THE EFFECT OF ANESTHETICS ON CARDIO-VASCULAR INTERACTION

我们用Ea/Ees指数比较了两种挥发性麻醉剂氟烷和异氟烷对脑室-动脉耦合的影响。Ea和Ees分别代表动脉有效弹性和左心室收缩末期弹性，分别作为心脏后负荷和心脏收缩力的指标。氟烷2MAC可显著降低心排血量、Ea和Ees，分别降低35%、18%和39%。异氟醚2MAC可显著降低心排血量、Ea和Ees，分别降低37%、38%和43%。氟烷使Ea/ Es从0.83增加到1.22，而异氟烷使Ees/Es保持在恒定水平。这些结果表明，在异氟醚麻醉期间，机械效率得到了很好的维持，因为它对左心室收缩力和动脉特性具有同等的影响，而氟烷通过抑制左心室收缩力而不是动脉系统来损害机械效率。我们的研究结果还表明，肾上腺素能受体刺激能够逆转氟烷对心脏的直接抑制作用，并且在氟烷麻醉期间，肾上腺素能受体刺激也可能伴随着氧供需平衡的损害。

We compared the effects of two volatile anesthetics, halothane and isoflurane, on ventriculo-arterial coupling using an index of Ea/Ees. Ea and Ees represent arterial effective elastance and left ventricular end-systolic elastance, and are used as indices of cardiac afterload and cardiac contractility, respectively. Halothane 2MAC significantly decreased the cardiac output, Ea, and Ees by 35%, 18%, and 39%, respectively. Isoflurane 2MAC significantly decreased the cardiac output, Ea, and Ees by 37%, 38%, and 43%, respectively. Halothane increased Ea/Ees from 0.83 to 1.22, whereas isoflurane maintained the Ees/Es at a constant level. These results suggest that mechanical efficiency is well maintained during isoflurane anesthesia because it has an equivalent effect on left ventricular contractility and arterial properties, whereas halothane can impair mechanical efficiency by depressing left ventricular contractility more than the arterial system.Our results also suggest that al-adrenoceptor stimulation is capable of reversing direct cardiac depressant effects of halothane, and that al-adrenoceptor stimulation may also be accompanied by a possible impairment of the oxygen supply-demand balance during halothane anesthesia.