Effects of Alfentanil on the Hemodynamic and Catecholamine Response to Tracheal Intubation

A randomized, placebo-controlled study was conducted in 60 ASA Class I, II, and III patients to determine the dose response of alfentanil in moderating the cardiovascular and catecholamine response to tracheal intubation (INT). Patients were randomly allocated into one of four groups to receive either 15 μg/kg alfentanil (A15), 30 μg/kg alfentanil (A30), 45 μg/kg alfentanil (A45), or normal saline (control), given intravenously (IV) before induction of anesthesia. One minute after administration of 4.0 mg/kg thiopental and 1.5 mg/kg succinylcholine IV, tracheal intubation was performed using direct laryngoscopy. In response to INT, increases in heart rate, systolic blood pressure, and systemic vascular resistance occurred in the control group. These changes were significantly more than corresponding changes of heart rate, systolic blood pressure, and systemic vascular resistance in all three alfentanil groups (P < 0.05). In contrast, cardiac index and ejection fraction decreased moderately in every group during the study period, but there were no differences among groups with respect to either cardiac index or ejection fraction at corresponding times following INT. In the control group, epinephrine and nor-epinephrine serum concentrations increased by 152 ± 52% and 58 ± 62%, respectively, following INT (different from A30 and A45, P < 0.05). However, up to a dose of 30 μg/kg (A30), a dose-dependent decrease in the maximum percent changes of both epinephrine and norepinephrine occurred in response to INT. A larger dose of alfentanil was no more efficacious as the catecholamine response to tracheal intubation was not significantly different when comparing the A45 and A30 groups. It is concluded that 30 μg/kg is the optimal dose of alfentanil for providing complete attenuation of the cardiovascular and catecholamine response to tracheal intubation.