Thiopental Modification of Ischemic Spinal Cord Injury in the Dog

Spinal cord ischemia was produced in male mongrel dogs by permanent occlusion of the infrarenal aorta. All animals were anesthetized with a mixture of nitrous oxide and 1.5% halothane. Group 1 animals were the controls. Group 2 animals were pretreated, 30 minutes prior to aortic occlusion, with sodium thiopental, 20 mg per kilogram of body weight, over 5 minutes, followed by an infusion of 10 mg/kg/hr for 2½ hours. Groups 3 animals received the identical dose of sodium thiopental and, in addition, received mannitol, 1 gm/kg, and methylprednisolone 1 mg/kg. There were no differences in hemodynamic data or arterial blood gases among the groups, except that the thiopental bolus caused a transient reduction in mean arterial pressure. Ninety percent of Group 1 animals were paraplegic, while only 30% of Group 2 and 40% of Group 3 animals were paraplegic. The difference in the incidence of paraplegia in Groups 2 and 3 compared with Group 1 was statistically significant (p < 0.05). Therefore, thiopental significantly decreased the incidence of paraplegia, while methylprednisolone and mannitol did not enhance its protective effect.