Evaluation of cerebral autoregulation of oxygen by NIRS method during postnatal transition period in term and late preterm newborns without resuscitation requirement.

Background: Pulse oximetry is commonly used to monitor arterial oxygen saturation and heart rate during the transition period and reference intervals have been determined. However, the effect of the change in arterial oxygen saturation on tissue oxygenation does not seem to be the same. So, a non-invasive method for monitoring cerebral or regional tissue oxygenation will be potentially useful for vulnerable infants. This study aims to evaluate the effectiveness of cerebral autoregulation in the first 10 min after delivery in term and late preterm newborns without resuscitation requirement.

Methods: Cerebral tissue oxygen saturation was measured in the first 10 min after birth with near-infrared spectroscopy (NIRS) from the left forehead. Peripheral oxygen saturation was measured with pulse oximetry from the right hand and cerebral fractional tissue oxygen extraction was calculated.

Results: Nineteen late preterms and 20 term infants were included in the study. There was no statistically significant difference between median cerebral tissue oxygen saturation and cerebral fractional tissue oxygen extraction values of late preterm and term infants (p < 0.001). There was a strong inverse relationship between cerebral tissue oxygen saturation and cerebral fractional tissue oxygen extraction (p < 0.001).

Conclusions: In late preterm infants similar to term infants, arterial oxygen saturation and cerebral tissue oxygen saturation increased with time, but inverse reduction of cerebral fractional tissue oxygen extraction showed the presence of an active autoregulation in the brain. This can be interpreted as the ability of the brain to protect itself from hypoxia by regulating oxygen uptake during normal fetal-neonatal transition process. A larger scale multi-center randomized control trial is now needed to further inform practice.