Hemodynamic effects of endotoxin in calves

Abstract

The hemodynamic effects of Escherichia coli endotoxin were studied in 14 intact and 5 open-chest calves. The most striking effect was pulmonary arterial hypertension with concomitant elevation of the pulmonary arterial wedge pressure. Left heart filling pressure remained essentially constant. Since cardiac output uniformly fell, pulmonary vascular resistance increased markedly indicating that endotoxin produced pulmonary vasoconstriction. A substantial component of pulmonary venoconstriction also could be inferred. Systemic arterial hypotension occurred uniformly but its mode and time of onset were variable. Arterial blood O2 saturation fell in all animals without concomitant change in arterial blood carbon dioxide tension; thus venous admixture increased. Hemoconcentration, hepatosplanchnic pooling, and metabolic acidosis were either absent or minimal. In 3 animals that survived the first dose of endotoxin, a subsequent second dose elicited similar hemodynamic responses; thus tolerance to endotoxin was not demonstrated. The response to endotoxin was substantially different from that seen in dogs and resembled more closely that described in cats and sheep in that the lung appears to be the major "target organ.".