In COPD, Nocturnal Noninvasive Ventilation Reduces the FIO2 Delivered Compared With Long-Term Oxygen Therapy at the Same Flow.

BACKGROUND: Nocturnal noninvasive ventilation is recommended for patients with hypercapnic COPD. Long-term oxygen therapy improves survival in patients with hypoxemic disease. However, leaks during noninvasive ventilation are likely to reduce the fraction of inspired oxygen. OBJECTIVES: To compare nocturnal inspired O2 fractions during noninvasive ventilation with daytime pharyngeal inspired O2 fractions during nasal cannula oxygen therapy (with the same O2 flow) in patients with COPD at home (ie, real-life conditions). METHODS: This single-center prospective observational study included 14 subjects with COPD who received long-term O2 therapy. We analyzed pharyngeal inspired O2 fractions in the evening, with a nasopharyngeal probe (sidestream gas analyzer). The O2 flow was measured with a precision flow meter, at the usual flow. Then, the same O2 flow was implemented for noninvasive ventilation with a study's home ventilator. The all-night noninvasive ventilation parameters were delivered in pressure mode with a single-limb leaking circuit. Daytime and nighttime inspired O2 fractions were compared. RESULTS: The mean ± SD daytime pharyngeal inspired O2 fraction, measured with normobaric basal O2 flow, 0.308 ± 0.026%, was significantly higher than the mean ± SD nighttime inspired O2 fraction, measured during noninvasive ventilation (0.251 ± 0.011; P < .001). CONCLUSIONS: The nighttime inspired O2 fraction decreased with a modern noninvasive ventilation pattern, pressure target, and intentional leaks. This partial lack of O2 therapy is likely to be harmful. It might explain the poor results in all but 2 randomized controlled trials on long-term noninvasive ventilation in COPD. (ClinicalTrials.gov registration NCT02599246.).

Leaks can dramatically decrease FiO2 on home ventilators: a bench study.

BACKGROUND: Long term oxygen therapy improves survival in hypoxemic patients with chronic obstructive pulmonary disease (COPD). Because pressure support ventilation with a home care ventilator is largely unsupervised, there is considerable risk of leakage occurring, which could affect delivered FiO2. We have therefore conducted a bench study in order to measure the effect of different levels of O2 supply and degrees of leakage on delivered FiO2. Ventilator tested: Legendair® (Airox™, Pau, France). Thirty-six measures were performed in each four ventilators with zero, 5 and 10 l.min-1 leakage and 1,2,4 and 8 l O2 flow. FINDINGS: FiO2 decreased significantly with 5 l.min-1 leakage for all O2 flow rates, and with 10 l.min-1 at 4 and 8 l.min-1 O2. CONCLUSION: During application of NIV on home ventilators, leakage can dramatically decrease inspired FiO2 making it less effective. It is important to know the FiO2 dispensed when NIV is used for COPD at home. We would encourage industry to develop methods for FiO2 regulation Chronic use of NIV for COPD with controlled FiO2 or SpO2 requires further studys.