Burns are the fourth most common type of trauma worldwide, after traffic injuries, falls, and interpersonal violence.
Any burn that does not penetrate the epidermis is considered to be a first-degree burn. A second-degree, or partial-thickness, burn penetrates into but not through the dermis. Since the dermal plexus of vessels and nerves is intact, the wound will blanch with pressure and the pain will be severe. A burn that completely destroys the dermis and enters the fat is considered to be a third-degree, or full-thickness, burn. Since all the vasculature and nerves of the dermis are destroyed, there is no blanching and the burn is much less painful than a second-degree burn. Fourth-degree burns extend into muscle, bone, or tendon.
In the United States, the prevalence of burns has a bimodal distribution according to age group, with young children (especially toddlers) accounting for 24% of burns and people 20 to 59 years of age accounting for 55%. Exposure to flame is the most common cause among people older than 5 years of age. Scald burns are more common in children under the age of 5 years. Most burns (75%) occur at home, and 13% occur at work. Approximately 95% of burns are accidental; 2% are related to abuse, and 1% are self-inflicted.
A. A profound hypermetabolic and catabolic response develops in patients with burns covering more than 20% of total body-surface area, leading to muscle wasting and, if untreated, death from multiple organ failure. The foremost strategy for reducing metabolic stress is to expeditiously remove the burned tissue and cover the exposed area with skin or some other form of barrier. Patients with the hypermetabolic response have an elevated core temperature (approximately 38°C), so setting the patient’s room temperature at around 18°C will reduce the metabolic demand. Minimizing pain and distress also reduces metabolic demand, but eliminating pain is challenging. Likewise, minimizing infection and sepsis reduces metabolic demand but is very difficult to achieve. The use of propranolol to reduce the hypermetabolic effects of catecholamines has received a great deal of study and appears to be beneficial, at least in children. Patients with major burns need nutritional support in order to keep up with the high metabolic demand. Placing an enteral feeding tube and starting nutrition as soon as possible, even during the initial resuscitation, is recommended.
A. A second-degree burn heals through reepithelialization. At the wound edge, the basal cells start migrating across the viable wound bed. The limit of migration from the wound edge is only 1 to 2 cm, but in superficial wounds, the keratinocytes in the remnant hair follicles and other skin adnexa migrate onto the surface to reepithelialize the wound. If adnexa are close together, such as in the scalp, reepithelialization is much faster (within 4 to 5 days) than if the adnexa are less densely packed. Elderly patients tend to have fewer hair follicles than younger patients, so reepithelialization can be impaired. Any wound that requires more than 2 to 3 weeks to reepithelialize has a high chance of becoming a hypertrophic scar. Therefore, as a simple rule, any wound that requires more than 2 to 3 weeks to heal should be considered for excision and skin grafting to reduce the chances of hypertrophic scarring.