Fig. 3. The hemodynamic response (mean ± SD) to target, controlled infusions of dexmedetomidine. There were significant changes in cardiac output and heart rate after infusion step 1. Stroke volume remained unchanged until higher doses. Mean arterial blood pressure (MAP) showed a biphasic (low, then high) response to increasing infusions of dexmedetomidine. *Significant change from preinfusion baseline, P < 0.05.