BACKGROUND: This study compared the effect of the three different infusion doses of remifentanil on the hemodynamic response to rapid sequence anesthesia induction and tracheal intubation.

METHODS: In this prospective, randomized double-blind study, 60 ASA I or II patients without any airway abnormalities, who were scheduled to undergo elective surgery requiring endotracheal intubation, were allocated to receive remifentanil 0.25, 0.5, or 1.0 µg/kg/min. Anesthesia was induced with a remifentanil infusion and propofol 2.0 mg/kg. Rocuronium 1.0 mg/kg was given after a loss of consciousness and endotracheal intubation was performed 1 min after the rocuronium injection. The remifentanil infusion was stopped immediately before intubation. The noninvasive blood pressure (BP) and heart rate (HR) were recorded before induction (baseline), immediately before intubation, and at 1 min intervals until 5 min after intubation.

RESULTS: The HR and BP measured immediately before intubation decreased significantly in the three doses. The HR was similar in the three doses, and the BP was significantly different only between the 0.25 and 1.0 µg/kg/min doses (P < 0.05). The hemodynamic response to endotracheal intubation was very well blunted in 0.5 and 1.0 µg/kg/min, but not in 0.25 µg/kg/min. The HR and BP increased significantly 1 min after intubation in the 0.25 µg/kg/min (P < 0.05). There were no significant differences between the 0.5 and 1.0 µg/kg/min doses until 5 min after intubation.

CONCLUSIONS: Remifentanil 0.5 µg/kg/min infusion without a bolus provides excellent hemodynamic stability for a rapid sequence endotracheal intubation using propofol and rocuronium. There are no advantages in using remifentanil doses higher than 0.5 µg/kg/min.