右美托咪定对丙泊酚引起老年患者意识消失半数有效浓度的影响

Effect of dexmedetomidine on EC50 of propofol on loss of consciousness in elderly patients

目的探讨右美托咪定对丙泊酚引起老年患者意识消失时半数有效浓度(EC50)的影响。方法 58例年龄在60～75岁之间的老年患者,排除严重的系统疾病,随机分为两组:右美托咪定组(A组)31例,生理盐水组(B组)27例。两组均先10min分别泵入右美托咪定或生理盐水(60ml/h),然后丙泊酚以靶控输注(TCI)泵入,设定初始血浆浓度(Cp)2.0μg/ml,待丙泊酚Cp和效应室浓度(Ce)达平衡时,观察意识消失与否,记录相应时点的生命体征,达平衡时所用丙泊酚的总量。结果 A组18例、B组16例在Cp与Ce达平衡时意识消失,A组泵入右美托咪定后丙泊酚意识消失时的EC50为1.023μg/ml,95%CI为0.959～1.091μg/ml,Cp和Ce达平衡时丙泊酚用量为(66.03±21.14)mg。B组患者意识消失时丙泊酚的EC50为1.310μg/ml,其95%CI为1.196～1.435μg/ml,Cp和Ce达平衡时丙泊酚用量为(85.81±24.57)mg。A组较B组EC50减少为21.9%,丙泊酚用量减少为23%(P<0.05)。结论右美托咪定能显著降低老年患者丙泊酚意识消失时的EC50,减低丙泊酚的用量。

Objective To investigate the effect of dexmedetomidine on EC50 of propofol on loss of consciousness（IX）C） in elderly patient＇s Methods Fifty-eight ASA I or II grade patients, aged 60-75 years, scheduled for selective surgery were randomly allocated to receive dexmedetomidine （group A）and normal saline （group B） before target controlled infusion （TCI）of propofol. 31 patients in the group A received intravenous infusion of 0. 4 μg/kg dexmedetomidine and 27 patients in the group B received intravenous infusion of 10 ml normal saline in 10 minutes prior to propofol infusion. The target plasma concentration （Cp） in the first patient was set to 2 /μg/ml. When it was balanced between Cp and Ce（eoncentration of effect-site）, status of consciousness, vital signs and proprofol usage were recorded. Results Eighteen patients in group A and 16 in group B lost their consciousness when Cp and Ce balanced. EQ0 was 1. 023 μg/ml, 95% confidence interval（CI） ：0. 959-1. 091μg/ml and total propofol usage was （66.03±21.14） mg in group A and EC50 was 1. 310μg/ml,95% CI：1. 196-1. 435μg/ml and total propofol usage was （85.81±24. 57） mg in group B. Conclusion Dexmedetomidine can decrease the EC50 of pmpofol on loss of consciousness in elderly patients