CHANGES IN CEREBRAL HEMODYNAMICS AND OXYGENATION IN THE 1ST 24 HOURS AFTER BIRTH ASPHYXIA

Objective. To investigate whether or not postasphyctic cerebral hypope rfusion and decreased cerebral metabolism occur in the perinatally asp hyxiated neonate, as has been reported in adults and newborn animals. Methods. Using near-infrared spectroscopy, we monitored changes in oxy hemoglobin (HbO2), deoxyhemoglobin (HbR), total hemoglobin (HbO2 + HbR , which represents changes in cerebral blood volume [CBV]), and cytoch rome oxidase (Cytaa3, which indicates changes in oxidation level of th is intracerebral mitochondrial enzyme). Thirty-one neonates (gestation al age >34 weeks), divided into three groups, were monitored between 2 and 12 hours or between 12 and 24 hours of life. Group I consisted of healthy newborns: N = 8 (2 to 12 hours) and N = 5 (12 to 24 hours). P atients in group II were moderately asphyxiated newborns but neurologi cally normal in the first 24 hours of life: N = 6 (2 to 12 hours) and N = 3 (12 to 24 hours). Group III consisted of severely asphyxiated ne wborns with an abnormal neurologic behavior within 24 hours after birt h: N = 5 (2 to 12 hours) and N = 4 (12 to 24 hours). Results. From 2 t o 12 h, CBV levels in groups I and II were stable. In group III CBV de creased in all infants. This decrease in CBV was associated with a dro p in both HbO2 and HbR. Cytaa3 was stable in groups I and II, but show ed a marked decrease in two of the five infants of group III. There wa s a positive relationship between CBV and mean arterial blood pressure in groups II and III. Between 12 and 24 hours, all groups showed stab le CBV and Cytaa3 patterns. A positive relation existed now between tr anscutaneous PCO2 and CBV in groups II and III. Conclusions. CBV, HbO2 , HbR, and Cytaa3 decreased in the first 12 hours of life in severely asphyxiated neonates who subsequently developed neurologic abnormaliti es. We therefore suggest that posthypoxic-ischemic reperfusion injury of the brain during early neonatal life occurs in neonates with severe birth asphyxia.