Inhalation Injuries

Apologies regarding the delay in bringing you this post... Hope you've missed us! Today we address inhalation injuries in the Emergency Room setting.

Inhalation injury is a nonspecific term that refers to damage to the respiratory tract or lung tissue from heat, smoke, or chemical irritants carried into the airway during inspiration. Respiratory damage is related to the concentration of the gas and its solubility. More water-soluble gases (e.g., chlorine, ammonia, sulfur dioxide, hydrogen chloride) dissolve in the upper airway and immediately cause mucous membrane irritation, which may alert people to the need to escape the exposure. Permanent damage to the upper respiratory tract, distal airways, and lung parenchyma occurs only if escape from the gas source is impeded. Less soluble gases (e.g., nitrogen dioxide, phosgene, ozone) may not dissolve until they are well into the respiratory tract, often reaching the lower airways. These agents are less likely to cause early warning signs (phosgene in low concentrations has a pleasant odor), are more likely to cause severe bronchiolitis, and often have a lag of ≥ 12 h before symptoms of pulmonary edema develop.

Symptoms and signs:

·      Dyspnea

·      Hoarseness, stridor

·      Marked cough, hemoptysis

·      Decreased level of consciousness, confusion

·      Cherry red skin (unreliable, usually a post-mortem finding)

·      Singed nasal hairs, soot on oral/nasal membranes, sooty sputum

·      PO2 normal but O2 saturation low suggests carbon-monoxide poisoning

Investigations:

·      Co-oximetry (Carboxyhemaglobin levels)

·      ABG

·      CXR

·      Bronchoscopy

Possible causes:

·      Direct thermal injury to upper airways

·      Smoke inhalation, leading to bronchospasm and edema

·      Carbon-monoxide or cyanide poisoning

Management:

·      Secure airway (early intubation in direct thermal injuries)

·      Humidified oxygen

·      Bronchodilators

·      Pulmonary toilet (removal of secretions)

·      Hyperbaric oxygen chamber or 100% O2 in carbon-monoxide poisoning

The most serious immediate complication is acute respiratory distress syndrome (ARDS), which usually occurs within 24 h. Patients with significant lower airway involvement may develop bacterial infection. Ten to 14 days after acute exposure to some agents (e.g., ammonia, nitrogen oxides, sulfur dioxide, mercury), some patients develop bronchiolitis obliterans progressing to ARDS. Bronchiolitis obliterans with organized pneumonia can ensue when granulation tissue accumulates in the terminal airways and alveolar ducts during the body’s reparative process. A minority of these patients develops late pulmonary fibrosis.

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