Oxygen is most commonly administered via which device and flow rate?

• A. Nonrebreathing mask 10-15 L/min
• B. Nasal cannula 2-6 L/min
• C. Simple face mask 6-10 L/min
• D. Venturi mask 4-8 L/min

Answer: (A)

Oxygen delivery effectiveness depends on how much oxygen concentration you can reliably deliver to the patient and how well you can meet their inspiratory flow needs. The nonrebreathing mask with a reservoir and one-way valves is designed to push a high fraction of oxygen toward the patient while minimizing rebreathing of exhaled air. When you set flow at 10–15 L/min and ensure the bag stays inflated, most of what the patient inhales comes from the mask’s oxygen reservoir rather than the room air, yielding a very high FiO2 (typically near 80–95% depending on fit and leakage). This high concentration is often what’s needed quickly in hypoxic or critically ill patients, making it the most commonly used initial device for oxygen therapy in emergency scenarios.

Other devices deliver lower or more variable oxygen concentrations: a nasal cannula provides a modest FiO2 suitable for mild hypoxemia, a simple face mask offers moderate oxygen but less reliable high concentrations, and a Venturi mask can deliver a precise, but lower, FiO2 and is used when specific oxygen levels must be maintained rather than delivering the maximum possible oxygen.