Pulmonary chemical agents: Difference between revisions

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*Symptoms may take 2-24 hours to develop
*Symptoms may take 2-24 hours to develop


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

Revision as of 19:34, 8 July 2016

Background

  • Ammonia, methyl isocyanate, methyl bromide, hydrochloric acid and chlorine, phosgene
  • Common toxic industrial chemicals, transported widely across country
  • Can affect central or peripheral airways
    • burning and irritation to epithelial lining causing airway edema or pulmonary edema, hypoxia, and hypotension

Chlorine

  • Smells of a swimming pool or bleach
  • Most common exposure is secondary to mixing household cleaners
  • Irritation of conjunctivae, nose, pharynx, larynx, trachea, and bronchi
  • Individuals with gas exposure may not need decon, if skin symptoms absent
  • Rare ocular injury as tears protect mucous membranes from direct damage

Phosgene

  • Smell of freshly cut hay or grass
  • Not to be confused with phosgene oxide (vesicant)
  • Denser than air, settles in low-lying places – trenches/basements
  • Rapid olfactory fatigue can occur leading to prolonged exposure
  • Exposure may be secondary to fire at textile factory/house, metalwork, or burning Freon
  • Symptoms dependent on concentration
    • Low: mild cough, chest tightness, shortness of breath
    • Moderate: Lacrimation
    • High: Non-cardiogenic pulmonary edema within 2 to 6 hours after exposure with death within 24-48 hours
  • Symptoms may take 2-24 hours to develop

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 edema/airway obstruction and laryngospasm
  • 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

Differential Diagnosis

Chemical weapons

Workup

Management

  • 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
  • Diuretics and corticosteroids not shown to be effective
  • Inhaled beta agonists for bronchoconstriction

Disposition

See Also

External Links

References