Pulmonary chemical agents

Background

Pathophysiology

  • Choking agents combine with water in respiratory tract to form acids
  • Both chlorine and phosgene react with water in respiratory tract to form hydrochloric acid

Clinical Features

Symptoms dependent on the water solubility of the chemical

  • Highly water-soluble
    • Anhydrous, ammonia, Hydrogen chloride, Sulfur dioxide, Formaldehyde
    • Rapidly react with water causing damage to upper airway to vocal cords
    • Direct tissue damage causing bronchiolar/alveolar edema/airway obstruction and laryngospasm
    • Nasopharyngeal and tracheal chemical burns, upper airway obstruction
    • Laryngospasm (can occur immediately upon exposure)
    • Respiratory distress/failure, hypoxia
    • Cough
    • Chest pain
    • Arrhythmias (hydrochloric acid)
  • Moderately water-soluble
    • Damage to moderate-sized airways (bronchioles)
    • Bronchospasm and wheezing
  • Poorly water-soluble
    • Phosgene, Nitrogen dioxide
    • Inhaled deeply into alveoli
    • Lack of irritation of mucous membranes can cause them to go undetected
    • Respiratory distress, tachypnea, cough, pulmonary edema

Differential Diagnosis

Chemical weapons

Management

  • Decontaminate patient!
    • Liquid phosgene can cause off-gassing with release of toxin from clothes post-exposure
  • Do not allow patient to be active as it worsens condition
  • Inhaled beta agonists for bronchoconstriction
  • Diuretics and corticosteroids not shown to be effective

See Also

References

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