丙泊酚诱导下右美托咪定抑制女性患者喉罩置入心血管反应的半数有效剂量

The ED_(50) of dexmedetomidine for suppressing cardiovascular responses to placement of laryngeal mask in female patients with induction of propofol

目的：测定靶控输注丙泊酚诱导下右关托咪定抑制女性患者喉罩置入心血管反应的半数有效剂量（ED50）。方法：选择择期行妇科腹腔镜手术患者，年龄18～55岁，ASA分级Ⅰ或Ⅱ级，右美托咪定初始剂量为1．0μg／kg，根据患者的心血管反应情况采用改良序贯法调节下一例患者的给药剂量，递增递减梯度为0．1μg／kg，泵注时间为10min。右美托咪定泵注结束后靶控输注丙泊酚，脑电双频指数（BIS）稳定在45～55后推注维库溴铵0．1mg／kg，3min后置入喉罩。心血管反应阳性定义为喉罩置入后2min内最高的SBP和（或）HR高出基础值15％。在试验过程中，出现至少7个心血管反应阳性转阴性拐点则终止研究。依据概率单位回归分析法计算右关托咪定抑制喉罩置入过程中心血管反应的ED50、（95％的有效剂量）ED95及相应的95％可信区间（CI）。结果：右美托咪定抑制喉罩置入心血管反应的ED50、ED95分别为0．65μg／kg、0．94μg／kg，相对应的95％CI分别为0．44—0．80μg／kg、0．79～2．47μg／kg。结论：靶控输注丙泊酚诱导下，右美托咪定抑制女性患者喉罩置入心血管反应的ED。为0．65μg／kg。

Objective To determine the ED50 of dexmedetomidine for suppressing cardiovascular responses to placement of laryngeal mask airway （LMA） in patients undergoing gynecological laparoscopic surgery with induction of propofol. Methods ASA Ⅰ or Ⅱ Patients aged 18 to 55 undergoing elective gynecological laparoscopic surgery were enrolled. After an bolus dose of dexmedetomidine over 10 min, anaesthesia was induced with target-controled propofol, and then bolus of vecuronium of 0.1 mg/kg was injected when the BIS was between 45 and 55. LM palcement was performed 3 minutes after vecuronium injection. The modified Dixon＇ s up-and-down method was used to determine the bolus dose of dexmedetomidine, starting from 1.0 μg/kg （step size：0.1 μg/kg）. Cardiovascular response was defined as an increase in SBP and/or HR by 15% of baseline within 2 min after placement of LMA. The test ended after at least 7 crossovers （ successive ＇response＇ or ＇non- response＇） were obtained. Probit analysis was used to calculate ED50, ED95 and 95% confidence interval （CI）. Results The ED50 and ED95 （95% confidence interval） of dexmedetomidine for suppressing cardiovascular responses to placement of LMA was 0.65μg/kg （0.44-0.80）μg/kg and 0.94 μg/kg （0.79-2.47）μg/kg. Conclusion Under induction of target-controled propofol, the ED50 of dexmedetomidine is 0.65μg/kg for suppressing cardiovascular responses to placement of LMA in female patients.