Autonomic activity during dexmedetomidine or fentanyl infusion with desflurane anesthesia

Abstract 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 μ g/kg given intravenously over 10 minutes, 0.4 μ g · kg −1 · h −1 , n=20) or fentanyl (0.5 μ g · kg −1 bolus, 1 μ 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.