Rokkas C K, Sundaresan S, Shuman T A, Palazzo R S, Nitta T, Despotis G J, Burns T C, Wareing T H, Kouchoukos N T
Division of Cardiothoracic Surgery, Washington University School of Medicine, St. Louis, Mo.
J Thorac Cardiovasc Surg. 1993 Dec;106(6):1024-35.
Spinal cord ischemia with resultant paraplegia or paraparesis remains an important clinical problem after operations on the thoracoabdominal aorta. Because hypothermia has a protective effect on ischemic neural tissue, we developed a baboon model of spinal cord ischemia to simulate the situation encountered clinically for resection of aneurysms of the thoracoabdominal aorta and to determine whether profound hypothermia produced by hypothermic cardiopulmonary bypass has a protective effect on spinal cord function. After cardiopulmonary bypass was established, the aorta was clamped distal to the left subclavian artery and proximal to the renal arteries for 60 minutes. Group I animals (n = 9) underwent aortic clamping at normothermia (37 degrees C), and group II animals (n = 9) were cooled to a rectal temperature of 15 degrees C before aortic clamping and underwent cardiopulmonary bypass at this temperature until the aorta was unclamped. Of the eight operative survivors in group I, six animals were paraplegic and two were paraparetic, whereas all six group II animals that survived the procedure were neurologically intact (p = 0.0002). The protective effect of hypothermia was associated with blunting of the hyperemic response of spinal cord blood flow (determined by the radioactive microsphere technique) in the lower thoracic and the lumbar segments of the spinal cord after unclamping of the aorta. Profound hypothermia produced by hypothermic cardiopulmonary bypass may be an effective method of protection of the spinal cord in patients undergoing repair of aneurysms of the thoracoabdominal aorta and may reduce the prevalence of ischemic injury to the spinal cord.
在胸腹主动脉手术后，脊髓缺血导致的截瘫或轻瘫仍然是一个重要的临床问题。由于低温对缺血性神经组织具有保护作用，我们建立了一个脊髓缺血的狒狒模型，以模拟临床上切除胸腹主动脉瘤时遇到的情况，并确定低温体外循环产生的深度低温是否对脊髓功能有保护作用。建立体外循环后，在左锁骨下动脉远端和肾动脉近端夹闭主动脉60分钟。第一组动物（n = 9）在常温（37摄氏度）下进行主动脉夹闭，第二组动物（n = 9）在主动脉夹闭前将直肠温度降至15摄氏度，并在此温度下进行体外循环，直到主动脉松开。在第一组的8只手术存活者中，6只动物截瘫，2只轻瘫，而在第二组中，所有6只存活下来的动物神经功能均完好（p = 0.0002）。低温的保护作用与主动脉松开后脊髓下胸段和腰段脊髓血流的充血反应减弱有关（通过放射性微球技术测定）。低温体外循环产生的深度低温可能是保护接受胸腹主动脉瘤修复术患者脊髓的有效方法，并可能降低脊髓缺血性损伤的发生率。
