Abstract: To determine the optimal dosage of midazolam administered in the epidural puncture. Method: 150 patients were divided into 5 groups randomly, 30 patients each group. Group 1 were given saline 2 mLiv before epidural puncture. Group 2～5 had 0.02、0.04、0.06、0.08 mg/kg midazolam adiministered before epidural puncture respectively. The changes of MAP, HR, R, SpO₂, memory and sedative degree were observed. Results: The MAP, HRincreased dramatically by 2.3 kPa and 12 bpm in group 1 and group 2 and there were no differences in MAP and HR changes between the two groups. There were no differences in MAP and HR changes in group 3 post-puncture. After midazolam was administered MAP and HR decreased respectively by 1.1 kPa and 8 bpm in group 4 and 5. RR AND SpO₂ kept normal in all groups. The memory rates were 100%, 87%, 40%, 17% and 0 in group 1～5 respectively. Sedative degree: the patients kept conscious or could be awaked easily in group 1～4 and there were 9 patients in group 5 with difficulty to awake but the lid reflex existed. Midazolam of 0.04～ 0.06 mg/kg iv before epidural puncture provides ideal procedural state, stabilizes the Vital signs, eliminates the vicious memory and brings patients comfort.

Key words: midazolam, epidural anesthesia, memory, sedation