What is the typical oxygen flow rate for a nonrebreather mask?

• A. 12-15 L/min
• B. 2-6 L/min
• C. 4-8 L/min
• D. 8-12 L/min

Answer: (A)

Nonrebreather masks are designed to deliver very high oxygen concentration by keeping a reservoir bag inflated so most of the inhaled air comes from oxygen in the bag rather than room air. To maintain that inflation throughout the breath, the flow must be high enough to outpace the patient’s inspiratory effort. That’s why the typical flow is around 12 to 15 liters per minute. At this rate, the bag stays filled and the delivered FiO2 can approach 100% when the mask fits well.

Flows of 2–6 L/min are too low to keep the reservoir inflated and would allow more room air to mix in, reducing FiO2. The lower ranges listed are not reliably sufficient for the high oxygen concentration this mask aims to provide, whereas 12–15 L/min is the standard for achieving the intended high oxygen delivery.