Safety was assessed by monitoring vital signs and recording adverse events. During anesthesia all patients receive continuous ECG, BIS, pulse oximetry, capnography monitoring. AP was measured every 3-5min. Arterial blood gases were checked by doctor prescription. An adverse event was recorded if systolic blood pressure was <90 or >160 mmHg or if heart rate was <50 or >110 beats/min; desaturation was estimated as peripheral oxygen saturation (or SaO2) <90%. Interventions for bradycardia, tachycardia, hypertension and hypotension comprised titration or interruption of study agent, or additional drug therapy.