不同剂量右美托咪定对硬膜外麻醉的老年患者镇静遗忘效应

Amnesia and sedative effect with different doses of dexmedetomidine for elderly patients under epidural anesthesia

目的观察不同剂量右美托咪定对硬膜外麻醉的老年患者镇静遗忘效应。方法选择60例71-83岁,美国麻醉医师协会（ASA）评级为Ⅰ-Ⅱ级,拟在连续硬膜外麻醉下行下肢手术的骨科患者,随机分为3组（Ⅰ、Ⅱ、Ⅲ组）,每组20例。硬膜外麻醉后静脉输注右美托咪定负荷剂量0.5μg/kg,之后3组分别以0.2、0.3、0.4μg/（kg·h）泵注至手术开始缝合刀口时停药,观察用药后3组平均动脉压（MAP）、心率（HR）、血氧饱和度（Sp O2）和OAA/S镇静评分,术后24 h随访患者用药后至手术结束前对有关操作的遗忘程度。结果 3组用药后MAP、HR均低于麻醉前（P〈0.05）,以Ⅲ组的心率减慢最显著。Ⅱ、Ⅲ组镇静遗忘作用优于Ⅰ组,但Ⅲ组有25%患者出现深度镇静,导致Sp O2下降。结论静注右美托咪定0.5μg/kg的负荷剂量后,以0.3μg/（kg·h）输注对硬膜外麻醉的老年患者具有安全舒适的镇静遗忘作用。

Objective To observe the amnesia and sedation effect with different doses of dexmedetomidine for elderly patients under epidural anesthesia. Methods Sixty patients aged from 71 to 83 years old,ASA Ⅰ-Ⅱ grade,receiving lower limb orthopedic surgery were selected and divided into three group（ 20 in each group）. After intravenous infusion of epidural dexmedetomidine with a loading dose of 0. 5 μg / kg,then infused at a rate of 0. 2、0. 3、0. 4 μg /（ kg·h） in three guoups respectively until suture incision. MAP,HR,Sp O2 and OAA / S sedation score were observed and recorded at different time points： before anesthesia（ T1）,15 minutes after infusion（ T2）,30 minutes after infusion（ T3）,60 minutes after infusion（ T4）,and the end of the operation（ T5）. The degree of amnesia about the operation after 24 hours was followed up aslo. Results After administration of dexmedetomidine,MAP,HR was lower than that before anesthesia（ P〈0. 05）,and HR was decreased more obiviously in group Ⅲ. The effect of sedative and amnesia in group Ⅱand group Ⅲwas better than that in groupⅠ,while deep sedation-induced Sp O2 decline was found in a quarter of patients in group Ⅲ.Conclusions It will receive safe and comfortable sedation and amnesia effect in aged patients to administrate dexmedetomidine at loading dose of 0. 5 μg / h,and then at a rate of 0. 3 μg /（ kg·h） infusion.