Background: Little is known about the effectiveness of ambulatory domicilary oxygen therapy. At present ambulatory oxygen in the UK is provided with small oxygen cylinders but in other countries such as the USA and Italy, liquid oxygen systems with higher oxygen carrying capacity are widely used. Both these systems are used without adequate evidence of their effectiveness.
Objectives: To determine the effectiveness of long-term ambulatory domicilary oxygen therapy in patients with chronic obstructive pulmonary disease.
Search strategy: The Cochrane Airways Group specialised trials register was searched. In addition, bibliographies of each trial retrieved were also searched for additional papers that may contain further studies. Authors of identified trials were contacted for other published and unpublished studies.
Selection criteria: Only randomised controlled trials in patients with chronic obstructive pulmonary disease were considered for inclusion. Trials must have randomised patients into long-term ambulatory oxygen therapy or placebo while at home. Ambulatory oxygen can be provided either through portable oxygen cylinders or with liquid oxygen canisters and the placebo group using compressed or liquid air.
Data collection and analysis: Two reviewers assessed all potential trials independently. Data abstraction was completed by one reviewer and re-checked by the second reviewer.
Main results: Only two studies met the inclusion criteria. These provided data on 70 patients. Statistically significant effects of oxygen were found in only one of the studies, a crossover trial involving 9 patients with severe hypoxia at rest. This study reported a reduction in minute ventilation at maximal exercise (WMD -11.00 L/min; 95%CI -17.53, -4.47L/min) and an increase in PaO2 at rest (WMD 17.00 mmHg; 95%CI 9.13,24.87 L/min) with oxygen therapy when compared to placebo. The other study recruited patients who did not have resting hypoxaemia.
Reviewer's conclusions: Evidence available to date does not allow any firm conclusions to be drawn concerning the effectiveness of ambulatory domicilary oxygen therapy in patients with COPD. Further studies are required in order to understand the role of ambulatory oxygen in the management of patients with COPD on long-term oxygen therapy. These studies should separate patients who desaturate from those who do not desaturate.