Volatile anesthetic preconditioning modulates oxidative stress and nitric oxide in patients undergoing coronary artery bypass grafting

BACKGROUND: Myocardial preconditioning using volatile anesthetics such as isoflurane and sevoflurane have beneficial effects in decreasing morbidity in cardiac surgical patients. Studies in animal models have indicated that reactive oxygen and nitrogen species probably play a role in mediating these effects. However, data from human studies are scarce and the differential effect of sevoflurane vs. isoflurane on reactive oxygen species (ROS) and reactive nitrogen species (RNS) has not been studied extensively. MATERIALS AND METHODS: Randomized clinical control trial comparing preconditioning effects of volatile agents isoflurane and sevoflurane when administered during coronary artery bypass surgeries on cardiopulmonary bypass (CPB). Serum samples were collected at 3 time points before induction, after cross clamp release and one hour after separation from CPB. Levels of oxidative stress markers and nitric oxide were analyzed in these samples. RESULTS: Hemodynamic indices, cardio-pulmonary bypass duration, and ICU stay were similar between the groups. CKMB values 12 hours post-op were decreased in majority of patients in the sevoflurane group compared to isoflurane. Serum malondialdehyde and nitrate levels were lower with sevoflurane (P < 0.05) when compared to the isoflurane group, but no significant differences in protein carbonyl content or protein thiol content were evident between the 2 groups. Sevoflurane also prevented the decrease in total thiols during later stages of surgery. CONCLUSIONS: Volatile anesthetics, isoflurane and sevoflurane modulate oxidative and nitrosative stress during CABG. Between the two pre-conditioning agents, isoflurane seems to provide better protection during the pre-bypass period, while sevoflurane provides protection during both pre- as well as post-bypass period.