Ambulatory oxygen for exercise-induced desaturation and dyspnea in chronic obstructive pulmonary disease (COPD): systematic review and meta-analysis

Introduction: Ambulatory oxygen therapy is indicated in patients that use long term oxygen therapy (LTOT) and current guidelines suggest its use in patients who exhibit exertional desaturation if there is a demonstrable improvement in exercise capacity. Evidence for this is largely derived from single assessment studies which have shown clear benefit in this setting when oxygen versus air is used. The long term effects, however, of ambulatory oxygen therapy in this particular group of patients is controversial.
Methods: We conducted a systematic review of published literature from 1980 to June 2014 for trials in which ambulatory oxygen was compared to placebo in chronic obstructive pulmonary disease (COPD) patients not on LTOT. We also reviewed the effectiveness of devices delivering ambulatory oxygen. Outcome measures were focused towards exercise capacity, Borg scores and the ability of the delivery devices to maintain oxygen saturations on exercise.
Results: Twenty three studies (620 patients) were included in the review. Nine studies evaluated the clinical
effectiveness of ambulatory oxygen and 14 studies evaluated the impact of the delivery devices. Ambulatory oxygen had no statistical effect on improving exercise capacity when assessed by the 6-minute walk test (6MWT) or the endurance shuttle walk test (ESWT); p=0.44 and p=0.29 respectively. End of test Borg scores showed no statistical improvement with ambulatory oxygen therapy during 6MWT (p=0.68). Oxygen conserving devices significantly improved oxygen saturations on exercise compared with continuous flow nasal cannulae (p=0.04).
Conclusion: Ambulatory oxygen therapy has limited long term benefit in improving functional exercise capacity or Borg dyspnea scores.