Fig. 2. Mean QTc interval duration (± SE; milliseconds; left axis ) and heart rate (± SE; beats/min; right axis , dotted line ) versus time interval (minutes) between injection of antiemetic and QTc interval measurement. ( A ) Droperidol, 0.75 mg, or ( B ) ondansetron, 4 mg, administered in patients with postoperative nausea and vomiting. In both groups, analysis of variance for repeated measurement was significant ( P < 0.001). * P < 0.05 versus baseline in the same treatment group.