目的 比较不同剂量右美托咪定(DEX)对高龄患者椎管内麻醉的镇静效果、麻醉后寒颤及早期术后认知功能的影响。方法 选择择期实施椎管内麻醉的下肢手术高龄患者随机分为右美托咪定组0.2 μg·kg^-1·h^-1组(L组)、0.4 μg·kg^-1·h^-1(M组)和0.75 μg·kg^-1·h^-1(H组),每组25例。患者在椎管内麻醉后10 min静脉泵注DEX 0.5 μg/kg,随后L组患者0.2 μg·kg^-1·h^-1,M组为0.4 μg·kg^-1·h^-1,H组为0.75 μg·kg^-1·h^-1泵注维持,三组患者均于手术结束前30 min停药。比较三组患者于麻醉前(T0)、开始使用(T1)、手术开始后10 min(T2)、20 min(T3)、30 min(T4)以及1 h(T5)患者Ramsay评分、BIS值、MAP和HR,并观察记录患者寒战分级、寒战发生率; 术后1 d和术后7 d分别测定简易智力状态量表(MMSE)评分,记录术前及术后认知功能障碍的发生率。 结果 L、M、H三组Ramsay评分在T2、T3及T4时间点明显高于T0、T1(P＜0.05),且同时间点M、H组均高于L组(P＜0.05)。三组BIS 值在T2、T3及T4时间点明显低于T0、T1(P＜0.05),且同时间点M、H组均低于L组(P＜0.05)。三组MAP、HR在T2、T3、T4时间点均明显低于T0、T1(P＜0.05),且同时间点M、H 组低于L组(P＜0.05)。M、H组寒颤发生率明显低L组(P＜0.05)。L、M、H组术后7 d MMSE评分较术前明显降低,L、M、H组术后7 d术后认知功能障碍(POCD)发生率差异无统计学意义。结论 较术前相比,DEX对高龄腰硬联合麻醉下下肢手术患者具有良好的术中镇静作用,减少术后POCD 的发生,可有效减少患者椎管内麻醉后寒战的发生,0.4 μg·kg^-1·h^-1的DEX是患者较合适的临床应用剂量。

Objective To compare the effects of intraspinal administration of different dosages of dexmedetomidine (DEX) on sedation, shivering, and early postoperative cognitive function of elderly patients.Methods Elderly patients with lower extremity surgery under intravertebral anesthesia were randomly divided into group L, group M, and group H, with 25 cases in each group.The patients were given intraspinal anesthesia, and 10 min later slowly injected with DEX 0.5μg/kg.Then, the group L, group M, and group H were injected with DEX at 0.2 μg/(kg·h), 0.4 μg/(kg·h), and 0.7 μg/(kg·h) for maintenance.All the three groups stopped injection 30 min before the end of the surgery.Ramsay score, BIS, MAP, and HR, shivering grade, and shivering rate of the three groups were compared before anesthesia (T0), at the time of injection (T1), and 10 min (T2), 20 min (T3), 30 min (T4), and 1 h (T5) after surgery.Simple Mental State Scale (MMSE) was used at 1d and 7d after the surgery to measure the preoperative and postoperative incidence rate of cognitive dysfunction.Results The Ramsay scores of the three groups at T2, T3, and T4 were significantly higher than those at T0 and T1 (P<0.05), and at the same time point, the Ramsay scores of the group M and group H were higher than those of the group L (P<0.05).The BIS values of the three groups at T2, T3, and T4 were significantly lower than those at T0 and T1 (P<0.05), and at the same time point, the BIS values of the group M and group H were lower than those of the group L (P<0.05).The MAP and HR of the three groups at T2, T3, and T4 were significantly lower than those at T0 and T1 (P<0.05), and at the same time point, the MAP and HR of the group M and group H were lower than those of the group L (P<0.05).The incidence rates of shivering of the group M and group H were significantly lower than that of the group L (P<0.05).At 7 d after the operation, the MMSE scores of the three groups were significantly lower compared with preoperation, but there was no statistically significant difference in the incidence rate of POCD.Conclusion Compare with preoperation, DEX shows a better sedative effect and prevents POCD and shivering in elderly patients with lower extremity surgery.DEX at 0.4 μg/(kg·h) is appropriate in clinical application.