Hydrogen fluoride toxicity

Background

• Hydrogen fluoride (HF) is a byproduct of standard fire suppression systems. It is also used as rust remover and in glass etching, metal cleaning, and petroleum processing.
• Oral ingestion has very high mortality rate
• Onset and severity of symptoms correlated with concentration
  • Dilute solutions (<20%) may have delayed onset up to 24hr post-exposure
  • Moderate solutions (20-50%) develop symptoms within 1-8hr
  • Concentrated solutions (>50%) develop symptoms immediately
    • These patients are at highest risk for systemic toxicity/death
    • Pain immediately (even if wound appears minor) implies severe injury
• Burn itself may appear relatively minor
• Toxicity caused by binding of calcium and magnesium leading to electrolyte derangement and myocardial dysfunction

Clinical Features

• Exposure to HF may result in rapidly progressive or fatal respiratory failure despite minimal external evidence of injury.
• Symptoms include shortness of breath, cough, or hypoxia; there must be a high level of suspicion for HF inhalation.

Differential Diagnosis

Burns

• Smoke inhalation injury (airway compromise)
• Chemical injury
  • Acrolein
  • Hydrochloric acid
  • Tuolene diisocyanate
  • Nitrogen dioxide
• Systemic chemical injury
  • Carbon monoxide toxicity
  • Cyanide toxicity
• Specific types of burns
  • Caustic burns
    • Airbag-related burns
    • Tar burn
    • Cement burn
  • Electrical injuries
    • Lightning Injuries
• Associated toxicities
  • Carbon monoxide toxicity
  • Cyanide toxicity
  • Hydrogen fluoride toxicity

Evaluation

• Clinical diagnosis
• Trend calcium, magnesium, and potassium levels
  • Hydrofluoric acid chelates calcium and poisons the Na+/K+ pump
  • Expect hypocalcemia, hypomagnesemia, and hyperkalemia
• Monitor EKG for signs of electrolyte abnormality
  • QTc prolongation
  • Ventricular tachycardia

Management

• Treatment is supportive.
  • If hypocalcemia is present, administer nebulized calcium gluconate (1.5 ml of 10% calcium gluconate in 4.5 ml water) q4hr until normalization of serum calcium levels.
  • In the absence of significant burns, consider steroids if symptoms do not improve.

Complications

• Bronchopneumonia can develop within a week.

See Also

• Burns