Bleeding: Meaning (information, definition, explanation, facts)

Bleeding is the loss of blood from the body. Children are put more in danger by bleeding as they have less blood to lose. The average adult human can lose approximately 2 quarts (2 liters) of blood without lasting harm but will be in medical danger after 4 quarts (4 liters) and could die of hypovolemic shock if more blood is lost.

First aid

A major technique of first aid is to control bleeding through direct pressure with the hand (possibly protected by a plastic bag, a glove or a piece of stuff); it can be replaced when necessary by the application of a bandage over the wound.

When the direct pressure is not possible (e.g. there is a foreign body inside the wound, or a broken bone comes outside, or the wound is too large for the hand), then it is possible to compress the artery against a bone, between the wound and the heart (see Pressure point).

In extreme cases of an injured limb, a tourniquet may be used. If the medical care are delayd (after a few hours), the injured limb must generally be amputated afterwards, just below the level the tourniquet is applied; this is "losing a limb to save a life". This risk is very low in the urban environment of a developped country (the delay before a rescue team arrives is a few minutes after the call), but must be taken into account in wilderness or in countries that do not have organised prehospital medical services. Some first aid instruction no longer teaches the use of the tourniquet because the risk may be greater than the benefit; some other consider that saving a life is above the rest.

Risk of blood contamination

Concerning the direct exposure of the first-aider's skin to the blood: the skin is watertight, so if the skin is not wounded (skin disease or very recent wound), there is no risk of contamination by a disease of the casualty. Before any further activity (especially eating, drinking, touching the eyes, the mouth or the nose), the hand must be carefully and softly washed with clear water, then bathed five minutes in diluted bleach (sodium hypochlorite).

However, to avoid any risk, it is highly recommended to protect the hands, e.g. by a plastic bag or a cloth, before pressing the wound. If there is nothing to protect the hands (well an accident might happen happen on a nude beach), watch your hand to be sure they are not wounded, or use a distant compression of the artery (pressure point with your hand if you know the anatomic references, or a tourniquet).

In case of blood exposure, even on safe skin, the first-aider should go to the emergency service, where an anti-retroviral therapy will be started just in case.

Blood lost by bleeding can be replaced by blood transfusion. The human body also generates blood at a rate of about 2 quarts (2 liters) per week.

The practise of causing bleeding intentionally to remove excess or "bad" blood from a person's body is called bloodletting or phlebotomy.