Effect of high-flow oxygen therapy on exercise tolerance in idiopathic pulmonary fibrosis: a randomized crossover trial

Background: Exercise capacity in idiopathic pulmonary fibrosis (IPF) is limited due to exercise-induced hypoxemia. This study is aimed to examine the effect of high-flow nasal cannula oxygen therapy (HFNC) on exercise tolerance in patients with IPF. Methods: This single-center, open-blind, randomized crossover trial assessed the influence of HFNC compared to venturi mask (VM) as the control test. Patients underwent constant load symptom-limited exercise tests at 80% of peak work rate with HFNC and VM in random order. The setting for HFNC was 60L/min, a FiO₂ of 50%, and VM was 12L/min, a FiO₂ of 50%. We measured endurance time as the primary outcome and heart rate, SpO2, dyspnea, and leg fatigue from modified borg scale at isotime and endpoint, comfort by using devices as the secondary outcomes. Results: 24 subjects (75.0% male; median [IQR] aged 77.5 years [68.8, 83.0]) were included. Compared to VM, HFNC significantly improved in endurance time (647.5sec [454.0, 1014.8] vs 577.5sec [338.0, 861.5), minimum SpO₂ (96.0% [95.0, 98.0] vs 94.0% [92.8, 96.0]) and leg fatigue from modified borg scale at isotime (3.0 [1.6, 4.0] vs 5.0 [3.0, 6.3]) and endpoint (4.0 [2.8, 5.0] vs 5.0 [3.8, 6.3]). There were no significant differences in maximum HR, dyspnea at isotime and endpoint, and comfort. Conclusion: HFNC increased exercise tolerance in stable IPF with exercise-induced hypoxemia.