Comparison of the clinical performance of the modified Marsh model for propofol between underweight and normal-weight patients with Crohn's disease

Background The aim of this retrospective study was to compare the clinical performance of the modified Marsh model for propofol between underweight and normal-weight patients with Crohn's disease. Methods The medical records of 50 patients who underwent elective surgery for Crohn's disease were reviewed retrospectively. Propofol and remifentanil were administered using target effect-site concentration (Ce)-controlled infusion with the modified Marsh and Minto models. Target Ce values of propofol were adjusted within a range of 2.5-3 µg/ml to maintain a bispectral index (BIS) value of less than 60 during anesthesia maintenance. Dosages of anesthetic agents administered during surgery were compared between underweight and normal-weight patients. The infusion profiles of patients were applied as inputs to calculate the Ce values in the Schnider model. Results The total midazolam and remifentanil dosages required for underweight patients were higher than those required for normal-weight patients to maintain BIS values at less than 60 within a target propofol Ce range of 2.5-3 µg/ml. Simulation results suggested that the Schnider model may be an appropriate pharmacokinetic model for target-controlled infusion in underweight patients, as the clearance was consistently higher in the Schnider model than the modified Marsh model, particularly in underweight patients. Conclusions The modified Marsh model might cause inadvertent propofol underdosing in underweight patients. Future studies are necessary to compare the predictive performance of the modified Marsh and Schnider pharmacokinetic models in underweight patients.