右美托咪定应用于硬膜外阻滞时的量效分析

Analysis of dose-effect of dexmedetomidine used in epidural blocks

目的分析硬膜外神经阻滞麻醉下不同剂量右美托咪定对患者镇静入睡的量效作用。方法 82例行择期下肢手术患者（ASAⅠ-Ⅱ级）在连续硬膜神经阻滞下（穿刺间隙L2-3,药物为1.00%利多卡因＋0.33%罗哌卡因）分为1组（n=19）、2组（n=22）、3组（n=20）、4组（n=21）,分别泵入右美托咪定0.7、0.8、0.9、1.0μg/kg负荷剂量,每组在30min内泵完,然后改为0.7、0.8、0.9、1.0μg·kg^-1·h^-1的速度持续剂量泵入,如4个组中有患者在不到30min就入睡停止负荷剂量转为该组的持续剂量泵入,手术结束包扎创面时停药。记录30min内患者是否入睡和右美托咪定泵入后的10、30、60、90min 4个时点的平均动脉压、心率。采用Probit法计算右美托咪定50%有效量（ED50）和95%有效量（ED95）及95%CI。结果右美托咪定的ED50和ED95分别为0.65μg/kg（95%CI：0.36-0.73μg/kg）、1.00μg/kg（95%CI：0.90-1.74μg/kg）,它可使心率减慢、血压升高。结论虽然右美托咪定可使心率减慢、血压升高,但在连续硬膜外神经阻滞下静脉给药患者可安静入睡,未出现不适及疼痛。

Objective To analyze the dose-effects of different doses of dexmedetomidine for sedation and sleep of the patients under epidural nerve block anesthesia. Methods A total of 82 patients undergoing elective lower limbs surgery（ASA grade I -II ） were randomly divided into 4 different doses of dexmedetomidine groups（group 1,n= 19;group 2, n =22;group 3, n=20 ;group 4, n = 21）, under continuous epidural nerve block, the loading dose of dexmedetomidine 0.7,0.8,0.9,1.0μg·kg^-1·h^-1 was intravenously pumped for 30 min, then pumped at a rate of 0.7,0.8,0.9,1.0 μg·kg^-1·h^-1 in the group 1,2,3 and 4 respectively. If any patient in 4 groups fell asleep at less than half an hour, the loading dose was stopped and the continuous dose was changed to pump, the drug administration was discontinued at wound dressing after operation. Whether the patient falling asleep was recorded,and the mean arterial blood pressure,heart＇rate at 4 time points of 10,30,60,90 min after infusion of dexmedetomidine were also recorded. The 50% effective dose（ED50） ,ED95 and 95%; confidence interval（CI） were calculated by using the Probit method. Results ED50 and ED95 of dexmedetomidine were 0.65 μg/kg（95% CI：0. 36-0.73 μg/kg）and 1.00 μg/kg（95% CI：0. 90-1.74 μg/kg） ,which could decrease the heart rate and increase the arterial blood pressure. Conclusion Although dexmedetomidine can decrease the heart rate and increase the arterial blood pressure,but the patients quietly fall asleep without discomfort and pain occurrence by the intravenous administration under continuous epidural nerve block.