The various methods have been used to prevent or minimize the increase of blood pressure and heart rate to endotracheal intubation. Opioids are the most widely used drug for hemodynamic stability. The purpose of this study was to compare the effects of fentanyl with those of alfentanil on hemodynamic changes to induction of anesthesia and endotracheal intubation.

Forty five patients were divided into three groups. They received intravenous fentanyl 1.0 µg/kg, alfentanil 5 µg/kg or saline 10 ml (control group), respectively. Baseline mean arterial blood pressure and heart rate were measured before the induction of anesthesia. Tracheal intubation was done 3 min after the injection of muscle relaxant. Mean arterial blood pressure and heart rate were measured every minute for 3 min after the induction of anesthesia and tracheal intubation and the results were compared with baseline value.

Mean arterial blood pressure decreased significantly compared with baseline value after the induction of anesthesia, but there were no significant differences among the three groups. Heart rate initially increased and then decreased. After tracheal intubation, mean blood pressure and heart rate increased significantly in all groups. The extent of this was significantly lower in the alfentanil group and slightly lower in the fentanyl group than in the control group.

Alfentanil is more effective than fentanyl at inhibiting cardiovascular responses following intubation, but further studies are needed to define the optimal injection time and drug dosage.