Diseases

Burns are classified based upon their depth. A first degree burn is superficial and causes local inflammation of the skin. Sunburns often are categorized as first degree burns. The inflammation is characterized by pain, redness, and a mild amount of swelling. The skin may be very tender to touch. Second degree burns are deeper and in addition to the pain, redness and inflammation, there is also blistering of the skin. Third degree burns are deeper still, involving all layers of the skin, in effect killing that area of skin. Because the nerves and blood vessels are damaged, third degree burns appear white and leathery and tend to be relatively painless. Burns are not static and may mature. Over a few hours a first degree burn may involve deeper structures and become second degree. Think of a sunburn that blisters the next day. Similarly, second degree burns may evolve into third degree burns. Regardless of the type of burn, inflammation and fluid accumulation in and around the wound occur. Moreover, it should be noted that the skin is the body's first defense against infection by microorganisms. A burn is also a break in the skin, and the risk of infection exists both at the site of the injury and potentially throughout the body. Only the epidermis has the ability to regenerate itself. Burns that extend deeper may cause permanent injury and scarring and not allow the skin in that area to return to normal function.

Burn location is an important consideration.If the burn involves the face, nose, mouth or neck, there is a risk that there will be inhalation injury and enough inflammation and swelling to obstruct the airway and cause breathing problems.If there are circumferential burns to the chest, as the burn progresses, the tissue involved may not allow enough motion of the chest wall to allow adequate breathing to occur. If circumferential burns occur to arms, legs, fingers, or toes, the same constriction may not allow blood flow and put the survival of the extremity at risk. Burns to areas of the body with flexion creases, like the palm of the hand, the back of the knee, the face, and the groin may need specialized care. As the burn matures, the skin may scar and shorten, preventing full range of motion of the body area.

Burns can also occur when chemicals are spilled onto the body and generate a reaction that creates heat. Chemical burns may be classified by their pH or acidity.

• Acids are those with pH less than 7 and include common household compounds like acetic acid, hydrochloric acid, or sulfuric acid.
• Bases or alkali compounds have a pH greater than 7. Ammonia is a common alkali found in the home.

Electrical burns may cause serious injury that is not readily apparent. Often the entry and exit points for the electrical shock may not be easily found.Electricity flows more easily through tissues in the body that are designed to deal with electricity. Nerves and muscles are "wired" for this task and often are damaged. If significant muscle damage occurs, muscle fibers break down and chemicals can be released into the bloodstream causing electrolyte disturbances and kidney failure.

In addition to the depth of the burn, the total surface area of the burn is significant. Burns are measured as a percentage of total body area affected. The "rule of nines" is often used, though this measurement is adjusted for infants and children. This calculation is based upon the fact that the surface area of the following parts of an adult body each correspond to approximately 9% of total (and the total body area of 100% is achieved):

• Head = 9%
• Chest (front) = 9%
• Abdomen (front) = 9%
• Upper/mid/low back and buttocks = 18%
• Each arm = 9%
• Each palm = 1%
• Groin = 1%
• Each leg = 18% total (front = 9%, back = 9%)

As an example, if both legs (18% x 2 = 36%), the groin (1%) and the front chest and abdomen were burned, this would involve 55% of the body. Picture of the Rule of Nines - Burns on an AdultOnly second and third degree burn areas are added together to measure total body burn area. While first degree burns are painful, the skin integrity is intact and it is able to do its job with fluid and temperature maintenance.If more than15%-20% of the body is involved in a burn, significant fluid may be lost. Shock may occur if inadequate fluid is not provided intravenously. As the percentage of burn surface area increases, the risk of death increases as well. Patients with burns involving less than 20% of their body should do well, but those with burns involving greater than 50% have a significant mortality risk, depending upon a variety of factors, including underlying medical conditions and age.