Sundberg A, Wattwil M, Wiklund L
Acta Anaesthesiol Scand. 1987 Feb;31(2):143-7. doi: 10.1111/j.1399-6576.1987.tb02537.x.
Administration of small doses of bupivacaine epidurally at the upper thoracic level will partially block the cardiac sympathetic nerves but not the sympathetic outflow via the adrenals. Local anaesthetics have direct systemic effects on the myocardium and the systemic circulation. The present study aimed to examine the effect of high thoracic epidural anaesthesia (TEA) in elderly patients, and to examine the effect of raising plasma bupivacaine concentrations in these patients, who had earlier had the sympathetic innervation of the heart blocked by thoracic epidural anaesthesia. Fifteen elderly patients scheduled for thoracotomy took part in the study. All received high thoracic epidural anaesthesia including the upper five thoracic dermatomes. When epidural block was established, ten patients received bupivacaine 3 mg/min intravenously for 20 min, while five patients received a corresponding volume of normal saline solution. After TEA was established, heart rate, mean arterial blood pressure and cardiac output decreased. When bupivacaine was given to these patients intravenously during the block, mean arterial blood pressure increased, while cardiac output decreased still more. The mechanisms behind these effects seem to be a direct constriction of the systemic blood vessels and a depressive effect on the myocardium, which was blocked from the influence of the cardiac sympathetic nerves by the high thoracic epidural block.
在上胸段硬膜外给予小剂量布比卡因会部分阻断心脏交感神经，但不会阻断经肾上腺的交感神经传出。局部麻醉药对心肌和体循环有直接的全身作用。本研究旨在探讨高位胸椎硬膜外麻醉（TEA）对老年患者的影响，并研究提高这些患者血浆布比卡因浓度的效果，这些患者先前已通过胸椎硬膜外麻醉阻断了心脏的交感神经支配。15例计划行开胸手术的老年患者参与了本研究。所有患者均接受包括上五个胸段皮节的高位胸椎硬膜外麻醉。当建立硬膜外阻滞时，10例患者静脉注射布比卡因3mg/min，持续20分钟，而5例患者接受相应体积的生理盐水溶液。建立TEA后，心率、平均动脉血压和心输出量均下降。当在阻滞期间给这些患者静脉注射布比卡因时，平均动脉血压升高，而心输出量下降得更多。这些效应背后的机制似乎是体循环血管的直接收缩和对心肌的抑制作用，高位胸椎硬膜外阻滞使心肌免受心脏交感神经的影响。
