Rosen & Barkin's 5-Minute Emergency Medicine Consult (403 page)

CODES

• 780.91 Fussy infant (baby)
  
• 780.92 Excessive crying of infant (baby)
  
• 789.7 Colic
  

BASICS

• An irritant is any noncorrosive substance that on immediate, prolonged, or repeated contact with respiratory mucosa will induce a local inflammatory reaction.
  
• Respiratory irritants are inhaled as gases, fumes, particles, or liquid aerosols.
  
• Inhaled irritants:
  
  • Pulmonary toxicity is determined primarily by their water solubility.
    
• Inhalation accidents frequently involve a mixture of irritant gases as well as chemical asphyxiants:
  
  • Carbon monoxide
    
  • Hydrogen cyanide
    
  • Hydrogen sulfide
    
  • Oxides of nitrogen
    
• Risk factors include exposure to potential irritants:
  
  • Occupational
    
  • Leisure
    
  • Intentional
    
  • Accidental
    
• Pathophysiology:
  
  • Cellular injury through interaction with respiratory mucosal water with subsequent formation of acids, alkalis, and free radicals
    

• Settings:
  
  • Industrial: Chemical manufacturing, mining, plastics, and petroleum industries
    
  • Home: Improper use or storage of cleaning chemicals
    
  • Fires: Combustion yields toxic gases.
    
  • Civil Disturbance: Riot control agents.
    
• Immediate onset
  of upper airway inflammation with highly water-soluble irritant gases or with aerodynamic diameter >5 mm:
  
  • Ammonia (fertilizers, refrigerants, dyes, plastics, synthetic fibers, cleaning agents):
    
    • Immediate symptoms range from mild edema and erythema to full-thickness burns and airway obstruction.
      
  • Sulfur dioxide (fumigants used on produce, bleaching, tanning, brewing, wine making, combustion of coal, and smelting of sulfide-containing ores):
    
    • Combines with water, forming sulfuric acid.
      
  • Hydrogen chloride (formed during combustion of chlorinated hydrocarbons such as polyvinyl chloride):
    
    • Combines with water, forming hydrochloric acid.
      
  • Chloramine (generated when ammonia and bleach are mixed):
    
    • When exposed to moist surfaces, releases hypochlorous acid.
      
  • Acrolein (production of plastics, pharmaceuticals, synthetic fibers; formed during combustion of petroleum products, cellulose, wood, paper):
    
    • May cause protein damage via free radical production and sulfhydryl binding.
      
  • Formaldehyde (production of plywood, particle board, insulation; combustion product of gas stoves and heaters):
    
    • Combines with water to form sulfuric acid and formic acid.
      
  • Hydrogen fluoride (combustion of fluorinated hydrocarbons):
    
    • Depletes calcium stores, resulting in cell death.
      
  • Riot control agents (Capsaicin [OC], Chlorobenzylidenemalononitrile [CS], and Chloroacetophenone [CN]):
    
    • Lacrimation agents which cause temporary ocular discomfort.
      
• Latent period
  of minutes to hours before onset of symptoms with irritant gases of intermediate water solubility or aerodynamic diameter of 1–5 mm:
  
  • Chlorine (product of chlorinated chemicals; bleaching agent):
    
    • Upper and lower airway damage after reacting with water to form hydrochloric and hypochlorous acids
      
• Delayed onset
  of symptoms up to 24 hr after inhalation with irritant gases of poor water solubility or aerodynamic diameter <1 mm (with little or no warning of exposure):
  
  • Oxides of nitrogen produced:
    
    • In manufacture of dyes and fertilizers
      
    • By electric arc welding and gas blowing
      
    • By fermentation of nitrogen-rich silage (silo-filler’s disease)
      
    • In combustion of nitrocellulose and polyamides
      
  • Phosgene/carbonyl chloride (arc welding and pesticide production: Combustion of chlorinated hydrocarbons and solvents)
    
  • Ozone (produced during arc welding)
    
  • Cadmium oxide (oxyacetylene welding and electroplating)
    

DIAGNOSIS

• Dependent on water solubility
  
• Highly water-soluble gases:
  
  • Eye, nose, throat burning
    
  • Shortness of breath
    
  • Wheezing
    
  • Cough
    
  • Hoarseness
    
  • Stridor
    
  • Obstruction
    
• Intermediate water solubility:
  
  • Upper and lower tract involvement
    
  • Mucosal irritation
    
  • Bronchospasm
    
  • Dyspnea
    
  • Wheezing
    
  • Cough
    
  • Rales
    
  • Possible delayed pulmonary edema
    
• Other:
  
  • Dermal irritation
    
  • Headache
    
  • Nausea
    
  • Vomiting
    
  • Confusion
    
  • Seizures
    
  • Syncope
    

• Known exposures
  
• Type of chemical/industry
  
• Rapidity of symptom
  
• Material safety data sheet from exposure site
  
• Water solubility of agent
  

• HEENT:
  
  • Conjunctival injection
    
  • Lacrimation
    
  • Chemosis
    
• Respiratory
  
• Stridor
  
  • Voice changes
    
  • Dyspnea
    
  • Wheezing
    
  • Cough
    
• GI:
  
  • Vomiting
    
• Dermatologic:
  
  • Skin erythema/irritation
    
  • Erythematous rash
    
• Neurologic:
  
  • Confusion
    
  • Seizure activity
    

History of exposure to irritant gases in addition to noted symptoms confirm diagnosis.

ECG in the following patients:

• Elderly
  
• Cardiac history
  
• Evidence of significant pulmonary symptoms
  

• Arterial blood gas to assess:
  
  • Oxygenation
    
  • Ventilation status
    
  • pH
    
  • Pulse oximetry is unreliable.
    
• Carbon monoxide level:
  
  • If smoke inhalation with concomitant irritant gas inhalation (see “Carbon Monoxide Poisoning”)
    
• Methemoglobin level:
  
  • If oxides of nitrogen are suspected
    
• Serum calcium level:
  
  • If hydrogen fluoride is suspected
    
• Lactate:
  
  • Elevation may indicate cellular poisoning from carbon monoxide or cyanide.
    
• Pregnancy test in all females of childbearing age
  
• Rapid dextrose
  
• Cardiac enzyme levels if acute coronary syndrome suspected
  

CXR:

• Frequently normal on initial presentation
  
• May take up to 24 hr to reveal pulmonary edema or evidence of diffuse injury.
  

• Spirometry:
  
  • Assess evidence suggesting airway narrowing and bronchoconstriction.
    
• Direct laryngoscopy:
  
  • Assess evidence of upper airway edema.
    
• Corneal fluorescein:
  
  • Assess evidence of corneal burns/injury.
    

• Asthma exacerbation
  
• Allergic stimuli (pollen)
  
• Physical stimuli (cold air)
  
• Bronchitis
  
• Pneumonia
  
• Occupational asthma
  
• Hypersensitivity pneumonitis
  
• Congestive heart failure
  

TREATMENT

Rescuer’s goal is to prevent self-contamination with use of protective clothing or equipment (self-contained breathing apparatus).

• ABCs:
  
  • 100% oxygen through a tight-fitting, nonrebreathing face mask
    
  • Early intubation may be necessary to protect airway from edema.
    
  • Mechanical ventilation
    
  • Continuous positive airway pressure or positive end-expiratory pressure may enhance oxygenation.
    
• Decontaminate by removing clothes and irrigating skin and ocular tissues.