34-degrees-C) water, and trials were randomized. The magnitude of the gasping response was determined by mouth occlusion pressure (P0.1). For each subject, P0.1 values for the 1st min of immersion were integrated, and control trial values, although minimal, were substracted from their cold water counterpart to account for any gasping due to the experimental design. Results were averaged and showed that the highest P0.1 values were elicited from whole body exposure, followed in descending order by exposures of the upper torso, legs, lower torso, and arms. Correction of the P0.1 response for differences in exposed surface area (A) and cooling stimulus (DELTA-T) between regions gave a cold sensitivity index [CSI, P0.1/(A.DELTA-T) for each region and showed that the index for the upper torso was significantly higher than that for the arms or legs; no significant difference was observed between the indexes for the upper and lower torso. Similarly, no significant difference was demonstrated among the CSIs of the arms, legs, and lower torso. In general, the results suggested an increased cold receptor density and/or sensitivity in the upper torso compared with the extremities.