Arain Shahbaz R, Williams David J, Robinson Brian J, Uhrich Toni D, Ebert Thomas J
Department of Anesthesiology, The Medical College of Wisconsin and Veterans Affairs Medical Center, Milwaukee, 53295, USA.
Anesth Analg. 2002 May;94(5):1137-40, table of contents. doi: 10.1097/00000539-200205000-00014.
Compared with equi-minimum alveolar anesthetic concentration (MAC) isoflurane, desflurane is associated with greater levels of sympathetic nerve activity in humans but similar reductions in blood pressure. To explore these divergent effects, we evaluated vascular alpha(1)-adrenoceptor responses in the human forearm during isoflurane and desflurane anesthesia to determine if alpha(1)-adrenoceptor responses were more substantially attenuated during desflurane administration. Bilateral forearm venous occlusion plethysmography was used to examine arterial blood flow and to determine changes in forearm vascular resistance during brachial artery infusions of saline and phenylephrine (0.2, 0.4, 0.8, and 1.6 microg/min) in 22 conscious subjects and during anesthesia with 0.65 and 1.3 MAC isoflurane or desflurane. Infusion of phenylephrine into the brachial artery increased the forearm vascular resistance in a dose-dependent manner. The arterial response to phenylephrine was significantly attenuated by 0.65 and 1.3 MAC desflurane and similarly attenuated during 1.3 MAC isoflurane (P < 0.05). Impaired arterial alpha(1)-adrenoceptor responsiveness occurred during desflurane. However, this effect was statistically similar (P > 0.05) to the impaired responses during isoflurane. Blood pressure decreases during volatile anesthesia may be, in part, caused by decreased alpha(1)-adrenoceptor responsiveness.
alpha-receptors on blood vessels regulate constriction and dilation and therefore modulate blood pressure. This research indicates that vasoconstriction via the alpha(1)-receptor vascular response is impaired during isoflurane and desflurane anesthesia.
与等效最低肺泡麻醉浓度（MAC）的异氟烷相比，地氟烷在人体中与更高水平的交感神经活动相关，但血压降低程度相似。为了探究这些不同的效应，我们评估了异氟烷和地氟烷麻醉期间人体前臂血管α₁ - 肾上腺素能受体反应，以确定在地氟烷给药期间α₁ - 肾上腺素能受体反应是否更显著地减弱。在22名清醒受试者以及在0.65和1.3 MAC异氟烷或地氟烷麻醉期间，使用双侧前臂静脉阻塞体积描记法检查动脉血流，并确定在肱动脉输注生理盐水和去氧肾上腺素（0.2、0.4、0.8和1.6微克/分钟）期间前臂血管阻力的变化。向肱动脉输注去氧肾上腺素以剂量依赖方式增加前臂血管阻力。0.65和1.3 MAC地氟烷使对去氧肾上腺素的动脉反应显著减弱，在1.3 MAC异氟烷期间也有类似程度的减弱（P < 0.05）。地氟烷麻醉期间发生动脉α₁ - 肾上腺素能受体反应性受损。然而，这种效应与异氟烷麻醉期间反应受损在统计学上相似（P > 0.05）。挥发性麻醉期间血压下降可能部分是由α₁ - 肾上腺素能受体反应性降低引起的。
血管上的α受体调节收缩和舒张，从而调节血压。这项研究表明，在异氟烷和地氟烷麻醉期间，通过α₁受体血管反应的血管收缩受损。
