【摘要】 目的　探讨低流量紧闭麻醉（ＬＦＣＣＡ）时异氟醚吸入浓度（Ｃｉ）和呼出浓度（Ｃｅ）与时间（Ｔ）及挥发罐开启浓度（Ｃｏ）的关系。方法　选４３例ＡＳＡⅠ～ Ⅱ级择期手术需气管内全麻的患者行静吸复合麻醉，按Ｃｏ不同将患者随机分为三组，Ⅰ、Ⅱ、Ⅲ组Ｃｏ分别为１．５％、３．０％、５．０％。氧流量固定为０．５Ｌ·ｍｉｎ^－１，持续静注异丙酚以维持适当麻醉深度。用Ｄａｔｅｘ监测仪监测Ｃｉ、Ｃｅ。用最小二乘法求出 Ｃｉ、Ｃｅ与时间及Ｃｏ的相关方程。结果　在 ２４０分钟的观察中，Ｃｅ和 Ｃｉ未达到相等，Ｃｅ／Ｃｉ随时间延长而增大。Ｃｉ、Ｃｅ与时间呈线性相关。Ｃｏ越大，相关方程的斜率越大，即Ｃｉ、Ｃｅ随时间上升越快。Ｃｉ、Ｃｅ与时间、Ｃｏ之间亦呈线性相关。结论　在ＬＦＣＣＡ时，Ｃｉ、Ｃｅ随时间的延长而升高，随Ｃｏ的增大而升高加快，因此在实施过程中，随着麻醉时间的延长，应调整Ｃｏ，以防麻醉过深。更多还原

【Abstract】 Objective To evaluate the relations among inspired or expired isoflurane concentration （Ci, Ce） and anaesthesia duration （T ） or/and vaporizer output concentration （Co ） during lowflow closed circuit anaesthesia（LFCCA）. Methods Under intravenous combined inhalational anaesthesia, 43 ASA gradeⅠ or Ⅱ patients undergoing elective surgical procedure,were randomly divided into 3 groups according to the different Co,the Co of group Ⅰ,Ⅱ or Ⅲ　was 1. 5%,3. 0% or 5. 0% respectively. The fresh oxygen flow was fixed at 0.５L· min^-l. Simultaneously,propofol was continuously administered via vein to achieve adequate anaesthesia depth. Datex monitor was applied to measuring Ci and Ce. The coeffecients and regression equations among Ci or Ce and T and /or Co,were worked out by least square method. Results Ci and Ce did not equilibrate during 240-min inhalational anesthesia. The ratio of Ce/Ci increased following anaesthesia. There was linear correlation between Ci or Ce and T ;The higher Co,the higher sloope of the equation,meaning Ci and Ce increased more rapidly. There also was linear correlation among Ci or Ce and T and Co. Conclusion The prolongation of LFCCA duration requires lowering properly the vaporizer output concentration in order to prevent deep anesthesia,更多还原