Emergency bleeding control

# Overview
Severe bleeding poses a very real risk of death to the casualty if not treated quickly. Therefore, preventing major bleeding should take priority over other conditions because it saves failure of the heart or lungs.  Most protocols advise the use of direct pressure, rest and elevation of the wound above the heart to control bleeding.  Many bleeding control techniques are taught as part of first aid throughout the world, although some more advanced techniques such as tourniquets, are often taught as being reserved for use by health professionals, or as an absolute last resort, in order to mitigate the risks associated with them, such as potential loss of limbs.

# Basic External Wound Management
The type of wound (incision, laceration, puncture etc.) will have a major effect on the way a wound is managed, as will the area of the body affected and the presence of any foreign objects in the wound.  The key principles of wound management are:
- Elevation - Keeping the wound above the level of the heart will decrease the pressure at the point of injury, and will reduce the bleeding.  This mainly applies to limbs and the head, as it is impractical (and in some cases damaging) to attempt to move the torso around to achieve this.  Most protocols also do not use elevation on limbs which are broken, as this may exacerbate the injury.
- Direct Pressure - Placing pressure on the wound will constrict the blood vessels manually, helping to stem any blood flow.  When applying pressure, the type and direction of the wound may have an effect, for instance, a cut lengthways on the hand would be opened up by closing the hand in to a fist, whilst a cut across the hand would be sealed by making a fist.   A patient can apply pressure directly to their own wound, if their consciousness level allows.  Ideally a barrier, such as sterile, low-adherent gauze should be used between the pressure supplier and the wound, to help reduce chances of infection and help the wound to seal.  Third parties assisting a patient are always advised to use protective latex or nitrile medical gloves to reduce risk of infection or contamination passing either way.  Direct pressure can be used with some foreign objects protruding from a wound, and to achieve this, padding is applied from either side of the object to push in and seal the wound - objects are never removed.

# Secondary Eternal Wound Management

## Pressure Points
In situations where direct pressure and elevation are either not possible or proving ineffective, and there is a risk of exsanguination, some training protocols advocate the use of pressure points to constrict the major artery which feeds the point of the bleed.  This is usually performed at a place where a pulse can be found, such as in the femoral artery.  There are significant risks involved in performing pressure point constriction, including necrosis of the area below the constriction, and most protocols give a maximum time for constriction (often around 10 minutes).  There is particularly high danger if constricting the carotid artery in the neck, as the brain is sensitive to hypoxia and brain damage can result within minutes of application of pressure.  Other dangers in use of a constricting method include rhabdomyolysis, which is a build up of toxins below the pressure point, which if released back in to the main bloodstream may cause cardiogenic shock

### Epistaxis
Epistaxis or a nosebleed is a special case, where almost all first aid providers train the use of pressure points.  The appropriate point here is on the bony part or 'bridge' of the nose, which should constrict the capillaries sufficiently to stop bleeding in the lower part of the nose, although this will not stop bleeding which originates in the nasopharynx or the tear ducts

## Tourniquet
Another method of achieving constriction of the supplying artery is via the use of a tourniquet, which a tightly tied band which goes around a limb to restrict blood flow.  Tourniquets are routinely used in order to bring veins to the surface for cannulation, although their use in emergency medicine is more limited, and is restricted in most countries (with France being a notable exception) to professionals such as physicians and paramedics, as this is often considered beyond the reach of first aid and 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.  This is reflective of the higher chance of receiving massive trauma (such as amputation) and the increased time involved in reaching definitive care.
Improvised tourniquets, however, usually fail to achieve force enough to  compress the arteries of the limb and thus do not only fail to stop arterial bleeding but actually increase bleeding due to the impaired venous bloodflow. Some argue that tourniquets should never be used in the pre-hospital setting, not even for amputations. Evidence from mine-infested areas also show a higher mortality for mine victims treated with tourniquets pre-hospitaly.
An emergency tourniquet should in any case never be applied to the forearm or lower leg since the arteries in these locations run between bones and can not be compressed.
Do not apply a tourniquet to control bleeding, except as a last resort. Doing so may cause more harm than good. A tourniquet should be used only in a life-threatening situation and should be applied by an experienced person.  If continuous pressure hasn't stopped the bleeding and bleeding is extremely severe, a tourniquet may be used until medical help arrives or bleeding is controllable.  It should be applied to the limb between the bleeding site and the heart and tightened so bleeding can be controlled by applying direct pressure over the wound.
To make a tourniquet, use bandages 2 to 4 inches wide and wrap them around the limb several times. Tie a half or square knot, leaving loose ends long enough to tie another knot. A stick or a stiff rod should be placed between the two knots. Twist the stick until the bandage is tight enough to stop the bleeding and then secure it in place.
Check the tourniquet every 10 to 15 minutes. If the bleeding becomes controllable, (manageable by applying direct pressure), release the tourniquet.

## Clotting Agents
Some protocols call for the use of clotting accelerating agents, which can either by externally applied as a powder, 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.

# Basic Internal Wound Management
Internal wounds (usually to the torso) are harder to deal with than external wounds, although they often have an external cause.  The key dangers of internal bleeding include hypovolaemic shock (leading to exsanguination, causing a tamponade on the heart or a haemothorax on the lung.
In the event of the bleeding being caused by an external source (trauma, penetrating wound), the patient is usually inclined to the injured side, in order to ensure that the 'good' side can continue to function properly, without interference from the blood inside the body cavity.
The definitive treatment for internal bleeding is always surgical treatment, and medical advice must be sought as soon as possible for any victim of internal bleeding.

## Aortic Aneurysm
The aortic aneurysm is a special case where the aorta, the body's main blood vessel, become ruptured through an inherent weakness.  This is one of the most serious medical emergencies a patient can face, as the only treatment is rapid surgery, although exertion, raised blood pressure or sudden movements could cause a sudden catastrophic failure

# Management of Bleeding in Specific Situations
Click on the links below for a detailed management of bleeding in specific situations:
- Hematemesis
- Hematochezia
- Hemoptysis
- Postpartum hemorrhage
- Upper gastrointestinal bleed
- Vaginal bleeding
- Aneurysm
- Intracranial hemorrhage
- Hemorrhagic stroke
- Subarachnoid hemorrhage