Design: Randomised controlled crossover non-inferiority trial
Population: 40 patients with COPD or ILD and exertional desaturation
Primary outcome: Six-minute walk distance
Effect: Mean difference 0 m (95% CI −14 to 13); dyspnoea lower with oxygen

A pragmatic, randomised crossover non-inferiority trial enrolled 40 patients — 20 with COPD and 20 with ILD — who desaturated by more than 3% on exertion. Each did two six-minute walk tests in random order: one on ambient air and one on 1–2 L/min of pulsed oxygen from a portable backpack concentrator.

Walk distance was identical (mean difference 0 m, 95% CI −14 to 13 m), meeting the 35 m non-inferiority margin. Breathlessness was significantly lower with oxygen in both COPD and ILD. Patient preference was evenly split, and five patients gained a clinically meaningful 35 m or more with oxygen.

Portable oxygen is often prescribed to improve exercise capacity. This trial suggests that, at these low pulsed flows, it eases breathlessness rather than extending distance, and that only a minority respond. A trial walk on and off oxygen can identify who benefits.

Low-flow pulsed portable oxygen did not increase walking distance on average.
It did reduce breathlessness during exertion, which may matter more to patients.
Consider a supervised walk test on and off oxygen before prescribing a portable device.
About half of patients preferred walking without the device.

Why it matters

Ambulatory oxygen is expensive and burdensome, and most patients may not walk further with it.

The statistics, in plain English

The confidence interval of −14 to 13 m sits entirely inside the 35 m margin, so air was shown to be no worse for distance. The trial measured one walk per condition, not long-term use.