A patient who is suspected to be hypoxic but breathing adequately should receive oxygen through which device?

• A. bag-valve mask
• B. nasal cannula
• C. nonrebreathing mask
• D. mouth-to-mask device

Answer: (C)

When someone is hypoxic but still breathing on their own, you want to give the highest possible oxygen concentration without needing to actively ventilate them. A nonrebreathing mask does this best because it has a reservoir and one-way valves that prevent the patient from rebreathing their exhaled air, delivering near-maximal FiO2 with each breath as long as the oxygen flow is adequate. This makes it ideal for spontaneously breathing patients who require high-flow oxygen.

The other options don’t fit as well. A nasal cannula delivers a lower FiO2, which may be insufficient for significant hypoxemia. A mouth-to-mask device is less reliable and typically provides less consistent, lower FiO2. A bag-valve mask can deliver high FiO2 but is intended for patients who need ventilation support; using it while the patient is breathing adequately is less appropriate and risks overventilation.