Blood carboxyhaemoglobin and cyanide levels in fire survivors.

Blood carboxyhaemoglobin and cyanide concentrations were measured in 53 fire survivors, 36 of whom had clinical evidence of smoke inhalation. Carboxyhaemoglobin and cyanide levels were raised only in patients with smoke inhalation. Blood carboxyhaemoglobin measurement can be used to confirm the diagnosis of severe smoke inhalation in cases in which the clinical data are inconclusive, provided that the time of sampling after exposure is taken into account. A nomogram has been constructed for this purpose. There is no quick method of measuring blood cyanide levels, but the close relation between cyanide and carboxyhaemoglobin levels suggests that carboxyhaemoglobin concentrations, which can be rapidly and easily measured, could be used to identify those who might benefit from treatment with cyanide antidotes.