Inhalation injury

Background

• Inhalational injury a concern with history of being trapped in enclosed space for some time with toxic gases / fumes

Clinical Features

General

• Initial signs/symptoms - cough, wheezing, dyspnea, irritated mucous members (runny eyes/nose), chest pain, hypoxia
• Specific features dependent on type of exposure

Inert Gases

• Inert gases (carbon dioxide, fuel gases) displace air and oxygen producing asphyxia
• Present with severe hypoxia

Irritant Gases

• Irritant gases (ammonia, formaldehyde, chlorine, nitrogen dioxide) when dissolved in water lining respiratory tract produce a chemical burn and inflammatory response
• More soluble the gas produces more upper airway burns/irritation symptoms
• Less soluble gases produce more pulmonary injury and respiratory distress

Systemic Toxins

• Includes carbon monoxide, hydrogen cyanide, hydrogen sulfide
• Interfere with delivery of oxygen for use in cellular energy production
• Liver, kidney, brain, lung and other organ damage

Allergic

• Inhaled gases, particles, aerosols
• Produce bronchospasms and edema similar to asthma

Smoke Inhalation / Thermal

• Most fatalities from burn injuries are attributed to smoke inhalation
• Soot in posterior pharynx, singed nasal hair
• Hyperacute - severe wheezing, bronchoconstriction, significant hypoxemia
• Acute pulmonary edema - onset at 48-72 hours post injury in a previously asymptomatic patient
• Bronchopneumonia often at 10 days post-injury

Differential Diagnosis

Inhalation injury

Unintentional

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

Terrorism

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

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

Toxic gas exposure

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

Evaluation

• Look for evidence of exposure
  • Estimated time of exposure
  • Open or enclosed space
  • Associated events such as fire, blast, etc.?
  • Is the exposure known?
  • Material on patient? Does patient smell of chemical?

Examples - smoke inhalation from burning building, leak of a solvent, chemical fumes

• Physical examination with focus on airway and pulmonary system
• Observe for evidence of airway compromise or respiratory distress
• Chest x-ray, pulse oximetry, arterial blood gas
• Consider carboxyhemoglobin and/or cyanide level if any suspicion based on history

Management

General

• Separate patient from fumes/toxic agent
• Decontaminate if not done on scene
• Secure airway if necessary and ventilate, observe for respiratory distress and airway compromise
• Oxygen at 6-12 liters per minute via mask

Inert Gases

• Remove victim from the gas
• Fresh air or oxygen
• Observe for sequelae from hypoxia (myocardial infarction, cerebral injury)

Allergic

• Aerosolized bronchodilators
• Corticosteroids in patients with history of reactive airway disease

Smoke Inhalation / Thermals

• Ensure adequate oxygenation, ventilation, pulmonary toilet and fluid resuscitation

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

• Smoke inhalation injury
• Inhalant abuse
• Burns