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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 will be in medical danger after 2 liters (2 quarts) and could die of hypovolemic shock if more blood is lost.
There are four types of bleedings:
- minor traumatic bleedings: these are little and superficial wounds; the loss of blood is not dangerous and the bleeding will stop spontaneously; the main risk is the wound itself (dysfunction of the organs involved and infection);
- severe traumatic bleeding: the flow of blood can soak a paper or cloth hankerchief in a few seconds; in such a situation, the bleeding will cause the death of the casualty in a few minutes;
- externalised bleeding: the blood flow through a natural orifice, such as the nose, the ears, the mouth (spitting and vomitting blood), the vagina (except for the natural menstruation), the urethra and the anus; the blood comes from the interior of the body and reveals a hidden trauma or a disease;
- internal bleeding: the blood flows inside the body; it cannot be seen, but can be suspected by shock symptoms.
Minor traumatic bleeding
The minor traumatic bleeding stops spontaneously, the loss of blood is not dangerous in itself. But the wound can still endanger the life of the casualty. See Wound.
Severe traumatic bleeding
The general behaviour is:
- protect: remove the cause of wound so nobody else gets hurt, or lead the casualty away and mark out the dangerous area; when the casualty cannot walk, do not move him unless the danger is deadly and real;
- stop the bleeding;
- let the casualty in the position he feels comfortable;
- ask someone to call for help, or do it yourself if you are alone; describe the general state of the casualty (alert or unalert, breathing or not) and the wound itself;
- follow the instructions given by the EMS.
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 casualty is concious and alert, he can press himself on the wound for a short time (e.g. the time the bystander makes the protection, get a protection for the hands, or get something to make a bandage).
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 delayed (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. However, this should always be the last choice.
The only minor situation is a spontaneous nosebleed, or a nosebleed caused by a slight trauma (such as a child putting his finger in the nose). Just sit down, blow through the bleeding nostril to evcuate the forming clot (this first clot is usually not efficient), and press the nostril with a finger, the head bowed downwards, during ten minutes, the time the clot forms correctly (a shorter compression is not efficient). Consult a doctor when the bleeding does not stop or starts again.
Any other situation (including nosebleed due to a severe nose trauma or to a head trauma) must be considered as an emergency: place the person in a comfortable situation (lying or seated), call for help and follow the instructions.
The shock symptoms are not specific to an internal bleeding, but are always a medical emergency. In such a situation, the role of a bystander is to lay the person down, and call for help.
See the article Internal bleeding.
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 it is 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.
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