Optimal dosages of propofol and remifentanil for minimizing hemodynamic changes during laryngeal microscopic surgery

Background: Laryngeal microscopic surgery (LMS) is stressful to the patient due to intubation and suspension laryngoscopy.The aim of this study was to determine the optimal dosages of propofol and remifentanil for minimizing hemodynamic changes during LMS.Methods: Eighty outpatients undergoing LMS were randomly divided into four groups.In all patients, endotracheal intubation was done with an effect-site concentration of propofol at 3 or 4μg/ml.Group I (propofol 3μg/ml) and II (propofol 4μg/ml) patients received remifentanil 0.5μg/kg and an infusion at 0.1μg/kg/min.Group III (propofol 3μg/ml) and IV (propofol 4μg/ml) patients received remifentanil 1.0μg/kg and an infusion at 0.2μg/kg/min.Hemodynamic changes and bispectral index (BIS) values during intubation and suspension laryngoscopy were compared among the groups.In addition, extubation time, emergence time, and state of recovery (Steward score) were compared.Results: After intubation and suspension laryngoscopy, the mean arterial pressure (MAP) was significantly lower than baseline values in groups II and IV (P ＜ 0.05).After suspension laryngoscopy, the heart rate (HR) was significantly lower than baseline value in group II (P ＜ 0.05).Extubation time was significantly shorter in groups I, II, and III compared to group IV, and the time for responding to verbal commands was significantly shorter in groups I and II compared to group IV (P ＜ 0.05).The incidence of hypotension was higher in group IV than in the other groups (P ＜ 0.05). Conclusions:The results suggest that an effect-site concentration of propofol at 4μg/ml with remifentanil 0.5μg/kg and infusion of 0.1μg/kg/min provide proper anesthesia with minimal hemodynamic changes during LMS.(Korean J Anesthesiol 2008; 55: 314～9)