BACKGROUND: Laryngoscopy and tracheal intubation often provoke an undesirable increase in blood pressure and heart rate. This study was done to determine median effective dose (ED50) of nicardipine for prevention of hemodynamic response to tracheal intubation during induction of anesthesia with thiopental, propofol, or etomidate.

METHODS: Fourty-five ASA physical status 1 adult patients were allocated into three group; thiopental group (n = 15), propofol group (n = 15), and etomidate group (n = 15). The first patient of each groups received 10µg/kg of nicardipine 1 minute before induction. Subsequent dose was determined by the hemodynamic response of the previous patient to tracheal intubation based on Dixon's up and down sequential allocation. The test dosing interval was set at 3µg/kg. If mean arterial pressure increased more than 20% after tracheal intubation, dose of the subsequent patient was increased by 3µg/kg. If not, it was decreased by 3µg/kg. Blood pressure was measured after arrival at the operating room, before tracheal intubation, and 1, 2, 3, 4, and 5 minutes following intubation by non invasive method.

RESULTS: ED50 of nicardipine for attenuation of hypertensive response after tracheal intubation were 18.0µg/kg (95% Confidence Limit [CL], 14.8-22.0µg/kg), 6.2µg/kg (CL, 2.6-9.5µg/kg), and 16.7µg/kg (CL, 13.6-20.7µg/kg) in thiopental group, propofol group andetomidate group, respectively.

CONCLUSIONS: We concluded that less nicardipine dose in propofol group was needed to prevent hypertensive response after tracheal intubation (P < 0.05).