Background:A noninvasive ventilation (NIV) mask has been designed to deliver NIV with expiratory washout (EW) to improve efficacy of ventilation via clearing carbon dioxide (CO2) from anatomical deadspace. This study compared the performance and comfort of this mask with EW with a standard mask during NIV therapy.

Methods:Sixteen participants with severe stable chronic obstructive pulmonary disease (COPD) completed this crossover study. Participants attended a single visit to receive, in random order, two 60-minute interventions with bi-level NIV therapy while wearing either the mask with EW or a standard NIV mask, with a 30-60 minute washout in between. The primary outcome was transcutaneous carbon dioxide (PtCO2) at 60 minutes. Oxygen saturation, heart rate, respiratory rate, minute ventilation, tidal volume, leak, dyspnoea score and comfort ratings were also assessed.

Results:The mean difference [95% CI] in the PtCO2 between the mask with EW and the standard mask at 60 minutes was [-0.74 mmHg [-2.81 to 1.33, P = 0.45]. The mask with EW elicited a lower tidal volume [-128.65 mL (-189.99 to -67.30), P<0.0001] and minute ventilation [-2.28 L·min?¹ (-3.12 to -1.43), P<0.0001], and a higher leak [7.96 L·min?¹ (4.39 to 11.54), P<0.0001], than the standard mask. There were no significant differences in other physiological responses or ratings of dyspnoea or comfort.

Conclusions: The mask with EW did not significantly reduce PtCO2 more than the standard mask. The mask with EW did significantly reduce minute ventilation and tidal volume compared to a standard mask.