围体外循环期挥发麻醉药血/气分配系数的动态变化

为观察围体外循环 (CPB)期挥发麻醉药血 /气分配系数 (λB/G)的变化规律 ,选择 6例接受瓣膜置换术的患者 ,分别于诱导前、切皮时、主动脉插管时、CPB复温开始时即刻、CPB停机时和缝皮时采集桡动脉血 ,并记录每个时点患者的肛温和红细胞比容。用 2次平衡法同时测定地氟醚、异氟醚和氟烷在上述各时点的λB/G,测定温度为当时的肛温。发现 :挥发麻醉药λB/G在围CPB期不同时点间存在显著性差异 (P <0 .0 5)。CPB停机和缝皮时的λB/G明显小于诱导前基础水平 (P <0 .0 5) ,而复温时的λB/G与诱导前基础值无显著性差异 (P >0 .0 5)。结果提示 ,挥发麻醉药λB/G在心血管麻醉围CPB期处于动态变化过程中 ,并受到患者体温和血液稀释的综合影响

Dynamic Changes in Blood/Gas Partition Coefficient of Volatile Anesthetics during Cardiopulmonary Bypass

In order to determine and estimate blood/gas partition coefficient of volatile a nesthetics during open heart surgery, blood samples were obtained from six adult patients undergoing valvular replacement with hypothermic cardiopulmonary bypas s 6 times: before induction, skin incision, aortic cannulation, before rewarming during bypass, weaning of bypass and skin suture. Blood/gas partition coefficient of desflurane, isoflurane and halothane were measured simultaneousl y at rectal temperature when blood was sampled. Significant differences were fou nd in blood/gas partition coefficient of the three anesthetics between differen t times during operation ( P <0.05). Blood/gas partition coefficient at weanin g of bypass was the lowest, about 75% of that before anesthesia induction. The r esults of this study indicate that blood/gas partition coefficients of volatile anesthetics vary dynamically during open heart surgery and they are influenced b y the combination of hypothermia and hemodilution.