In COPD, FiO2 decrease during nocturnal non-invasive ventilation compared to normobaric O2 therapy

Rationale: Nocturnal noninvasive ventilation (NIV) is now recommended for hypercapnic chronic pulmonary obstructive disease (COPD) patients (GOLD 2017). Long-term oxygen therapy (LTOT) improve survival in hypoxemic COPD patients. Leaks with NIV should decrease FiO2. Aims and Objectives: Compare nocturnal FiO2 under NIV to day time pharyngeal FiO2 with nasal cannula oxygen therapy (with the same O2 flow) in COPD patient at home. Methods: In an observational study, 14 COPD patients were enrolled at home. In the evening a naso-pharyngeal probe allowed to analyze pharyngeal FiO2 with LTOT. The usual O2 flow was adjusted with a precision flowmeter. Then patient NIV parameters were transcribed on the study home ventilator (Vivo 50 Breas) with the same O2 flow. The all-night non-invasive ventilation parameters were registered in a pressure support mode with single limb leaking circuit. Daytime and night-time FiO2 were compared. Results: The overall results of all 14 patients showed that the measured FiO2 was much lower during the nighttime compared to the daytime measurement: 25,1+-1,1 % versus 30,8+-2,6 % (P Conclusion: With modern pattern of NIV, pressure target and intentional leaks, nighttime FiO2 decrease. This partial removing of O2 therapy should be harmful. It might explain poor results of all but two randomized controlled trial about long term NIV in COPD.