Tourniquet

A tourniquet is a band placed around an arm or leg and tightened until it stops arterial blood flow past that point. It is used to control severe bleeding from a limb, and in surgery to keep the operating field free of blood. The name comes from the French tourner, to turn, after the stick twisted to tighten early versions.

Binding a limb to slow bleeding goes back to antiquity. The first clear account of a tourniquet used in battle is usually credited to the French army surgeon Étienne Morel at the siege of Besançon in 1674: he pushed a stick through the bandage on a wounded soldier's thigh and twisted it tight. One later history places the episode in Flanders instead. In 1718 Jean-Louis Petit introduced a screw tourniquet, a design that was easier to tighten and hold. In 1873 Friedrich von Esmarch introduced a rubber bandage and tourniquet for bloodless surgery.

On the battlefield its reputation swung back and forth. Tourniquets put on too loosely, or left on too long, caused nerve damage, dead muscle and amputation. The official British manual of 1918, Injuries and Diseases of War, told medical officers to remove any tourniquet an orderly had applied, and warned that one left on for six hours meant the limb "will surely die." Experience in Iraq and Afghanistan reversed that. Studies of US casualties found that tourniquets applied early, before the casualty went into shock, were associated with better survival.

1. The band goes on the limb above the wound, between the wound and the heart.
2. It is tightened, often with a rod called a windlass, until the bleeding stops and no pulse can be felt below it.
3. The time is recorded, traditionally written on the casualty, so the next person knows how long it has been on.

A loose tourniquet is worse than none. It blocks the veins carrying blood out of the limb but not the artery bringing it in, so the limb fills and the bleeding increases. Two hours is the duration most commonly recommended as the safer limit, though successful use for three to four hours has been reported. Beyond that, the chance of nerve and muscle damage rises.

• Baghdad, 2006. Over seven months at a US combat support hospital, 232 casualties had tourniquets applied. Of those whose tourniquet went on before shock set in, 90% survived. Of those already in shock, 10% did. Five casualties who needed a tourniquet and didn't get one all died. No limb was lost to tourniquet use alone.