tourniquet (tŏrˈnĭkĕt, –kā, tûrˈ–) [key], compression device used to cut off the flow of blood to a part of the body, most often an arm or leg. It may be a special surgical instrument, a rubber tube, a strip of cloth, or any flexible material that can be tightened to exert pressure. Compression should not be maintained for more than 20 min at a time because of the danger of congestion and gangrene. In cases of a bleeding emergency, a tourniquet is used to stop the flow of blood if other means, e.g., the application of a pressure bandage to the wound, are not effective. In arterial hemorrhage (bright red blood spurting out in jets) the tourniquet is applied above the wound, i.e., between the wound and the heart. In hemorrhage from a vein (an even flow of dark red blood) the tourniquet is applied below the wound, i.e., away from the heart.