Which oxygen concentration does a nasal cannula typically deliver?

• A. 4%-6%
• B. 24%-44%
• C. 60%-90%
• D. 100%

Answer: (B)

Nasal cannula is a low-flow oxygen delivery method that provides only modest increases in FiO2. At typical flow rates of 1–6 L/min, the oxygen concentration delivered is about 24% at 1 L/min up to around 44% at 6 L/min, with the exact value depending on how the patient breathes and whether the mouth is open or closed. This makes the 24–44% range the best match for what a nasal cannula delivers.

Concentrations like 4–6% are far too low for oxygen therapy, and 60–90% or 100% would require higher-flow, more controlled delivery systems (such as a nonrebreather or other devices) to achieve and maintain those FiO2 levels.