Creatine phosphokinase release as a measure of tourniquet effect on skeletal muscle.

In anesthetized dogs, a pneumatic tourniquet was applied to a hind limb for one, two, or three hours. Resultant ischemic damage to skeletal muscle was assessed by creatine phosphokinase (CPK) levels in the femoral venous blood of the experimental limb after the tourniquet was released. The CPK levels did not rise after release of one-hour occlusion in three experiments. The elevation of CPK values was demonstrated after occlusion for two hours in three of four experiments, and after occlusion of three hours in all four experiments. When a three-hour occlusion was interrupted for 15 minutes after each hour in three experiments, elevation of CPK levels was minimal or absent. Thus, skeletal muscle injury, as measured by the level of venous CPK elevation, becomes apparent after two to three hours of occlusion and can be prevented by short periods of recirculation.