目的测定右美托咪定含服用于患儿面罩吸入麻醉诱导前镇静的半数有效剂量(ED_(50))与95%有效剂量(ED_(95))。方法选择ASAⅠ级接受面罩吸入麻醉诱导的患儿,年龄2~6岁,体重指数18~25 kg·m~(-2),预计40例。麻醉前1 h口内含服右美托咪定,根据预计试验起始剂量设为3μg·kg~(-1),剂量按改良序贯法进行调整,根据上一例患儿吸入麻醉诱导时面罩接受时的镇静效果,下一例患儿增加或减少0.25μg·kg~(-1)。重复此过程至出现第七个交换点即研究结束,镇静效果以面罩接受满意程度四分法进行评估。采用Probit概率单位回归分析法计算右美托咪定的ED50和ED95及相应的95%可信区间(95%CI)。结果共入选患儿31例,年龄(4.57±1.46)岁,体重指数(22.13±2.66)kg·m~(-2)。患儿接受面罩的镇静效果满意15例,不满意16例,右美托咪定含服镇静的ED50为3.04μg·kg~(-1)(95%CI:2.77~3.67μg·kg~(-1)),ED95为3.67μg·kg~(-1)(95%CI:3.35~6.16μg·kg~(-1))。未见严重不良反应发生。结论麻醉前1 h右美托咪定含服用于患儿面罩吸入麻醉诱导前镇静的ED50和ED95分别为3.04μg·kg~(-1)和3.67μg·kg~(-1)。 Objective To determine the half effective dose (ED_ (50)) and 95% effective dose (ED_ (95)) of dexmedetomidine for sedation before induction of inhalation anesthesia in children. Methods Anesthesia-induced ASA class I patients received masks were enrolled in this study. Their ages ranged from 2 to 6 years. The body mass index was 18 to 25 kg · m -2. A total of 40 patients were enrolled. Dexmedetomidine was given intrabuginally 1 h before anesthesia, and the initial dose was set at 3 μg · kg -1. The dose was adjusted according to an improved sequential method. According to the previous example, When receiving the sedative effect, the next case of children increased or decreased 0.25μg · kg ~ (-1). This process was repeated until the seventh exchange, the end of the study, was completed and the sedation was evaluated using a quarter-mask of satisfaction ratings. The ED50 and ED95 and the corresponding 95% confidence intervals (95% CI) of dexmedetomidine were calculated using Probit Probability Regression Analysis. Results A total of 31 children were enrolled in this study. Their ages (4.57 ± 1.46) years and body mass index (22.13 ± 2.66) kg · m -2. The sedation effect of children receiving masks was satisfactory in 15 cases and not satisfied in 16 cases. The ED50 of dexmedetomidine in sedation was 3.04 μg · kg -1 (95% CI: 2.77 ~ 3.67 μg · kg ~ (-1)), 1), ED95 was 3.67μg · kg -1 (95% CI: 3.35-6.1μg · kg -1). No serious adverse reactions occurred. Conclusions The ED50 and ED95 of dexmedetomidine premedication before inhalation anesthesia induction were 3.04μg · kg ~ (-1) and 3.67μg · kg ~ (-1), respectively.