The definition of shock is “a lack of oxygen to the tissues of the body, usually caused by a fall in blood volume or blood pressure.” Severe bleeding can result in shock, which can kill. If the casualty has lost a large quantity of blood this can cause a reduction in blood supply to the brain (do not forget that children can’t afford to lose as much blood as adults).
They may have pale clammy skin (with blue/grey tinges if it is severe), dizziness or passing out (when they try to stand or sit up), a fast or weak pulse and rapid shallow breathing. These are all common signs of shock.
Lay the casualty down and if there is no evidence to suggest that there are broken bones, elevate the legs. Call 999/112 for emergency help. Also, keep the casualty warm (but be sure not to overheat them), loosen any tight clothing they may be wearing and monitor their breathing to make sure things are steady and safe. Be sure to give nothing to them via the mouth.