What is the oxygen flow rate for a non-rebreather mask (NRB)?

• A. 10-15 L/min
• B. 2-4 L/min
• C. 6-8 L/min
• D. 20-30 L/min

Answer: (A)

Non-rebreather masks are designed to deliver a very high concentration of oxygen, which depends on keeping the reservoir bag inflated during inhalation. To achieve that, the oxygen flow must be high enough to fill the reservoir and meet the patient’s inspiratory needs. That’s why the typical flow rate is in the range of 10–15 liters per minute. At this flow, the mask can provide near-high FiO2 when the seal is good and the bag remains inflated.

If the flow is too low, the reservoir collapses or air leaks around the mask, letting in room air and reducing the oxygen concentration delivered to the patient. The other options correspond to different devices or contexts: 2–4 L/min is appropriate for a nasal cannula, 6–8 L/min is commonly cited for a simple face mask, and 20–30 L/min is higher than needed for a standard NRB and is more typical for other devices or high-flow setups.