Vascular occlusion produced over 24 hours increases spinal cord tolerance to occlusion

Occlusion over a 24-hr period of vessels which supply the spinal cord was tolerated better than occlusion of the same vessels acutely. Spinal cord ischemia was produced in 12 New Zealand White rabbits by transection of four or five pairs of lumbar segmental arteries arising from the abdominal aorta plus 30-min occlusion of the remaining segmental artery pair either acutely or 24 hr later. Of these 12 rabbits, 6 were occluded acutely and served as controls. Recovery, or failure to recover, as assessed by examining the rabbits for permanent loss of sensory and motor function in the hindlimbs, was compared in the two groups. The duration of the temporary occlusion was sufficient to lead to a total or near total loss of sensory and motor function in all control rabbits but resulted in no deficit in all but 1 of the rabbits which had the occlusion produced in two stages. These results have implications for the care of patients subjected to spinal cord ischemia during and after operations on the thoracic aorta.