The effect of sevoflurane vs. TIVA on cerebral oxygen saturation during cardiopulmonary bypass--randomized trial

Neuropsychological and neurological deficits are still major causes of mortality and morbidity after cardiac surgery. These complications are thought to be caused by embolisms and cerebral hypoxia. Thus, continuous neuromonitoring is essential during cardiac surgery due to cerebral oxygen desaturation during different periods. Near-infrared spectrophotometry (NIRS), a non-invasive method, appears to offer many advantages for monitoring cerebral oxygenation and hemodynamics. Desaturation of cerebral oxygen may occur at the beginning of cardiopulmonary bypass (CPB) or during the low perfusion and rewarming stages if not corrected.

This study was designed to assess the effects of sevoflurane on cerebral protection during CPB.

Eighty patients were divided into two groups. Anesthesia was maintained either with fentanyl and midazolam (total intravenous anesthesia, TIVA) or with one minimum alveolar concentration of sevoflurane and fentanyl. Cerebral desaturation was defined as an absolute decrease in saturation of 20% from baseline cerebral saturation. When desaturation occurred, PaCO2, hematocrit and PaO2 levels were checked and corrected. If desaturation continued, anesthetic depth was increased to reserve saturation with 50-100 mg of propofol. NIRS values and hemodynamics were recorded at predetermined time intervals.

Cerebral oxygen saturation values on the right side were higher in the sevoflurane group than in the TIVA group. The values on the left side were higher in the sevoflurane group than in the TIVA group, and meaningful differences were seen at the lowest temperature and at 36°C.

Oxygen saturation was higher in the sevoflurane group than in the TIVA group. Thus, the effect of sevoflurane was useful for maintaining cerebral oxygen saturation during CBP.