Identification and selective perfusion of the spinal cord-feeding arteries by intrathecal pO₂ monitoring for spinal cord protection

Objectives: to study whether spinal cord-feeding arteries could be identified by the changes in the intrathecal pO₂ (I-pO₂), and to examine whether selective perfusion of feeding arteries identified by this method could protect the spinal cord against ischaemia. Design: controlled animal experiments. Materials and methods: in experiment 1, using 16 mongrel dogs, 18 segmental arteries were cannulated through which oxygenated saline was injected and the I-pO₂ change was observed. When the I-pO₂ increase was more than 0.5 mmHg, the artery was considered to be a spinal cord-feeding artery. In experiment 2, involving 10 dogs, the segmental arteries identified as spinal cord-feeding arteries were perfused with arterial blood and the recovery of I-pO₂ and evoked spinal potentials (ESP) was examined. Results: of 208 segmental arteries examined, 176 (84.6%) arteries were correctly judged and 32 (15.4%) were not. It was observed that the I-pO₂ recovered from 13.9 to 30.5 mmHg and the ESP recovered from 20.9% and 8.2% to 66.5% and 44.7% of each control for the first negative (N1) and second negative (N2) components, respectively. Conclusion: spinal cord-feeding arteries were successfully identified using the I-pO₂ monitoring method. Perfusion of these arteries with arterial blood improved the I-pO₂ and ESP, which were significantly depressed by ischemia.