每日一题_2022.06.03

A 68-year-old woman with a long history of smoking and hypertension presents with moderate back pain. A CT angiogram identifies an enlarged thoracic aorta (5.6 cm in diameter), with a pedunculated outpouching near the takeoff of the left subclavian artery. An esmolol infusion is started overnight for blood pressure and heart rate control. The next morning, she undergoes an endovascular repair of the aneurysm and is then admitted to the cardiovascular ICU. Several hours later, the patient has decreased lower extremity movement on neurologic examination.

Which of the following is the most appropriate course of action?

A. Clamp the spinal drain.

B. Increase the blood pressure.

C. Transfuse red blood cells.

D. Obtain an emergent CT myelogram.

答案解析：

胸髓的血液供应在很大程度上依赖于单个脊髓前动脉和两个脊髓后外侧动脉向头侧行至尾侧。这些动脉在很大程度上依赖于前、后神经根动脉和节段性髓动脉的血供。这些动脉起源于节段性（肋间）动脉，起源于胸主动脉（见下图）。节段性髓动脉中最大的是Adamkiewicz的动脉，大多数人起源于胸主动脉下段(T8-L1)。

血管内覆膜支架在主动脉内展开可能导致通过肋间动脉的血流中断。术后脊髓缺血风险较高的患者包括：1）由于既往腹主动脉瘤修复术导致侧支循环减少/破坏，胸主动脉严重动脉粥样硬化导致侧支循环减少，或胸主动脉移植物覆盖更广泛的患者，2）低血压导致脊髓灌注压降低，或3）脊髓液压力或中心静脉压升高。

脊髓灌注压计算为平均动脉压减去脑脊液压（或中心静脉压）。通常在胸主动脉覆膜支架手术前放置脊髓引流管，以降低血流阻力，从而促进脊髓灌注。

在术后早期，当脊髓可能从术中缺血性损伤中恢复时，维持脊髓灌注尤其关键。主动脉修复后神经功能下降是一种神经系统急症；采取措施改善脊髓灌注对于尽可能减少长期尖叫至关重要。可以打开或重新定位脊髓引流管以增加脑脊液的引流以改善脊髓灌注。血压升高也会增加脊髓灌注。

正确答案：B