Nasal cannula delivers oxygen in the range of:

• A. 2-6%
• B. 10-20%
• C. 22-44%
• D. 50-60%

Answer: (C)

Nasal cannula is a low-flow oxygen delivery device, and the amount of oxygen it provides depends on how much flow you set and how the patient breathes. As you increase flow from low to higher, the FiO2 delivered rises but stays well below the high concentrations you get with masks. In practice, 1 L/min is about the low end of its delivery (roughly in the mid-20s percent), and at the maximum commonly used flow around 6 L/min the FiO2 approaches the mid-40s percent. So the typical FiO2 range for a nasal cannula is roughly 22–44 percent. The other ranges are not correct for this device: they are either too close to room air, or exceed what a nasal cannula can reliably deliver without switching to a higher-flow or mask device.