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
- 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
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