Long term high flow humidified oxygen treatment in COPD – effect on blood gases

Introduction: Long term oxygen therapy (LTOT) improves survival in patients with COPD with resting hypoxemia. The AIRVO device delivering nasal high flow (NHF) warmed and humidified oxygen-enriched air to COPD patients in need of LTOT. Short term studies suggest that this may reduce PaCO2 in COPD.Aim: To investigate the treatment effect on arterial blood gases (PaO2, PaCO2 and SaO2) in patients with resting hypoxemia over 12 months.Method: In this prospective, randomized controlled, one-year study, 200 COPD patients treated with LTOT, all GOLD class 4, were randomized to NHF (n=100) or usual care (n=100) between March 2013 and June 2015.Results: The groups are comparable in average days in study, age, gender, smoking status, pack years, BMI, FEV1%, 6 minutes walking test, administered oxygen (L/min), PaO2 PaCO2 and Sa02 at baseline and number of exacerbations and admissions one year prior to study start. Treated with a mean NHF-flow of 20 L/min, no significant difference was seen in PaO2 or SaO2 over the study, but a significantly different change in PaCO2 was seen after 6 months (p<0.05) and after 12 months (p<0.01) in favor of patients treated with NHF. Increase in PaCO<2 was approximately 0.05 kPa for AIRVO-NHF and 0.40 kPa for control patients.Conclusion: These results show a significant difference in change of PaCO2 of 0.35 kPA more for control than for the AIRVO-NHF group of COPD patients needing LTOT.