Thermoregulatory, cardiovascular, and psychophysical response to alcohol in men in 40 degrees C water

The goals of the study were to test the hypotheses that ethyl alcohol (ETOH) in low-to-moderate doses would alter thermo-regulation and/or disrupt the normal relationship between physiological and psychophysical indexes of heat stress during 40 degrees C water immersion and to characterize the cardiovascular response to the combined stimuli of heat, water immersion, and ETOH. Six healthy men underwent three trials of 21 min of immersion in water at 40.0 +/- 0.1 degrees C after consuming 0, 0.27, or 0.54 g ETOH/kg. Esophageal temperature (Tes) rose by approximately 1.0 degrees C during immersion for each trial. Per unit of Tes rise, changes during immersion in skin temperature, sweat rate, heart rate, systolic and diastolic blood pressure, and psychophysical assessments of comfort and overheating did not differ significantly by trial. Across trials, there was an apparent threshold for activation of thermoregulatory responses at an approximately 0.5 degrees C increase in Tes occurring after approximately 9 min of immersion. This threshold was identified psychophysically by increased ratings of overheating and decreased comfort. Above the threshold, there was an attenuation of the rate of increase of Tes. Cardiovascular stress was mild (rate-pressure product approximately 12,000) and not significantly increased by ETOH. Hypotension and tachycardia when subjects stood to exit the tub were observed. The data suggest that ETOH at the doses administered does not affect thermoregulatory, cardiovascular, or psychophysical indexes of heat stress during 40 degrees C water immersion.