Pulmonary Burn

The term "pulmonary burn" is a misnomer. True thermal damage to the lower respiratory tact and pulmonary parenchyma is extremely rare, unless live steam or exploding gases are inhaled.

The air temperature near the ceiling of a burning room may reach 540°C (1000°F) or more, but air has such poor heat-carrying capacity that most of the heat is dissipated in the oropharynx, nasopharynx, and upper airway. Thus the heat dissipation in the upper airway can cause significant thermal injury to the proximal tracheobronchial tree.

Thermal injury to the respiratory tract is usually immediate and manifests as mucosal and submucosal erythema, edema, hemorrhage, and ulceration.124 Thermal injury is usually limited to the upper airway (above the vocal cords) and proximal trachea for two reasons: (1) the oropharynx and nasopharynx provide an effective mechanism for heat exchange because of their relatively large surface area, associated air turbulence, and mucosal fluid lining that acts as a heat reservoir; and (2) sudden exposure to hot air typically triggers reflex closure of the vocal cords, reducing the potential for lower airway injury. Animal models have demonstrated that significant heat exchange also occurs in the subglottic airway between the vocal cords and the tracheal bifurcation, with protection and sparing of the distal airways. Thus the lower tracheobronchial tree is rarely exposed to hot, ambient gas at a fire scene. An exception is the inhalation of super-heated steam, where because of heat dissipation in the respiratory tract as the steam condenses into water, severe injury has been reported in the distal airways with measurable injury in the alveoli. In these patients the lower tracheobronchial tree is rapidly obstructed, and they usually die from untreatable asphyxiation.