Fentanyl attenuates cardiovascular responses to tracheal extubation

We carried out a controlled, randomized, double-blind study to examine the effects of intravenous fentanyl (1 or 2 micrograms kg-1) on hemodynamic changes during tracheal extubation and emergence from anesthesia in 60 ASA physical status I or II patients undergoing elective gynecological surgery. Anesthesia was maintained with 0.5%-1.5% isoflurane and 60% nitrous oxide (N2O) in oxygen. Muscle relaxation was achieved with vecuronium. The patients were randomly assigned to three group (each, n = 20), and fentanyl (1 or 2 micrograms kg-1), or saline (as a control) was given at the time of peritoneal closure. Changes in heart rate (HR) and blood pressure (BP) were measured during and after tracheal extubation. Adverse effects, including postoperative sedation and respiratory depression, were also assessed. The HR, systolic BP, and diastolic BP increased significantly during tracheal extubation in the control group (P < 0.05). Fentanyl 2 micrograms kg-1 attenuated the increases in these variables more effectively than fentanyl 1 microgram kg-1. The time interval from the study drug to extubation was similar in each group. Postoperative somnolence and respiratory depression were not observed in any patients in any of the three groups. We concluded that a bolus dose of intravenous fentanyl 2 micrograms kg-1 given at the time of peritoneal closure was of value in attenuating the cardiovascular changes associated with tracheal extubation and emergence from anesthesia, and that this treatment did not prolong the recovery. However, further studies are required to assess this technique in patients with cardiovascular or cerebrovascular diseases.