右美托咪啶对靶控输注异丙酚意识消失时BIS值的影响

Effect of dexmedetomidine on bispectral index value at loss of consciousness caused by propofol given by target-controlled infusion

目的评价右美托咪啶对靶控输注异丙酚意识消失时脑电双频谱指数（Bis）值的影响。方法择期行普外科手术患者120例，性别不限，年龄25～50岁，体重41～68kg，ASA分级I或Ⅱ级，采用随机数字表法，将患者随机分为3组（n=40）：异丙酚组（P组）、右美托咪啶0．5倒kg＋异丙酚（D，P组）和右美托咪啶1．09g／kg＋异丙酚（D2P组）。每组再分为5个亚组（n=8）：异丙酚效应室靶控浓度0、1、2、3和4mg／L组（P0-4组）。P0-4组靶控输注异丙酚，效应室靶浓度分别为0、1、2、3和4mg／L；D，P0-4组静脉输注右美托咪啶0．5tcJkg，输注速率0．05μg·kg^-1·min^-1，输注结束后5min时靶控输注异丙酚，效应室靶浓度分别为0、1、2、3和4mg／L；D2P0-4组静脉输注右美托咪啶1．0μg/kg，输注速率0．1gg·ks^-1·min^-1，输注结束后5min时靶控输注异丙酚，效应室靶浓度分别为0、1、2、3和4mg／L。异丙酚靶控输注3min时记录OAMS评分和BIS值，OAMS评分≤2分判定为意识消失。采用Probit法计算半数患者意识消失时异丙酚的效应室靶浓度（EC50）和半数患者意识消失时的BIS值（BIS50）及其95％可信区间，采用Smith法计算BIS值对意识消失的预测概率。结果与P组比较，D1P组和D2P组EC50降低，BIS50升高（P〈0．05或0．01），预测概率差异无统计学意义（P〉0．05）；D，P组和D2P组EC50、BI％和预测概率比较差异无统计学意义（P〉0．05）。结论右美托咪啶复合靶控输注异丙酚时BIS值可准确预测患者的意识水平，而意识消失时的BIS值增加。

Objective To investigate the effect of dexmedetomidine on bispectral index （BIS） value at loss of consciousness （LOC） caused by propofol given by target-controlled infusion （TCI） .Methods One hundred and twenty ASA I or II patients, aged 20-50 yr, weighing 41-68 kg, scheduled for general surgery were randomly divided into 3 groups （n = 40 each）： propofol group （group P）, dexmedetomidine 0.5 μg/kg ＋ propofol group （group D1P） and dexmedetomidine 1.0 μg/kg ＋ propofol group （group D2P）. The patients in each group were randomly assigned into 5 subgroups （ n = 8 each） ： groups P0-4 receiving TCI of propofol with the target effect-site concentration （Ce） set at 0, 1, 2, 3 and 4 mg/L respectively. Groups D1P0-4 received iv infusion of dexmedetomidine 0.5 μg/kg at a rate of 0.05 μg·kg^-1·min-1 and TCI of propofol with the target Ce set at 0, 1, 2, 3 and 4 rag/L respectively at 5 min after the end of dexmedetomidine infusion. Groups D2 P0-4 received iv infusion of dexmedetomidine 1.0 μg/kg at a rate of 0.1μg·kg^-1·min-1 and TCI of propofol with the target Ce set at 0, 1, 2, 3 and 4 mg/L respectively at 5 min after the end of dexmedetomidine infusion. Three minutes after TCI of propofol was started, OAMS score and BIS value were recorded. The OAMS score ≤ 2 was defined as LOC. The ECho and 95 % confidence interval of propofol for LOC and BISs0 and 95 % confidence interval at LOC were calculated by Probit analysis. Prediction probability （Pk） of BIS value at LOC was calculated using Smith method. Results Compared with group P, EC50 was significantly decreased, BIS50 was significantly increased （ P 〈 0.05 or 0.01）, and no significant change was found in Pk in groups D2 P and D1P （ P 〉 0.05 ）. There were no significant differences in EC50, BIS50 and Pk between groups D2 P and D1P （ P 〉 0.05）. Conclusion BIS value can accurately predict the level of consciousness during anesthesia with dexmedetomidine and TCI of propofol, but BIS value is increased at LOC.