Is remote preconditioning as effective as direct ischemic preconditioning in preventing spinal cord ischemic injury?

Spinal cord injury remains a devastating complication of thoracic and thoracoabdominal aortic operations. The aim of this study was to assess the affectivity of direct ischemic preconditioning (PC) and remote PC in preventing spinal cord ischemic injury in an experimental model.

Thirty-eight New Zealand white rabbits were divided into five groups: One group served as Sham group (n = 7). Rabbits in other groups had their abdominal aorta cross-clamped for 40 min. Before aortic occlusion, aorta was clamped twice at the same site of aortic occlusion for 5 min followed by 15 min of reperfusion after each ischemic episode in one group (Direct PC, n = 8), left renal artery was clamped twice for 5 min followed by 15 min of reperfusion after each renal ischemic episode in one group (Remote PC, n = 8), left renal artery was first clamped for 5 min followed by 15 min of reperfusion and then aorta was clamped for 5 min followed by 15 min of reperfusion in one group (Remote + Direct PC, n = 8), and no PC method was used in Control group (n = 7).

In all PC groups, neurological status of rabbits (Tarlov score) at post-ischemia 24th and 48th hours was better than the control group (P < 0.05), but worse than Sham group (P < 0.05). Mean viability index values in PC groups were higher than control group (P < 0.01). Post-ischemia serum NSE and MDA levels obtained in all three PC groups were significantly lower than control group (P < 0.05 and P < 0.01).

The use of direct ischemic PC and/or remote PC is an effective way of reducing spinal cord ischemic injury because of aortic occlusion, while direct PC is more effective. The combined use of direct PC and remote PC did not provide better protection.