CEREBRAL OXYGEN-METABOLISM IN NEWBORNS

Objective. A better understanding of the developmental changes in brai n energy metabolism that occur in human neonates is critically importa nt for designing rational treatment strategies that ensure an adequate supply of nutrients to the brain and minimize deleterious side effect s of therapeutic interventions in sick newborns. Methods. Cerebral met abolic rate for oxygen (CMRO2) was measured with positron emission tom ography in 11 sick newborns of different gestational ages. Results. In five preterm infants, mean hemispheric CMRO2 was 0.06 to 0.54 mL 100 g-1 min-1. Two of these preterm infants with virtually absent CMRO2. ( 0.06 mL 100 g-1 min-1) had minimal or no evidence of parenchymal brain injury detected in the newborn period. In six term infants, mean hemi spheric CMRO2 was 0.0 to 1.3 mL 100 g-1 min-1. Two with no neurologica l disease had mean hemispheric CMRO2 of 0.4 and 0.7 mL 100 g-1 min-1 a nd were normal at 6 and 7 months, respectively. Conclusions. CMRO2 in four newborns who had minimal or no detectable brain injury was consid erably below the threshold for brain viability in adults of 1.3 mL 100 g-1 min-1. This indicates that energy requirements in fetal and newbo rn brain are minimal or can be met by nonoxidative metabolism.