[The use of heart rate variability analysis to determine changes in autonomic nervous system activity induced by laryngoscopy and endotracheal intubation].

Background: Laryngoscopy and intubation are associated with marked autonomic system activation that can be assessed by heart rate variability analysis (HRV)--a new method, comparing R-R intervals in 12-lead continuous ECG recording.
Methods: Fifty-two ASA I and II adults patients of both sexes were enrolled in the study. Patients were induced with fentanyl and thiopental, paralysed with vecuronium, and intubated. Continuous ECG was recorded and selected time-domain parameters (RMSSD, SDNN, NN50 and pNN50) were analyzed before and after intubation at 5- min intervals.
Results: Endotracheal intubation resulted in transient supraventricular and ventricular extrasystoles in six patients. Seven patients developed transient bigeminy. Equivocal changes of RMSSD, SDNN, NN50 and pNN50 were observed.
Conclusion: Because of the large incidence of cardiac rhythm disturbances, the HRV proved to be useless for assessment of autonomic system changes.