Figure 3. The effect of high-flow nasal cannula oxygen therapy on changes in mean airway pressure (A) and tidal volume (B) in patients with stable hypercapnic chronic obstructive pulmonary disease. nCPAP: nasal continuous positive airway pressure; nBiPAP: nasal bi-level positive airway pressure. Adapted from Braunlich et al. Int J Chron Obstruct Pulmon Dis 2016;11:1077-85, according to the Creative Commons license Dove Medical Press30.