Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Cardiovascular Anesthesia
Introduction: Several thousand vascular, orthopedic, and neurosurgical operations are performed annually that can be associated with spinal cord ischemia, and if the latter is severe, paraplegia can result. All techniques to prevent spinal cord ischemia are only moderately effective. We determined the effectiveness of a regional hypothermic infusion of adenosine for the prevention of spinal cord ischemia in a pig model.
Methods: With IAICUC approval, 16 pigs were randomly assigned in a prospective double blind fashion to receive regional infusion of hypothermic adenosine (25 mg/kg in 30ml/kg at 8[degree sign]C) or hypothermic normal saline (30ml/kg at 8[degree sign]C). Under general anesthesia with ketamine and forane, a right femoral arterial line and pulmonary artery catheter were placed. A left thorocotomy was performed and the left atrium and proximal aorta were cannulated. The aorta was cross-clamped at the level of the diaphragm for one hour. During the time of aorta cross-clamping, hypothermic adenosine or normal saline was infused distal to the aortic cross-clamp. Fluorescent microspheres were injected in the left atrium to determine regional blood flow in the peri-aortic cross-clamp period. Following the time of cross-clamping, wounds were closed. Neurologic status via Tarlov scale  and blood urea nitrogen (BUN) were observed for 72 hours by a blinded observer.
Results: Every adenosine treatment animal had complete hind limb spastic paraplegia following aortic cross-clamping (all Tarlov grade 0). Of the control animals, one had complete neurologic recovery (Tarlov 4), and the rest of the pigs had complete hind limb spastic paraplegia (Tarlov 0). There were no differences in hemodynamics and temperature between the two groups.
Discussion: Herold et al  found that regional infusion of hypothermic adenosine was able to completely prevent neurologic injury in a rabbit 40 minute of spinal cord ischemia model compared to hypothermic normal saline infusion which had no benefit. In a pig model we found that regional infusion of hypothermic adenosine had no benefit in preventing neurologic injury compared to hypothermic normal saline infusion.
1. Tarlov IM: Spinal cord Compression: Mechanism of paralysis and treatment. Springfield, Charles C Thomas, p 147, 1957
2. J Thorac Cardiovasc Surg 107:536-542, 1994.