Mechanisms of Fire Smoke Toxicity (Carbon Monoxide and Cyanide Excluded)

The main cause of death in a fire is related to inhalation of toxic smoke. The main components in the gas phase are those previously present before the fire and those formed during the fire. During a fire, only the upper part of the flames emits smoke. The nature of the fuel influences the height of the flames, the initial thermokinetic energy, the temperature, the velocity of smoke emission, and the concentration of toxic gas. The chemical composition and the amount of smoke emitted during the fire mainly depend on thermokinetic characteristics. The smoke is composed of soot (particulate phase), toxic gases phase (asphyxiant and irritant), and an aqueous vapor phase. These different phases are responsible for a significant inflammatory response. When people are exposed, two toxidromes are identified: a cellular hypoxic toxidrome either by consumption of oxygen from the ambient air, transport defect of oxygen or by blockage of the mitochondrial respiratory chain (monoxide carbon, essentially cyanides) and the irritant toxidrome (induced by aldehydes, isocyanates, nitrogen compounds, sulfurous compounds, etc.). Irritants exert their deleterious effect on the upper respiratory tract, at the mucociliary escalator level and alveolarcapillary membrane level by complex mechanisms. The clinical signs appear quickly, and persist over a prolonged period of time. The clinical management is symptomatic, combining oxygen, sometimes mechanical ventilation, specific antidote treatment, and beta-2 agonists. Bronchoscopy may be a useful examination for diagnostic or therapeutic purposes. The severity of the lung injury is responsible for prolonged and difficult treatments in intensive care units.