Individual and group effects of propofol on autonomic dynamics. Instantaneous autonomic indices extracted from the ECG for one subject (left) and averaged for six subjects (right) at baseline and during five levels of PROP administration. Confidence regions in gray are limited by median absolute deviations. The arrow at the end of L2 (mean RR plot) marks beginning of intermittent Phenylephrine administration. The arrow at the beginning of L4 (IDLE plot) marks beginning of loss of consciousness.