What is a PRO of high flow nasal cannula?

• A. Reduces humidity
• B. Delivers a higher FiO2 than standard cannula
• C. Cheapest option
• D. Can help to clear CO2

Answer: (D)

High flow nasal cannula provides a stream of heated, humidified gas at high flow, which washes out the dead space in the upper airway between breaths. By continuously flushing this space, less exhaled CO2 is rebreathed with the next breath, improving CO2 elimination. That direct effect on ventilation makes CO2 clearance a clear benefit of HFNC. While HFNC can deliver high FiO2 and the gas is comfortable due to humidification, the standout pro related to gas exchange is the reduction of rebreathing CO2. The other options don’t fit: humidity isn’t reduced (it’s increased), and while it can provide high FiO2 and support comfort, those are not as specific or as central a advantage as effective CO2 clearance.