Cerebral oxygenation and electrical activity after birth asphyxia: their relation to outcome

To determine the value of regional cerebral oxygen saturation (rSo2), fractional cerebral tissue oxygen extraction (FTOE) measured by near-infrared spectroscopy (NIRS), and amplitude integrated electroencephalogram (aEEG) after birth asphyxia in relation to neurodevelopmental outcome.

NIRS measured rSo2, FTOE, and aEEG were monitored simultaneously, together with arterial oxygen saturation (Sao2) and blood pressure during the first 48 hours after severe birth asphyxia in 18 term infants. FTOE was calculated as [Sao2-rSo2]/Sao2. Neurodevelopmental outcome was assessed at 3, 9, and 18 months and 3 and 5 years of age. At the time points 6, 12, 18, 24, 30, 36, 42, and 48 hours after birth, the mean values of Sao2, rSo2, FTOE, and mean arterial blood pressure were calculated over a 1-hour period. A stepwise-regression model was used to investigate the relative contribution of rSo2, FTOE, or aEEG to developmental outcome.

Nine Infants died during the neonatal period as a result of neurologic deterioration, and 8 infants had a normal outcome at 5 years of age. One child developed learning disabilities and a mild diplegia. The rSo2 and FTOE remained stable in infants with a normal outcome. The rSo2 increased and the FTOE decreased after 24 hours in the infants with an adverse outcome. (rSo2: 65% vs 84% at 12 and 48 hours, respectively; FTOE: 0.32 vs 0.12 at 12 and 48 hours, respectively). aEEG showed the closest relationship with outcome, but also rSo2 showed a significant correlation 24 hours after birth.

rSo2 and FTOE seem to reflect secondary energy failure. aEEG showed the closest relationship with outcome after severe birth asphyxia.