Use of Nasal High Flow in Stable COPD: Rationale and Physiology.

High-flow nasal cannula (HFNC) is a device able to deliver heated and humidified oxygen at high flows (up to 60 L/minutes). Potential benefits of HFNC are several and include the improvement of lung mucociliary clearance, the washout of upper airway dead space, the generation of a low level of positive airway pressure (PEEP effect), the decrease in inspiratory resistance and at the same time the increase in expiratory resistance. The present review aimed to describe the evidence surrounding the use of HFNC in stable chronic obstructive pulmonary disease patients.