The impact of high-flow nasal cannula oxygen therapy on exercise capacity in fibrotic interstitial lung disease: a proof-of-concept randomized controlled crossover trial

BACKGROUND: Patients with fibrotic interstitial lung disease (FILD) often experience gas exchange abnormalities and ventilatory limitations, resulting in reduced exercise capacity. High-flow nasal cannula (HFNC) oxygen therapy is a novel treatment, whose physiological beneficial effects have been demonstrated in various clinical settings. We hypothesized that HFNC oxygen therapy might be superior to conventional oxygen therapy for improving exercise capacity in FILD patients. METHODS: We performed a prospective randomized controlled crossover trial with a high-intensity constant work-rate endurance test (CWRET) using HFNC (50 L/min, FiO(2) 0.5) and a venturi mask (VM) (15 L/min, FiO(2) 0.5) for oxygen delivery in FILD patients. The primary outcome variable was endurance time. The secondary outcome variables were SpO(2), heart rate, Borg scale (dyspnea and leg fatigue), and patient’s comfort. RESULTS: Seven hundred and eleven patients were screened and 20 eligible patients were randomized. All patients completed the trial. The majority of patients were good responders to VM and HFNC compared with the baseline test (VM 75%; HFNC 65%). There was no significant difference in endurance time between HFNC and VM (HFNC 6.8 [95% CI 4.3–9.3] min vs VM 7.6 [95% CI 5.0–10.1] min, p = 0.669). No significant differences were found in other secondary endpoints. Subgroup analysis with HFNC good responders revealed that HFNC significantly extended the endurance time compared with VM (VM 6.4 [95%CI 4.5–8.3] min vs HFNC 7.8 [95%CI 5.8–9.7] min, p = 0.046), while no similar effect was observed in the VM good responders. CONCLUSIONS: HFNC did not exceed the efficacy of VM on exercise capacity in FILD, but it may be beneficial if the settings match. Further large studies are needed to confirm these findings. TRIAL REGISTRATION: UMIN-CTR: UMIN000021901.