At a flow rate of 6 L/min, a nasal cannula can deliver an approximate oxygen concentration up to which percentage?

At a flow rate of 6 L/min, a nasal cannula can deliver an approximate oxygen concentration up to which percentage?

• A. 44%.
• B. 24%.
• C. 52%.
• D. 35%.

Answer: (A)

Oxygen concentration from a nasal cannula rises with flow but is limited by mixing with room air as you breathe in. The typical relationship is about 24% at 1 L/min and adds roughly 3–4 percentage points for each extra liter, topping out around 44% at 6 L/min. So at 6 L/min you can approximate about 44% FiO2. The other options don’t fit this pattern: 24% is what you’d see at a much lower flow, around 1 L/min; 35% is closer to what you’d get at some mid-range flows but not the maximum for 6 L/min; 52% would require a device capable of delivering substantially more oxygen without entraining room air.

Oxygen concentration from a nasal cannula rises with flow but is limited by mixing with room air as you breathe in. The typical relationship is about 24% at 1 L/min and adds roughly 3–4 percentage points for each extra liter, topping out around 44% at 6 L/min. So at 6 L/min you can approximate about 44% FiO2. The other options don’t fit this pattern: 24% is what you’d see at a much lower flow, around 1 L/min; 35% is closer to what you’d get at some mid-range flows but not the maximum for 6 L/min; 52% would require a device capable of delivering substantially more oxygen without entraining room air.