右美托咪定对丙泊酚靶控输注意识消失半数有效浓度的影响

目的探讨右美托咪定对丙泊酚靶控输注(TCI)时患者意识消失的半数有效浓度(EC50)的影响。方法择期全身麻醉手术患者40例(ASAⅠ～Ⅱ级),随机分成两组(n=20):右美托咪定组(D组)和对照组(C组)。D组麻醉诱导前经微量泵泵注右美托咪定负荷量0.4μg/kg(15min)静脉输注完毕,然后以0.4μg/(kg·h)维持输注,C组泵注等量生理盐水。麻醉诱导采用丙泊酚TCI,设定起始血浆靶浓度为2.3μg/ml,按相邻浓度比值为1.18序贯法给药,达到设定的血浆靶浓度后进行镇静/警觉评分(OAA/S),后静脉注射舒芬太尼及顺阿曲库铵,纯氧通气3min后气管插管。记录患者静脉输注右美托咪定或生理盐水前(T0),静脉输注15min后(T1),丙泊酚血浆靶浓度达到设定靶浓度时(T2),诱导后插管前(T3),插管后1min(T4)、3min(T5)、5min(T6)各时点的BIS及其MAP、HR。计算并比较D、C组丙泊酚TCI患者意识消失的EC50。结果 D、C组丙泊酚TCI患者意识消失的EC50分别为2.94μg/ml(95%的可信区间为2.79～3.10μg/ml)和3.67μg/ml(95%的可信区间为3.44～3.90μg/ml),D组低于C组(P<0.05)。T1时D组患者BIS值低于C组(P<0.05);T4时C组HR、MAP较T0时均升高(P<0.05)而D组无变化(P>0.05);T1～T6时D组患者的HR均低于C组(P<0.05)。结论右美托咪定以负荷量0.4μg/kg继以0.4μg/(kg·h)维持静脉输注可以使患者产生明显的镇静作用,降低BIS值,减轻气管插管反应,并能使丙泊酚TCI患者意识消失的EC50降低为2.94μg/ml。

Effect of dexmedetomidine on the EC50of propofol target-contorolled infusion for unconsciousness

Objective To evaluate the effect of dexmedetomidine on the median effective concentration(EC50) of propofol target-controlled infusion(TCI) for unconsciousness.Methods Forty patients(ASAⅠ~Ⅱ) scheduled for elective operation under general anesthesia were enrolled in this study.All patients were randomly divided into two groups(n=20):dexmedetomidine group(group D) and control group(group D).In D group,0.4 μg/kg of the loading dose dexmedetomidine was administered intravenously by micro pump for over 15 minutes before general anesthetic induction,then0.4 μg/(kg·h) was sustaining,while in group C,same volume of 0.9% normal saline was given by the same way.Propofol was used to anesthetic induction by target-controlled infusion(TCI),2.3 μg/ml was set as start target plasma concentration,followed by increments in the ratio of 1.18 between relation concentration with sequential method.OAA/S was determined when propofol got the target plasma consciousness of set,then sulfentanil and Cis-atracurium were administered intravenously,and pure oxygen was inhaled for 3 min before endotracheal intubation was enforced.The parameters of BIS、MAP and HR were recorded before dexmedetomidine or 0.9% normal saline infused intravenously(T0),15 min after intravenous infusion(T1),the time that propofol got the target plasma concentration of set(T2),pre-intubation(T3),1 min after intubation(T4),3 min after intubation(T5),5 min(T6) after intubation.The EC50 of propofol for unconsciousness in group D and C was computed and compared.Results EC50 of propofol TCI for unconsciousness was 2.94 μg/ml(95% confidence interval was 2.79~3.10 μg/ml)in group D and 3.67 μg/ml(95% confidence interval was 3.44~3.90 μg/ml) in group C.The EC50 of propofol TCI for unconsciousness in group D was lower than in group C(P<0.05).At T1,BIS in group D was lower than in group C(P<0.05).In group C,HR,MAP at T4 increased than T0(P<0.05),however,in group D showed no change(P>0.05);HR in group D was lower than in group C from T1 to T6(P<0.05).Conclusion Dexmedetomidine with a 0.4 μg/ml loading dose followed by 0.4 μg/(kg·h) maintain infusion causes sedation and decreases BIS,reduces the response of endotracheal intubation,and decreases the EC50 of prepofol for unconsciousness to 2.94 μg/ml.