External Chemical Burns

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10 Interesting Facts of External Chemical Burns

External chemical burns are cutaneous or ocular tissue injuries caused by direct contact with a caustic agent
May result from household exposures (eg, general cleaning products, drain cleaners, rust removers) or occupational exposures
Diagnosis is based on history of exposure and physical examination findings, which may include tissue damage ranging from erythema to necrosis
Deeper burns are usually painless (owing to nerve damage)
Be alert to signs of associated airway burns from inhalation or aspiration of chemical
Dilution of offending agent with irrigation is the primary treatment tool for nearly all chemical burns
- Continue wound irrigation with copious amounts of water (for cutaneous burns) or normal saline (for ocular burns)
  - Continue until pH of burn site (or drainage runoff) neutralizes
- An exception to the aforementioned irrigation is a burn from an elemental alkali metal (eg, sodium, potassium, lithium). Particles must be physically removed; do not irrigate
- Also avoid water irrigation for phenol and calcium oxide exposures
In addition to dilution by irrigation, some chemical burns require additional immediate monitoring and/or alternative treatment to prevent systemic toxicity (eg, hydrofluoric acid, chromic acid, phenol, white phosphorus)
Follow general procedures of Advanced Burn Life Support for airway management and IV fluid administration; follow Advanced Trauma Life Support procedures if there is associated trauma (eg, chemical blast injury, motor vehicle injury)
Transfer all patients with serious chemical burns to a verified burn center after consultation with a burn surgeon
Low-degree chemical burns usually heal without complications. Prognosis of higher-degree burns depends on chemical involved, extent of injury, and age of patient

Pitfalls

Conduct history, physical examination, and treatment using protective equipment for medical personnel and universal precautions to prevent exposure to burn agent or any transmissible infection
- Paper gowns may not be protective
Do not irrigate the following exposures with water: elemental sodium, potassium, or lithium
- Particles must be physically removed
Also avoid water irrigation for phenol and calcium oxide exposures
Severity grading of chemical burn injuries must be updated, because full extent of tissue damage can develop over several days, even after causative agent has been removed
Hydrofluoric acid causes superficial burns, deep tissue liquefying necrosis, and systemic poisoning; some of its effects are not visible until hours or days after exposure
- Always consider this agent when pain is out of proportion to what is noted on physical examination

External chemical burns are cutaneous or ocular tissue injuries caused by direct contact with a caustic agent
- Most injuries are minor, but some substances cause more severe injury and should be treated even with small surface-area exposure
- Most compounds cause injury through chemical reactivity rather than thermal injury, but the result is generally the same, and thus the term burn is used
Classification of chemical burns and disposition decisions are made by extrapolating recommendations from general thermal burn guidelines

Classification

For skin injury (identical to thermal burn classifications)
- By depth of tissue damage
  - Superficial (first-degree) burn: involves epidermis only
  - Partial-thickness (second-degree) burn: involves epidermis and upper layers of dermis
  - Full-thickness (third-degree) burn: involves all layers of dermis
  - Fourth-degree burn: extends into underlying muscles, tendons, and bones
- By extent of involvement (percent of total BSA involvement)
  - Adults
    - Head and neck: 9%
    - Anterior trunk: 18%
    - Posterior trunk: 18%
    - Arms, including hands: 9% each
    - Legs, including feet: 18% each
    - Genitalia: 1%
  - Children
    - Percentages are adjusted for proportionally larger heads (up to 20% in infants) and smaller legs (down to 13% in infants)
    - Simplistic dichotomization, with fixed numbers for adult and for 1 model child, is a common approach, but the other approach, a Lund-Browder chart, provides gradations by pediatric age group and thus improves accuracy of percentage of total BSA involvement for children
- By severity (used to recommend disposition as outpatient, inpatient, or referral to burn center)
  - Minor burn (disposition: outpatient management)
    - Partial-thickness burns on:
      - Less than 5% of total BSA in patients younger than 10 years or older than 50 years
      - Less than 10% of total BSA in patients aged 10 to 50 years
    - Full-thickness burns on:
      - Less than 2% of total BSA in patients of all ages
  - Moderate burn (disposition: hospital admission)
    - Partial-thickness burns on:
      - 5% to 10% of total BSA in patients younger than 10 years or older than 50 years
      - 10% to 20% of total BSA in patients aged 10 to 50 years
    - Full-thickness burns on:
      - 2% to 5% of total BSA in patients of all ages
    - Suspected inhalation injury, circumferential burn, comorbid conditions predisposing patient to complications (eg, diabetes)
  - Major burn (disposition: referral to burn center)
    - Partial-thickness burns on:
      - More than 10% of total BSA in patients younger than 10 years or older than 50 years
      - More than 20% of total BSA in patients aged 10 to 50 years
    - Full-thickness burns on:
      - More than 5% of total BSA in patients of all ages
      - Known inhalation injury
      - Any significant burn to face, eyes, ears, hands, feet, genitalia, or joints
      - Significant associated injuries (eg, fracture, other major trauma)
For ocular injury
- Roper-Hall classification system
  - Grade I injury: corneal epithelium is damaged, but no corneal opacity and no limbal ischemia are seen
  - Grade II injury: cornea is hazy but iris details are visible; ischemia involves less than one-third of limbus
  - Grade III injury: total epithelial loss is present, stromal haze obscures iris details, and ischemia involves one-third to one-half of limbus
  - Grade IV injury: cornea is opaque with no view of iris or pupil and ischemia involves more than one-half of limbus
By causative agent
- Acids
- Bases (alkalies)
- Organic agents
Severity grading of chemical burn injuries must be updated, because full extent of tissue damage can develop over several days, even after causative agent has been removed

Diagnosis

Clinical Presentation

History

Approach the patient wearing protective gear (ie, gloves, gown, eye protection); take universal precautions to prevent exposure to burn agent or any transmissible infection
History taking must be rapid and must happen concurrently with start of irrigation of chemical burn
Obtain exposure history
- Identification of specific agent, if possible, from patient or bystander; in nearly all cases identification will not change immediate treatment
  - Contact regional poison control center early
  - Material safety data sheets may be available for occupational exposures
  - If agent is household chemical, container is helpful
  - Concentration and volume of agent is helpful
- Mechanism of exposure
  - May include spill, splash, aerosol, or blast or other high-pressure exposure
  - May suggest potential for inhalation injury, airway compromise, or other physical trauma
  - Almost all chemical burn injuries are accidental; attacks are rare
  - Identify whether history is suggestive of intentional harm or self-harm
- Duration of exposure before decontamination is associated with degree of injury
Assess pain
- Cutaneous pain ranges from moderate (first-degree burn) to severe (second-degree burn)
  - Absence of pain and presence of numbness in affected area characterize third- and fourth-degree burns
- Ocular symptoms vary according to depth of injury and may include irritation, foreign body sensation, visual changes, inability to open eyelids, and/or severe pain
- Oral pain, chest pain, or pain with swallowing may indicate aspiration, inhalation, or ingestion of burn agent
- For hydrofluoric acid burn from low concentration (less than 10%), pain may not appear until 6 to 18 hours after exposure
  - Pain occurs more quickly after exposure with higher concentrations
  - Pain may also be worse than expected for appearance of burn
Assess for symptoms of inhalation of caustic agent
- Dyspnea may indicate aspiration or inhalation of a caustic agent, in addition to the external burn
- May also indicate smoke inhalation when thermal injury is present in addition to the chemical injury

Physical examination

Conduct physical examination wearing protective gear (ie, gloves, gown, eye protection); take universal precautions to prevent exposure to burn agent or any transmissible infection
Physical examination must happen concurrently with start of irrigation of chemical burn
Identify the greatest threats to life in a primary survey using a systematic approach (eg, Advanced Burn Life Support primary survey)
- Evaluate airway for signs or symptoms of immediate or impending airway compromise due to chemical aspiration or inhalation
Identify all burned areas of skin and determine depth and extent of chemical burns
- Depth of burn (by degree)
  - Appearance ranges from erythema to blistering and eschar of affected area
    - First-degree burn: dry, blanching erythema and pain on palpation
    - Second-degree (partial-thickness) burn
      - Superficial: blistering with blanching erythema; pain on palpation
      - Deep: may appear paler, with mottling and little or no blanching
    - Third-degree (full-thickness) burn: hard, leathery eschar with no blanching; painless (owing to nerve damage)
    - Fourth-degree burn: involvement of deep tissues, including muscle, tendon, and/or bone; painless (owing to nerve damage)
  - Initial physical assessment may underestimate depth of injury owing to delayed effect of some caustic agents; a classic example is hydrofluoric acid, whose action depends on concentration
- Extent of burn by percentage of total BSA
  - Adults
    - Head and neck: 9%
    - Anterior trunk: 18%
    - Posterior trunk: 18%
    - Arms, including hands: 9% each
    - Legs, including feet: 18% each
    - Genitalia: 1%
  - Children
    - Percentages adjusted for proportionally larger heads (up to 20% in infants) and smaller legs (down to 13% in infants)
    - Lund-Browder chart improves accuracy of percentage of total BSA involvement for children
Identify ocular chemical burns
- Examination should be postponed until irrigation is completed; thorough examination of ocular burns by an ophthalmologist is important
- Most patients, especially with exposure of eye to alkali, have swelling and/or spasm of eyelids, making examination difficult
- Periorbital edema, erythema, deepithelialized skin, and loss of eyelashes and eyebrows may also be noted
- Degree of ocular injury is defined by Roper-Hall classification; use fluorescein dye to assess cornea
  - Grade I injury: corneal epithelium is damaged, but no corneal opacity and no limbal ischemia are seen
  - Grade II injury: cornea is hazy but iris details are visible; ischemia involves less than one-third of limbus
  - Grade III injury: total epithelial loss is present, stromal haze obscures iris details, and ischemia involves one-third to one-half of limbus
  - Grade IV injury: cornea is opaque with no view of iris or pupil and ischemia involves more than one-half of limbus
Identify signs of mucosal chemical burns
- Initial examination of oral and nasal mucosa may have normal findings, as burn injury may not be immediately apparent
- Erythema or blistering may indicate associated inhalation, aspiration, or ingestion of chemical burn agent

Causes

Direct skin or eye contact with a caustic agent
- Acids
  - About a quarter of all chemical burns are caused by strong acids
    - Acids coagulate proteins; pH less than 2 can produce coagulation necrosis on contact
      - These processes tend to limit the depth of tissue damage, compared with alkali chemical burns (the exception is hydrofluoric acid)
    - Inorganic acids damage skin by direct binding and salt formation; these reactions may be exothermic, producing heat that contributes to tissue injury
  - Common ingredient in the following:
    - Household products
      - Bathroom cleaners often contain hydrochloric acid
      - Drain cleaners often contain concentrated sulfuric acid
      - Bleach contains hypochlorous acid (usually neutral pH commercially)
    - Swimming pool chemicals
      - Concentrated hydrochloric acid is used as an acidifier for home swimming pools
    - Industrial compounds
      - Hydrofluoric acid is commonly used in glass etching, frosting, and polishing; ceramics polishing; removal of metal castings; stone and marble cleaning; and in the textile industry
      - Chromic acid is used in circuit board manufacturing, etching copper, and in laboratories
- Alkalies
  - Approximately half of all chemical burns are caused by alkalies
    - Alkalies denature proteins
    - Alkalies with pH more than 11.5 produce severe tissue injury through liquefaction necrosis, which loosens tissue planes and allows deeper penetration of agent
      - For this reason, alkali burns tend to be more severe than acid burns
    - Inorganic alkalies damage skin by direct binding and salt formation; these reactions may be exothermic, producing heat that contributes to tissue injury
    - Alkalies are the most common cause of ocular chemical injuries, occurring most commonly in industrial settings or as a result of assault
  - Common alkalies include:
    - Household cleaners containing hydroxides, carbonates, or caustic sodas of sodium, potassium, ammonium, lithium, barium, and calcium
      - Oven cleaners often include potassium hydroxide
      - Drain cleaners often include potassium hydroxide
      - Multipurpose house cleaners may include ammonia
    - Hair care products
      - Hair relaxers may contain calcium and lithium hydroxide
    - Cleaning solutions for industrial purposes
    - Structural bond in cement and concrete
      - Wet cement (pH of approximately 12) can cause a severe alkali chemical burn
    - Fertilizers
    - Illicit manufacture of methamphetamine (anhydrous ammonia)
- Organic agents
  - Organic solutions dissolve lipid membrane of cells and disrupt cellular protein structure
    - Chemical disinfectants
      - Phenol (carbolic acid) is common ingredient
    - Petroleum products
      - Creosote
      - Gasoline

Risk factors and/or associations

Age

Highest incidence for adults is between the ages of 20 and 60 years
Older patients have increased risk for clinical complications

Gender

In the United States, most chemical burns occur in men

Most chemical burns occur accidentally in the home or workplace

Occupational hazard for firefighters
Occupational hazard for employees in many industrial settings with potential exposure to toxic industrial chemicals and wet cement
Occupational/environmental hazard for people living or working in conflict areas

Rarely intentionally inflicted (eg, acid attacks as hate crimes, “honor” attacks, or domestic violence)

Diagnostic Procedures

Primary diagnostic tools

Physical examination is the principal diagnostic tool for evaluation of external burns
- Conduct rapid history and physical examination wearing protective gear; take universal precautions to prevent exposure to burn agent or any infection transmission from or to patient
- Evaluate initial depth and extent of burns to skin while starting irrigation
- For burns to eye, irrigate eye to neutral pH before examining
- Evaluate for associated inhalation, aspiration, or ingestion exposures
Identify the causative agent, but do not delay treatment during this process
- Caustic agents may be identified through the following:
  - Poison control center can identify contents of most household agents
  - Material safety data sheets, if available, for work-related injuries
  - Containers found at injury site and brought in by family members or prehospital staff
  - Report of motor vehicle crash in setting of petroleum-related burns
- Identification of specific burn agent is important to:
  - Reduce risks for healthcare professionals
  - Identify agents that:
    - Cause systemic toxicity risk and require additional monitoring or treatment (eg, formic acid, hydrofluoric acid)
    - Require specific alternative treatment (eg, phenol, elemental metals)
Obtain oxygen saturation if pulmonary injury is suspected
Monitor ECG in any patient with burns of large extent, especially those posing higher risk for cardiac system complications
Monitor ECG in patient with high-risk hydrofluoric acid exposure:
- More than 5% of total BSA
- More than 50% acid concentration
- Prolonged exposure
- Associated inhalation or ingestion
Obtain chest radiograph for suspected inhalation or aspiration injuries
There are no specific recommendations for laboratory studies generalizable to all chemical burns
- Basic metabolic profile, CBC, and urinalysis may be helpful to obtain as baseline in patients with moderate or severe burns who will be admitted
- Specific exposures where there is a risk of systemic absorption and toxicity may require laboratory testing (eg, hydrofluoric acid, petroleum distillates)

Laboratory

Electrolyte, BUN, creatinine, bicarbonate, and glucose levels
- Mild burns (first-degree)
  - Consultation with a medical toxicologist is recommended
- Moderate to severe burns
- Patients with extensive exposures (including those with associated inhalation or ingestion) to any chemical agent known to cause systemic toxicity, including electrolyte abnormality, metabolic acidosis or alkalosis, or renal dysfunction
- Patients with high-risk hydrofluoric acid burns, including:
  - Large burns (exposure more than 5% of total BSA)
  - More than 50% acid concentration
  - Inhalation or ingestion exposure
  - Prolonged duration of exposure
Serum free calcium level
- Patients with high-risk hydrofluoric acid burn (follow serially), including:
  - Large burns (exposure more than 5% of total BSA)
  - More than 50% acid concentration
  - Inhalation or ingestion exposure
  - Prolonged duration of acid exposure

Imaging

Chest radiography
- Obtain for patients with symptoms suggesting chemical aspiration, chemical inhalation, or smoke inhalation

Differential Diagnosis

Chemical burns typically result from an observed event; thus, other causes can often be ruled out according to history

However, injuries caused by hydrofluoric acid and some agents used in warfare may develop over the course of several hours or days, so cause may be unsuspected

Most common

Thermal and electrical burns (Related: Thermal Burns)
- Characterized by erythema, blistering, eschar, or charred tissue at contact site, with involvement of deeper tissue layers in higher-degree burns
  - Whereas most of these signs can be observed both in chemical burns and in thermal or electrical burns, chemical burns do not cause charring of cutaneous tissues or clothing
  - Traces of causative agent on skin suggest a chemical burn (eg, powder, film)
- Exposure history is key to diagnosis

Treatment Goals

Initial goals in emergency department
- Reduce concentration of and limit duration of exposure to causative agent by irrigation
- Relieve pain
- Monitor for and manage early systemic complications
Goals after initial care
- Prevent infection
- Promote healing

Disposition

Admission criteria

Most patients with minor exposure can be treated as outpatients

Admit all patients with moderate to severe burns

Patients with moderate burns should be managed as inpatients, but transfer to a burn unit is not necessary in most cases
- Partial-thickness burns on 5% to 10% of total BSA in patients younger than 10 years or older than 50 years
- Partial-thickness burns on 10% to 20% of total BSA in patients 10 to 50 years of age
- Full-thickness burns on 2% to 5% of total BSA in patients of all ages
- Burns of face, hands, feet, genitals, perineum, or across major joints
- Suspected inhalation injury, circumferential burn, or comorbid conditions predisposing patient to complications (eg, diabetes)

Patients with major burns should be transferred to a burn center

Partial-thickness burns on more than 10% of total BSA in patients younger than 10 years or older than 50 years
Partial-thickness burns on more than 20% of total BSA in patients aged 10 to 50 years
Full-thickness burns on more than 5% of total BSA in patients of all ages
Known inhalation injury
Any significant burn to face, eyes, ears, hands, feet, genitalia, or joints; significant associated injuries (eg, fracture, other major trauma)

Criteria for ICU admission

In accordance with general recommendations for ICU admission, patients are admitted when at risk for severe systemic toxicity, including significant electrolyte abnormalities, ECG changes, or anticipated or present organ failure

Recommendations for specialist referral

Consult a medical toxicologist for any question of expected toxic effects or for any patient with symptoms or signs of systemic toxicity
Consult a verified burn center for all moderate to severe chemical burns; management should be discussed even when burns are not severe enough to warrant immediate transfer
In the United States, public resources can assist with treatment recommendations based on specific chemical agent involved:
- Regional poison control center
- Online Toxic Substances Portal, by the Agency for Toxic Substances and Disease Registry, may be used to identify specific treatments beyond simple irrigation of burn sites
Consult ophthalmologist immediately for any patient with a chemical burn injury at or near the eye, particularly after injury with an alkaline agent
Consult pulmonologist for any patient with symptoms suggesting inhalation of a caustic agent or with suspected smoke inhalation
Consult plastic surgeon for evaluation of burns to face and neck
For burns extensive enough to require transfer to burn center, multidisciplinary teams (including wound care specialists) manage patients as necessary after primary assessment

Treatment Options

Wear protective equipment and maintain universal precautions to prevent exposure to burn agent or any transmissible infection

Paper gowns may not be protective

High-priority prehospital treatment of chemical burns includes rapid removal of burn agent by direct removal of any visible dry residue and copious irrigation of liquid exposures

Remove all clothing that has been in contact with caustic agent
Brush or pick off visible chemical residue with tissues (for elemental metals, this is primary treatment)
Dilute chemical agent by copious rinsing or irrigation with water (for all agents except those for which irrigation would cause significant exothermic reaction, conversion to toxic alkali, or similar counterproductive reaction)
- Use showers or eyewash stations if available, making sure that the material that is rinsed off drains away from body
- An alternative workplace irrigating solution for skin and eyes may be available outside the United States (marketed in a proprietary device as Diphoterine); this solution is amphoteric (has both acid and base properties) with chelating ability and should be used if available. Another proprietary product, Hexafluorine, is similar and is effective for hydrofluoric acid burns
- Rinse with copious amounts of water during transport to hospital (unless known chemical for which water is contraindicated)
- For eye injuries, rinse with normal saline if available, rather than water, and continue irrigation from the scene to the emergency department; this is essential to minimize tissue damage. Rinse with water if saline is not available
Contraindications for water irrigation
- Calcium oxide (dry lime)
- Phenol (use polyethylene glycol [ie, macrogol])
- Elemental metals of periodic groups 1 and 2 (eg, sodium, potassium, magnesium, lithium, cesium)
- White phosphorus
- Titanium tetrachloride

Initial hospital treatment of chemical burns includes removal of any visible dried residue (if not already performed) and continued copious irrigation with water (or saline for eyes)

Ensure that the patient has undergone decontamination for an appropriate length of time based on recommendations in the material safety data sheet, or for at least 20 minutes or until the burning process has stopped
Consult a medical toxicologist for any question of expected toxic effects and for any patient with symptoms or signs of systemic toxicity
Contact a verified burn center to discuss patients with moderate to severe chemical burns; some patients will require transfer, and some chemical burns require additional specific treatment during or after irrigation
Patients with more extensive burns may also require airway management (including intubation if indicated), fluid resuscitation and monitoring of fluid status, and pain control
- Manage airway
  - If any concerns about airway exist, intubate earlier rather than when decompensation happens
    - Endotracheally intubate all patients with deep burns on more than 35% to 40% of total BSA
    - Intubate if patient requires prolonged transport and if there is concern for potential airway obstruction
    - Extensive chemical burns of face, mouth, or other portions of airway may lead to massive edema, and obstruction may result from upper airway swelling
      - Signs of obstruction include hoarseness, change in voice, use of accessory respiratory muscles, and high anxiety
- For severe burns on more than 20% of total BSA in adults or more than 10% in children, begin fluid resuscitation with IV lactated Ringer solution; goal is to stabilize clinical status
- Follow Advanced Burn Life Support protocols (and follow Advanced Trauma Life Support guidelines for associated traumatic injuries)
Treat the chemical burn (administer opioids for pain relief if needed)
- Dilute concentration of chemical in burned tissue by prolonged irrigation (this should be repeated, even if done in prehospital setting); dilution is the most important aspect of treatment
  - Exceptions (do not irrigate):
    - For exposure to elemental metals of periodic groups 1 and 2 (eg, sodium, potassium, magnesium, lithium, cesium): remove solid residue by brushing, picking off with gauze, or scraping off with razor
      - Do not irrigate; irrigation would cause exothermic reaction and conversion to toxic alkali
      - Contact poison control center for disposal instructions
  - Exceptions (irrigate, then interrupt irrigation to apply another agent before resuming irrigation):
    - Phenol cutaneous burns: wipe skin with sponges soaked in 50% polyethylene glycol (macrogol) before continuing irrigation with water (phenol is water insoluble)
    - Chromic acid cutaneous burns: treat with phosphate buffer soaks
    - Calcium oxide (dry lime)
    - White phosphorus cutaneous burns
      - Continue irrigation with cool water to keep burn wet (if it dries, it will oxidize and may spontaneously ignite), but remove all macroscopic clusters of phosphorus in contact with patient. Visualization of these clusters may be aided by:
        Use of Woods lamp (UV light)
        Application of 0.5% copper sulfate solution (to turn the particles black)
    - Titanium tetrachloride
  - Additional guidance for cutaneous chemical burn irrigation
    - Unroof all blisters to remove blister fluid that may contain chemical; brush off any remaining chemical powder or residue
    - Irrigate cutaneous burns with water continuously for at least 20 to 30 minutes and for up to 2 hours (possibly longer for alkalies) or until patient’s pain has decreased and runoff is at appropriate pH
    - In large burns, prolonged lavage may cause hypothermia, particularly in children; water should be at room temperature
  - Additional guidance for ocular chemical burn irrigation
    - Irrigate ocular surface for at least 30 minutes using 1 to 3 L of fluid
      - Check pH of ocular surface every 15 to 20 minutes
      - Goal is pH of 7
    - Irrigating solutions include water, normal saline, Ringer lactate, phosphate buffer, and several proprietary products (Diphoterine or Cederroth eye wash); the choice of fluid is less important than the rapid start of irrigation
    - Perform irrigation by placing catheters in medial sulcus; this allows for prolonged irrigation without runoff of solution into opposite eye
      - Alternatively, an irrigating contact lens may be fitted over the globe. Use extreme caution when employing this irrigating modality to prevent additional injury to eye
    - After irrigation, evert the lids and perform comprehensive examination of eye to determine extent of injury and ensure that no particulate matter remains
- Administer additional treatment for specific chemical burns
  - Treatment for hydrofluoric acid burns
    - Hydrofluoric acid penetrates easily to deep tissues, where free fluoride ions cause liquefactive necrosis and chelation of intracellular calcium and magnesium with irreversible damage; immediate burn center consultation is required
    - Be alert to signs or symptoms of hypocalcemia due to systemic toxicity
      - Systemic toxicity unlikely in small burns from less than 20% acid concentration; risk is increased with any of the following factors:
        Large burns (exposure more than 5% of total BSA)
        Burns caused by acid concentration of more than 50%
        Inhalation or ingestion
        Increased duration of acid exposure
      - For patients with these risk factors, begin cardiac monitoring on arrival and place an IV catheter in anticipation of treatment with IV calcium gluconate infusion for systemic hypocalcemia
        Monitor serum calcium level and ECG (prolongation of QTc interval) for signs of hypocalcemia
        Administer IV calcium gluconate for systemic hypocalcemia
        Hypomagnesemia and hyperkalemia may also occur
      - Some dermal burns may require additional treatment with topical calcium gluconate gel, intradermal calcium, or intra-arterial calcium; consult a medical toxicologist for all high-risk hydrofluoric acid exposures
General chemical burn treatment after irrigation is complete:
- Give tetanus vaccine if indicated
- Irrigation is generally considered adequate for cleansing of burn, except in cases of dirty or contaminated-appearing wound
- Keep burned part elevated if possible (especially hands, feet, and face) to prevent edema
- For patients who meet burn unit referral criteria:
  - If anticipating early transfer (ie, within first 24 hours) to a burn center, there is no need to debride or to apply topical antibiotic to the burn before transfer
    - Apply a clean, dry cover to the burn
    - Keep patient warm with blankets
  - If transfer is delayed, discuss management with physician who will accept the patient at a burn center
- For patients who will not be transferred to a burn center, care for cutaneous burns according to general recommendations for thermal burns, based on depth of burn (Related: Thermal Burns)
- Care of ocular burns should be directed by an ophthalmologist or burn specialist
  - Initial surgical management includes debridement of necrotic material by an ophthalmologist
  - Ophthalmic antibiotic drops or ointments (without steroids initially) are usually indicated if there is corneal injury; ophthalmologist should be consulted
  - Ongoing burn care will be determined by an ophthalmologist in inpatient setting or in outpatient setting with close follow-up
    - Roper-Hall grade III and IV burns may be treated with a variety of procedures, including keratoplasty, limbal stem cell transplant, amniotic membrane transplantation, and correction of eyelid abnormalities

Nondrug and supportive care

Procedures

Wound care

General explanation

Blister care, debridement of wound, and choice of dressing are according to general recommendations for thermal burns (Related: Thermal Burns)

Comorbidities

Chemical burns can be the result of explosions and coexist with thermal burns or other injuries, including bone fractures
- Advanced Trauma Life Support protocol is prioritized over wound care
Acute inhalation or aspiration injury
- Supplemental oxygen, airway management, and lung-protective ventilation are necessary

Special populations

Infants and children
- Thinner dermis layer; therefore, exposure causes deeper injuries than in adults
- Higher surface area to body weight ratio than in adults, so fluid losses are proportionately higher in children than in adults; monitor fluid status carefully and in consultation with a burn center
- High risk of hypothermia owing to high surface area to volume ratio and low fat mass
- Thrashing, resisting care, and dislodging equipment (eg, catheters) may indicate pain
- Consider potential child abuse

Monitoring

Monitoring is generally not required with minor exposures; any systemic signs should be monitored frequently with cardiac monitoring and laboratory testing, depending on agent involved (eg, hydrofluoric acid, chromic acid, phenol, petroleum products, white phosphorus)

Complications

Acute systemic toxicity is uncommon with most small chemical burns, but it may be anticipated with some chemical agents and larger burns
- Hypocalcemia
  - More than 5% of total BSA
  - More than 50% acid concentration
  - Prolonged exposure
  - Associated inhalation or ingestion
- Many chemical exposures can result in renal dysfunction or failure (eg, with chromic acid, phenol, formic acid, or petroleum products) (Related: Acute Kidney Injury)
Burn shock ²
- Severe burns on more than 20% of total BSA can cause dehydration owing to increased capillary permeability and water evaporation through wounds
- Extensive edema and fluid loss from damaged blood vessels into the burned tissue lead to rapid hypovolemia
- Manifests as reduced cardiac output, loss of consciousness, and cardiac arrest
Hypothermia
- Large-extent burns lead to hypothermia through extensive fluid evaporation
- Extensive irrigation of large chemical burns with cold water can rapidly cause hypothermia, particularly in children
Wound infection
- Most common infecting organisms are Streptococcus species and Pseudomonas aeruginosa
- Treat with systemic antibiotics based on results of wound cultures
Scarring

Prognosis

Prognosis depends on severity of injury, causative agent, and patient age
High-grade (Roper-Hall grades III and IV) ocular burns can result in opacification of cornea and complete loss of vision
Chemical burns account for up to 30% of burn deaths

Prevention

Occupational exposure
- Users should wear protective gear when handling potentially caustic agents
- Users should read instructions and material safety data sheets before handling caustic substances
- Industrial work sites where hazardous chemicals are in use must follow the Occupational Safety and Health Administration requirements:
  - Chemical manufacturers and importers are required to prepare labels and material safety data sheets to convey the hazard information to their downstream customers
  - All employers with hazardous chemicals in their workplaces must have labels and material safety data sheets for their exposed workers and must train workers to handle chemicals appropriately
  - Training for employees must also include information on chemical hazards in their work areas and measures to protect themselves
Home exposure
- Store chemicals in secure cabinet
- Avoid direct contact with caustic agents

Sources

Robinson EP et al: Hand chemical burns. J Hand Surg Am. 40(3):605-12; quiz 613, 2015

Reference