The clinical effective dose of rocuronium for lightwand tracheal intubation after induction with alfentanil, propofol, and low concentrations of sevoflurane

BACKGROUND The aim of this study was to determine the clinical effective dose of rocuronium for tracheal intubation using a lightwand after induction with propofol, alfentanil, and a low concentration of sevoflurane. METHODS Twenty-eight adults scheduled to undergo elective surgery lasting less than one hour were enrolled in this study. All patients received alfentanil (10 microg/kg) and propofol (1.5 mg/kg) for the induction of anesthesia. Tracheal intubation using a lightwand was attempted 3 minutes after administering rocuronium and mask ventilation with 2 vol% of sevoflurane. The initial rocuronium dose was 0.5 mg/kg. The rocuronium dose for consecutive patients, determined by Dixon's up-and-down method, was increased or decreased by 0.05 mg/kg according to the result of the previous patient. The mean arterial pressure and heart rate were recorded before induction, 1 min before intubation, 1 and 2 min after intubation. RESULTS The 50% clinical effective dose (cED(50)) of rocuronium for tracheal intubation using a lightwand was 0.20 +/- 0.05 mg/kg according to Dixon's up and down method. Isotonic regression revealed the cED(50) and cED(95) (95% confidence intervals) to be 0.20 mg/kg (0.10-0.3 mg/kg) and 0.35 mg/kg (0.16-0.49 mg/kg), respectively. CONCLUSIONS The cED(50) and cED(95) of rocuronium for tracheal intubation using the lightwand were 0.20 mg/kg and 0.35 mg/kg, respectively, after induction with alfentanil, propofol, and a low concentration of sevoflurane.