Epidemiology

Chemical burns are an unusual type of burn because the tissue injury is caused by the chemical reaction rather than by thermal damage. Chemical burns are common at work, at home, or in association with hobbies. One study found 22% of all pediatric burns to be a result of chemical burns,¹ whereas other studies have estimated the percentage of admitted burned patients with chemical burns to be between 10% and 14%.^2,3 With the recent concerns over terrorism, chemical agents have been emphasized as a possible method of attack, so knowledge of chemical burns is critical in the education of today’s emergency physicians. In addition, failure to recognize chemical burns or to treat them appropriately can have a detrimental impact not only on patients but also on care providers.

Pathophysiology

Different chemical burns affect tissue by different mechanisms. Table 190.1 provides different categories of chemical agents and their mechanism of tissue damage. Most chemical burns involve skin; accordingly, knowledge of skin anatomy is key to understanding the pathophysiology of various chemical burns because of the link to treatment. A direct injury results when the epidermis is penetrated. Systemic absorption is possible once the injury extends through the dermis.

Table 190.1 Chemical Agents and Their Mechanisms of Tissue Damage

Presenting Signs and Symptoms

A classic example of a chemical burn is an industrial worker who “got something” on his or her arm and pain and sloughing of the skin developed over the next few minutes. The burning may have continued despite irrigation. An alternative example may be someone who got something on his or her clothes and noticed burning and a “rash” after touching the clothing.

In our modern times, chemical agents may be used in a terrorist attack, so multiple victims with similar burns and systemic toxicity should trigger concern for a mass casualty event. In addition, burns that appear to worsen over short periods may not be thermal burns, as initially thought, but instead may be chemical.

Differential Diagnosis and Medical Decision Making

With chemical agents, the initial complaint may be a red, burning rash; because some agents cause a delayed onset of symptoms, chemical burns should be considered in the differential diagnosis of all rashes. However, there is usually a direct cause-and-effect relationship that makes the diagnosis easy. Treatment, however, varies with the agent, identification of which may be more difficult. The most important task is to identify the offending agent. Various resources can be used, but the best source of information is usually patients themselves. The job site may provide clues, but the employer should also have the material safety data sheet available. Paramedics or others can bring in bottles of the agent, which may have a list of ingredients. The presence of systemic symptoms may also suggest specific agents.

Although the specific agent may be difficult to identify without other information, further testing can assist in the diagnosis. pH paper can be used on the wound to determine the presence of acid or base. A chemistry panel may suggest acidosis, whereas hypocalcemia may suggest exposure to hydrofluoric acid.

The gowns and gloves readily available in the hospital are not sufficient for many substances. Most chemicals penetrate these materials immediately. Relatively inexpensive, chemical-resistant, multilayer suits are available. Furthermore, respiratory precautions may be indicated for some agents. For these reasons, both hospital and community resources may be required for safe and expedient decontamination.