Spinal cord protection during aortic cross-clamping using retrograde venous perfusion

Background. Paraplegia remains a devastating complication following thoracic aortic operation. We hypothesized that retrograde perfusion of the spinal cord with a hypothermic, adenosine-enhanced solution would provide protection during periods of ischemia due to temporary aortic occlusion. Methods. In a rabbit model, a 45-minute period of spinal cord ischemia was produced by clamping the abdominal aorta and vena cava just below the left renal vessels and at their bifurcations. Four groups (n = 8/group) were studied: control, warm saline, cold saline, and cold saline with adenosine infusion. In the experimental groups, saline or saline plus adenosine was infused into the isolated cavae throughout the ischemic period. Clamps were removed and the animals to recovered for 24 hours before blinded neurological evaluation. Results. Tarlov scores (0 = paraplegia, 1 = slight movement, 2 = sits with assistance, 3 = sits alone, 4 = weak hop, 5 = normal hop) were (mean ± standard error of the mean): control, 0.50 ± 0.50; warm saline, 1.63 ± 0.56; cold saline, 3.38 ± 0.26; and cold saline plus adenosine, 4.25 ± 0.16 (analysis of variance for all four groups, p< 0.00001). Post-hoc contrast analysis showed that cold saline plus adenosine was superior to the other three groups (p< 0.0001). Conclusion. Retrograde venous perfusion of the spinal cord with hypothermic saline and adenosine provides functional protection against surgical ischemia and reperfusion.