胸段硬膜外阻滞对异氟醚MAC的影响

Effects of Thoracic Epidural Blockade on MAC of Isoflurane

为了探讨硬膜外阻滞对异氟醚ＭＡＣ的影响，对５０例ＡＳＡⅠ～Ⅱ级开胸或上腹部手术病人，随机分成Ａ、Ｂ、Ｃ、Ｄ、Ｅ组，每组１０例，硬膜外给予不同浓度的利多卡因和生理盐水，吸入麻醉剂为异氟醚－５０％笑气－氧气。结果表明，硬膜外注药前吸入麻醉药的ＭＡＣ各组间无明显差异。注药后，在维持麻醉平稳的情况下，Ａ、Ｂ、Ｃ、Ｄ组的ＭＡＣ均有不同程度的下降；注药后１０～６０ｍｉｎ的前４组ＭＡＣ与Ｅ组比较均呈显著差异（Ｐ＜０．０５），注药后２０～５０ｍｉｎ，Ｃ、Ｄ组的ＭＡＣ与Ａ组比较亦呈显著差异（Ｐ＜０．０５）。由此可见，硬膜外阻滞可降低异氟醚的ＭＡＣ。吸入麻醉药的ＭＡＣ与硬膜外应用利多卡因的量呈高度负相关（ｒ＝０．８６）。

To evaluate the effects of epidural blockade on MAC of Isoflurane, fifty patients who had undergone thoracotomy or upper abdominal surgery were studied.They were divided into five groups(A,B,C,D and E),according to the lidocaine concentration of epidural administration.Each group consisted of 10 patients.0.5%,1.0%,1.5%,2.0% lidocaine 10ml were injected into the epidural cavity of group A,B,C and D respectively. The group E only received the same amount of saline.Inhaled anesthetics were Isoflurane and 50%N 2O.The results showed that parameters of circulatory function and respiratory function did not change markedly among groups or within each group. MAC had no difference among groups before epidural administration of lidocaine.MAC of the group E kept high level during experiment(>1.5%). After epidural administration of lidocaine,MAC of the group A,B,C and D10～60min after epidural administration of lidocaine were lower than those of the group E( P <0.05) and MAC of the group C and D from 20 to 50min were lower than those of the group A and E( P <0.05).In conclusion, epidural blockade may reduce MAC of Isoflurane and the reduced amplitude has a positive correlation with lidocaine concentration of epidural administration.