Maintenance of anesthesia in morbidly obese patients using propofol with continuous BIS-monitoring : a comparison of propofol-remifentanil and propofol-epidural anesthesia

Purpose : Aim of this study was to evaluate maintenance of anesthesia using propofol with continuous Bispectral Index (BIS)-monitoring in morbidly obese patients receiving propofol-remifentanil and propofol-epidural anesthesia. Methods : In the first group in ten morbidly obese patients receiving remifentanil analgesia, a propofol infusion was started at 10 mg/kg/hr and modified by aiming at BIS values between 40-60 together with predefined hemodynamic parameters. In the second group, the propofol dose resulting from the first group was prospectively evaluated in a matched cohort of six morbidly obese patients receiving propofol-epidural analgesia aiming for the same BIS and hemodynamic parameters. In both groups, propofol concentration and infusion rates, BIS and hemodynamic values were collected. Results : In the propofol-remifentanil group (Body Mass Index (BMI) 39-60 kg/m 2 ), the mean propofol infusion rate that corresponded to the predefined BIS and hemodynamic parameters was 4.8 mg/kg/hr (SD 1.5). On this basis, a maintenance dose of 5 mg/kg/hr was started in the propofol-epidural group (BMI 38-58 kg/m 2 ). In this second group, the mean propofol infusion rate that corresponded to predefined BIS and hemodynamic parameters was 5.0 mg/kg/hr (SD 0.6). Between the two groups, there was no difference in the propofol concentration-BIS relation. Conclusion : Using both BIS and hemodynamic parameters as an endpoint, a maintenance dose of propofol of 4-6 mg/kg/hr is proposed for maintenance of anesthesia in morbidly obese patients undergoing bariatric surgery either in combination with remifentanil or epidural analgesia. There was no difference in propofol concentration-BIS relation in morbidly obese patients receiving propofol-remifentanil or propofol-epidural anesthesia.