<Dd> Epistaxis, or nosebleed, is a special case, where almost all first aid providers train the use of pressure points . The appropriate point here is on the soft fleshy part of the nose, which should constrict the capillaries sufficiently to stop bleeding, although obviously it does not stop bleeding from the nasopharynx or tear ducts . </Dd> <P> Another method of achieving constriction of the supplying artery is a tourniquet - a band tied tightly around a limb to restrict blood flow . Tourniquets are routinely used to bring veins to the surface for cannulation, though their use in emergency medicine is more limited . Tourniquet use is restricted in most countries to professionals such as physicians and paramedics, as this is often considered beyond the reach of first aid and those acting in good faith as a good samaritan . A key exception is the military, where many armies carry a tourniquet as part of their personal first aid kit . </P> <P> Improvised tourniquets, in addition to creating potential problems for the ongoing medical management of the patient, usually fail to achieve force enough to adequately compress the arteries of the limb . As a result, they not only fail to stop arterial bleeding, but may actually increase bleeding by impairing venous bloodflow . </P> <P> Some protocols call for the use of clotting accelerating agents, which can be either externally applied as a powder or gel, or pre-dosed in a dressing or as an intravenous injection . These may be particularly useful in situations where the wound is not clotting, which can be due to external factors, such as size of wound, or medical factors such as haemophilia . </P>

Where should you tie the tourniquet in order to control life threatening bleeding from a limb