Circulatory shock in pregnant sheep: I. Effects of endotoxin on uteroplacental and fetal umbilical circulation

Abstract

The response of the uteroplacental and fetal circulations and oxygen transfer to injection of E. coli endotoxin into the pregnant sheep was investigated. Endotoxin injection into the mother was comprised of three distinct phases: First came a precipitous fall in arterial pressure and uteroplacental blood flow with an increase in uteroplacental vascular resistance. This phase was followed by a progressive recovery period during which flow, pressure, and resistance returned to control values. A third phase occurred during which arterial pressure and uteroplacental blood flow decreased until death of the animal. Despite the marked changes in uteroplacental hemodynamics and a decrease in uteroplacental oxygen transfer, the fetal circulation did not show any major alteration until the terminal phase of shock, when arterial pressure and umbilical flow decreased. There was a fall in fetal oxygen content difference.