THE CARDIOVASCULAR RESPONSES TO THE BREATHING OF 100 PER CENT OXYGEN AT NORMAL BAROMETRIC PRESSURE

Abstract

Cardiac minute volumes of normal [male] [male] as detd. by the ballistocardiograph were consistently lower during inhalation of 100% O2 (Linde, U.S.P.) as compared with detns. on the same subjects breathing air. Reductions in both heart rate and stroke vol. contributed to this effect. vSystolic blood pressures did not change, but diastolic pressures showed a slight but significant rise. These results are interpreted as evidence of an increase in the general peripheral vascular resistance. It is suggested that the cardiovascular effects of O2 inhalation be kept in mind in conditions of hy-peroxygenation of the blood, such as denitrogenation, and that they may play a part in the physiologic responses to changes in barometric pressure.