Spinal cord ischemia: An evaluation of pharmacologic agents in minimizing paraplegia after aortic occlusion

Abstract

Superoxide dismutase (SOD), barbiturates, and hypothermic crystalloid were evaluated for their effectiveness in minimizing ischemic damage to the spinal cord at 40 minutes of aortic occlusion. Forty-two dogs underwent proximal and distal thoracic aortic occlusion for 40 minutes with infusion of test agents into the occluded segment. The dogs were divided into six groups. Group 1 (n = 6) served as control. Group 2 (n = 6) received hypothermic crystalloid. Group 3 (n = 6) animals received thiopental. Group 4 (n = 7) received SOD. Group 5 (n = 9) received hypothermic crystalloid and thiopental. Group 6 (n = 8) received hypothermic crystalloid, thiopental and SOD. The animals were observed for neurologic deficit for 72 hours. In group 1, six of six dogs showed complete paralysis. Five of six dogs from group 2, five of six dogs from group 3, and five of seven dogs from group 4 showed complete paraplegia. The remaining dogs in these groups showed varying degrees of recovery. Four of nine dogs in group 5 had complete paraplegia, three dogs showed varying degrees of recovery, and two dogs had no neurologic deficit. In group 6, one dog had complete paraplegia, three had partial recovery, and four had no neurologic deficit. Group 6 was the only group that showed significantly less late neurologic impairment than the control group. We concluded that although cold perfusion, barbiturates, and SOD are not protective when used alone, they are effective when all are used in combination. The combination of cold perfusion, barbiturates, and SOD significantly decreases neurologic deficit after 40 minutes of aortic occlusion.

Epidural cooling for the prevention of ischemic injury to the spinal cord during aortic occlusion in a rabbit model: Determination of the optimal temperature

“…Selective perfusion of excluded segment of the aorta has been shown to be effective in the reduction of neurologic injury in animal models. [37][38][39] However, variations in Martelli et al 551 blood supply to the spinal cord from the aorta and interruption of the blood flow during aortic reconstruction limit its use. Subarachnoidal space, filled with CSF, is an ideal space for the cooling of the spinal cord.…”

No additional neuroprotection provided by barbiturate-induced burst suppression under mild hypothermic conditions in rats subjected to reversible focal ischemia

“…4 Little is known about the combined effects of bar-biturates and hypothermia under compromised conditions. 29,30,52 Kim and colleagues 27 reported that the inhibitory potency of mild hypothermia on the suppression of EEG signals by thiopental in humans is not simply additive, but synergistic. Hägerdal and colleagues 23 measured high-energy phosphates and lactate in rats subjected to cerebral hypoxia, and found that hypothermia of 27˚C offered better protection according to the metabolic criteria than phenobarbital and, at 32˚C, administration of phenobarbital did not increase the degree of protection provided by hypothermia alone.…”

Clinical application of intrathecal lidocaine administration in surgery of the descending thoracic aorta

“…Hypothermia augments tolerance to ischemia by lowering cellular metabolism and energy consumption in the spinal cord, however, Kirchner et ai. [13] noted that no improvement was observed with hypothermia alone. Reduced CSF pressure and vascular resistance in the spinal cord by CSF drainage were suggested for maintaining perfusion pressure in the spinal cord [14].…”