title: Effects of maternal anemia on cardiac output, systemic oxygen consumption, and regional blood flow in pregnant sheep.
abstract: We measured regional blood flows and cardiac output and calculated regional oxygen deliveries (blood flow X arterial blood oxygen concentration) and systemic oxygen delivery, oxygen extraction, and oxygen consumption as maternal hematocrit was varied randomly between 31% and 8% by exchange transfusion with plasma or packed sheep red blood cells. We observed three patterns of response: In the heart, brain, and adrenal glands, oxygen delivery was constant or nearly constant over the range of hematocrits studied; in the kidneys, splanchnic organs, and uteroplacental tissues, oxygen delivery was a linear function of hematocrit; in the carcass tissues, oxygen delivery decreased slowly as hematocrits were reduced from 31% to 15% and dropped rapidly at hematocrits less than or equal to 15%. Systemic oxygen consumption was maintained at normal levels, despite reductions in hematocrit to about 15%, because oxygen extraction increased as compensation. At lower hematocrits, systemic oxygen consumption fell in association with a metabolic acidemia, suggesting that, with this severity of acute anemia, oxygen supply to some tissues in the pregnant sheep was inadequate for tissue metabolic demands.
mesh_terms: D000740:Anemia / Q000503:physiopathology / Q000662:veterinary*; D000818:Animals; D002302:Cardiac Output / Q000662:veterinary*; D005260:Female; D006400:Hematocrit / Q000662:veterinary; D010101:Oxygen Consumption; D011247:Pregnancy; D012039:Regional Blood Flow; D012756:Sheep; D012757:Sheep Diseases / Q000503:physiopathology*