What is the action of oxygen when used as a therapy?

• A. It raises the amount of oxygen in the blood and delivered to the tissues
• B. It reduces oxygen delivery to tissues
• C. It increases carbon dioxide in the blood
• D. It has no effect on tissue oxygenation

Answer: (A)

Supplemental oxygen therapy increases the amount of oxygen available in the blood, enhancing delivery to tissues. By raising the arterial oxygen tension (PaO2), it increases the dissolved oxygen in plasma and boosts overall oxygen content (CaO2). This improves the oxygen actually delivered to tissues (DO2), which is especially important when a patient is hypoxemic or challenged by limited oxygen extraction. It won't decrease oxygen delivery, it doesn't raise carbon dioxide levels, and it does affect tissue oxygenation—often making a crucial difference when baseline oxygenation is poor.