目的 通过比较右美托咪定和咪达唑仑硬膜外麻醉时的镇静、遗忘及并发症等, 探讨右美托咪定辅助镇静的临床应用。方法 择期行下肢或中下腹部手术的患者90例, 随机分为3组, 右美托咪定组（D组）、咪达唑仑组（M组）和对照组（C组）。三组患者均于硬膜外麻醉平面固定、效果完善后, 手术前20 min开始神经安定镇痛：D组和M组负荷剂量分别为0.6 μg /kg和0.06 mg /kg, 维持量分别为0.5 μg /( kg·h)和 0.05 mg /( kg·h)；C组泵注生理盐水50 ml/(kg·h)。负荷剂量均于10 min内泵完, 维持量于手术结束前30 min停止。监测并记录入室( T₀) 、麻醉平面固定后神经安定镇痛前( T₁)、神经安定镇痛后5 min(T₂) 、10 min(T₃) 、20 min(T₄) 、30 min(T₅) 及术毕(T₆) 时患者平均动脉压血压( MAP)、脉搏（HR）、血氧饱和度（SpO₂）及脑电双频指数(BIS)值, D、M组患者BIS值达到75(BIS75) 时所用的时间和用药剂量, 随访患者的不良反应及遗忘程度。结果 与T₀比较, D组患者MAP T₂、T₃时明显升高, HR T₂时明显下降（P<0.05）, T₃、T₄时极明显下降（P<0.01）；M 组患者MAP T₃、T₄时明显降低, HR T₃～T₅时明显下降, SpO₂ T₂、T₃时明显下降, D组和M组BIS均于T₂时开始下降（P<0.05）, D组T₄、T₅时下降极明显（P<0.01）。D组患者BIS达75时所需的时间短于M组（P<0.05）, 患者呼吸抑制的发生率极明显低于M组（P<0.01）, 但遗忘程度M组明显优于D组（P<0.01）。结论 右美托咪定和咪达唑仑均能达到硬膜外麻醉中辅助镇静的目的, 右美托咪定0.6 μg/kg作为负荷剂量, 既能满足术中镇静的需要, 又不会发生呼吸抑制。在遗忘作用方面, 咪达唑仑具有较好的遗忘作用, 右美托咪定辅助镇静时, 虽然患者能回忆术中部分事件, 但均无强迫体位等不良回忆。

Objective To investigate the sedative effects of dexmedetomidine on patients undergoing epidural block by comparing with midazolam. Methods Ninety patients were randomly divided into 3 groups, who received intravenous infusion of dexmedetomidine(D) , midazolam (M) and saline (C), separately. Patients in group D received dexmedetomidine 0.6 μg /kg as loading dose and following maintenance dose 0.5 μg /(kg·h), those in group M received midazolam 0.06 mg/kg and following 0.05 mg/(kg·h), while group C received 0.9 % normal saline. The loading dose was administered intravenously for 10 min, started as soon as analgesic effect was satisfactory, and stopped at 30 min before the end of operation. MAP, HR, SpO₂ and BIS score, which were used to evaluate the sedative effects, were recorded at the basement, before administration, 5 min, 10 min, 20 min, 30 min after administration and at the end of operation. At the same time, the side effects and incidence of amnesia were recorded. Results In group D, MAP increased at T₂ and T₃ compared with T₀, meanwhile HR decreased at T₂ (P<0.05 or P<0.01), markedly at T₃ and T₄ (P<0.01). In group M, MAP decreased at T₃ and T₄ compared with T₀, HR from T₃ to T₅ and SpO₂ at T₂ and T₃. BIS decreased from T₂ in both group D and group M (P<0.05), but significantly in group D at T₄ and T₅. Patients in group D had a shorter duration of BIS score down to 75 and a significantly lower suppressive rate of respiration compared with patients in group M, who had better amnesia. Conclusions Dexmedetomidine and midazolam are both suitable for sedation and amnesia to patients with epidural block, and dexmedetomidine 0.6 μg /kg as a loading dose is appropriate to patients with no respiratory suppression. As for amnesia, midazolam is better, while patients who receive dexmedetomidine have no bad memory, except some of recollection in the operation.