硬膜外麻醉下异丙酚联合咪达唑仑镇静对内隐记忆的影响

Effects of propofol-midazolam sedation on implicit memory during epidural anesthesia

目的探讨术中异丙酚联合咪达唑仑镇静对内隐记忆的影响,分析内隐记忆消失的中潜伏期听觉诱发电位(MLAEP)参数界值,为临床镇静深度监测提供一项新的客观指标。方法 硬膜外麻醉下择期手术病人45例(ASA Ⅰ～Ⅱ级),随机分为异丙酚组(P)、联合用药一组(PM1)、联合用药二组(PM2)3组,每组15例。P组:异丙酚2 mg·kg-1·h-1;PM1组:异丙酚1.5 mg·kg-1·h+咪达唑仑0.03 mg·kg-1·h-1;PM2组:异丙酚1.5 mg·kg-1·h-1+咪达唑仑0.06 mg·kg-1·h-1。所有病人经异丙酚或异丙酚联合咪达唑仑镇静15 min后,让病人听录音带即内隐记忆刺激。记录入室时(T1)、行硬膜外麻醉后(T2)、静脉给药后15min(T1)、切皮后2min(T4)、内隐记忆刺激完成即刻(T5)等时点的心率(HR)、平均动脉压(MAP)、MLAEP。术后6 h进行记忆调查,测定病人的模糊辨听率。结果 异丙酚镇静Pa、Nb波潜伏期延长、波幅降低(P<0.05),但联合用药组潜伏期延长更明显、波幅降得更低(P<0.05)。所有病人外显记忆均消失;P组均存在内隐记忆,两联合用药组内隐记忆均消失。结论异丙酚和咪达唑仑联合镇静可以消除外显记忆和内隐记忆。MLAEP参数Pa、Nb波潜伏期、波幅可以作为评价术中镇静深度的客观监测指标。

Objective To investigate the effects of propofol and midazolam in combination on implicit memory and the relationship between the depth of sedation monitored by mid-latency auditory evoked potential (MLAEP) and implicit memory.Methods Forty five ASA Ⅰ - Ⅱ patients (22 male, 23 female) aged 18-75 yr, weighing 40-79 kg undergoing elective surgery under epidural anesthesia were randomly divided into 3 groups : I group P received propofol 2 mg·kg-1 ·h-1 during operation ( n = 15) ; Ⅱ group PM1 received propofol 1.5 mg·kg-1 ·h-1 + midazolam 0.03 mg · kg · h-1 ( n = 15) and Ⅲ group PM2 received propofol 1.5 mg · kg-1 · h-1 + midazolam 0.06 mg · kg-1 ·h-1 ( n = 15 ) . The patients were premedicated with intramuscular atropine 0.5 mg. 2 % lidocaine was used for epidural anesthesia. The sedation depth was maintained at OAA / S score of 2 (lethargic response to name) and monitored by MLAEP. 15 min after induction of sedation the patients were subjected to listening to an audiotape (implicit memory priming) . 6 h after operation implicit memory was tested directly and indirectly. MAP, HR and MLAEP were monitored and recorded before and after epidural anesthesia was successfully performed (T1-2 ) , 15 min after induction of sedation (T3), 2 min after skin incision (T4) and at the end of implicit memory priming stimulation (T5 ) . Results There were no significant differences in sex, age, height, body weight, duration of anesthesia and operation, the total amount of local anesthetic consumed and the level of education among the 3 groups (P > 0.05). Pa and Nb latencies were prolonged and Pa / Pb amplitudes depressed after the patients being sedated with propofol in group P ( P < 0.05) . The Pa and Nb latencies were significantly longer and Pa / Nb amplitudes lower in group PM, and PM2 than in group P ( P < 0.05) . The intraoperative explicit memory was lost among all patients. Implicit memory was spared in group P but lost in group PM, and PM2. Conclusion Both explicit and implicit memory were lost during sedation with propofol combined with midazolam. Pa, Nb latencies and Pa / Nb amplitudes can be used to assess the depth of sedation and anesthesia.