Influence of segmental spinal cord perfusion on intrathecal oxygen tensionduring experimental thoracic aortic crossclamping

Purpose: The purpose of this study was to evaluate the possibility of ident ifying alterations in blood supply to the spinal cord during thoracic aorti c crossclamping. Methods: In 17 pigs, a multiparameter Po-2, Pco(2) and pH sensor was introd uced into re intrathecal space for continuous monitoring of cerebrospinal f luid (CSF) oxygenation during aortic crossclamping. An epidural laser Doppl er probe was used to measure spinal cord flux, After insertion of an aortic shunt from the left subclavian to the left iliac artery and interruption o f the right subclavian and lumbar arteries (L2-L5), the thoracic aorta just . distal to the left subclavian artery was clamped for 60 minutes. By place ment of the distal aortic crossclamping below the level of L1 in group A (n = 9 animals), perfusion of only the abdominal visceral arteries was mainta ined. In group B (n = 8 animals), the distal aortic crossclamping was above the Level of T12, and thus some spinal cord perfusion was maintained throu gh thr aortic shunt. Results: The significant decrease in CSF Pot was observed within 3 minutes after the placement of the proximal aortic crossclamping and was normalized in ail animals after establishment of the shunt flow. In group A, distal a ortic crossclamping caused a decrease in CSF Po-2 With at least 50% Of the preclamping values within 3 minutes. The mean CSF Pot of 2.99 +/- 0.70 kPa at 60 minutes of distal aortic crossclamping in group B was significantly h igher than in group A (0.11 +/- 0.11 kPa; P < .001), In group A, Pco(2) mea surements showed no significant changes in 3 minutes after distal aortic cr ossclamping but revealed significantly higher values at 30 and 60 minutes c ompared with group B. Spinal cord flux values showed similar changes as CSF Po-2 during the whole experiment in both groups. Conclusion: In this experimental model of aortic crossclamping, continuous CSF oxygen tension monitoring allows rapid detection of alterations in spin al cord circulation.