Strauch Justus T, Lauten Alexander, Spielvogel David, Rinke Sindy, Zhang Ning, Weisz Donald, Bodian Carol A, Griepp Randall B
Department of Cardiothoracic Surgery, Mount Sinai School of Medicine/New York University, One Gustave L. Levy Place, P.O. Box 1028, New York, NY 10029, USA.
Eur J Cardiothorac Surg. 2004 May;25(5):708-15. doi: 10.1016/j.ejcts.2004.01.007.
During thoracoabdominal aortic aneurysm repair, prolonged compromise of spinal cord blood supply can result in irreversible spinal cord injury. This study investigated the impact of mild hypothermia during aortic cross-clamping on postoperative paraplegia in a chronic porcine model.
The thoracic aorta was exposed and cross-clamped in 30 juvenile pigs (20-22 kg) for different intervals at normothermia (36.5 degrees C), and during mild hypothermia (32.0 degrees C). Three pigs were evaluated at each time and temperature. Myogenic motor-evoked potentials (MEPs) were monitored, and postoperative recovery evaluated using a modified Tarlov score.
There were no significant hemodynamic or metabolic differences between individual animals, and the groups had equivalent arterial pressures (mean 64.3+/-3.6 mmHg). Time to recovery of MEPs correlated with severity of injury; all animals with irreversible MEP loss suffered postoperative paraplegia. At normothermia, animals with 20 min of aortic cross-clamping emerged with normal motor function, but those cross-clamped for 30 min suffered paraplegia. With mild hypothermia, animals tolerated 50 min of aortic cross-clamping without evidence of neurologic injury, but were all paraplegic after 70 min of ischemia. Animals appeared to recover normal motor function after 60 min of aortic cross-clamping at hypothermia initially, but exhibited delayed-onset paraplegia 36 h postoperatively.
Our observations indicate that mild hypothermia dramatically increases the tolerance of the spinal cord to ischemia in the pig, and therefore suggests that cooling to 32.0 degrees C should be encouraged during surgery which may compromise spinal cord blood supply. An ischemic insult of borderline severity may result in delayed paraplegia.
在胸腹主动脉瘤修复过程中，脊髓血供的长期受损可导致不可逆的脊髓损伤。本研究在慢性猪模型中探讨了主动脉阻断期间轻度低温对术后截瘫的影响。
在30只幼年猪（20 - 22千克）中暴露胸主动脉并在常温（36.5摄氏度）和轻度低温（32.0摄氏度）下进行不同时间的阻断。每次在每个时间和温度下评估3只猪。监测肌源性运动诱发电位（MEP），并使用改良的塔尔洛夫评分评估术后恢复情况。
个体动物之间没有显著的血流动力学或代谢差异，各组的动脉压相当（平均64.3±3.6 mmHg）。MEP恢复时间与损伤严重程度相关；所有MEP不可逆丧失的动物均发生术后截瘫。在常温下，主动脉阻断20分钟的动物运动功能正常，但阻断30分钟的动物发生截瘫。在轻度低温下，动物耐受50分钟的主动脉阻断且无神经损伤迹象，但缺血70分钟后均发生截瘫。最初在低温下主动脉阻断60分钟后动物似乎恢复了正常运动功能，但术后36小时出现迟发性截瘫。
我们的观察结果表明，轻度低温显著增加了猪脊髓对缺血的耐受性，因此表明在可能损害脊髓血供的手术期间应鼓励将体温降至32.0摄氏度。临界严重程度的缺血性损伤可能导致迟发性截瘫。
