Pulmonary chemical agents
Background
- Include ammonia, methyl isocyanate, methyl bromide, hydrochloric acid and chlorine gas, 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 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
- Blister chemical agents (Vesicants)
- Lewisite (L)
- Sulfur mustard (H)
- Phosgene oxime (CX)
- Pulmonary chemical agents (Choking agents)
- Incendiary agents
- Cyanide chemical weapon agents (Blood agents)
- Prussic acid (AKA hydrogen cyanide, hydrocyanic acid, or formonitrile)
- Nerve Agents (organophosphates)
- Acetylcholinesterase inhibitors
- Household and commercial pesticides (diazinon and parathion)
- G-series (sarin, tabun, soman)
- V-series (VX)
- Lacrimating or riot-control agents
- Pepper spray
- Chloroacetophenone
- CS
Evaluation
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