Effects of sevoflurane before cardiopulmonary bypass on cerebral oxygen balance and early postoperative cognitive dysfunction.

Postoperative cognitive dysfunction (POCD) is associated with cardiopulmonary bypass (CPB). We investigated the effect of different doses of inhaled sevoflurane administered prior to CPB on cerebral oxygen supply and demand, and the incidence of associated early POCD. One hundred and twenty patients were randomly allocated into four treatment groups (n = 30, each) and administered a high- [1.5 minimum alveolar concentration (MAC)], moderate- (1.0 MAC), low- (0.5 MAC), or no- sevoflurane dose prior to CPB. Standard blood gas parameters, serum S-100 protein, and neuron-specific enolase (NSE) were measured at different time points. The mini-mental state examination (MMSE) was administered 1 day before and 24 and 72 h after surgery. The jugular bulb venous oxygen saturation (SjvO2) in the moderate- and high-dose groups at a nasopharyngeal temperature of 25-28 °C was significantly higher compared with the control group, while the arteriovenous oxygen content difference (AVDO2) and cerebral extraction of oxygen (CEO2) were significantly reduced. The serum S-100 protein and NSE concentrations of the moderate- and high-dose groups at 1 and 6 h after the cessation of CPB were significantly lower than that of the control group. The 24 h postoperative MMSE scores of the moderate- and high-dose groups were significantly higher than those of the low-dose and control groups. An inhaled optimal concentration of sevoflurane may be beneficial for cerebral oxygen balance during CPB, and may ameliorate cognitive damage. However, the effect is dose-dependent.