Autonomic activity during dexmedetomidine or fentanyl infusion with desflurane anesthesia

To evaluate autonomic activity with dexmedetomidine or fentanyl infusion and desflurane anesthesia during laparoscopic gastric banding.

Randomized, single-blinded, open-label study.

Operating rooms at a university hospital.

40 patients scheduled for laparoscopic gastric banding with a mean body mass index of 50 kg/m2.

Patients received either dexmedetomidine (0.5 microg/kg given intravenously over 10 minutes, 0.4 microg.kg-1.h-1, n=20) or fentanyl (0.5 microg.kg-1 bolus, 1 microg.kg-1.h-1, n=20) during anesthesia. Response entropy of the electroencephalogram was maintained at 45+/-5 by adjusting end-tidal desflurane concentration.

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.

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.

Both dexmedetomidine and fentanyl facilitated anesthesia and attenuated autonomic activity. Dexmedetomidine produced a greater decrease in sympathovagal balance than fentanyl.