- Design
- Randomised controlled crossover non-inferiority trial
- Population
- 40 patients with COPD or ILD and exercise-induced desaturation
- Primary outcome
- Six-minute walk distance
- Effect
- Difference 0 m (95% CI −14 to 13); dyspnoea lower with oxygen
A pragmatic randomised crossover trial in BMJ Open Respiratory Research (21 September) enrolled 40 patients — 20 with COPD, 20 with interstitial lung disease — who desaturated by more than 3% on exertion. Each did two six-minute walk tests in random order, one breathing air and one with 1–2 L/min pulsed oxygen from a backpack concentrator.
Walking distance was identical (mean difference 0 m, 95% CI −14 to 13 m), meeting the prespecified non-inferiority margin of 35 m. Oxygen significantly reduced breathlessness in both COPD and ILD. Only five patients walked more than 35 m further with oxygen, and preferences were split almost evenly (51% oxygen, 49% air).
Portable oxygen is costly, heavy and often abandoned. This trial suggests that for most patients it does not extend exercise capacity, but it does ease breathlessness, and a minority are genuine responders. That makes a single-patient trial on the patient's own device a reasonable prescribing step.
- Do a walk test on air and on oxygen before prescribing ambulatory oxygen
- Prescribe when it improves breathlessness or distance for that patient, not on desaturation alone
- Ask about weight, noise and practicality — the device has to be used to help
- Offer pulmonary rehabilitation, which improves exercise capacity more reliably
- In India, consider cost carefully before recommending a portable concentrator
Why it matters
It tempers the assumption that exertional desaturation automatically warrants portable oxygen.
Don't overread it
These were single walk tests with low-flow pulsed oxygen; higher flows or continuous delivery might perform differently.
The statistics, in plain English
Non-inferiority here means air was not worse than oxygen by more than 35 m; the interval of −14 to 13 m is well inside that. A crossover design lets each patient serve as their own control, which helps with 40 patients, but single tests on one day do not show long-term effects.
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