20. Spinal Cord Protection During Aortic Crossclamping Using Retrograde Venous Perfusion
Patrick E. Parrino, Irving L. Kron, Scott D. Ross, Kimberly S. Shockey, Michael J. Fisher, John R. Gaughen, Jr., John A. Kern, Curtis G. Tribble
University of Virginia Health Sciences Center
Charlottesville, Va.
Background: Paraplegia continues to be a devastating and unpredictable complication of thoracic aortic aneurysm repair. A myriad of techniques have been used to protect the spinal cord from ischemia with variable success. We hypothesized that retrograde perfusion of the spinal cord with a hypothermic, drug enhanced solution would provide protection during ischemia/reperfusion and would not be a cumbersome intervention. This technique has not previously been reported in the literature.
Methods: Using New Zealand white rabbits, we isolated the abdominal aorta and vena cava at their distal limits and just below the left renal artery and vein. Atraumatic vascular clamps were placed on both vessels at all four sites and left in place for 45 minutes. In the experimental groups, an infusion of saline or saline + drug was infused into the isolated caval segment. We studied four groups of eight animals; control, warm saline infusion, cold (4°C) saline infusion, and cold saline with adenosine (0.74mg/mL) infusion. The solutions were infused (1mL/kg/min) into the vena cavae throughout the 45 minute ischemic period, after which the clamps were removed. The animals were then closed and allowed to recover for 24 hours before assessment by a blinded observer who evaluated neurologic function based on the Tarlov scale.
Results: Tarlov scores (Scale: 0=paraplegia, 1=slight movement, 2=sits with assistance, 3=sits alone, 4=weak hop, 5=normal hop) were as follows, and represent the mean ± SEM: Control group: 0.50 ± 0.50; warm saline: 1.63 ± 0.56; cold saline: 3.38 ± 0.26; cold saline + adenosine: 4.25 ± 0.16. ANOVA for all four groups p<1X10-5; contrast analysis demonstrated cold saline + adenosine was more beneficial than the other three groups with p<0.0001
Conclusion: Retrograde perfusion of the spinal cord with hypothermic saline and adenosine is protective during ischemia/reperfusion. This technique is easily performed and does not require bypass circuits, subarachnoid access, or other cumbersome interventions.