右美托咪啶对瑞芬太尼抑制切皮时患者体动反应半数有效效应室靶浓度的影响

目的 评价右美托咪啶对瑞芬太尼抑制切皮时患者体动反应半数有效效应室靶浓度(EC50)的影响.方法 择期拟行乳房肿瘤切除术患者40例,年龄20～50岁,体重45～58 kg,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将其随机分为瑞芬太尼组(R组)和右美托咪啶复合瑞芬太尼组(RD组),每组20例.R组和RD组切皮前分别静脉输注生理盐水和右美托咪啶1.0μg/kg,输注时间10min,同时靶控输注异丙酚,血浆靶浓度设为3.0 mg/L,13 min后开始靶控输注瑞芬太尼.采用序贯法进行试验,RD组和R组初始效应室靶浓度分别为2.5和3.0μg/L,待两药浓度均达靶浓度后切开皮肤3 cm,有体动反应,则下一例采用高一级浓度,无体动反应,则下一例患者采用低一级浓度,相邻浓度比值为1.2,发生体动反应的标准为患者出现躯干、四肢或头颈可见的运动.计算瑞芬太尼抑制患者体动反应的EC50及其95％可信区间.结果 RD组瑞芬太尼抑制切皮时体动反应的EC50为1.7 μg/L,95％可信区间为1.5～1.9 μg/L,R组瑞芬太尼抑制切皮时体动反应的EC50为2.5 μg/L,95％可信区间为2.2～2.7 μg/L,差异有统计学意义(P＜0.01).结论 靶控输注异丙酚(血浆靶浓度3.0 mg/L)下,静脉输注右美托咪啶1.0μg/kg可降低瑞芬太尼抑制切皮时患者体动反应的EC50.

Effect of dexmedetomidine on median effective target effect-sire concentration of remifentanil required for preventing body movement in response to skin incision

Objective To investigate the effect of dexmedetomidine on the median effectivetarget effectsite concentration (EC50) of remifentanil required for preventing body movement in response to skin incision made under propofol sedation.Methods Forty ASA Ⅰ or Ⅱ patients aged 20-50 yr weighing 45-58 kg scheduled for elective breast tumor excision were randomly allocated into 2 groups ( n =20 each):group remifentanil (group R) and group remifentanil + demedetomidine ( group RD).Sedation was induced with propofol TCI at target plasma concentration of 3.0 mg/L in both groups.In group RD dexmedetomidine 1.0 μg/kg was infused iv over 10 min before start of propofol TCI,while in group R equal volume of normal saline was infused instead of dexmedetomidine.Remifentanil TCI was started with target effect-site concentration set at 3.0 and 2.5 μg/L in groups R and RD respective at 13 min after beginning of propofol TCI.Skin incision (3 cm in length) was made when the target concentrations of propofol and remifentanil TCI were reached.Body movement was assessed by a nurse not involved in this study.EC50 and 95％ confidence interval (CI) of remifentanil were determined by up-and-down technique.The target effect-site concentration was increased or decreased by 20％ depending on the response of the previous patient to skin-incision.Results The EC50 of remifentanil for preventing body movement in response to skin incision performed under propofol sedation was 1.7 μg/L (95％ CI 1.5-1.9 μg/L) and 2.5 μg/L (95％ CI 2.2-2.7μg/L) in groups RD and R respectively.The EC50 of remifentanil was significantly lower in group RD than in group R.Conclusion Dexmedetomidine 1.0 μg/kg can decrease EC50 of remifentanil for preventing body movement in response to skin incision made under propofol sedation.