二次平衡法测定吸入麻醉药液/气分配系数

Double-equilibration technique for measuring liquid/gas partition coefficients of isoflurane

吸入麻醉药的分配系数是指在一定大气压和一定温度下,吸入麻醉药分子在两个物相间的运动达到平衡时浓度比值。吸入麻醉药在不同介质中的分配系数是决定其许多药理学特点的重要理化性质,但其测定方法国内尚无报道。为此,我们采用注射器一锥形瓶二次平衡法测定了在1个大气压、37℃条件下异氟醚(接近理想的吸入麻醉药)的橄榄油/气(O/G)、生理盐水/气(S/G)、水/气(W/G)分配系数,结果分别为90.2±2.41、0.626±0.019、0.741±0.025。虽然O/G和S/G相差150倍,但本结果中两者的变异系数均小于3%,这表明本方法适用范围广且结果重复性好。

This study was designed to establish methods to measure partition coefficients of inhaled anesthetics at 1 atmosphere and 37 C by using syringe-flask double equilibration technique. Olive oil/gas (O/G), saline/gas (S/G), and water/gas (W/G) partition coefficients of isoflurane were 90.20±2.01, 0.6256±0.109, and 0. 741±0.025, respectively. Even though O/G was 150 folds of S/G,coefficients of variation for both O/G and S/G were less than 3%. The results indicate that the established double-equilibration technique has a very high repeatability and is applicable to wide ranges of inhaled anesthetics' solubilities.