Burns

Published on 06/06/2015 by admin

Last modified 06/06/2015

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7 Burns

Burns and fire-related injuries account for significant morbidity and mortality in the pediatric population. In children younger than 18 years of age, fires and burns are the third leading cause of death from unintentional injury in the United States. Approximately one-third of all burns occur in children and adolescents younger than 20 years of age. Boys and children younger than 5 years of age are at highest risk of burn injuries. Burns may be thermal (resulting from flame, scald, steam, or contact), electrical, or chemical in cause (Figure 7-1). In children younger than 5 years of age, scalds resulting from bathing injuries or hot liquid spills account for the majority of burns. Fire and flames are the leading causes of burns in children older than 5 years of age. Electrical burns are seen primarily in adolescents. Child abuse accounts for up to 20% of burns in children and thus needs to be considered in all cases of pediatric burns, particularly in those with inconsistent mechanisms or specific patterns of injury (see Chapter 12). Carbon monoxide poisoning can occur with smoke inhalation and is responsible for many early deaths related to fire.

Figure 7-1 Causes and clinical types of burns.

Significant advances in burn treatment have occurred over the past 50 years. Of those children younger than 16 years of age with burns of more than 80% of body surface area (BSA), mortality rate has declined to just below 25%. This is largely a result of aggressive prehospital, emergency, and inpatient hospital care in addition to the development of specialized burn centers. Many burn injuries are preventable using relatively simple measures. Lowering the temperature of water heaters from 130° to 120°F increases the time to causing a full-thickness burn from less than 30 seconds to 10 minutes. Smoke detectors in homes can alert occupants to potential thermal dangers in the home. Flame-retardant children’s sleepwear has decreased the incidence of full-thickness burns caused by flames or fire.

Etiology and Pathogenesis

The clinical effects of burn injuries result from the loss of integrity of the skin and its vital functions. The skin serves to protect the body from infection, controls heat loss, and plays a vital role in fluid regulation. The epidermis prevents water loss and has a protective fatty acid layer that kills many infectious organisms. The deeper dermis contains sweat glands and vessels that regulate evaporative and radiant heat loss. Therefore, burns may result in infection, extensive fluid loss and disorders of thermoregulation.

Three zones of injury typically occur with a burn: hyperemia, stasis, and coagulation necrosis. Hyperemia is the result of vasodilatation secondary to inflammatory mediators without direct cell injury. Stasis occurs in the dermis and is characterized by vasoconstriction and thrombosis that results in reversible cell injury. Coagulation necrosis results in an irreversible surface injury known as an eschar.

Larger burns may produce systemic effects (Figure 7-2). Bacterial colonization of burned tissue may result in infection caused by disruption of the protective epidermal barrier and the inability of immune system elements and antibiotic agents to penetrate burned tissue. Capillary permeability is increased by the release of osmotically active substances into the interstitial space and the release of vasoactive mediators into the systemic circulation. Edema with resulting intravascular hypovolemia results in both injured and noninjured tissues. Circulating factors reduce myocardial function, thus decreasing cardiac output. Direct heat damage and a microangiopathic hemolytic process result in acute hemolysis of erythrocytes. All of these acute processes may result in renal failure, liver dysfunction, mental status changes, and hypoxia. After the initial injury, a hypermetabolic and immunosuppressive state may ensue, resulting in malnutrition, infection, and multisystem organ failure.

Figure 7-2 Metabolic and systemic effects of burns.

Clinical Presentation

The diagnosis of a burn injury is typically evident from the patient’s history and clinical presentation. The differential diagnosis includes erythroderma, toxic epidermal necrolysis, and staphylococcal scalded skin syndrome; however, these are quickly distinguished from burns based on history and presentation. Certain patterns of injury are classic for an intentional burn as a result of child abuse (Figure 7-3). Scald injuries of the buttocks and thighs accompanied by perineal or foot injury that spares the flexion creases is classic for intentional injury with defensive posturing. Symmetric burns of the hands or feet with clear lines of immersion are classic for forced submersion injuries. Small, round, deep burns are suggestive of intentional cigarette burns. Any deep wound with some geometric pattern may suggest a contact burn, such as an iron. Suspicion should be raised for abuse in any case with a nonspecific history, a mechanism that is inconsistent with the clinical presentation, delayed presentation, or a classic injury pattern.