Perfusion of the subarachnoid space in cadavers: a technique applicable for prevention of paraplegia in surgery of the thoracic aorta.

BACKGROUND: No safe technique of subarachnoid perfusion during thoracoabdominal aneurysm surgery has been described. We tested the hypothesis that in cold cadavers, perfusion of the subarachnoid space at the lumbar level with warm solution is feasible and increases the temperature at the thoracic level without an increase in cerebrospinal fluid (CSF) pressure. METHODS: Six cadavers were used. A 5 Fr silastic catheter in the subarachnoid space between the second and third lumbar vertebra (L2-3) was used as an inflow and a 16-gauge catheter at L4-5 as an outflow. Normal saline at 38 degrees C was infused at 999 mL/h. Temperatures of inflow and outflow, of the thoracic subarachnoid space (T8), and of the cisterna magna, were recorded. CSF pressures were measured from the outflow catheter. RESULTS: Outflow temperature was 9+/-1 degrees C at 10 minutes. At 15 minutes it was 27+/-4 degrees C, and thoracic subarachnoid temperatures was 22+/-5 degrees C. There was no statistical difference between the temperatures recorded at 10 and 15 minutes. The temperature of the cisterna magna was 8.5+/-1.2 degrees C at 15 minutes, significantly higher than the baseline (p=0.01), but lower than that at the T8 level (p=0.0001). CSF pressures during the experiment did not changed significantly from baseline and remained below 10 cm H20. CONCLUSIONS: The technique described is simple to implement, and effective in changing the temperature of the subarachnoid space at the thoracic level. Whether spinal cord cooling by this technique safely reduces the risk of paraplegia remains to be established in an animal model.