早孕对50％患者意识消失时的血浆异丙酚浓度的影响

目的观察早孕对50％患者意识消失时对指令无反应的血浆异丙酚浓度的影响。方法ASAI～Ⅱ级，年龄18-40岁患者，早孕组（n=27）拟行人工流产术，非早孕组（n=28）拟行择期腹腔镜手术。麻醉诱导采用靶控输注异丙酚，每组的第一个患者的靶控输注血浆异丙酚浓度2.0μg/ml。达到预设异丙酚血浆浓度后经过10min的平衡时间，所有患者给予睁眼指令。观察完患者的反应后采动脉血样做实测血清异丙酚浓度分析。采用“up-and-down”法，根据患者的反应决定下一个患者的血浆异丙酚浓度，直到每组至少出现6个交叉对为止。50％患者意识消失时对指令无反应的血浆异丙酚浓度和实测血清浓度根据6个独立交叉对的中点值的平均值决定。结果50％患者意识消失时对指令无反应的血浆异丙酚浓度在早孕组和非早孕组分别为（3.0±0.27）μg／ml和（2.8±0.38）μg/ml，组间差异无统计学意义（P〉0.05）。执行误差在两组间差异无统计学意义（P〉0.05），分别是30％和35.7％。结论早孕并不降低患者意识消失时的血浆异丙酚浓度。

Effect of early pregnancy on the C50 of propofol for loss of consciousness

Objective To investigate the effect of early pregnancy on plasma propofol concentrations at which 50% of the patients did not respond to verbal commands for loss of consciousness（C50 for loss of consciousness）. Methods ASAⅠ or Ⅱ patients aged 18-40 yr,scheduled to undergo elective pregnancy termination in pregnant group （n=27）and laparoscope surgery in nonpregnant group（ n = 28）. Anesthesia was induced with propofol using a computer assisted target-controlled infusion （TCI）. Plasma propofol concentrations of first patient were 2.5μg/ml at each group. After a 10-min equilibration period of the predeter-mined propofol blood concentration, a verbal command to open their eyes was given to the patients. Artery blood samples for analysis of the serum propofol concentration were taken at 11 min after equilibration of the propofol concentration. According to the patients＇ responses, plasma propofol concentrations were determined in next patient using tbe“up-and-down”method until at least six independent crossover pairs were observed in each group. The C50 of propofol for loss of consciousness was determined using the average of the midpoint of six independent crossover pairs. Serum propfol concentrations at which 50% of the patients did not respond to verbal commands were determined by same method. Results There was no significant difference in C50 of propofol for loss of consciousness between the pregnant （3.0±0.27μg/ml） and nonpregnant（2.8±0.38μg/ml） groups. No difference was found in performance error between the pregnant （30%）and nonpregnant （35.7%） women. Conclusion Early pregnancy does not decrease the concentration of propofol required for loss of consciousness.