The long-term effect of ambulatory oxygen in normoxaemic COPD patients: a randomised study

To study the long-term benefits of ambulatory oxygen (AO) in combination with pulmonary rehabilitation (PR) in chronic obstructive pulmonary disease (COPD) patients experiencing exertional desaturation.

Normoxaemic COPD who participated in outpatient PR and desaturated >4% and <90% during endurance shuttle walk test (ESWT) were randomised to control (n=23) or AO 2 L/min from a portable oxygen concentrator (n=22) to be used during exercise. PR consisted of supervised training for 20 weeks combined with unsupervised daily training at home followed by 13 weeks without supervised training.

Only 45 of 165 eligible patients wanted to participate. Mean forced expiratory volume in 1 s=32% (SD 13.8) and Medical Research Council (MRC)=4.5 (3-5). Supplemental oxygen improved oxygen saturation during ESWT by 2.3% (95% CI: 1.2%-3.5%; p<0.001). In the study period of 33 weeks, 10 and 6 patients withdrew from the AO group and control group, respectively. Patients spent an average of 7.9 h/week on oxygen. PR improved ESWT by 18,076 s (95% CI: 101-258 s; p<0.001) and St. George's Respiratory Questionnaire (SGRQ) score by 2.6 units (95% CI: 0.1-5.1 s; p=0.04) after 7 weeks, and these gains remained at 33 weeks of evaluation. There were no differences between the AO group and control group at 33 weeks of evaluation with regard to change in ESWT (223 vs. 241 s; p=0.32), change in SGRQ (-3.6 vs. -4.5 units, 0.91), and number of patients with acute exacerbation in COPD (AECOPD), hospital admission or dropout (17 of 22 vs. 20 of 23, p=0.59).

AO seems not to provide additional beneficial effects in patients with COPD participating in pulmonary rehabilitation and experiencing exertional desaturation without severe resting hypoxaemia.