异丙酚靶控输注时患者呼吸抑制的半数有效浓度

EC50 of propofol for respiratory depression by target-controlled infusion

目的测定异丙酚靶控输注（TCI）时患者呼吸抑制的半数有效浓度（EC50），观察患者镇静状态的变化。方法择期全身麻醉手术患者50例（ASAⅠ～Ⅱ），按不同异丙酚血浆靶控浓度分为5组（n=10）：Ⅰ组，1．5mg／L；Ⅱ组，2．0mg／L；Ⅲ组，2．5mg／L；Ⅳ组，3．0mg／L；Ⅴ组，3．5mg／L。采用Datex—Ultima呼吸力学监测仪旁气流面罩法（FiO2：1．0）测定呼吸功能指标，同时观察脑电双频谱指数（BIS）和警觉-镇静（OAA／S）评分。记录患者各观察指标的基础值（T0），及异丙酚TCI启动后1（T1）、3（T3）、5（T，）、7（T7）、10min（T10）等时段的潮气量（VT）、每分通气量（MV）、呼气末二氧化碳分压（PETCO2）、呼吸频率（RR）、收缩压（SBP）、舒张压（DBP）、心率（HR）、脉搏血氧饱和度（SpO2）、脑电BIS，并进行OAA／S评分。应用Probit法分析异丙酚TCI时患者呼吸抑制的EC50。结果与Ⅰ组相比，Ⅱ～Ⅴ组患者输注异丙酚后VT下降（P〈0．05），呼吸抑制的持续时间明显延长；RR增加（P〈0．05）；Ⅱ组1例、Ⅲ组2例、Ⅳ组8例，Ⅴ组10例患者VT下降达到呼吸抑制标准；其中Ⅳ组8例，Ⅴ组10例患者出现呼吸暂停。所有患者SpO2维持在95％以上；BIS值及OAA／S评分均明显降低（P〈0．05）；出现呼吸抑制及呼吸暂停时BIS值分别为60．2±4．0、52．1±3．6，OAA／S评分均为0。异丙酚TCI时呼吸抑制的EC50为2．65mg／L（95％可信区间：2．41-2．90mg／L）。结论采用2．0～2．5mg／L血浆浓度异丙酚TCI能产生适度的清醒镇静或催眠作用，且对患者的呼吸抑制程度较小。

Objective To measure the median effective concentration （EC50） of propofol for respiratory depression administered by target-controlled infusion （TCI） and evaluate the change of sedation. Methods Fifty ASA Ⅰ - Ⅱ patients undergoing elective surgery were divided into five groups （n=10） according to different plasma concentrations of propofol TCI： 1.5 mg/L （group Ⅰ ）, 2.0 mg/L （group Ⅱ ）, 2.5 mg/L （group Ⅲ ）, 3.0 mg/L （group Ⅳ） and 3.5 mg/L （group Ⅴ ）. Respiratory function was monitored by side stream method （FiO2：1.0） with Datex-Uhima breathing mechanics monitoring device. The level of sedation was assessed by observers with the alertness/sedation scale （OAA/S） and the value of bispectral index（BIS）. tided volume （VT）, minute ventilation volume （MV）, end tidal carbon dioxide tension （PETCO2）, respiratory rate, SpO2, BIS, OAA/S, systolic blood pressure, diastolic blood pressure and heart rate were recorded before propofol TCI （T0）, 1 min（T1 ）, 3 min（T3）, 5 min（Ts）, 7 min（T7） and 10 min（T10） after propofol TCI. EC50 of propofol for respiratory depression was determined using Probit analysis. Results VT decreased with propofol concentration inereasement in group Ⅱ , Ⅲ , Ⅳ and Ⅴ （P〈0.05） more than that in group Ⅰ （1.2%- 9.3%） , but RR and the duration of respiratory depression increased （P〈0.05）. Respiratory depression was found in one case of group Ⅱ , two cases of group Ⅲ , eight cases of group Ⅳ and ten cases of group Ⅴ. Apnea was found in eight cases of group Ⅳ and ten cases of group Ⅴ. The value of BIS and OAA/S decreased in all groups （P〈0.05）. The value of BIS was 60.2±4.0 for respiratory depression and 52.1 ±3.6 for apnea, and the score of OAA/S was 0. EC50 of propofol for respiratory depression was 2.65 mg/L （95% confidence interval was 2.41-2.90 mg/L）. Conclusion Propofol TCI can realize satisfactory sedative and hypotic effect with mild respiratory depression at the plasma concentration of 2.0-2.5 mg/L.