Distribution of cardiac output in ovine pregnancy

Abstract

Cardiac output and organ blood flows were measured in 6 nonpregnant and 24 pregnant ewes from 38-141 days of gestation employing radionuclide-labeled microspheres. From the nonpregnant state to term increases in cardiac output, from 73.7 .+-. 4.6 ml/min per kg of maternal weight to 148 .+-. 2.4 ml/min per kg, and heart rate, from 88.5 .+-. 10.3 to 106 .+-. 4.6 beats/min, were noted, while mean arterial blood pressure was unchanged. Near term, the blood flows to the uterus and mammary gland represented approximately 18% of cardiac output. The blood flow to nonreproductive organs increased from 76.6 .+-. 6.8 ml/min per kg of nonreproductive tissue in the nonpregnant state to 132 .+-. 3.5 ml/min per kg at 130-140 days'' gestation (P < 0.01). No significant changes in renal blood flow were detected.