Monitoring the effects of propofol and sevoflurane on cerebral oxygen supply-demand balance using transcranial Doppler sonography and jugular bulb saturation in pediatric open heart surgery

Abstract

Background Increasing awareness of neurologic abnormalities associated with congenital heart surgical intervention has heightened investigations for prevention of neurologic injury during the perioperative period. This study investigated the effects of propofol and sevoflurane on cerebral oxygen supply demand balance using transcranial Doppler sonography and jugular bulb saturation in pediatric open heart surgery. Methods After obtaining institutional approval and a written consent from parents, 60 children who were admitted for elective open cardiac surgery for correction of congenital heart disease using CPB were included in this study. Children were randomized into two groups; group (P) and group (S). Induction of Anesthesia was achieved by 5 μg/Kg I.V. fentanyl, propofol 2- 2.5 mg/Kg (in propofol or P group) or sevoflurane 2-3 MAC (in sevoflurane or S group). Anesthesia was maintained by propofol infusion between 75-100 μg/kg/min in P group or sevoflurane 2 MAC in S group. Calculated parameters from the blood gas variables included cerebral metabolic rate of oxygen (CMRO 2 ), cerebral extraction of oxygen (CeO 2 ) and cerebral blood flow equivalent (CBF). Arterial blood gases (ABG) and velocities of flow were monitored by Trancranial Doppler at 5 time points : before the surgery, before CPB, during CPB (after establishment of full flow), after CPB and after recovery. Neurological examination and CT scan were done before surgery and 2 days after that. Results There is no significant difference between the two groups in demographic data. Children in propofol group showed lower heart rate values after induction and after CPB than those in sevoflurane group. Mean arterial pressure was statistically higher in sevoflurane group compared with propofol group after induction. Children in sevoflurane group showed significantly higher; velocity maximum, velocity mean and pulsatile index, in the after induction and after bypass periods than those in propofol group. Velocity minimum showed no difference between the two groups. SjvO 2 , CMRO 2 , CeO 2 and CBF was significantly different after induction in sevoflurane group compared with propofol group. Perioperative blood gases showed no difference between the studied groups. Conclusion Compared with propofol anesthesia, sevoflurane anesthesia provides a wider margin of safety against impaired cerebral oxygenation and better preservation of systemic hemodynamics. Moreover, cerebral oxygen saturation may not reflect changes in cerebral oxygenation as monitored by jugular venous oxygen tension measurement in children undergoing CPB.