A burn takes place when the skin comes into contact with a heat source.[1] Burns can occur from many different sources. The most common sources that cause burns are fire/flame, scalds, hot objects, electrical, and chemical agents, respectively.[2] Injuries related to a burn are highly variable, as is their severity. Morbidity and mortality tend to increase as the surface area of the burn increases.[3] It is vital to classify a burn accurately, as it can help determine the outcome, as well as guide initial management.[2] The skin location, the degree of temperature, and duration are contributing factors to the severity of the burn. There is a synergistic effect between the temperature and duration of exposure.[4] Skin exposure to 140 degrees Fahrenheit (60 degrees Celsius) for 10 seconds can cause a full-thickness burn.[1]

The basis of burn classification is depth. When examining a burn, there are four components needed to assess depth: appearance, blanching to pressure, pain, and sensation.[2] Burns can be categorized by thickness according to the American Burn Criteria using those four elements. Burn injuries tend to be a dynamic process. Some burns, especially partial-thickness, may progress over 2 to 4 days, peaking at day 3.[4]

Partial Thickness

Superficial (first-degree) involves the epidermis of the skin only. It appears pink to red, there are no blisters, and it is dry. It is moderately painful. Superficial burns heal without scarring within 5 to 10 days.[1][4]

Superficial partial-thickness (second-degree) involves the superficial dermis. It appears red with blisters and is wet. The erythema blanches with pressure. The pain associated with superficial partial-thickness is severe. Healing typically occurs within 3 weeks with minimal scarring.[1][4]

Deep partial-thickness (second-degree) involves the deeper dermis. It appears yellow or white, is dry, and does not blanch with pressure. There is minimal pain due to a decreased sensation. Healing occurs in 3 to 8 weeks with scarring present.[1][4]

Full Thickness

Third-degree involves the full thickness of skin and subcutaneous structures. It appears white or black/brown. With pressure, no blanching occurs. The burn is leathery and dry. There is minimal to no pain because of decreased sensation. Full-thickness burns heal by contracture and take greater than 8 weeks. Full-thickness burns require skin grafting.[1][4]

Fourth degree shows charred skin with possible exposed bone.

Fifth degree has charred, white skin, and exposed bone.

Sixth degree has loss of skin with exposed bone.

Burns are a common injury seen in emergency departments around the world.[3] Even as emergency management improves, burns continue to have significant morbidity and mortality. Burn treatments, such as intravenous fluids and surgical options, are based upon the classification of the burn. It is essential to accurately classify burns to optimize treatment and provide an accurate prognosis.[5][6]