Table 4.

Comparison of the characteristics among standard oxygen therapy, high-flow nasal cannula, and continuous positive airway pressure.

	Standard Oxygen Therapy	High-Flow Nasal Cannula	Continuous Positive Airway Pressure
Optimal gas conditioning	/	+++	+
Generation of positive end-expiratory pressure	/	+	+++
Wash-out of nasopharyngeal dead space	/	+++	+
Improvement in mucociliary clearance	/	+++	/
Flow and oxygen concentration setting	/	+++	+++
Reduced breathing effort	/	++	+++
Reduction in upper airway resistance	/	+	+++
Patient’s comfort	++	+	/

/ no effect; + low effect; ++ medium effect; +++ high effect.