Ischemic preconditioning and spinal cord function monitoring in the descending thoracic aorta approach

To evaluate the effectiveness of acute ischemic preconditioning (IP), based on somatosensory evoked potentials (SSEP) monitoring, as a method of spinal cord protection and to asses SSEP importance in spinal cord neuromonitoring.

Twenty-eight dogs were submitted to spinal cord ischemic injury attained by descending thoracic aorta cross-clamping. In the C45 group, the aortic cross-clamping time was 45 min (n=7); in the IP45 group, the dogs were submitted to IP before the aortic cross-clamping for 45 min (n=7). In the C60 group, the dogs were submitted to 60 min of aortic cross-clamping (n=7), as in the IP60 group that was previously submitted to IP. The IP cycles were determined based on SSEP changes.

Tarlov scores of the IP groups were significantly better than those of the controls (p = 0.005). Paraplegia was observed in 3 dogs from C45 and in 6 from C60 group, although all dogs from IP45 group were neurologically normal, as 4 dogs from IP60. There was a significant correlation between SSEP recovery time until one hour of aortic reperfusion and the neurological status (p = 0.011), showing sensitivity of 75% and specificity of 83%.

Repetitive acute IP based on SSEP is a protection factor during spinal cord ischemia, decreasing paraplegia incidence. SSEP monitoring seems to be a good neurological injury assessment method during surgical procedures that involve spinal cord ischemia.