Emergency bleeding control

Wounds are normally described in a variety of ways. Descriptions may include wound size (length) and thickness; plainly visible wound characteristics such as shape and open or closed; and origin, acute or chronic.[3] The most common descriptors of wounds are these:

• Incision: Straight edges to the wound margins, as if sliced with a knife. These can vary in size, and may be caused by a variety of objects, including a scalpel, a knife, any piece of straight, sharp metal, or a piece of glass. Tissue is rarely missing from the wound site, and the margins of the wound may be easily matched from one side of the wound to the other for the purposes of closure.[4]
• Laceration: Jagged edges to the wound margins, more closely resembling a tear than a slice. The direction of the wound is random rather than straight, and it may have multiple branches.[5] Most often caused by an object with a broken or serrated edge, such as a piece of broken glass or metal, but may also be caused by a blow from a blunt object to tissue with bone immediately behind it.
• Puncture: Sharp object penetrates the tissue and travels inward, but does not move laterally in any direction from the point of entry.[6] Such wounds can be misleading, as they may appear quite small on surface examination, but extend quite deeply into the body, even damaging nerves, blood vessels, or internal organs. They may cause substantial internal bleeding or secondary injuries, such as a collapsed lung, which may not be readily evident during primary assessment. Occasionally, the object causing the injury remains in the wound as an impaled object. A stab wound from a knife or other sharp object, or a bullet wound, are examples of this type of injury. Medical professionals usually refer to this type of wound as penetrating trauma.
• Abrasion: A scraping or scratching. Generally quite superficial, and affecting only the surface layers of the epidermis.[7] No internal organs, nerves, or blood vessels other than capillaries, are affected. This may be the result of a fall, or of sliding (friction) against rough surfaces. The road rash often suffered by falling motorcyclists is an example of this type of wound.
• Contusion: Simple bruising. In this type of injury, the capillaries in the epidermis and dermis are damaged, without breaking the skin.[8] Blood oozes out of these vessels into the spaces between cells or interstitial space, causing swelling and discoloration. Blood loss is generally limited, and not of serious consequence. It may, however, act as a signpost, pointing to more serious injuries.
• Avulsion: A full thickness laceration-type wound, often semi-circular in shape. This creates a flap that, when lifted, exposes the deeper tissues to view, or extrudes them from the wound itself.[9] Avulsions often occur in mechanical accidents involving fingers (sometimes referred to as degloving), or, more seriously, may affect the orbit of the eye or the abdominal cavity, exposing the internal viscera. Avulsions are difficult to repair, and no avulsion should ever be considered a minor injury.
• Amputation: Similar to, but distinct from, an avulsion. Whereas an avulsion is characterized by a "flap" of skin being removed, an amputation is characterized by a complete loss of a limb. This can occur at any point on the extremity, and is usually followed by significant arterial bleeding. However, as serious as this injury is, an amputated limb that is cooled and transported to the hospital can sometimes be surgically reattached.

• Types of wounds
• 
  Laceration moulage
• 
  Abrasion on the palm of the hand
• 
  Contusion

External bleeding is generally described in terms of the origin of the blood flow by vessel type. The basic categories of external bleeding are:

• Arterial bleeding: As the name suggests, blood flow originating in an artery. With this type of bleeding, the blood is typically bright red to yellowish in colour, due to the high degree of oxygenation. Blood typically exits the wound in spurts, rather than in a steady flow; the blood spurts out in time with the heartbeat. The amount of blood loss can be copious, and can occur very rapidly.[10]
• Venous bleeding: This blood is flowing from a damaged vein. As a result, it is blackish in colour (due to the lack of oxygen it transports) and flows in a steady manner. Caution is still indicated: while the blood loss may not be arterial, it can still be quite substantial, and can occur with surprising speed without intervention.[11]
• Capillary bleeding: Capillary bleeding usually occurs in superficial wounds, such as abrasions. The colour of the blood may vary somewhat (distal portion of circulation with oxygenated and unoxygenated blood mixing), and generally oozes in small amounts, as opposed to flowing or spurting.[12]

The type of wound (incision, laceration, puncture, etc.) has a major effect on the way a wound is managed, as does the area of the body affected and presence of any foreign objects in the wound. Key principles of wound management are:[13]

Pressure points

The arterial 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 that 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.[15] 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. Pressure on the carotid artery can also cause vagal tone induced bradycardia, which can eventually stop the heart. Other dangers in use of a constricting method include rhabdomyolysis, which is a buildup of toxins below the pressure point, which if released back into the main bloodstream may cause kidney failure.

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. The aortic aneurysm is a special case where the aorta, the body's main blood vessel, becomes ruptured through an inherent weakness, although exertion, raised blood pressure or sudden movements could cause a sudden catastrophic failure.[19] This is one of the most serious medical emergencies a patient can face, as the only treatment is rapid surgery.

In the event of bleeding caused by an external source (trauma, penetrating wound), the patient is usually inclined to the injured side, so that the 'good' side can continue to function properly, without interference from the blood inside the body cavity.

Treatment of internal bleeding is beyond the scope of simple first aid, and a person giving first aid should consider it potentially life-threatening. The definitive treatment for internal bleeding is always surgical treatment, and medical advice must be sought urgently for any victim of internal bleeding.[20]

• Bandage
• First aid