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Cerebral oxygen consumption during asphyxia in fetal sheep
D R Field1, J T Parer, R A Auslender
1Department of Anesthesia, University of California, San Francisco 94143.
Journal of Developmental Physiology
|September 1, 1990
Summary
Fetal asphyxia initially decreases cerebral oxygen consumption. Severe hypoxemia prevents compensatory increases in cerebral blood flow, leading to significantly reduced brain oxygen use and potential neuronal damage.
Area of Science:
- Perinatal physiology
- Fetal medicine
- Neuroscience
Background:
- Fetal asphyxia is a critical condition impacting brain oxygenation.
- Understanding cerebral blood flow regulation during asphyxia is vital for fetal well-being.
Purpose of the Study:
- To investigate cerebral blood flow and oxygen consumption in fetal sheep during induced asphyxia.
- To determine the impact of varying degrees of hypoxemia on fetal brain metabolism.
Main Methods:
- Measurements of cerebral blood flow, arteriovenous oxygen content difference, and oxygen uptake in fetal sheep.
- Induction of profound fetal asphyxia by reducing uterine blood flow.
- Sequential measurements during asphyxia to assess hemodynamic and metabolic changes.
Main Results:
- Initially decreased cerebral oxygen consumption was observed during asphyxia.
- Despite acidosis, cerebral fractional oxygen extraction remained stable up to 36 minutes.
- In severe hypoxemia (arterial oxygen content < 1.0 mmol/l), cerebral blood flow did not increase, and oxygen consumption dropped to 48% of control.
Conclusions:
- Compensatory mechanisms for cerebral blood flow are overwhelmed in severe fetal hypoxemia.
- Profound hypoxemia during asphyxia may exceed physiological limits, potentially leading to neuronal injury.