Burns

Burn injuries account for an estimated 700,000 annual ED visits per year. Of these, 45,000 require hospitalization. Approximately half of these patients are hospitalized at one of the 125 specialized burn treatment centers in the United States.

Most burns are not life threatening, but each burn causes a significant amount of pain for the patient and often some degree of psychological trauma. At temperatures greater than 120 º F, a child's skin is burned severely enough to require surgery in 3 seconds. Rapid evaluation by the emergency physician (EP) is essential to address pain management, provide initial wound care, evaluate appropriate disposition, mitigate the psychological impact of the burn, and identify intentional burns. Follow-up for even superficial thickness burns is imperative, particularly when involving the hands, feet, face, genital area, or other particularly sensitive areas.

To effectively evaluate, treat, and prevent potential future burns, understanding the different methods of categorizing burns is helpful. The general categories include life-threatening versus non–life-threatening, accidental versus intentional, recreational versus occupational, and domestic (home or residence) versus industrial.

Identifying the type of burn is essential because interventions must be appropriately tailored to the underlying cause. Type of burns include thermal burns, chemical burns, and radiation burns. Thermal burns can be further classified according to skin depth and percentage of total body area burned. Additional descriptions for thermal burns include contact, flame, heat, and scalding. Accurate documentation of the burn location (such as ophthalmic, hand, face, inhalation, soles, or perineum) and measurement of involved surface area are essential for follow-up and specialist referral/consultation.

The skin is the largest organ of the body. Although not very active metabolically, the skin serves multiple functions essential to the survival of the organism, which may be compromised by the presence of a burn, including the following:

• Thermal regulation and prevention of fluid loss by evaporation
• Hermetic barrier against infection
• Sensory receptors that provide information about environment 

The skin is divided into 3 layers, as follows:

• Epidermis: This is the outermost layer of skin composed of cornified epithelial cells. Outer surface cells die and are sloughed off as newer cells divide at the stratum germinativum.
• Dermis: This is the middle layer of skin composed of primarily connective tissue. It contains capillaries that nourish the skin, nerve endings, and hair follicles.
• Hypodermis: This is a layer of adipose and connective tissue between the skin and underlying tissues.

The most common type of burns are thermal burns. Soft tissue is burned when it is exposed to temperatures above 115ºF (46°C). The extent of damage depends on surface temperature and contact duration. A thermal burn causes coagulation of soft tissue. As the marginally perfused areas become reperfused, it is thought that there is a release of vasoactive substances causing formation of reactive oxygen species, which leads to increases in capillary permeability. This causes fluid loss as well as increasing plasma viscosity with resultant microthrombi formation.¹

This third spacing of fluid "seals" at 18-24 hours, which is why the guidelines for fluid resuscitation are based on a 24-hour time scale. After the initial 24 hours, the fluid requirements abruptly drop as the capillary permeability returns to normal. Underresuscitation in this initial 24-hour time period leads to significant morbidity from hypovolemia and shock.

Burns may cause a hypermetabolic state manifested by fever, increased metabolic rate, increased minute ventilation, increased cardiac output, decreased afterload, increased gluconeogenesis resistant to glucose infusion, and increased skeletal and visceral muscle catabolism. Patients need support in this state, which continues until wound closure is complete.¹ To a large degree, how the individual responds to the increased energy demands determine recovery.