eMedicine Specialties > Pediatrics: Surgery > General Surgery

Burns, Thermal

Author: Monika I Sidor, MD, Staff Physician, Department of Surgery, University of Michigan at Ann Arbor
Coauthor(s): Brian E Benson, MD, Staff Physician, Division of Otolaryngology, New Jersey Medical School; Robert A Schwartz, MD, MPH, Professor and Head of Dermatology, Professor of Medicine, Professor of Pediatrics, Professor of Pathology, Professor of Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School; Franklin Desposito, MD, Professor of Pediatrics and Clinical Director, Center for Human and Molecular Genetics, UMDNJ-New Jersey Medical School; Consulting Staff, Department of Pediatrics, UMDNJ-University Hospital; Michael Lucchesi, MD, Chair, Associate Professor, Department of Emergency Medicine, State University of New York at Brooklyn
Contributor Information and Disclosures

Updated: Aug 29, 2006

Introduction

Background

Approximately 1.2 million people seek medical treatment for burns each year in the United States. Roughly 50,000 of these (4.2%) require hospitalization. Approximately one third of burn injuries (30-40%) are in children. Although the incidence has been decreasing, fire continues to be a major cause of fatalities in children. Fires are second only to motor vehicle accidents as the leading cause of death in children. Fires account for up to 34% of fatal injuries in children younger than 16 years.

Pathophysiology

The skin is the largest organ in the body, ranging in area from 0.25-1.8 m². It is composed of 3 main layers, as follows:

• The epidermis is the outermost layer, and itself is composed of 2 layers. In the epidermis, the outer layer of anucleated cornified cells (stratum corneum) acts as a barrier to the entrance of microorganisms and the loss of water and electrolytes. The inner layer of the epidermis is composed of viable cells (Malpighian layers) that mature and differentiate into cornified cells of the stratum corneum.
• Beneath the epidermis is the dermis (corium), which is composed of a dense fibroelastic connective tissue stroma containing collagen, elastic fibers, and an extracellular gel termed the ground substance. The dermis contains an extensive vascular and nerve network and special glands and appendages that communicate with the overlying epidermis.
• The innermost layer of the skin is the subcutaneous tissue, which is composed primarily of areolar and fatty connective tissue. This layer contains skin appendages, glands, and hair follicles.

Burns are divided into 4 categories, depending on the depth of the injury, as follows:

• First-degree burns are limited to the epidermis. A typical sunburn is a first-degree burn. It is characterized by erythema, pain, and minor microscopic changes. Pain usually lasts 48–72 hours, and the damaged epithelium peels off in 5-10 days. First-degree burns do not lead to scarring and require only local wound care.
• With second-degree burns, the point of injury extends into the dermis, with some residual dermis remaining viable. The healing is directly related to the amount of undamaged dermis. Deep dermal burns lead to severe hypertrophic scarring and may take 25–35 days to heal.
• Third-degree, or full-thickness, burns involve destruction of the entire dermis, leaving only subcutaneous tissue exposed. It is characterized by lack of sensation in the burned skin, a leathery texture, and no capillary refill.
• Fourth-degree burn is a term that is rarely seen in literature and periodicals. This type of burn is usually associated with lethal injury. Fourth-degree burns extend beyond the subcutaneous tissue, involving the muscle, fascia, and bone. Occasionally termed transmural burns, these injuries often are associated with complete transection of an extremity.

The extent of body surface area (BSA) involved in second-degree burns, at the least, has great impact on the morbidity and mortality associated with the injury. Deep burns may have a clearcut area of irreversible skin necrosis. Surrounding the area of necrosis is an area of inflammation and ischemia. The tissue in this area may survive or may die. Edema, infection, further exposure, and dehydration may contribute to an increase in the area of ischemia and further irreversible skin necrosis. Surrounding the ischemic zone is an area of hyperemia. Increased blood flow in this zone is promoted by numerous mediators that are liberated from the injured tissue.

In children, scalding, which is most common in toddlers, accounts for 85% of all injuries. Immersion in water at 52°C (126°F) takes 2 minutes to cause full-thickness burns compared to only 5 seconds of immersion in water at 60°C (140°F). Water heaters in the home should be set from 49-55°C (120-130°F). Water heaters placed in apartment houses pose a particular problem because boilers are usually set at 70°C (158°F) in order to deliver adequate amounts of hot water, which can cause full-thickness skin burns within one second.

Direct contact with flame accounts for another 13% of burns. In the United States, sleepwear is legally required to be flame retardant; this requirement has led to a dramatic decrease in the number of clothing ignition incidents. Recently, the US Consumer Product Safety Commission has voted to loosen some of the children's sleepwear flammability standards that were previously set by the Federal Flammable Fabrics Act.

Frequency

United States

The National Burn Information Exchange, a voluntary burn patient registry established in 1964, reports that children younger than 4 years have a high percentage of burn accidents and account for more than 50% of the total number of pediatric burns. Most burn injuries in children occur at home and appear to be largely preventable.

International

Countries without strict manufacturing laws regarding children's clothing (in particular sleepwear) have a much higher incidence of clothing ignition incidence. Garments that are not flame retardant can ignite spontaneously when introduced to a significantly high temperature (eg, a splash of hot oil from a stove).

Mortality/Morbidity

Over 5000 burn-related deaths occur each year in the United States.

Sex

Most burn injuries in older children are related to fires. In these injuries, boys are involved much more frequently than girls.

Age

Children younger than 4 years account for more than 50% of the total number of pediatric burns.

Clinical

History

A careful history is extremely important. For example, a person who is trapped in a smoke-filled space for even a few moments can inhale toxic amounts of smoke without incurring any burn to the skin. Inquire about the etiology of the burn, duration of exposure, age, and associated medical conditions.

Physical

As with all trauma patients, physical examination of patients with burns should take place in the prehospital care area, in the primary survey of the emergency department (ED), as well as in the secondary survey and subsequent evaluations.

• Calculation of the total BSA burned is important. In the prehospital setting, the evaluation method must be quick and accurate.
  • Most prehospital care providers use the rule of nines. Essentially, the rule of nines divides the body into 11 areas of 9% each. Each arm is 9% (2), the anterior and posterior portions of each leg are each 9% (4), the anterior upper and lower portions of the thorax are 9% each (2), the posterior upper and lower portions of the thorax are 9% each (2), and the area including the neck and head is 9% (1). The total is 9% times 11, or 99%. The perineum comprises the remaining 1%.
  • The BSA burned is based on the percent of second- and third-degree burns. This rule is acceptable for adults and is less accurate for children who tend to have proportionally larger heads and smaller legs. Burn calculations with the rule of nines tend to overestimate the size of the burn. This overestimation is advantageous, especially for prehospital care providers who need to start the triage process at a high level.
  • A quicker, but less accurate, method for determining burn size is to use the palm of the patient's hand, which is roughly equivalent to 1% of the patient's BSA. The palm-of-the-hand approach is most convenient for splash-type nonconfluent burns and should never be used for significant burns (>10% BSA).
  • The most accurate yet time-consuming method of determining skin involvement is with the Lund and Browder chart. Essentially, the health care provider has an anterior and a posterior diagram of the patient, which is divided into sections. When calculating the percentage of skin involvement, the clinician colors in the areas on the chart for both the anterior and posterior regions of the patient. The sum of the colored areas is the BSA involved. Different charts are available for different age groups.
• Acute upper gastrointestinal tract erosions and ulcers may occur in patients with severe burn injuries. The lesions are termed stress or Curling ulcers. Painless gastrointestinal tract bleeding is the most common clinical finding. Blood loss usually is minimal and can be prevented with prophylactic administration of H2 blockers.
• Thermal burns to the respiratory tract, oral cavity, pharynx, larynx, or lung parenchyma are rare. Dry heat from a flame cannot deliver sufficient kilojoules to the tissue to sustain tissue damage.
  • These types of injuries, which can develop into extremely difficult acute airway problems, usually are secondary to steam or other hot vaporized liquids. The water molecules in steam (aerosolized) can deliver very high amounts of kilojoules capable of causing upper respiratory and lung parenchymal injury.
  • Smoke inhalation also can result in inflammation of airways and lungs that is significant enough to cause clinical implications. Classic signs associated with significant smoke inhalation are burns to the face or nasal hairs, carbonaceous sputum, or both.

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