Changes in cerebral hemodynamics and oxygenation in the first 24 hours after birth asphyxia

To investigate whether or not postasphyctic cerebral hypoperfusion and decreased cerebral metabolism occur in the perinatally asphyxiated neonate, as has been reported in adults and newborn animals.

Using near-infrared spectroscopy, we monitored changes in oxyhemoglobin (HbO2), deoxyhemoglobin (HbR), total hemoglobin (HbO2 + HbR, which represents changes in cerebral blood volume [CBV]), and cytochrome oxidase (Cytaa3, which indicates changes in oxidation level of this intracerebral mitochondrial enzyme). Thirty-one neonates (gestational 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). Patients in group II were moderately asphyxiated newborns but neurologically 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 newborns with an abnormal neurologic behavior within 24 hours after birth: N = 5 (2 to 12 hours) and N = 4 (12 to 24 hours).

From 2 to 12 h, CBV levels in groups I and II were stable. In group III CBV decreased in all infants. This decrease in CBV was associated with a drop in both HbO2 and HbR. Cytaa3 was stable in groups I and II, but showed a marked decrease in two of the five infants of group III. There was a positive relationship between CBV and mean arterial blood pressure in groups II and III. Between 12 and 24 hours, all groups showed stable CBV and Cytaa3 patterns. A positive relation existed now between transcutaneous PCO2 and CBV in groups II and III.

CBV, HbO2, HbR, and Cytaa3 decreased in the first 12 hours of life in severely asphyxiated neonates who subsequently developed neurologic abnormalities. We therefore suggest that posthypoxic-ischemic reperfusion injury of the brain during early neonatal life occurs in neonates with severe birth asphyxia.