Relationship between intrathecal oxygen tension and ultrastructural changes in the spinal cord during experimental aortic clamping

Abstract

Objectives: to investigate spinal cord ultrastructure related to ceuebrospinal fluid (CSF) oxygenation. Design: experimental aortic occlusion model with intrathecal oxygen tension monitoring. Materials and methods: two groups of pigs underwent proximal (P) or double (D) aortic occlusion for 30 min followed by 1 h of reperfusion. In a third group (I) segmental arteries distal to T3 were clamped for 90 min. A thin pO2, pCO2 and pH sensor was placed intrathecally for continuous monitoring of CSF. Spinal cord segments were studied by electron microscopy (EM). Results: in group P, CSF-pO2 rapidly decreased during clamping and major changes in pH and pCO2 were seen. EM demonstrated neuronal degeneration with loss of cellular integrity and severe affection of organelles. In the group D, CSF oxygenation decreased to about half, but with only moderate changes in the metabolic parameters. Group I showed no significant changes in CSF measurements. The latter groups were similar at EM, showing only mild mitochondrial changes. Conclusions: the level of CSF oxygenation during aortic cross-clamping or segmental artery interruption seems to correlate with ultrastructural changes in the spinal cord. This online intrathecal monitoring technique may provide valuable information on spinal cord circulation during thoracoabdominal aortic surgery.