Abstract: To investigate the effects of vecuronium on the bispectral index (BIS), response entropy (RE) and state entropy (SE) during propofol anesthesia. MethodsSixty patients undergoing elective surgery were randomly divided into four groups, 15 patients in each. Anesthesia was induced with target controlled infusion (TCI) of propofol. When the OAA/S score was below one, a laryngeal mask was inserted. Ventilation parameters were adjusted to target an endtidal carbon dioxide tension between 35 and 45 mmHg. The effectsite concentration of propofol was maintained at 2.0μg/ml or 3.0μg/ml for 5 minutes. Vecuronium 0. 1?mg/kg was given in groups vecuronium2.0 (V2.0) and vecuronium3.0 (V3.0). Normal saline was given in the other two control groups (C2.0 and C3.0). BIS, RE, SE, heart rate (HR) and mean arterial pressure (MAP) values were recorded before induction, just before neuromuscular block injection（the baseline）and 5 minutes after injection. ResultsCompared with the baseline, BIS, RE, SE significantly decreased after injection in the V2.0 and C2.0 groups（P＜0.05）, however these had no changes in the V3.0 and C3.0 groups（P＞0.05）. Compared with the control groups, BIS, RE, SE did not change after muscle relaxation injection in all patients（P＞0.05）. ConclusionNeuromuscular block alters the BIS, RE and SE scores in moderately sedated patients but not in deeply sedated patients.

Key words: Vecuronium, Bispectral index, Entropy, Propofol