Effectiveness of high-flow nasal cannula during exercise training in subjects with chronic respiratory failure

Abstract Backgrounds: There are no clinical data comparing the effect of exercise training using high fraction of inspired oxygen (FIO2) in combination with high flow through a high-flow nasal cannula (HFNC) with that of ordinary supplemental oxygen on exercise capacity in subjects with chronic respiratory failure (CRF) receiving long-term oxygen therapy (LTOT). The aim of this study was to compare the effect of 4 weeks of exercise training using high FIO2 in combination with high flow through an HFNC or supplemental oxygen via a nasal cannula on the 6-min walking distance of patients with CRF receiving LTOT.Methods: In this randomized study, 32 patients with CRF due to chronic obstructive pulmonary disease, interstitial pulmonary fibrosis, or bronchiectasis receiving LTOT were assigned to undergo 4 weeks of exercise training on a cycle ergometer using an HFNC (flow: 50 L/min) with a FIO2 of 1.0 (HFNC group; n=16) or ordinary supplemental oxygen via a nasal cannula (flow: 6 L/min) (oxygen group; n=16). Before and after 4 weeks of exercise training, a 6-min walking test, constant-load test, and blood sampling were performed.Results: Prior to exercise training, the endurance time of the constant-load exercise test using an HFNC was significantly longer than that reported with prescribed oxygen in daily LTOT (p=0.004) or a 6 L/min nasal cannula (p=0.0003). Following 4 weeks of exercise training, change in the 6-min walking distance was significantly greater in the HFNC versus the oxygen group (55.2±69.6 m vs. —0.5±87.3 m, respectively; p=0.04). The plasma levels of adrenaline, noradrenaline, and serum C-reactive protein were significantly decreased only in the HFNC group, after 4 weeks of exercise training.Conclusions: Despite heterogeneity in the effect among patients, exercise training using high FIO2 in combination with high flow through an HFNC is a potentially superior exercise training modality for CRF patients receiving LTOT.Clinical Trial Registration ― http://www.clinicaltrials.gov. Unique identifier: NCT02804243. Registered 13 June 2016.