Effect of high-dose of methylprednisolone on tourniquet ischaemia

High doses of corticosteroids have been found to have beneficial effects in various shock states. It has been well recognized that ischaemia is one of the important features in shock states. This prompted us to investigate the effect of high-dose methylprednisolone on tourniquet-induced ischaemia using mongrel dogs. After inflation of tourniquets to 600 mmHg on each thigh of the hind legs, one leg received an intravenous infusion of methyl-prednisolone, 3 mg.kg-1 dissolved in 20 ml of autologous blood. The other leg received the same amount of blood only, as a control. During two hours of tourniquet time and until 30 min after tourniquet deflation, venous blood was sampled five times from both hind legs for measurements of blood gas tensions (PvO2, PvCO2) and pH, lactic acid, creatinine kinase (CK), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH). During tourniquet ischaemia, PvO2 and pH dropped and PvCO2, lactic acid, CK, AST and LDH rose steadily and significantly in both groups of legs, indicating respiratory and metabolic acidosis, and muscle cell damage. However, those changes were significantly smaller in the methylprednisolone-treated legs. The beneficial effect of methylprednisolone could be attributed to its vasodilatory effect, cellular membrane stabilization and direct metabolic effect on skeletal muscle cells. Although the tourniquet-induced ischaemia in our study is slightly different from the clinical paradigm, the results suggest that high-dose methylprednisolone may provide a beneficial effect during tourniquet ischaemia.