Optimal fentanyl dosage for attenuating systemic hemodynamic changes, hormone release and cardiac output changes during the induction of anesthesia in patients with and without hypertension: a prospective, randomized, double-blinded study

Purpose

The purpose of this study was to compare the dose-related effects of fentanyl on systemic hemodynamics, hormone release and cardiac output in response to endotracheal intubation in patients with and without hypertension.

Methods

Forty-five patients without hypertension and 45 patients with hypertension (total 90 patients) undergoing elective general surgical, urological or gynecological procedures under general anesthesia were studied. The patients were randomly divided into three groups to receive either saline (control), 2.0 μg/kg fentanyl or 4.0 μg/kg fentanyl before tracheal intubation. Anesthesia was induced via intravenous target controlled infusion of propofol (plasma concentration, 4.0 μg/mL) followed by administration of the three drugs. Heart rate, blood pressure, and cardiac output were continuously monitored using Flo Trac/Vigileo system? and Bispectral index from before anesthetic induction until 10 min after tracheal intubation.

Results

In patients without hypertension, there was a significant difference in mean arterial pressure (MAP) among the three groups 2 min after intubation. Cardiac index (CI) in all three groups decreased before intubation compared with that in the awake period, returning to awake values after intubation in all three groups. There was a significant difference in CI between the 4 μg/kg fentanyl group and the other two groups immediately and 1 min after intubation. In patients with hypertension, a differential time course of MAP changes was observed among the three groups after intubation. CI in the three groups decreased after the induction of anesthesia and increased after intubation in control and 2 μg/kg fentanyl groups compared with that in the awake period.

Conclusions

The present study shows that it is preferable to administer 2 μg/kg fentanyl in patients without hypertension and 4 μg/kg fentanyl in patients with hypertension in order to minimize the changes in heart rate, systolic blood pressure and cardiac output associated with tracheal intubation.