Classifying Burn Injuries

Burns are classified by the cause and the severity, of the burn.

Causes include:

   
• Heat - including flame, radiation, or heat from steam, hot liquids, hot surfaces, hot objects.
   
• Chemical, including acids, caustics and other bases.
   
• Electrical, by lightning and electric current.
   
• Light, burns caused by intense light sources or ultraviolet light, including sunlight.
   
• Radiation from nuclear sources or ultraviolet light

Burn care specialists and first responders are trained never to assume the source of a burn. They must ask questions and be sure.

Severity of the burn by degrees

First degree burns, are the most common, and least damaging burns are superficial injuries that involve only the epidermis or outer layer of skin. The skin is reddened and extremely painful. The burn will heal on its own without scarring within two to five days. There may be peeling of the skin and some temporary discoloration.

Second degree burns occur when the first layer of skin is burned through and the second, or dermal layer, is damaged. In a second degree burn the damage stops at the dermal layer. The skin is moist, usually reddened and mottled, often blistered. Pain is intense. Second degree burns involving less than 10 percent of the body surface in children, or less than 15 per cent in adults are considered minor. In a healthy individual, second degree burns will heal themselves within three weeks, and little scarring will result.

Third degree burns, also called full thickness burns, involve all the layers of the skin. They are the most serious of all burns. The burn area is usually charred black but may include areas that are dry and white. Although third-degree burns can be intensely painful, some patients will report little or no pain; this means that nerve endings in the burned area have been destroyed. Third degree burns often require skin grafting. As these severe burns heal, dense scar tissue forms, presenting additional complications for rehabilitation.

Assessing the severity of burns

These factors determine the severity of a burn:

   
• Source of the burn - Chemical burns are particularly dangerous because the chemical may still be on the skin, continuing to damage it. Any burn caused by nuclear radiation is more severe than a burn caused by heat.
   
• Parts of the body burned - burns to the face are more severe because they can involve the eyes or airway management. Burns to hands and feet are also of special concern because they could damage movement of fingers and toes.
   
• Degree of the burn - the degree of the burn is important because second and third degree burns expose the tissues to infection and allow infectious agents access to the circulatory system.
   
• Extent of burned surface areas - It is important to know the percentage of the skin surface involved. Burn treatment staffs calculate the total burned area by the rule of nines: the adult body is divided into regions, each of which represents nine percent of the total body surface. These regions are the head and neck, each upper limb, the chest, the abdomen, the upper back, the lower back and buttocks, the front of each lower limb, and the back of each lower limb. Together these regions comprise 99 percent of the adult body. The remaining one percent is the genital area. Infants or small children have relatively larger heads and trunks, so a slightly different calculation is used.
   
• Age of the patient - This is important because small children and the elderly usually have more severe reactions to burns and their healing processes are somewhat different.
   
• Pre-existing conditions – A person with respiratory illnesses, heart disorders, diabetes or kidney disease are at greater risk than a healthy person.

The swelling and blistering that occur with burns are caused by the loss of fluid from damaged blood vessels. When the burned area is extensive, fluid loss can be great enough to cause shock. When this happens the burn victim requires immediate transfusion of blood or of a physiological salt solution to restore adequate fluid levels to maintain blood pressure. After serious burn injuries, healing aims at preventing infection and minimizing scarring as damaged tissues heal.

Serious burns are always complex injuries, and have the potential to involve muscles, bones, nerves, and blood vessels. The respiratory system can be damaged by smoke inhalation, and there are risks of airway obstruction, respiratory failure and respiratory arrest. Burns disrupt the body's normal fluid/electrolyte balance and its ability to maintain and regulate internal temperature. Joint function, manual dexterity, and physical appearance can also be significantly affected by burns.