Based on current guidelines, in which of the following situations should supplemental oxygen be administered?

• A. Any elderly patient whose oxygen saturation is less than 95%
• B. Any diabetic patient whose oxygen saturation is less than 98%
• C. Signs of myocardial infarction and an oxygen saturation of 97%
• D. Exposure to carbon monoxide and an oxygen saturation of 95%

Answer: (D)

When carbon monoxide exposure is suspected, give supplemental oxygen right away, even if the SpO2 reading looks reasonable. The reason is that pulse oximetry cannot distinguish carboxyhemoglobin from oxyhemoglobin, so a normal or near-normal reading can hide CO poisoning. Administering high-flow oxygen (usually 100%) helps displace CO from hemoglobin and speeds its elimination, improving oxygen delivery to tissues. Hyperbaric oxygen may be added in severe cases, such as significant neurologic symptoms, pregnancy, or very high CO levels.

In the scenario described, exposure to carbon monoxide with an oxygen saturation of 95% still warrants oxygen therapy because the reading can be falsely reassuring in CO poisoning. The other situations either involve readings that don’t indicate hypoxemia requiring oxygen, or lack a CO-specific indication for immediate high-flow oxygen.