Limb swelling after release of a tourniquet.

Using a water displacement method the authors found that an exsanguinated human limb will swell immediately by approximately 10% of its original volume after release of a pneumatic tourniquet. Exsanguination reduces limb volume by forcing blood from it. Approximately one-half of the post-tourniquet swelling is due to the return of the exsanguinated blood volume to the limb. Reactive hyperemia accounts for the remainder of the swelling the authors measured. Subsequently, additional swelling can occur from both hematoma formation and the accumulation of postanoxic edema fluid. In some cases, the placement of a circumferential postoperative plaster on a limb prior to tourniquet release may be a hazardous procedure.