Cerebral autoregulation in infants during sevoflurane anesthesia for craniofacial surgery.

Abstract

Data on cerebral pressure-flow autoregulation in the youngest children are scarce. We studied the correlation between mean arterial pressure and cerebral tissue oxygen saturation (rSO2 ) by near-infrared spectroscopy (NIRS) in patients undergoing nose, lip, and palate surgery. We tested the hypothesis that cerebral pressure-flow autoregulation is impaired in children less than 1year undergoing surgery and general anesthesia with sevoflurane under controlled mechanical ventilation. After approval from the Ethical board, 15 children aged <1year were included. Before anesthesia induction, a NIRS sensor (INVOSTM , Medtronic, Minneapolis, USA) was placed over the cerebral frontal lobe. Frontal rSO2 , a surrogate for cerebral perfusion, mean arterial pressure, end-tidal CO2 - and sevoflurane concentration, and arterial oxygen saturation were sampled every minute after the induction. A repeated measures correlation analysis was performed to study correlation between mean arterial pressure and cerebral rSO2 , and the repeated measures correlation coefficient (rrm ) was calculated. Fifteen patients, aged 7.7±1.9months, were studied. rSO2 showed a positive correlation with mean arterial pressure ([95% CI: 9.0-12.1], P<0.001) with a moderate to large effect size (rrm =0.462), indicating an impaired cerebral pressure-flow autoregulation. The slopes of the rSO2 -mean arterial pressure correlations were steeper in patients who were hypotensive (mean arterial pressure <50mm Hg) compared to patients having a mean arterial pressure ≥50mm Hg, indicating that at lower mean arterial pressure, the cerebral pressure dependence of cerebral oxygenation is even more pronounced. During sevoflurane anesthesia in the youngest pediatric patients, cerebral perfusion is pressure-dependent, suggesting that the efficiency of the cerebral blood flow autoregulation is limited.