A patient suspected of being hypoxic but breathing adequately should be given supplemental oxygen with a:

• A. Nonrebreathing mask
• B. Nasal cannula
• C. Bag-valve mask
• D. Simple face mask

Answer: (A)

When a patient is hypoxic but still breathing on their own, you want to deliver the highest concentration of oxygen safely without starting assisted ventilation. A nonrebreathing mask does that best because it has a reservoir and a one-way valve that prevents exhaled air from diluting the oxygen. With proper flow, it can deliver a very high FiO2 to a spontaneously breathing patient, making it the most effective choice in this scenario.

A nasal cannula is limited in the amount of oxygen it can deliver, topping out around moderate FiO2, which isn’t sufficient for someone who is clearly hypoxic. A simple face mask can provide more oxygen than a nasal cannula but usually not as reliably high as a nonrebreather, and its performance depends on fit and breathing pattern. A bag-valve mask is intended for patients who are not breathing or require assisted ventilation; using it on someone who is breathing adequately can complicate care and is not necessary here.