Burn

– Tissue injury, protein denaturation, edema, and loss of intravascular fluid resulting from exposure to or contact with a causative agent such as heat, electricity, chemicals, or friction.

Causes and Incidence

Causes include (1) exposure to, contact with, or inhalation of the products of thermal agents such as fire, radiation, or hot liquids; (2) contact with an electrical current; or (3) contact with or inhalation or ingestion of chemical agents (e.g., acids, alkalis, phenols, cresols, mustard gas, or phosphorus). In the United States, more than 2 million people are burned each year; 15% require hospitalization, and 5% sustain a life-threatening burn. Burns are the second leading cause of death among young children.

Disease Process

Thermal and chemical injury disrupts the normal protective function of the skin, causing local and systemic effects. The extent of these effects depends on the type, duration, and intensity of exposure to the causative agent. With electrical burns, heat is generated as the electrical current passes through body tissues, causing thermal burns along the path taken by the current. Local damage is marked by histamine release and severe vasoconstriction, followed in a few hours by vasodilation and increased capillary permeability, which allows plasma to escape into the wound. Damaged cells swell and platelets and leukocytes aggregate, causing thrombotic ischemia and escalating tissue damage. Systemic effects, which are caused by vascular changes and tissue loss, include hypovolemia, hyperventilation, increased blood viscosity, and suppression of the immune system. The severity of the burn determines the extent of local and systemic effects. Severity is judged by the quantity of tissue involved and the depth of the burn. The percentage of body surface area (BSA) system classifies quantity as follows: small, ,15% BSA; moderate, 15%-49% BSA; large, 50%-69% BSA; massive, .69% BSA. The depth of the burn is classified by degree. First-degree burns affect the epidermis only; second-degree burns (also called split thickness) affect the epidermis and dermis; third-degree burns (also called full thickness) affect all skin layers and extend to subcutaneous tissue, muscle, nerves, and bone.

Symptoms

The following signs and symptoms can be expected within the first 24 hours.

Local
First degree: wound is red, sensitive to touch, painful, and moist; surface blanches to light pressure Second degree (split thickness): blistering likely Third degree (full thickness): surface is white and pliable with no blanching, or black, charred, and leathery; hypoesthetic or anesthetic; hairs are easily dislodged from follicles.

Systemic
Hypovolemic shock, dehydration, hypothermia, hyperventilation; with inhalation injury: respiratory obstruction or respiratory failure, or both.

Potential Complications

Infection, pneumonia, and respiratory failure are the most common causes of death with severe burns. The prognosis depends largely on the severity and location of the burns and the expertise of the burn management team.

Diagnostic Tests

Clinical examination
To determine the severity of the injury (degree, BSA) and the causative agent.

Baseline laboratory studies
Complete blood count, serum electrolytes, blood urea nitrogen, creatinine, arterial blood gases, bilirubin, alkaline phosphatase, urinalysis.

Bronchoscopy
To determine extent of upper airway damage.

Treatments

First- and -second degree burns, 20% BSA.

Surgery
None.

Drugs
Analgesics for pain; prophylactic antibiotics to prevent infection; tetanus toxoid for immunization; topical antiinfective drugs.

General
Cleaning with soap and cold water; debridement of blisters; splinting and positioning of involved joints; elevation of affected area.

Third-degree burns, .20% BSA.

Surgery
Surgical debridement; escharotomy to relieve constrictures caused by scarring; fasciotomy with some electrical burns; skin grafting; amputation of severely burned extremities; reconstructive and plastic surgery to correct deformity.

Drugs
IV narcotic analgesics; tetanus immunization; topical antiinfective drugs; IV antibiotics.

General
Airway maintenance, humidification, and oxygen in inhalation injuries; IV fluid replacement; cleansing of wound; urinary catheter; nasogastric tube; central venous line; mechanical debridement; hydrotherapy; dressing changes; dietary calories, protein increased; parenteral nutrition; physiotherapy; hypertrophic scar management with pressure garments; long-term psychologic support; vocational counseling; instruction for long-term adaptations.

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