Efficacy of Noninvasive Ventilation With Expiratory Washout in Stable COPD Patients.

Background: A noninvasive ventilation (NIV) mask has been designed to deliver NIV with expiratory washout to improve efficacy of ventilation by optimizing clearance of expired gases from the anatomic dead space. This study compared the performance and comfort of a novel investigational mask with expiratory washout with a conventional mask during NIV therapy. Methods: In this pilot crossover study, participants with severe stable COPD attended a single visit to receive bi-level NIV through 2 masks; the investigational mask with expiratory washout and a conventional mask. The order of mask use was randomly allocated, and each mask was used for 60 min with a 30-60-min washout in between. The primary outcome was transcutaneous carbon dioxide at 60 min. Other physiologic and NIV device variables were also assessed. Results: The mean difference (95% CI) in the transcutaneous carbon dioxide between the investigational and conventional masks at 60 min, adjusted for baseline, was -0.74 mm Hg, 95% CI -2.81 to 1.33 mm Hg (P = .45). The investigational mask with expiratory washout elicited a lower tidal volume (-128.7 mL, 95% CI -190.0 to -67.3 mL; P < .001) and minute ventilation (-2.28 L/min,^, 95% CI -3.12 to -1.43 L/min; P < .001), and a higher leak (7.96 L/min, 95% CI 4.39-11.54 L/min; P < .001) than the conventional mask. There were no differences in other physiologic responses or ratings of dyspnea or comfort. Conclusions: NIV therapy delivered by using a novel mask with expiratory washout was similarly effective at reducing transcutaneous carbon dioxide, whereas the delivered tidal volume and minute ventilation were significantly lower when compared with a conventional mask in participants with severe COPD.