同等药效学指标下依托咪酯与丙泊酚脑电双频指数值的比较

Comparison of bispectral index value induced by etomidate and propofol at same pharmacodynamics index

目的研究靶控输注（target controlled infusion，TCI）依托咪酯使50％手术患者意识消失时血浆和效应室靶浓度（EC50）与脑电双频谱指数（bispectral index，BIS）。同时比较达到相同的药效学指标（意识消失EC50）时，依托咪酯与丙泊酚的BIS值有无差异。方法选择年龄18岁～64岁，ASAI～II的患者，不用任何术前药。靶控输注依托咪酯，以血浆靶浓度0．25mg／L为起点，达到预期血浆靶浓度后每30秒递增0．03mg／L，直至患者意识消失为止。采用概率单位回归分析方法计算患者意识消失时依托咪酯的血浆靶浓度和效应室靶浓度的EC05、EC50和EC95及其对应的BIS值。将所得BIS值与我们以前报道的丙泊酚意识消失时的BIS值进行比较。结果择期手术患者TCI依托咪酯意识消失时的血浆靶浓度EC05、EC50和EC95分别是0．46mg/L、0．59mg/L、0．71mg／L；效应室靶浓度的EC05EC50和EC95分别是0．37mg／L、0．51ms／L、0．64mg／L；5％、50％和95％患者意识消失时BIS分别是56、44、31。达到相同的药效学指标时（意识消失EC50），依托咪酯组的BIS值（44．50±9．96）明显低于丙泊酚组（57．93±11．28）（P〈0．01）。结论择期手术患者TCI依托咪酯意识消失时血浆和效应室靶浓度EC50为0．59mg/L和0．51mg/L；依托咪酯组意识消失EC50的BIS值明显低于丙泊酚组。

Objective To measure the predicted plasma and effect-site EC50 and bispectral index（BIS） of etomidate delivered with TCI, and to compare the difference in BIS value induced by etomidate and propofol at same pharmacodynamics index （EC50 of losing consciousness）. Methods Forty seven patients scheduled for surgery were anesthetized with etomidate using TCI. TCL started to get a predicted plasma etomidate concentration of 0.25 mg/L, and increased by 0.03 mg/L every 30 s until patients lost their consciousness. A quantal response model（probit analysis） was used to calculate the predict plasma and effect-site EC05, EC50 and EC95 of etomidate, and the corresponding BIS values were recorded and compared to that induced with propofol reported before. Results The predicted plasma etomidate concentration of ECso to losing consciousness was 0.59 mg/L with EC05 and EC95 of 0.46, 0.71 μg/ml, respectively. The corresponding effect-site concentration of ECso was 0.51 mg/L with EC05 and EC95 of 0.37 and 0.64 mg/L, respectively. In this study, BIS values to make 50% and 90% of patients losing their consciousness were 44 and 31-56, respectively. The BIS value induced with etomidate（45±10） was markedly lower than that with propofol（58±11 ） at the same pharmacodynamics index（EC50 of losing consciousness）. Conclusion The predicted plasma and effectsite EC50 of etomidate administered with TCI to lose consciousness is 0.59 mg/L and 0.51 mg/L, respectively. The corresponding BIS value with etomidate is markedly lower than that with propofol.