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Pulmonary chemical agents
From WikEM
Contents
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
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
- Blister chemical agents (Vesicants)
- Lewisite (L)
- Sulfur mustard (H)
- Phosgene oxime (CX)
- Pulmonary chemical agents
- Incendiary agents
- Cyanide chemical weapon agents
- Nerve Agents
- Acetylcholinesterase inhibitors
- Includes household and commercial pesticides (diazinon and parathion)
- G-series (sarin, tabun, soman) and V-series (VX)
- V-series high viscosity with oily consistency
Evaluation
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
