CENTRAL HEMODYNAMICS IN SEVERE POISONING BY HYPNOTIC DRUGS

Hemodynamic data have been recorded in nine patients during initial and late phases of severe poisoning by hypnotic drugs. Cardiac output (C.O.) was determined by the dye dilution method and right heart catheterization using “floating” catheter technique. Oxygen uptake was calculated from C.O. and arterio‐venous oxygen difference. During deep coma, characterized by hypothermia, the C.O., stroke volume and oxygen uptake were significantly decreased and the peripheral vascular resistance markedly increased. The arterio‐venous oxygen difference was generally normal, which implies that C.O. varied with oxygen uptake. Central venous pressures were normal or somewhat low, as also were the pressures in the pulmonary artery. During recovery the heart rate, stroke volume and C.O. increased in proportion to the increase in tissue metabolism as evaluated from the calculated oxygen uptake. The reduced tissue metabolism, reflected in reduced body temperature and low oxygen uptake, seems to be the main explanation of the hypo‐kinetic circulation in patients with deep coma because of poisoning by hypnotic drugs. The rather frequent roentgenological signs of pulmonary congestion or edema during the course of intoxication with hypnotic drugs do not seem to be explained by increased left ventricular filling pressures as reflected in elevated pulmonary artery diastolic pressures. A toxic effect on the vascular bed with increased permeability may be the most important underlying explanation.