ABSTRACT
OBJECTIVE: Cardioprotective properties have been shown with halogenated volatile agents. It was hypothesized that low-dose isoflurane administered before aortic cross-clamping may reduce the amount of dobutamine required to improve impaired postoperative cardiac function after various types of cardiac surgery. DESIGN: A prospective, randomized trial. SETTING: An anesthesia and intensive care unit, university hospital. PARTICIPANTS: Two hundred eighty cardiac surgery patients. INTERVENTIONS: All patients allocated to either isoflurane treatment (T) or no treatment (control group [C]) received total intravenous anesthesia. In the treatment group, isoflurane was administered at a 0.5 minimum alveolar concentration (MAC) from tracheal intubation to initiation of cardiopulmonary bypass (CPB). During weaning from CPB, dobutamine was introduced by using a hemodynamically driven decision tree. MEASUREMENTS AND MAIN RESULTS: The number of patients receiving dobutamine was comparable (66 v 78, p = 0.07, in T and C groups, respectively). The total amount of postoperative dobutamine indexed to patient weight, considered as the primary endpoint, was reduced in the isoflurane-treated group (4.2 +/- 8 v 7.2 +/- 15, p < 0.02, in T and C, respectively). Isoflurane was identified as an independent variable significantly (odds ratio [confidence interval]) influencing the total amount of postoperative dobutamine (0.53 [0.31-0.92], p < 0.02). Postoperative troponin I release at 20 hours was not affected by isoflurane treatment. CONCLUSIONS: This study revealed that exposure to 0.5 MAC isoflurane before CPB reduced the total amount of dobutamine required to normalize postoperative cardiac dysfunction in various types of cardiac surgical patients.