Smoke inhalation is an often lethal injury in house fires and is encountered by trauma surgeons who treat burn patients.
The mortality seen in smoke inhalation patients is sometimes greater than would be expected from the carboxyhemoglobin levels.
This is attributable, in part, to the synergistic effects of the methemoglobin resulting from the cyanide exposure – in addition to the carbon monoxide exposure.
Methemoglobin is not generally cardiovascularly significant at levels of 20 to 40%. However, couple with carboxyhemoglobin, the functional anemia can be life-threatening.
Methemoglobinemia can be treated using hyperbaric oxygen therapy.