SOURCE: Muo IM, et al. Carbon monoxide poisoning: Safety tips for practitioners in the long-term care setting. Ann Long-Term Care 2015;23:35-38.

The signs of carbon monoxide toxicity (CMT) may be subtle and easily mistaken for other disorders, simply because clinicians may not think of it. Symptoms such as change in mental status, chest pain, dizziness, headache, nausea, seizure, and syncope do not necessarily bring CMT to front-of-mind status. Most episodes of CMT occur in colder climates during winter, but CMT can occur in any environment, at any time of year.

Typical presentations of CMT include sinus tachycardia, tachypnea, and focal neurologic deficits. Since pulse oximeters do not detect carboxyhemoglobin levels, pulse oximetry is usually normal. Because the affinity of carbon monoxide (CM) for hemoglobin is several hundred-fold greater than oxygen, once carbon monoxide has bound to hemoglobin, oxygen binding is markedly reduced and tissue hypoxia ensues. Acute MI, angina, and heart failure may all represent CMT. Chronic CMT can lead to neurologic damage, including Parkinsonism and frontal lobe dysfunction, sometimes presaged by admission for altered mental status.

Hyperbaric oxygen treatment is generally considered the optimum treatment resource for CMT, although a Cochrane review did not confirm the superiority of hyperbaric oxygen over treatment with normobaric oxygen. When clinicians encounter syndromes reflecting potential tissue ischemia, CMT should sometimes be among the differential diagnoses. Prompt intervention may prevent important neurologic sequelae.