Cardiovascular responses to face immersion (the diving reflex) in human beings after alcohol consumption

The diving reflex is a complex cardiovascular-respiratory response to immersion. This multireflex response in animals consists of apnea; bradycardia (the experimental parameter most often measured); peripheral vasoconstriction (resulting in preferential perfusion of the brain and heart); decreased cardiac output (with a maintained or increased stroke volume); and an increase in mean arterial blood pressure. These cardiovascular alterations act in a manner that conserves oxygen for the heart and brain. Because alcohol is often involved in water accidents with associated submersions, these initial experiments dealt with human volunteers who consumed alcohol to a blood level of 0.1 g% (legal level of intoxication). The diving reflex was elicited before and after alcohol consumption. Heart rate, blood pressure, and cardiac output were measured before, during, and after face immersion in 4 C water. In the sober state, immersion decreased heart rate, increased stroke volume, increased blood pressure, and increased total peripheral resistance. In comparison to the sober state, alcohol consumption increased pre-immersion heart rate, but did not significantly alter pre-immersion blood pressure or stroke volume. Following alcohol consumption, facial immersion decreased heart rate, but not to the same low rate as in the sober state. Alcohol consumption also evoked a lesser increase in blood pressure and failed to increase stroke volume significantly.