Smoke inhalation injury

Background

• Main cause of mortality in fire-related death
• Associated with closed-space fires, especially when patient has decreased mental status (e.g. substance use, head injury)
• Thermal injury:
  • Due to inhaling superheated gases in an enclosed space
  • Direct thermal trauma and associated edema usually limited to upper airway, but lower respiratory tract may be injured if steam inhaled
• Chemical injury:
  • Direct toxicity to airways and lung parenchyma from noxious chemicals combusted

Clinical Features

Thermal injury

• Soot around nares or in mouth
• Carbonaceous sputum
• Singed nasal or facial hair
• Dyspnea, stridor, drooling, dysphonia, respiratory distress

Chemical injury

Varies depending on substance burned in fire

• Acrolein: found in wood and petroleum
  • Pulmonary edema, bronchorrhea, bronchospasm, VQ mismatch which can cause hypoxemia
  • Tearing, conjunctivitis
• Hydrochloric acid: product of polyvinyl chloride (structural component of high-rise buildings, plastics) combustion.
  • Can persist in air up to an hour after fire extinguished
  • PVCs and other arrhythmias
  • Delayed onset (2-12 hours) pulmonary edema
  • Dyspnea, chest pain
• Tuolene diisocyanate: seat cushions, carpet, insulation
  • Severe bronchospasm
• Nitrogen dioxide: fires involving automobiles, agrecultural waste
  • Uncommon but brief exposure can be lethal
  • Severe bronchospasm, laryngospasm, pulmonary edema
  • Later: interstitial lung disease

Systemic chemical injury

• Carbon monoxide toxicity
• Cyanide toxicity

Differential Diagnosis

Burns

• Smoke inhalation injury (airway compromise)
• Chemical injury
  • Acrolein
  • Hydrochloric acid
  • Tuolene diisocyanate
  • Nitrogen dioxide
• Systemic chemical injury
  • Carbon monoxide toxicity
  • Cyanide toxicity
• Specific types of burns
  • Caustic burns
    • Airbag-related burns
    • Tar burn
    • Cement burn
  • Electrical injuries
    • Lightning Injuries
• Associated toxicities
  • Carbon monoxide toxicity
  • Cyanide toxicity
  • Hydrogen fluoride toxicity

Inhalation injury

Unintentional

• Smoke inhalation injury
  • Cyanide
  • Carbon monoxide
• Chloramine
• Hydrocarbons
• Sewer gas
  • Hydrogen Sulfide
  • Ammonia toxicity
  • Methane
  • Carbon monoxide
• Hydrazine toxicity
• Nitrogen tetroxide

Terrorism

• Pulmonary chemical agents
  • Ammonia
  • Methyl isocyanate
  • methyl bromide
  • Hydrochloric acid
  • Chlorine
  • Phosgene
• Bioterrorism
  • Anthrax
  • Smallpox
  • Plague
  • Tularemia
  • Botulinum toxin
  • Viral hemorrhagic fever
  • Ricin

Toxic gas exposure

• Carbon monoxide toxicity
• Chemical weapons
• Cyanide toxicity
• Hydrocarbon toxicity
• Hydrogen sulfide toxicity
• Inhalant abuse
• Methane toxicity
• Smoke inhalation injury
• Ethylene dibromide toxicity

Evaluation

• Assess ABCs, burns resuscitation
• ABG or VBG, carboxyhemoglobin
• ECG, monitor on telemetry
• Chest x-ray
• Low threshold for direct or video laryngoscopy, fiberoptic airway eval

Management

AIRWAY

• Intubate if:
  • Respiratory distress, respiratory depression, or altered mental status
  • Progressive hoarseness
  • Supraglottic or laryngeal edema/inflammation on bronchoscopy or NPL
  • Full thickness burns to face or perioral region
  • Circumferential neck burns
  • Major burns over 40-60% of body surface area

Remember, the intubation will only get more difficult as edema worsens!

• Bronchodilators if evidence of bronchospasm
• See Carbon monoxide toxicity
• See Cyanide toxicity

Disposition

• Respiratory distress or airway compromise will need admission
• Observe for 1-4 hours if no signs or symptoms of inhalation injury develop or if all resolved within 1 hour consider discharging patient home with instructions for return for re-evaluation next day or sooner if pulmonary and/or airway symptoms develop

See Also

• Inhalation injury
• Burns
  • Carbon monoxide toxicity
  • Cyanide toxicity
• Intubation