What is a key consideration when administering oxygen to a patient with suspected carbon monoxide poisoning?

• A. Use a nasal cannula at 2 L/min to avoid oxygen toxicity.
• B. Administer room air with no supplemental oxygen.
• C. Provide 100% oxygen to displace CO and speed elimination; consider hyperbaric therapy if indicated.
• D. Use low-flow oxygen via mask at 6 L/min.

Answer: (C)

When carbon monoxide poisoning is suspected, the priority is to maximize oxygen delivery and rapidly outcompete CO for binding to hemoglobin. CO binds hemoglobin with a much higher affinity than oxygen, so even with normal air, tissues can remain hypoxic. Providing 100% oxygen raises the partial pressure of oxygen in the blood and increases the amount dissolved in plasma, which displaces CO from hemoglobin more quickly and speeds its elimination from the body. This is why the recommended treatment is to deliver high-flow, 100% oxygen right away.

In practice, that means delivering oxygen with a high-flow system (such as a non-rebreather mask at high rate, or a bag-valve mask with 100% O2) rather than relying on room air or low-flow methods. Room air or low-flow oxygen would not effectively displace CO or substantially improve tissue oxygenation.

Hyperbaric oxygen therapy is considered if there are signs of significant poisoning or specific risk factors—such as neurologic symptoms (confusion, seizures, loss of consciousness), metabolic acidosis, pregnancy, or very high CO exposure—because the elevated pressure further accelerates CO elimination and can improve neurologic outcomes.