胸段硬膜外麻醉对全麻下患者肝脏血流的影响

背景肝脏低灌注被认为是围手术期肝脏损害的一个重要病理生理因素。尽管硬膜外麻醉（EDA）应用广泛，但目前还没有关于阻滞平面仅局限在胸段的EDA对肝脏血流影响的相关数据。方法选择20例行全身麻醉的患者，通过经食道超声心动图（TEE）评估EDA前后肝右静脉和肝中静脉的肝血流指数。在T7～9间行硬膜外穿刺置管，推注１％的甲哌卡因，剂量中位数10ml（变化范围为8—16ml）。若EDA后，患者平均动脉压下降低于60mmHg，则持续输注去甲肾上腺素（NE）（EDA．NE组）。在研究过程中，其他患者不用任何儿茶酚胺类药物（EDA组）。另外将10例未接受EDA的患者作为对照组。结果本研究中，有5例患者必须连续输注NE以避免平均动脉压降至60intoHg以下。因此，EDA．NE组有5例患者，而EDA组有15例患者。在EDA组，肝脏两条静脉的血流指数下降中位数是24％（P〈0．01）。在EDA—NE组，所有5例患者的肝血流指数均下降，其中，肝右静脉下降的中位数为39（１１～45）％，而肝中静脉下降的中位数为32（7—49）％。对照纽患者肝血流指数保持恒定。与对照组相比，EDA组和EDA-NE组肝血流指数的减少差异具有显著性（Ｐ〈0．05）。相较于肝血流，心输出量不受EDA的影响。结论我们得出结论，胸段硬膜外阻滞与肝血流下降相关。胸段EDA复合连续静脉输注NE可能会导致肝血流进一步降低。

BACKGROUND： Hepatic hypoperfusion is regarded as an important factor in the pathophysiology of perio- perative liver injury. Although epidural anesthesia （EDA） is a widely used technique, no data are available about the effects on hepatic blood flow of thoracic EDA with blockade restricted to thoracic segments in humans. METHODS： In 20 patients under general anesthesia, we assessed hepatic blood flow index in the right and middle hepatic vein by use of multiplane transesophageal echocardiography before and after induction of EDA. The epidural catheter was inserted at TH 7-9, and mepivacaine 1% with a median （range） dose of iO （8 - 16） ml was injected. Norepinephrine （NE） was continuously administered to patients who demonstrated a decrease in mean arterial blood pressure below 60 mm Hg after induction of EDA （EDA-NE group）. The other patients did not receive any catecholamine during the study period （EDA group）. A further 10 patients without EDA served as controls （control group）. RESULTS： In five patients, administration of NE was necessary to avoid a decrease in mean arterial blood pressure below 60 mm Hg. Thus, the EDA-NE group consisted of five patients and the EDA group of 15. In the EDA group, EDA was associated with a median decrease in hepatic blood flow index of 24% in both hepatic veins （P 〈 0. 01 ）. In the EDA-NE group, all five patients showed a decrease in the blood flow index of the right （median decrease 39 [11 -45 ]%） and middle hepatic vein （median decrease 32 [ 7 -49 ]%）. Patients in the control group showed a constant blood flow index in both hepatic veins. Reduction in blood flow index in the EDA group and the EDA-NE group was significant in comparison with the control group （P 〈0. 05）. In contrast to hepatic blood flow, cardiac output was not affected by EDA. CONCLUSIONS： We conclude that, in humans, thoracic EDA is associated with a decrease in hepatic blood flow. Thoracic EDA combined with continuous infusion of NE seems to result in a further decrease in hepatic blood flow.