Effect of corticosteroid administration in ischemia--ischemic injury

In order to study the preservation of ischemic tissue, an in vivo end-artery model was designed using the rabbit ear. Ear surface-area necrosis and ear edema were quantitatively evaluated for 14 postoperative days in a total of 107 rabbits. The LD50 of ischemic injury was determined by effecting 8, 10, and 12 hours of circulatory arrest. Using a 12-hour ischemic interval in this model, methylprednisolone decreased edema formation (p less than 0.01) and dramatically halted the progression of ischemic injury to necrosis (p less than 0.05) when administered within 5 hours after the onset of ischemia and continued for 3 postoperative days. A single perioperative dose of methylprednisolone was ineffective in decreasing edema formation and preserving tissue. Administration of steroids greater than 5 hours after the onset of ischemia was similarly ineffective even when administered for 3 postoperative days.