Autonomic activity during dexmedetomidine or fentanyl infusion with desflurane anesthesia

Study Objective: To evaluate autonomic activity with dexmedetomidine or fentanyl infusion and desflurane anesthesia during laparoscopic gastric banding. Study Design: Randomized, single-blinded, open-label study. Setting: Operating rooms at a university hospital. Subjects: 40 patients scheduled for laparoscopic gastric banding with a mean body mass index of 50 kg/m(2). Interventions: Patients received either dexmedetomidine (0.5 mu g/kg given intravenously over 10 minutes, 0.4 mu g . kg(-1) . h(-1), n = 20) or fentanyl (0.5 pg . kg (-1) bolus, 1 mu g . kg(-1) . h(-1), n = 20) during anesthesia. Response entropy of the electroencephalogram was maintained at 45 +/- 5 by adjusting end-tidal desflurane concentration. Measurements: In the operating room, blood pressure, heart rate (HR), response entropy, end-tidal desflurane concentration, tone entropy, and power-spectral analysis of HR were measured with the patient awake; 20, 40, and 60 minutes from intubation and the start of drug infusion; and at extubation. Main Results: The mean end-tidal desflurane concentration during anesthesia was 4.0% +/- 0.6% with dexmedetomidine and 4.1% +/- 0.7% with fentanyl, indicating a similar anesthetic requirement in both groups. Autonomic activity, determined by tone entropy and spectral analysis of HR, decreased by 50% during anesthesia in both groups. The dexmedetomidine group showed a greater decrease in sympathovagal balance during anesthesia. Conclusion: Both dexmedetomidine and fentanyl facilitated anesthesia and attenuated autonomic activity. Dexmedetomidine produced a greater decrease in sympathovagal balance than fentanyl. (C) 2007 Elsevier Inc. All rights reserved.