Alternative use of isoflurane and propofol confers superior cardioprotection than using one of them alone in a dog model of cardiopulmonary bypass

Our previous clinical study reported that isoflurane preconditioning and high-dose propofol posttreatment attenuated myocardial ischemia/reperfusion injury of patients in surgery with cardiopulmonary bypass (CPB). This study was designed to confirm this cardiac protection by use of a dog CPB model and to elucidate the related mechanism. Adult mongrel male dogs undergoing standard CPB were assigned into 4 groups: Sham group, Propofol group, Isoflurane (Iso) group and isoflurane in combination of propofol (pre-Iso + P) group. After induction, anesthesia was maintained with propofol (Propofol group), isoflurane (Iso group) or isoflurane preconditioning in combination with propofol posttreatment (pre-Iso + P group). After 2 h cardiac arrest and CPB, aortic cross-clamping was released to allow 2 h reperfusion. The results demonstrated that joint use of isoflurane and propofol facilitated cardiac functional recovery, improved myocardial oxygen utilization and decreased cardiac enzyme release. Also, the oxidative damage caused by ischemia/reperfusion injury was remarkably attenuated. Linear regression analysis showed that cardiac function performance and oxidative stress status were inversely correlated, indicating the improved cardiac function was in closed association with the attenuation of oxidative stress. In addition, the cardiac oxygen consumption (VO2) was found to be significantly associated with the above cardiac function and oxidative stress parameters, suggesting VO2 was predictive for the levels of cardiac damage and oxidative stress. Therefore, we conclude that alternative use of isoflurane and propofol confers superior cardioprotection against postischemic myocardial injury and dysfunction, and this protection was probably mediated by attenuation of cardiac oxidative damage.