Abstract: Objective To study the effects of Midazolam on preventing patients underwent combined anesthesia from awareness and affect for regain consciousness in different time with intravenous injection (i.v). Methods 45 patients under went combined anesthesia were divided randomly into three groups(n=15): C,D₁ and D₂. These patients were induced and intubated with Fentanyl, Vercurium, Propofol iv. In group D₁ Midazolam (i.v) was administrated in the meantime with induction, in group D₂ Midazolam (i.v) after induction 30 min, while Midazolam was not administrated in group C. The anesthetic sum, time from operation and to extubation, awareness and recall were compared in C, D₁， and D₂ groups. Results It was beneficial to add Midazolam in combined anesthesia to avoid awareness and recall. The effects were different in refrain from awareness and affect for recovery time in the different time with i.v of Midazolam. Conclusion It was best that Midazolam (i.v) in the meantime with induction to prevent from awareness, reduce anesthetic sum, shorten the anesthesia recovery time and steady patient conditions.

Key words: administration＆dosage, combined anesthesia , awareness, recall, delayed awakening