Oxygen consumption of the fetal sheep in utero

Oxygen consumption was measured in 8 chronically instrumented fetal sheep by a combination of recently introduced techniques. Umbilical blood flow was measured by an electromagnetic flow transducer placed around the common portion of the umbilical artery. Blood representative of that in the umbilical artery was obtained from the distal aorta. The common portion of the umbilical vein was catheterized by direct puncture of the vessel at the base of the umbilicus. An accurate micromethod was used to measure oxygen content of blood from the umbilical vessels, and oxygen consumption was calculated by application of the Fick principle. The mean fetal oxygen consumption was 7.9 +/- 1.8 ml O2/min/kg fetus.