In carbon monoxide poisoning, when should hyperbaric oxygen be considered?

• A. Hyperbaric oxygen should be considered in severe cases.
• B. Hyperbaric oxygen is first-line for all cases.
• C. Hyperbaric oxygen is never used.
• D. Hyperbaric oxygen should be used only after 24 hours.

Answer: (A)

Hyperbaric oxygen is reserved for more severe carbon monoxide poisoning. In severe cases—such as when there is loss of consciousness, neurologic symptoms, myocardial ischemia, significant acidosis, or fetal distress in pregnancy—HBOT can speed up removal of CO from hemoglobin and improve tissue oxygen delivery, which may reduce the risk of delayed neurological sequelae and cardiac injury. For mild cases, standard 100% oxygen by a nonrebreather is typically enough, and HBOT isn’t routinely required due to limited availability and potential risks. It isn’t a blanket rule to use only after 24 hours, and it isn’t never used; it’s specifically indicated for severe presentations or high-risk situations.