Effect of High-Flow Oxygen on Exercise Performance in COPD Patients. Randomized Trial

Abstract

Background: High-flow oxygen therapy (HFOT) provides oxygen-enriched, humidified, and heated air at high flow rates via nasal cannula. It could be an alternative to low-flow oxygen therapy (LFOT) which is commonly used by patients with chronic obstructive pulmonary disease (COPD) during exercise training. Research Question: We evaluated the hypothesis that HFOT improves exercise endurance in COPD patients compared to LFOT. Methods: Patients with stable COPD, FEV1 40-80% predicted, resting pulse oximetry (SpO2) ≥92%, performed two constant-load cycling exercise tests to exhaustion at 75% of maximal work rate on two different days, using LFOT (3 L/min) and HFOT (60 L/min, FiO2 0.45) in randomized order according to a crossover design. Primary outcome was exercise endurance time, further outcomes were SpO2, breath rate and dyspnea. Results: In 79 randomized patients, mean ± SD age 58 ± 9 y, FEV1 63 ± 9% predicted, GOLD grades 2-3, resting PaO2 9.4 ± 1.0 kPa, intention-to-treat analysis revealed an endurance time of 688 ± 463 s with LFOT and 773 ± 471 s with HFOT, mean difference 85 s (95% CI: 7 to 164, P = 0.034), relative increase of 13% (95% CI: 1 to 28). At isotime, patients had lower respiratory rate and higher SpO2 with HFOT. At end-exercise, SpO2 was higher by 2% (95% CI: 2 to 2), and Borg CR10 dyspnea scores were lower by 0.8 points (95% CI: 0.3 to 1.2) compared to LFOT. Interpretation: In mildly hypoxemic patients with COPD, HFOT improved endurance time in association with higher arterial oxygen saturation, reduced respiratory rate and less dyspnea compared to LFOT. Therefore, HFOT is promising for enhancing exercise performance in COPD. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT03955770.

Keywords: COPD; exercise; high-flow; oxygen therapy; randomized controlled trial.

Conflict of interest statement

KEB reports grants to his institution from the Swiss National Science Foundation, and the Bockhoff Foundation. The high-flow equipment was provided by Fisher & Paykel Healthcare, Switzerland; the oxygen concentrators were provided by Philips AG Respironics, Switzerland. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2021 Bitos, Furian, Mayer, Schneider, Buenzli, Mademilov, Sheraliev, Marazhapov, Abdraeva, Aidaralieva, Muratbekova, Sooronbaev, Ulrich and Bloch.

Figures

Figure 1

Patient flow in the cross-over trial.

Figure 2

Primary outcome: difference with 95% confidence intervals in cycling endurance time between tests on high-flow oxygen therapy (HFOT) and low-flow oxygen therapy (LFOT) for the intention-to-treat and per-protocol analyses.

Figure 3

Changes in physiologic variables over the course of exercise in per-protocol analyses. Means and SD bars are shown for values at rest, at isotime (i.e., end-exercise time in tests with shorter endurance and corresponding time in tests with longer endurance), and at end-exercise. Open circles represent tests with high-flow, closed circles with low-flow oxygen therapy. (A–C) Depict pulse oximetry (SpO2), breath rate and heart rate. *P < 0.05 vs. rest within same treatment, ¶P < 0.05 high-flow vs. low-flow oxygen therapy at corresponding stage of exercise.