Noninvasive assessment of cerebral oxidative metabolism in the human newborn.

Magnetic resonance spectroscopy (MRS) and near infrared spectroscopy (NIRS) permit direct observations within the human brain of a number of metabolites important in cerebral oxidative metabolism. MRS identifies high energy phosphorus metabolites such as phosphocreatine and ATP, which are products of oxidative phosphorylation and of the anaerobic accumulation of lactate. NIRS makes it possible to measure cerebral haemodynamics and oxygen delivery and to detect changes in the redox state of mitochondrial cytochrome oxidase. Studies in the brain of newborn infants after perinatal asphyxia have shown a delayed reduction in high energy phosphorus metabolites and an accumulation of lactate. Haemodynamic abnormalities frequently precede the delayed failure of energy metabolism. NIRS and MRS provide unique information on deranged cerebral energy metabolism following hypoxia-ischaemia and will guide the introduction of new cerebroprotective interventions.