Effect of alcohol on acute ventilatory adaptation to mild hypoxia at moderate altitude

To evaluate the influence of alcohol on acute adaptation to mild hypoxia at moderate altitude.

Randomized, double-blind, placebo-controlled crossover trial.

University clinic and mountaineering resort at altitudes of 171 m and 3000 m, respectively, in the Austrian Alps.

10 healthy male alpinists, 22 to 24 years of age.

Single dose of 50 g of alcohol or placebo at altitudes of 171 m and 3000 m.

Arterial oxygen pressure (Pao2) and arterial carbon dioxide pressure (Paco2) before and 1 hour after consumption of alcohol or placebo.

At an altitude of 171 m, 50 g of alcohol caused no statistical change in Pao2 and Paco2 (median Pao2, 91.5 compared with 90.5 mm Hg [P = 0.89]; median Paco2, 37.5 compared with 36.0 mm Hg [P = 0.41]). At an altitude of 3000 m, the median Pao2 decreased from 69.0 to 64.0 mm Hg, a median decrease in the paired difference of 4.0 mm Hg (95.1% CI, 1.5 to 6.5 mm Hg; P < 0.01), and the median Paco2 increased from 32.5 to 34.0 mm Hg, a median increase in the paired difference of 3.0 mm Hg (95.1% CI, 2.0 to 4.0 mm Hg; P < 0.01) 1 hour after drinking 50 g of alcohol. Placebo did not influence Pao2 or Paco2 at either altitude.

Alcohol inhibits the initial stages of adequate acute ventilatory adaptation to mild hypoxia at moderate altitude. Caution in the use of alcoholic beverages at moderate altitude is therefore necessary.