Prolonged Tourniquet Ischemia of Extremities

The effects of the application of a tourniquet for five hours to the hind limbs of anesthetized dogs were studied under various conditions. The time required for the return of skin and muscle temperatures to normal after tourniquet ischemia was determined, as well as the degree of edema at the site of the application of the tourniquet and the neuromuscular damage. Massive edema and drop-foot were observed in untreated dogs after occlusion by the tourniquet for five hours. Heparin administered prior to tourniquet application, or just prior to tourniquet removal, afforded considerable amelioration of this damage, with a lessened degree of edema that resolved earlier. Drop-foot was prevented, and the return of skin and muscle temperatures to normal levels was more rapid if heparin was administered. Selective hypothermia afforded practically complete protection of the ischemic limbs from the changes observed in the control animals. The explanation of these beneficial effects of heparin and hypothermia is not apparent, and further studies are in progress.