Left ventricular mass and heart rate variability in middle-aged and elderly salt-sensitive hypertensive subjects

Sevoflurane anesthesia decreases cardiac vagal activity and heart rate variability

We evaluated cardiac vagal activity during sevoflurane anesthesia in neurosurgical patients. Heart rate variability was determined by power spectral analysis and entropy with the patient awake and during sevoflurane anesthesia. High frequency power (0.15-0.50 Hz) and heart rate entropy decreased during sevoflurane and these effects were significantly correlated (r = 0.71 +/- 0.12, P < 0.05). The results confirm that cardiac vagal activity was the primary determinant of heart rate variability, which was attenuated by sevoflurane.

Autonomic activity during desflurane anesthesia in patients with brain tumors

OBJECTIVE

Although intracranial tumors may affect autonomic function, there are few reports of autonomic changes during anesthesia. The purpose of this study was to evaluate autonomic effects of anesthesia in patients with brain tumors compared to neurosurgical controls.

METHODS

Two groups were evaluated: group 1 = 10 neurosurgical patients undergoing spinal cord surgery, group 2 = 10 patients with intracranial tumors. After placement of electrocardiogram and Response Entropy electroencephalogram (EEG) electrodes, 10 min baseline measures were made. Heart periods were transformed into a percentage index and heart rate entropy determined as a measure of variance of autonomic activity. Tone was evaluated as the balance between accelerator and inhibitory activity. Tone-entropy was measured during propofol anesthetic induction and the first 60 min of desflurane anesthesia before the start of surgery.

RESULTS

Blood pressure and heart rate were similar between the groups. Starting at awake levels, vagal heart tone was observed. Anesthesia decreased vagal dominance to near zero in both groups. Heart rate entropy and EEG activity decreased during anesthesia with no significant difference between the groups. Desflurane concentrations required to maintain anesthesia were significantly lower in patients in brain tumors.

CONCLUSION

Tone-entropy analysis of heart rate indicates anesthetic related depression of autonomic activity with no difference between groups. Normal titration of desflurane concentrations to maintain adequate blood pressure produced desflurane requirements that were lower in patients with brain tumors, while autonomic and EEG activity were similar.

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/m2.

INTERVENTIONS

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.

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.