Carbon monoxide poisoning: pathophysiologic principles underlying good treatment

Oliu G, Nogué S, Miró O

Carbon monoxide (CO) poisoning is the most common form of gas poisoning in Spain.

Most cases are household accidents due to incomplete combustion of gases by room

heaters, water heaters, braziers and similar devices, or the result of smoke inhalation,

where CO and cyanide poisoning account for most deaths. CO toxicity is a result of its

binding to 2 heme molecules. Binding to hemoglobin causes hypoxia, anoxia, and the

majority of acute symptoms. Binding to cytochromes in the mitochondrial respiratory

chain leads to consequent inhibition of respiration at the cellular level, contributing to

the differential signs and symptoms seen in some patients. The most frequent are

headache (96.9%), nausea (66.1%), vomiting (35.8%), unstable gait (32%), loss of

consciousness (29.2%), and tachycardia (20%). Children, pregnant women, the elderly,

and individuals with a history of heart disease are at risk of severe poisoning. A diagnosis

is confirmed by a blood test or pulse oximetry result indicating that CO is bound to

hemoglobin or by the detection of CO in expired air. If CO poisoning is suspected,

further exposure must be prevented by removing the victim from the source of

inhalation, while also protecting rescuers and medical caregivers, and by ventilating the

premises. Oxygen should be administered immediately at a normal pressure and at the

highest concentration possible (through a high-flow mask or at 100% if the patient is

intubated) even before laboratory findings confirm the diagnosis. This review includes a

discussion of the use of hyperbaric oxygen to treat CO poisoning.

Miró O, Nogué S, Oliu G