RESUMEN
We designed this study to test the hypothesis that cervical epidural anesthesia would increase the high-frequency [HF] component of heart rate variability [HRV] as a result of cardiac sympathectomy, whereas lumbar epidural anesthesia would cause sympathetic predominance. HRV and spontaneous baroreflex [SBR] sensitivity were assessed before and after cervical and lumbar epidural anesthesia by using plain 1.5% lidocaine in healthy patients. Electrocrdiogram and noninvasive beat-to-beat arterial blood pressure were monitored. HRV was analyzed. Our results indicate that cervical, but not lumbar, epidural anesthesia depresses phasic and tonic dynamic modulation of the cardiac cycle by vagal nerve in conscious humans, we hypothesized that cervical epidural anesthesia would produce an imbalance of cardiac autonomic status i.e an increase vagaly mediated HR component of HRV as result of cardiac sympathectomy, whereas lumbar epidural anesthesia would cause sympathetic predominance