A patient with renal failure and pulmonary edema presents with hypoxemia; which oxygen delivery device is appropriate?

• A. Nasal cannula
• B. Simple face mask
• C. Non-rebreather mask
• D. Bag-valve mask with reservoir

Answer: (C)

In pulmonary edema with hypoxemia, the goal is to deliver the highest possible oxygen concentration to a patient who is still breathing on their own. The non-rebreather mask provides a reservoir and one-way valves that prevent exhaled air from diluting the inhaled gas, allowing the patient to receive a high FiO2—usually around 80–95% with adequate flow. This makes it the most effective noninvasive option for rapidly increasing oxygen saturation in spontaneously breathing patients.

Nasal cannulas deliver relatively low oxygen concentrations and can be limited by the patient’s breathing pattern. Simple face masks offer more than a nasal cannula but provide variable FiO2 and can be unreliable if the patient breathes through the mouth or if flow isn’t sufficient. A bag-valve mask with reservoir can deliver very high or near 100% FiO2, but it’s designed for ventilation support and requires the patient to be apneic or not breathing effectively, plus it needs a second provider and a tight seal. In a spontaneously breathing patient with hypoxemia from pulmonary edema, starting with a non-rebreather mask is the best initial choice to maximize oxygen delivery while avoiding invasive airway management. If oxygenation remains poor or the patient tires, escalate to noninvasive ventilation or airway control as clinically indicated.