Cold spinoplegia and transvertebral cooling pad reduce spinal cord injury during thoracoabdominal aortic surgery

OBJECTIVE: We examined the protective effects of the new selective spinal cord cooling by using cold saline infusion into the cross-clamped aorta and a transvertebral cooling pad placed over the lumbar vertebral column from paraplegia caused by ischemic spinal cord injury on thoracoabdominal aortic surgery. METHODS: Eighteen rabbits were divided into three groups: groups I, II, and III (n = 6 for each group). In group I (37 degrees C; 5 mL) and group II (3 degrees C; 5 mL), saline was infused into the isolated aortic segment twice, at 0 and 5 minutes after aortic cross clamping. In group III, a 3 degrees C saline solution plus cooling pads placed just after cross clamping were combined. The infrarenal aorta was then isolated proximally and distally by vascular clamps for 12 minutes. In our preliminary study, only the abdominal aorta just distal to the left renal artery was clamped. At 48 hours after reperfusion, the groups clamped for 12 and 15 minutes were all paraplegic. The time of clamping the aorta was set at 12 minutes as the critical point when paraplegia occurred upon simple clamping of the infrarenal aorta only. The spinal cord temperature was monitored at the L4 level continuously during the procedures in all three groups. At 8, 24, and 48 hours after the operation, hind limb function was estimated by using the Tarlov score, which is often used for evaluating motor function in animals. A histopathologic study using hematoxylin and eosin stains was also performed. RESULTS: At 48 hours after the operation, the Tarlov scores in groups I, II, and III were 0 +/- 0, 2.0 +/- 1.9, and 4.0 +/- 0 (mean +/- SD), respectively. The Tarlov score and histopathologic analysis in group III were significantly superior to those of groups I (P < .01) and II (P < .05). The spinal cord temperature in groups II and III decreased by -1.8 degrees C and -4.3 degrees C at its minimum. The rabbits in group III were also protected from paraplegia. CONCLUSIONS: Selective spinal cord cooling with cold saline infusion into the isolated aortic segment and transvertebral regional cooling can reduce the neurologic damage of spinal cord ischemia.