Background: Heart rate variability (HRV) monitoring is a new, non-invasive method in the assessment of the autonomic nervous systems activity. LF/TP is the index of adrenergic activation, HF/TP is the index of cholinergic activation and the LF/HF ratio represents the dynamic balance between both parts of the autonomic system. The aim of this study was to evaluate the advantage of intraoperative HRV (spectral analysis) as a method of autonomic nervous system activity assessment, in comparison with traditional variables such as heart rate and blood pressure. Methods: 21 ASA I patients, aged between 17 and 72 years (mean age - 40.5), following surgery on the facial cranium due to neoplasmic changes were anesthetized by means of thiopental and suxamethonium for induction and nitrous oxide with fentanyl for anesthesia maintenance. HRV indices were calculated from 5-minute fragments of the recorded ECG. Results: LF/TP decreased following intubation and during anesthesia maintenance (p < 0.001). HF/TP decreased during anesthesia induction and intubation (p < 0.05), following intubation (p < 0.001) and during anesthesia maintenance (p < 0.05) and increased during and following extubation (p < 0.05). The LF/HF ratio decreased during the first 5 minutes following extubation (p < 0.05). The heart rate was elevated following intubation (p < 0.05) and had its lowest value following extubation (p < 0.01). The blood pressure remained unchanged during the procedure. Conclusion: HRV monitoring might provide a more convenient index of autonomic activity during general anesthesia, than classical estimates based on the heart rate or blood pressure.

Keywords: general anesthesia, Holter monitoring, Electrocardiography, Autonomic Nervous System, cholinergic, adrenergic