Effects of alcohol on respiratory variables in normal humans

The study is designed to clarify the effect of low doses of alcohol on respiratory variables in air breathing normal subjects. Each subject was given an initial loading dose of alcohol (0.270 g/kg) followed, half an hour later, by a second dose (0.135 g/kg). Blood alcohol increased to a mean value of 52.0 +/- 3.0 (SEM) mg/100 ml at 1 hour. Resting ventilation increased significantly from a mean value of 6.25 +/- 0.41 litres min(-1) to 7.20 +/- 0.31 litres min(-1) 1 hour after alcohol (p= 0.025). Mean inspiratory flow was also increased (p= 0.045). End-tidal PCO² (PET CO²) showed a highly significant fall (1.87 +/- 0.35 mm Hg; p < 0.001) without a significant change in CO2 production rate (p > 0.05). PET CO² variability (100 x SD/mean) was low (mean 2.4%) and unaffected by alcohol. The longest end-expiratory pauses (apnoeas) observed for each subject were shortened significantly by alcohol (1.030 +/- 0.194 s and 0.690 +/- 0.138 s; p = 0.01). Moderate doses of alcohol in normal subjects, therefore lower PET CO² and shorten end-expiratory pauses (apnoeic periods) but do not affect PET CO² variability.