Portable low-flow nasal oxygen versus ambient air in patients with chronic lung disease and exercise-induced hypoxaemia: a randomised controlled crossover non-inferiority trial.
Lichtblau M, Wick C, et al. • BMJ open respiratory research • 2026
In patients with chronic lung disease and exercise-induced hypoxaemia, ambient air was non-inferior to pulsed low-dose supplemental oxygen therapy by portable concentrator in 6-minute walk distance, but supplemental oxygen therapy improved dyspnoea.
Key Findings
Results
Ambient air was non-inferior to portable low-flow supplemental oxygen therapy (SOT) for 6-minute walk distance (6MWD) in patients with chronic lung disease and exercise-induced desaturation.
The mean difference in 6MWD between ambient air and SOT was 0 m (95% CI -14 to 13 m; p<0.001 for non-inferiority).
A predefined non-inferiority margin of 35 m was used.
40 patients were enrolled (mean age 66±13 years; 14 women; 20 with COPD, 20 with ILD).
The trial used a randomised controlled crossover design with each patient performing two 6MWD tests in randomised order.
Results
SOT significantly reduced dyspnoea scores compared to ambient air both overall and within COPD and ILD subgroups.
Secondary outcomes demonstrated significantly lower dyspnoea scores with SOT both overall and within COPD/ILD subgroups.
Perceived exertion was a pre-specified secondary outcome.
The dyspnoea benefit was observed consistently across both disease subgroups (COPD and ILD).
Results
Patient preferences for SOT versus ambient air were approximately evenly split.
49% of patients favoured ambient air and 51% preferred SOT.
Preference was assessed as a secondary outcome.
The near-equal split suggests no dominant patient preference for either intervention.
Results
Only a small minority of patients showed a clinically meaningful improvement in 6MWD with SOT.
A clinically meaningful improvement in 6MWD of >35 m was found in only five patients (out of 40, approximately 12.5%).
This finding highlights the need to identify responders to SOT.
The predefined clinically meaningful threshold was 35 m.
Methods
The study enrolled patients with chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD) who exhibited exercise-induced oxygen desaturation of >3%.
20 patients had COPD and 20 had ILD.
Mean age was 66±13 years; 14 of 40 participants were women.
SOT was delivered at 1-2 L/min via a portable backpack concentrator using pulsed flow.
Exercise-induced desaturation of >3% was the inclusion criterion for hypoxaemia.
Background
Exercise-induced desaturation in chronic lung disease is associated with functional limitation and increased mortality, yet evidence for SOT to improve exercise performance is inconsistent.
The authors describe exercise-induced desaturation as 'a common symptom in chronic lung disease (CLD)'.
Portable low-flow supplemental oxygen therapy is 'commonly prescribed for exercise-induced hypoxaemia'.
The authors note that 'evidence for SOT to improve performance is inconsistent,' motivating the pragmatic trial design.
Conclusions
The authors conclude that more effective and patient-acceptable oxygen delivery systems are needed, along with further research to identify SOT responders.
The findings 'highlight the need for more effective, patient-acceptable oxygen delivery systems.'
Further research is called for 'to identify responders to SOT.'
The pulsed low-dose delivery at 1-2 L/min by portable concentrator may be insufficient for meaningful exercise improvement in most patients.
What This Means
This research suggests that for people with chronic lung diseases like COPD or interstitial lung disease who experience a drop in blood oxygen levels during exercise, walking with a small portable oxygen concentrator (delivering 1-2 liters per minute) did not help them walk farther than walking without supplemental oxygen. In a study of 40 patients who each completed two standardized 6-minute walk tests — one with oxygen and one breathing regular air — the average walking distance was identical between the two conditions, and the difference was well within the pre-specified margin that would indicate one treatment was meaningfully worse than the other.
However, supplemental oxygen did provide one notable benefit: patients reported feeling less breathless (less dyspnoea) when using it, and this was true for both COPD and ILD patients. Patient preferences were almost evenly divided, with about half preferring the oxygen device and half preferring to walk without it. Only 5 out of 40 patients (about 12.5%) showed a clinically meaningful improvement in walking distance when using oxygen, suggesting that most patients do not benefit substantially in terms of physical performance from this type of oxygen delivery.
This research suggests that the current standard approach of prescribing low-flow portable oxygen for exercise-induced low oxygen levels may not improve how far most patients can walk, even though it may make breathing feel easier. The findings point to a need for better oxygen delivery technology and for ways to identify which patients are most likely to respond to supplemental oxygen therapy during exercise.
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Lichtblau M, Wick C, Titz A, Müller J, Schneider S, Hertig D, et al.. (2026). Portable low-flow nasal oxygen versus ambient air in patients with chronic lung disease and exercise-induced hypoxaemia: a randomised controlled crossover non-inferiority trial.. BMJ open respiratory research. https://doi.org/10.1136/bmjresp-2025-004048