Effect of conditioning on visceral organs during indirect ischemia/reperfusion injury

The mortality and morbidity rates of even extensive thoracoabdominal replacement have improved markedly in recent years. We investigated the effects of a temporary occlusion of the aorta as a direct precondition and temporary occlusion of the axillary artery for remote preconditioning to determine any effects that preconditioning may have on indirect (nonischemic) injuries to visceral organs (indirect effects of remote ischemia/reperfusion injury).

Thirty-seven New Zealand white rabbits were divided into five groups: controls (sham-operated; group 1); direct ischemia to the infrarenal aorta without preconditioning (group 2); direct ischemic preconditioning to the infrarenal aorta (group 3); remote ischemic preconditioning before clamping the infrarenal aorta (group 4); and simultaneous direct aortic and remote ischemic preconditioning before the clamping and during clamping of the infrarenal aorta (group 5). We used a 30-minute ischemia period for aortic occlusion for spinal cord ischemia/reperfusion. The axillary artery was used for remote preconditioning. After 24 hours, tissue specimens of the internal organs were obtained.

Myocardial congestion was the main pathology detected in all groups. Histopathologic evaluation of tissue samples taken from the hearts showed no significant differences in terms of the degree of polymorphonuclear leukocyte (PMNL) infiltration and edema between the groups. Lung congestion and pneumonic cell infiltration were detected in all the groups. Pneumonic cell infiltration was significantly high in groups 2 and 3. Cell infiltration was lowest in group 4 at 71.4% of normal values, which differed from the normal values of 25-33.3% in the other groups (P < 0.05). Although there is a difference between the groups in case of renal congestion, there is not any difference as tubular damage and PMN. There was a significant difference with regard to renal congestion between groups 2 and 3. Renal congestion was normal in 80% of the kidneys in group 3. This differed from the normal values observed in the other groups (14.3-57.1%, P < 0.05). Liver congestion was detected in all groups.

Different preconditioning methods may play an important role in distinct organ injuries during aortic cross-clamping. The visceral organs that exhibited positive and constructive results with direct and remote preconditioning included the lungs and kidneys during indirect ischemia/reperfusion injury. Remote ischemic conditioning was determined to be especially advantageous as a protection method, due to the fact that it is easy to use and effective for indirect ischemia/reperfusion injury.