Non-invasive ventilation with pursed lips breathing mode for patients with COPD and hypercapnic respiratory failure: A retrospective analysis.

Purpose: Long-term non-invasive ventilation (NIV) is recommended for patients with stable chronic obstructive lung disease (COPD) and chronic hypercapnia. High inspiratory pressure NIV (hiNIV) and a significant reduction of arterial pCO2 have been shown to prolong survival. Often, patients on hiNIV describe severe respiratory distress, known as "deventilation syndrome", after removal of the NIV mask in the morning. Mechanical pursed lips breathing ventilation (PLBV) is a new non-invasive ventilation mode that mimics the pressure-curve of pursed lips breathing during expiration. The clinical impact of switching patients from standard NIV to PLBV has not been studied so far.

Patients And Methods: In this hypothesis generating study, we retrospectively analysed the effects of switching COPD patients (stage GOLD III-IV) from conventional NIV to PLBV. Medical records of all patients who had an established NIV and were switched to PLBV between March 2016 and October 2017 were screened. Patients were included if they complained of shortness of breath on mask removal, used their conventional NIV regularly, and had a documented complete diagnostic workup including lung function testing, blood gas analysis and 6-minute walk test (6MWT) before and after 3-7 days of PLBV.

Results: Six male and 10 female patients (median age 65.4 years; IQR 64.0-71.3) with a previous NIV treatment duration of 38 months (median; IQR 20-42) were analysed. After PLVB initiation, the median inspiratory ventilation pressure needed to maintain the capillary pre-switch pCO2 level was reduced from 19.5 mbar (IQR 16.0-26.0) to 13.8 mbar (IQR 12.5-14.9; p<0.001). The median 6MWT distance increased from 200m (IQR 153.8-266.3) to 270m (IQR 211.3-323.8; p<0.001). Median forced vital capacity (FVC) increased from 49.5% to 53.0% of the predicted value (p = 0.04), while changes in FEV1 and residual volume (RV) were non-significant.

Conclusion: Based on this small retrospective analysis, we hypothesise that switching patients with COPD GOLD III-IV and chronic hypercapnia from conventional NIV to PLBV may increase exercise tolerance and FVC in the short term.