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Oxygen consumption is maintained in fetal sheep during prolonged hypoxaemia
A D Bocking1, S E White, J Homan
1Department of Obstetrics and Gynaecology, University of Western Ontario, Lawson Research Institute, St. Joseph's Health Centre, London, Canada.
Journal of Developmental Physiology
|April 1, 1992
Summary
Reducing uterine blood flow in pregnant sheep caused prolonged fetal hypoxemia, leading to decreased fetal oxygen levels and pH. Despite these changes, overall fetal oxygen consumption remained stable, indicating adaptive mechanisms.
Area of Science:
- Perinatal physiology
- Fetal medicine
- Reproductive biology
Background:
- Fetal hypoxemia can arise from restricted uterine blood flow.
- Understanding fetal responses to oxygen deprivation is crucial for perinatal care.
Purpose of the Study:
- To investigate the impact of prolonged hypoxemia on fetal oxygen consumption in sheep.
- To assess fetal physiological adjustments to reduced uterine blood flow.
Main Methods:
- Experiments utilized 12 chronically catheterized pregnant sheep at 115 days gestation.
- Uterine blood flow was restricted for 24 hours using a maternal iliac artery occluder.
- Fetal blood gases, pH, lactate, umbilical blood flow, and oxygen extraction were monitored.
Main Results:
- Experimental group showed decreased fetal arterial PO2 and pH, with elevated lactate levels.
- Umbilical blood flow initially increased then returned to baseline.
- Fetal oxygen extraction increased significantly during hypoxemia.
Conclusions:
- Prolonged hypoxemia in fetal lambs does not alter overall oxygen consumption.
- Fetal oxygen extraction increases to compensate for reduced oxygen delivery.
- The fetus maintains oxygen consumption despite severe hypoxemia.