This study was undertaken to validate a new method of measuring cerebral metabolic rate in the fetal @entity742 based on heat production in a local region of the brain. Heat production was compared to @entity26 use in 20 near-term fetuses during basal conditions, moderate @entity519 and @entity432 . Thermocouples were placed to measure core and brain temperature and a composite probe placed in the parietal cortex to measure changes in cortical blood flow (CBF) using laser Doppler flowmetry and tissue @entity4095 using fluorescent decay. Catheters were inserted in a brachiocephalic artery and sagittal sinus for blood sampling. With moderate @entity519 , induced by administering 10-12 % @entity26 to the ewes, fetal arterial @entity4095 declined from 23 +/- 1 to 11 +/- 1 Torr and brain tissue @entity4095 fell from 7.6+/- 0.7 to a nadir of 0.8 +/- 0.4 Torr, while CBF increased to 139 +/- 5 % of baseline. Cortical heat production, calculated as the product of CBF, the temperature gain from artery to brain tissue, and the specific heat of blood, decreased by 45 +/- 11 % in parallel to similar declines in @entity26 uptake. With severe @entity1763 induced by @entity432 for 10 min, fetal arterial @entity4095 declined from 23 +/- 1 to 9 +/- 2 Torr and brain tissue @entity4095 fell from 7.0 +/- 0.7 to essentially 0 Torr while CBF decreased 40 +/- 5 %. Cortical heat production decreased by 78 +/- 6 % while @entity26 use declined by 90 +/- 3 %. @entity413 uptake increased significantly relative to @entity26 use and @entity880 concentration increased in sagittal sinus blood. We conclude that local measurements of heat production in the brain provide a useful index of overall metabolic rate, closely reflecting @entity26 use in moderate @entity519 and indicating a significant contribution from anaerobic metabolism during severe @entity1763 .

Cerebral metabolism during XXXX and @entity519 in the fetal @entity742 : a novel method of continuous measurement based on heat production.

@entity742 :: ('9940', 'Species') :: ['sheep'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen'] @entity519 :: ('MESH:D000860', 'Disease') :: ['hypoxia'] @entity413 :: ('MESH:D005947', 'Chemical') :: ['Glucose'] @entity1763 :: ('MESH:D001237', 'Disease') :: ['asphyxia'] @entity880 :: ('MESH:D019344', 'Chemical') :: ['lactate'] @entity432 :: ('MESH:D001157', 'Disease') :: ['cord occlusion', 'complete cord occlusion'] @entity4095 :: ('MESH:C093415', 'Chemical') :: ['PO2']
@entity432 :: (MESH:D001157,Disease) :: ['cord occlusion']
