Effect of alcohol on apnea reflexes in young lambs.

This study examined the effect of alcohol on two apnea reflexes considered to be protective mechanisms through which animals and humans preserve vital functions while they are submerged in water. The laryngeal chemoreflex and the trigeminal diving reflex were studied in unanesthetized 1- to 3-wk-old lambs. Reflex stimulation resulted in reduced ventilation or apnea, bradycardia, hypertension, and blood flow redistribution in the dive pattern. After alcohol, reflex stimulation resulted in increased apnea response, preserved blood flow redistribution, but less hypertension. The onset of regular breathing following laryngeal water stimulation was significantly delayed, after alcohol, and mechanical ventilation was used in three lambs to terminate the prolonged poststimulus apnea. Airway occlusion pressure, an index of neuromuscular inspiratory drive, decreased significantly after alcohol. The study demonstrates a potent effect of alcohol on apnea reflex responses. The effect of alcohol on respiratory drive and on the apnea reflex response should be considered when humans ingest alcohol, in particular by those participating in water sports.