Particulate matter of smoke inhalation.

Smoke inhalational injury is a common event, which often complicates cutaneous burns, markedly increasing mortality, especially when it is associated with facial burning. The primary source of injury in the upper respiratory tract is heat, but thermal injury does not usually extend beyond the bifurcation of the trachea. Within the lung, it is the deposition of particles, derived from the substrate burnt, together with the toxic gases given off which causes the injury. The way in which the injuries are caused is not completely understood, but it appears to be a direct response to the stimulation of the inflammatory response. This seems to give rise to a feedback mechanism. The continued presence of particulate matter may lead to continuing damage and thus to impaired respiratory function in survivors. The nature of the particulate matter, like the toxic fumes given off, reflects the chemical nature of the substances burnt, and is not as is commonly assumed, merely carbon.