device which applies pressure to a limb or extremity in order to constrict blood flow in veins

A tourniquet is a tightly-compressed bandage used to stop bleeding. A tourniquet does this by stopping the flow of blood through a large artery in a limb. It can be made from clothing or any tightly-compressible material in the case of an emergency.

In patients with major limb damage a tourniquet is used if direct pressure has failed to control life-threatening bleeding.[1] The tourniquet goes on a limb as close to the joint (the knee or elbow) as possible, above the wound. It is not safe to use one on the neck or around the body as this could stop the breathing or damage the organs. Once on they should not be covered or hidden by anything like clothing. Sometimes, in some countries, a person writes one or two letters on the patient's forehead when a tourniquet is applied. They should not be removed except by a medical professional once on, as this can cause damage (called reprofusion damage) to the limb.

Alternatives include other bandages such as ones designed to be wrapped very tight or that come in packages which can be used alongside the bandage to make it tighter, the Israeli bandage, and chemicals. Coagulants and haemostatic chemicals, in forms such as powders or as an injectable drug, can be put on the skin or into to stop bleeding. One haemostatic agent that is used is intravenous tranexamic acid[2]

The body loses heat when it loses blood (this is because the blood is a tool it uses for thermoregulation, and it does so all of the time by controlling the blood vessels size) in serious bleeding. It will also become more acidic. Cold blood, compared to how warm blood normally is, does not clot as easy. This is how the body stops bleeding, so being without it makes how clotting usually naturally works more difficult in 'normal' patients. This is when outside forces need to help the bleeding stop. Also, this means that losing blood, causing more acidity, losing heat, losing blood, makes more bleeding happen, causing more problems.

A tourniquet will not be used to treat blood acidity, but it is an important and closely monitored process, important for blood. It is a precise number (range). See also: blood pH. The numbers are: pH 7.35-7.45. Acid is low and alkaline high numbers.


  1. "Recommendations | Major trauma: assessment and initial management | Guidance | NICE". 2016-02-17. Retrieved 2024-05-24.
  2. "Recommendations | Major trauma: assessment and initial management | Guidance | NICE". 2016-02-17. Retrieved 2024-05-24.