BACKGROUND: Laryngoscopy and tracheal intubation are associated with hemodynamic pressor responses, which lead to adverse effect. Opioids have been used to reduce the hemodynamic change. The purpose of this study was to investigate an optimal dosage of remifentanil for attenuating hemodynamic change.

METHODS: 120 ASA class 1-2 patients, scheduled for elective surgery, were divided randomly into 4 groups. Anesthesia was induced with vecuronium priming dose (0.01 mg/kg) and TCI of propofol target concentration 8 µg/ml. This was reduced to 4 µg/ml when the effect-site concentration had been 3 µg/ml. After the effect-site concentration had reached 4 µg/ml, vecuronium (0.09 mg/kg) was given. At the same time, control group received normal saline, group R0.25 received remifentanil 0.25 µg/kg, group R0.5 received remifentanil 0.5 µg/kg, group R1 received remifentanil 1 µg/kg over 60s and an infusion 0.2 µg/kg/min. Intubation was performed after maximum depression of the single twitch was shown by single twitch stimulation test. Sytolic blood pressure, mean arterial pressure, diastolic blood pressure, heart rate and BIS value were measured preinduction, after propofol induction, immediately before and after intubation and 1, 2, 3, 4 minutes after intubation, respectively.

RESULTS: Post-intubation mean arterial pressure decreased significantly from pre-intubation value in group R0.5 and R1 (P < 0.05). In group R0.5 and R1, hypotension and bradycardia occurred but there were no significant differences in their incidence between two groups.

CONCLUSIONS: We suggest that remifentanil 0.5 µg/kg bolus and an infusion of 0.2 µg/kg/min attenuate the pressor response to tracheal intubation in patients anesthetized with propofol TCI.