INTRODUCTION	Section 2 of 11
Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography

Background: Chemical burns are divided primarily into 2 groups: acid and alkali. In addition to the occupational hazards associated with industrial strength product use in the work place, a plethora of products are available and used by the general public. As with most environmental or toxicological exposures, knowing the specifics of the offending agent is key. Appropriate evaluation requires a complete assessment of the offending agent (composition, acid or alkali, concentration), type of exposure (inhalation, cutaneous, ocular, gastrointestinal), duration of exposure, and other events or injuries associated with the burn (explosion, fall, trauma).

Pathophysiology: Acids and alkalis cause injury via different mechanisms.

Acids produce coagulation necrosis by denaturing proteins upon tissue contact. An area of coagulation is formed and limits extension of injury. An exception is hydrofluoric acid, which produces a liquefaction necrosis similar to alkalis.

Hydrofluoric acid is also unique in that it may rapidly penetrate the skin to the vasculature, allowing for rapid fluoride ion dissemination. The fluoride may then precipitate with calcium, causing life-threatening hypocalcemia and metastatic calcification.

Alkalis cause a liquefaction necrosis, and are potentially much more dangerous than acid burns. Alkali agents liquefy tissue by denaturation of proteins and saponification of fats. In contrast to acids, whose tissue penetration is limited by the formation of a coagulum, alkalis can continue to penetrate very deeply into tissue.

Frequency:

• In the US: Accurate statistics are lacking. However, approximately 25,000-100,000 chemical burns are reported every year.

Mortality/Morbidity:

• Chemical burns result in approximately 20 deaths per year, with a mortality rate of less than 1%.

• Morbidity, defined as severe toxicity, occurs in less than 1% of those exposed.

• Bleach is associated with severe toxicity in less than 1% of cases. Death is rare, although anecdotal reports of fatalities exist.
  
  
• Alkali exposures are high risk.
  
  
• Drain cleaners are associated with severe toxicity in 1-2% of cases, with a mortality rate of less than 0.1%.
  
  
• Caustic ingestions are high risk and may result in airway compromise.
  
  
• Ocular exposures are high risk.

Age:

• Children and adults have similar exposure rates.

• Younger children tend to be exposed accidentally because of inadequate childproofing.

• Older children and young adults may be exposed because of impetuous behavior or experimentation.

	CLINICAL	Section 3 of 11
Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography

History:

• Although a careful physical examination is important, a thorough history usually helps determine how a patient should be treated.

• Type of exposure

• Determine the offending substance. It is not enough to rely solely on patient history. Obtain the substance's container, call the manufacturer, use a computerized poison index, and/or call your regional poison center.

• Determine whether the substance is acid, alkali, or chemical in composition, and ascertain the concentration.

• Determine whether the exposure was cutaneous, oral, gastrointestinal, ocular, or inhalation.

• Time and duration of exposure

• Symptoms immediately after the injury (pain, burning, numbness, change in level of consciousness, respiratory distress, vital signs, oral discomfort or swelling, ocular discomfort, change in vision)

• Decontamination or life-saving measures provided at the scene

• Other injuries possibly resulting from a fall, explosion, or fire

• Preexisting medical conditions

Physical:

• Airway

• Patients with oral or inhalation injury may experience significant edema or difficulty maintaining their airway and often require intubation.

• Particular attention should be paid to the presence of stridor, hoarseness, and oral swelling.

• Breathing: Patients may develop wheezing and labored breathing as a result of inhalation. Symptoms may range from discomfort and mild wheezing to respiratory failure requiring artificial ventilation.

• Circulation

• Assess circulation by determining perfusion to end organs—level of consciousness, skin color and temperature, capillary refill, and urinary output.

• Assess heart rate for appropriate rate and regularity.

• Disability: Perform a thorough neurologic evaluation to determine the presence and degree of deficit. Serial examinations are necessary to evaluate symptom progression or resolution.

• Environmental
  • As with many environmental injuries, patients may be at risk for becoming hypothermic, with associated increased morbidity and mortality. Attention should be paid to maintaining normal temperature.

  • Preventing further injury is also important. Wet or contaminated clothing should be removed, and the patient maintained warm and dry.

• Extremities: Close inspection of all extremities should be performed to rule out any other associated injuries.

• Special considerations

• Patients with oral or inhalation injury may experience significant swelling or difficulty maintaining their airway. Particular attention should be paid to the presence of drooling, stridor, hoarseness, and oral swelling. Intubation may be necessary.

• Oral burns are an underreported problem and may lead to severe contracture. Oral contractures can be divided into anterior, posterior, and total. Posterior oral contractures result from caustic ingestion and involve the posterior buccal mucosa, posterior tongue, retro-molar area and oro-pharynx. Total oral contractures typically result from caustic lye ingestion and involve the lips, tongue, oral cavity, and oro-pharyngeal mucosa.

• Seek, and document, the presence, size, and depth of cutaneous burns.

• Depths of burn classifications are superficial partial thickness, deep partial thickness, and full thickness. Depth determination involves describing the affected area's color, texture, and sensation.
  • First-degree burn: Redness without change in texture and intact sensation denotes a superficial injury.

  • Second-degree burn: Blister formation with or without denuding and pink to mildly pale tissue with intact sensation denotes deeper partial-thickness injury.

  • Third-degree burn: Areas that are white, leathery, and insensate denote full-thickness injury.

• Determining extent of involvement requires an estimate of the affected body surface area. Special attention also is paid to injuries of the face, hands, feet, and genitalia. Circumferential injury should also be noted.

• Body surface area can be estimated by using a standard chart with the Rule of 9's. However, the Lund and Browder Chart provides a more accurate estimate in children.

• Most small injuries can be approximated using the size of the patient's palm. The entire palm, including the fingers, represents approximately 1% of total body surface area (TBSA).

• Oral or gastrointestinal

• Oral or gastrointestinal exposure may cause severe burns, particularly if the exposure is to a strong alkali.

• Early injury may be represented by redness, swelling, and pain. Patients breathe through an open mouth, drool, speak with a hoarse voice, or have stridor.

• Remember that alkali compounds result in liquefaction necrosis—with potential for ongoing deep tissue penetration. Severe precipitous airway edema or obstruction may result.

• Children refusing to swallow their own saliva should be given particular attention. Risk of esophageal perforation and stricture is very real (although these are later complications and usually are not present when the patient is in the emergency department.

• Ocular

• Patients with ocular exposure or complaints require detailed ophthalmologic evaluation. However, initial examination is deferred until adequate decontamination has occurred with copious amounts of saline (minimum of 0.5 h).

• Complete evaluation includes general appearance of the globe, conjunctiva, anterior chamber, and cornea with attention to redness, pallor, or opacification.

• Examine the eye for presence of foreign bodies.

• Verify pupillary and extraocular muscle function.

• pH testing should be performed before and after each set of irrigations and should be continued until the pH returns to the normal range (7-8).

• Stain with fluorescein to look for areas of increased uptake signifying corneal abrasion.

• A slit lamp examination may be useful. It allows for a more detailed examination of the cornea and anterior chamber, including the presence of a hyphema or hypopyon.

• Document the visual acuity of patients with ocular exposure or complaints. Documentation should include right eye and left eye individually, then vision with both eyes.

Causes:

• Inadequate child-proofing

• Cleaning or caustic products are not stored out of reach of young children.

• Cleaning solutions or agents are stored in bottles other than the original container (eg, a potentially caustic solution in a soda pop bottle).

• Directions are not regarded or supplies are inappropriately mixed (eg, mixing bleach and ammonia products creates a noxious gas, which can precipitate acute bronchospasm and respiratory distress).

• Unintended exposures are caused by something breaking, exploding, or being squirted or sprayed.

• Common sources of acids

• Toilet bowl or drain cleaners may contain sulfuric or hydrochloric acid. They also may contain alkali.

• Automotive tire or metal cleaners and rust removers may contain hydrofluoric, sulfuric, or phosphoric acid.

• Engraving solution may contain hydrofluoric or nitric acid.

• Tile cleaners or glass etching may contain hydrofluoric acid.

• Battery fluid may contain sulfuric acid.

• Common sources of alkalis (bases)

• Drain or oven cleaners may contain sodium or potassium hydroxide.

• Cleaners and detergents may contain ammonia or any of the sodium or potassium polyphosphates.

• Household bleach or pool chlorination system or tablets may contain sodium or calcium hypochlorite.

• Cement, mortar, or plaster may contain calcium hydroxide or oxide.

• Denture cleaners or Clinitest tablets may contain sodium or potassium hydroxide.

• Dishwashing or clothing detergents may contain silicates or sodium carbonate.

• Toilet cleaners (lye) may contain potassium hydroxide or other strong alkali.