[Recent data on cerebral circulation and metabolism of the brain in newborn infants]

Recent advances in technology have made it possible to determine cerebral blood flow and metabolism in newborn infants. The mean cerebral blood flow rate falls from 60 to 30 ml/min/100 g during the first 3 hours of life and returns to the initial value after the first week. It increases by about 30% during rapid sleep and feeding. Cerebral blood flow is independent of gestational age and represents 20-25% of cardiac output as against 16% in adults. It is influenced by blood gases and its autoregulation is impaired by asphyxia. Infants with a cerebral blood flow rate below 20 ml/min/100 g are at high risk of leucomalacia. The high metabolic activity of the neonatal brain is reflected in its considerable consumption of oxygen (54% vs 30% in adults) and ketonic bodies which participate for 10% in cerebral energy metabolism. More than 80% of the endogenous glucose is utilized by the brain of neonates despite a transport capacity lower than in adults. In neonatal pathology, it is now possible to investigate cerebral metabolism using positron emission tomography or phosphorous magnetic resonance spectroscopy which provide for better diagnostic and prognostic evaluation of cerebral functions.