Chemical Burns

Published on 14/03/2015 by admin

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Last modified 22/04/2025

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190 Chemical Burns

Jeffrey Druck

Key Points

• Copious, immediate irrigation is the most important treatment of chemical burns.

• Elemental metal burns are the only chemical burns that should not be irrigated with water. Instead, wipe the material off with dry gauze and protect yourself from contamination.

• Identifying the cause of a chemical burn may be difficult, but the use of external resources (material safety data sheet, paramedics, employers, poison center) will help characterize the agents.

• Patients who exhibit no further signs of systemic toxicity may require only a chemistry panel and an electrocardiogram to complete an assessment.

• Patients with hydrofluoric acid burns require topical treatment with calcium gluconate gel, local infiltration of calcium gluconate, or for the most severe cases, intraarterial administration of calcium gluconate.

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

TYPE OF CHEMICAL AGENT	MECHANISM OF TISSUE DAMAGE	EXAMPLE OF AGENT
Acids	Coagulative necrosis	Sulfuric acid
Alkali agents	Saponification and liquefactive necrosis	Calcium hydroxide
Desiccants and vesicants	Dehydration of cells through exothermic reactions, release of amines within cells	Nitrogen mustards
Oxidizing and reducing agents	Denaturing of proteins and direct cytotoxic effects	Bleach
Protoplasmic poisons	Formation of salts with cellular proteins	Picric acid

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.

Hazardous Materials

The U.S. Department of Transportation requires color-coded identification of the type of material transported. These identifying codes are widely used. Additionally, a standard four-number code should be present to identify or characterize the agent more specifically. Figure 190.1 indicates the general categories and identifying colors, which include the following:

• Explosives (solid orange)

• Nonflammable gases (solid green)

• Flammable liquids (solid red)

• Flammable solids (white and red stripes)

• Oxidizers and peroxides (solid yellow)

• Poisons and biohazards (solid white)

• Radioactive materials (half white, half yellow, with a black radiation symbol)

• Corrosives (half white, half black)

• Other (usually white)

Fig. 190.1 General categories and identifying colors for hazardous materials signs.

Treatment

The first step in caring for patients with chemical burns is removal of the offending agent. This involves copious irrigation with several liters of either water or normal saline solution. All contaminated clothing should be removed, with care taken to ensure that health care providers are not exposed.

Elemental Metals: Do Not Irrigate

Regardless of the type of offending agent, copious irrigation is the first step, with one exception: elemental metals. Elemental sodium and potassium cause exothermic reactions when exposed to water, in addition to forming toxic alkali agents. Patients with these injuries should undergo specific decontamination and removal of the offending metal by brushing it off with gauze. The poison center may provide advice about proper disposal of the metal.

Figure 190.2 is an algorithm for the management of patients with possible chemical burns.

Fig. 190.2 Algorithm for the treatment of chemical burns.

Ocular Exposure

Ocular chemical burns are highly morbid injuries. The initial therapy of copious irrigation cannot be emphasized enough. Lid retraction with eversion is a key procedure to remove all chemical particles. Testing for the continued presence of chemicals can be accomplished with pH paper, but it is important to wait a minimum of 5 minutes after irrigation to make sure that the pH of the irrigation fluid is not being checked. Patients with burns caused by certain chemicals may require admission for continuous irrigation. Any patient with ocular exposure that results in corneal burns (identified by fluorescein examination) should have an ophthalmology consultation. Other elements of the examination are similar to any eye examination and include visual acuity, slit-lamp examination, and visual field evaluation. Tap water is recommended as the initial irrigating agent (because it is the most easily obtained and time until irrigation is a key element), but normal saline, lactated Ringer solution, and buffered solutions all work effectively.⁴

Ingestions

Although discussion of the management of caustic chemical ingestion is beyond the scope of this chapter, two key concepts should be emphasized. First, the primary issue is maintenance of the airway. Second, the extent of burn is usually limited to the initial exposure, and decontamination of the gastrointestinal tract is difficult and not recommended; the only substance that has been suggested is water, but because of possible exothermic reactions resulting from attempted water irrigation, water decontamination of the gastrointestinal tract is controversial. Endoscopy is the only method for definitive assessment of the degree of injury, but the common complications of perforation and mediastinitis should also be assessed.⁵ Some recent studies suggest that not every patient with a chemical burn involving the esophagus requires endoscopy, but consultation with gastroenterology and toxicology is recommended.⁶

Inhalational Injury

Again, the primary issue in patients with inhalational injury is maintenance of the airway. For a variety of chemicals, the initial chest radiograph and the absence of respiratory symptoms belie the serious pulmonary edema or tracheobronchitis that may develop even days later. Consultation with the local poison control center while supportive measures are being instituted is the recommended pathway of care.

Directed Therapies

Specific agents are known to cause specific toxicities. If the substance is known, therapy should be directed against that toxicity (Table 190.2).

Table 190.2 Specific Therapies for Chemical Burns

AGENT	SPECIFIC TOXICITY	ADDITIONAL TREATMENT
Hydrofluoric acid	Severe hypocalcemia and continued liquefactive necrosis	Superficial wounds: calcium gluconate 2.5% gel Deep wounds: local infiltration (10% solution) or intraarterial injection (5% solution) of calcium gluconate
Formic acid	Severe acidosis	Bicarbonate administration, possible exchange transfusions or hemodialysis for high serum levels and persistent acidosis
Cement (alkali burn)	Persistent burns when exposed to water if not irrigated away completely	Thorough irrigation
Phenol	Systemic absorption causing central nervous system depression, coma, and death	Because a more dilute solution is absorbed more rapidly, deep, continuous irrigation is performed until undiluted polyethylene glycol solution is available for topical application; all other treatment is supportive for systemic symptoms
White phosphorus	Continued thermal burning resulting from burns on exposure to oxygen; systemic absorption causing acidosis and electrocardiographic abnormalities, possibly sudden death	Removal of as much phosphorus as possible through irrigation with cool water, then placement of a solution of 5% sodium bicarbonate and 3% copper sulfate in 1% hydroxyethyl cellulose
Elemental metals (sodium, potassium)	Exothermic reaction when exposed to water	Wiping away of material and contacting a poison control center for disposal instructions
Nitrates	Methemoglobinemia	Administration of methylene blue
Monochloroacetic acid	Systemic lactic acidosis	Administration of dichloroacetate and possible hemodialysis
Nitrogen mustards	Vesicle formation	Steroid and antibiotic dressings after copious irrigation

Hydrofluoric Acid

Hydrofluoric acid is used in glass etching, automotive and industrial wheel cleaning, brick cleaning, semiconductor manufacturing, metal purification, and other industries. Immediate irrigation is indicated, as with other chemical injuries, but hydrofluoric acid can cause progressive tissue damage. Extensive exposure of an uncovered arm or leg can be fatal. Pain may be delayed but can subsequently continue for hours or days. The hydrofluoric acid ion does not dissociate but rather penetrates tissues deeply and reacts with calcium and magnesium. Hypocalcemia can result.

Patients with mild, limited superficial exposure can be treated with topical calcium gluconate, which must usually be mixed in the emergency department by combining calcium gluconate powder with commonly available lubricant jelly. Affected fingers and hands can be placed in a medical glove that contains the solution.⁷

Subcutaneous infiltration of 10% calcium gluconate may help relieve the pain, but it also irritates the tissue. Slow infiltration with the smallest available needle, preferably 30 gauge, or dilution of the solution may minimize tissue damage. Intraarterial administration of 10 mL of calcium gluconate mixed in 50 mL of 5% dextrose in water through the radial or ulnar artery via an arterial line over a 4-hour period may be beneficial for severe exposures to the hand.

Cardiac dysrhythmias may result from systemic hypocalcemia and hypomagnesemia. The electrocardiogram should be monitored for QT prolongation. Calcium and magnesium should be administered as needed.

Follow-Up, Next Steps in Care, and Patient Education

After determination of the offending agent and copious irrigation until no further chemical remains (for acids and bases, this can be determined with pH paper), disposition of the patient should be based on the presence of systemic symptoms, the size and depth of the burn, the nature of the agent, and access to appropriate follow-up. All patients should be warned about scarring and the potential for infection. The circumstances of the exposure should be verified, and appropriate state and local authorities should be notified about exposures in industrial incidents.

Red Flags

Scenarios Suggestive of Specific Types of Chemical Burns

Scenario	Suspicious Agent
Circumferential lower extremity burns above the sock line	Cement
Burn in a glass etcher	Hydrofluoric acid
Burn from fireworks	White phosphorus
Mass exposure (terrorist attack)	Nitrogen mustard