Intrathecal oxygen concentration as a new indicator of spinal cord ischemia

A number of approaches have been put forward to monitor spinal cord ischemia during thoracic and thoracoabdominal aortic occlusion. However, none of these can ultimately prevent devastating complications which result from ischemic spinal cord injury. A direct measurement of the oxygen content of the spinal cord may accurately indicate the perfusion state, but in practice it is impractical. We surmised that intrathecal and/ or epidural oxygen concentration(I-pO₂ and E-pO₂, respectively) accurately reflect oxygen content in the spinal cord. So, we examined whether or not I-pO₂ and/or E-pO₂ correlated with the spinal cord pO₂ (S-pO₂) in dogs. In nine mongrel dogs, a model of graded spinal cord ischemia was developed by stepwise alternation of the level of aortic occlusion with an intraaortic balloon catheter. I-pO₂, E-pO₂ and S-pO₂ were measured with a mass spectrometer. Our results show that, both I-pO₂ and E-pO₂ significantly correlated with S-pO₂. I-pO₂ correlated with S-pO₂ better than E-pO₂ did. Therefore, I-pO₂ can be used as a new indicator for spinal cord ischemia, and I-pO₂ monitoring would be useful to prevent paraplegia associated with thoracic aortic surgery.