Ambulatory Oxygen for Exercise-Induced Desaturation and Dyspnea in Chronic Obstructive Pulmonary Disease (COPD): Systematic Review and Meta-Analysis

Determination of whether supplemental oxygen therapy is beneficial during exercise training in patients with COPD: A systematic review and meta-analysis

Exercise training is an integral component of the pulmonary rehabilitation program for patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to systematically search the published literature and analyze the evidence on the efficacy of supplemental oxygen in improving outcomes during exercise training in patients with COPD. The PubMed, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL) and Google scholar databases were searched electronically for articles in the English language published up to May, 2019. In total, 7 trials were included in this systematic review and meta-analysis. There was considerable heterogeneity amongst the included studies. Meta-analysis indicated no significant difference in power (random: MD = −2.38; 95% CI, −5.79 to 1.03; P=0.86) and maximum energy expenditure (VO₂ max) (random: MD = −0.01; 95% CI, −0.06 to 0.07; P=0.45) between the oxygen and control groups on maximal exercise testing. Qualitative analysis of the included studies revealed no benefits of supplemental oxygen in improving exercise capacity and dyspnea scores. Data on the quality of life assessed by the Chronic Respiratory Disease Questionnaire was pooled for 95 participants in the study group and 91 participants in the control group. The results indicated no beneficial effects of supplemental oxygen in improving quality of life outcomes (random: MD = −0.09; 95% CI, −0.16 to −0.01; P=0.59). On the whole, the findings of this study indicate that supplemental oxygen during the exercise training of patients with COPD does not improve exercise capacity, dyspnea scores and quality of life. However, the quality of the evidence is weak. Multi-center randomized controlled trials with homogenous methodology and intervention are required to provide stronger evidence on this subject.

Exercise response to oxygen supplementation is not associated with survival in hypoxemic patients with obstructive lung disease

Purpose

Hypoxemia is associated with more severe lung disease and worse outcomes. In some patients with chronic obstructive lung diseases who desaturate on exertion, supplemental oxygen improves exercise capacity. The clinical significance of this exercise response to oxygen supplementation is not known.

Patients and methods

We identified chronic obstructive lung disease patients at our center who underwent a 6-minute walking test (6MWT) for ambulatory oxygen assessment and who desaturated breathing air and therefore had an additional walk test on supplemental oxygen, between August 2006 and June 2016. Responders were defined as walking ≥26 m further with oxygen. Survival was determined up to February 1, 2017. We compared survival in oxygen responders and nonresponders in patients with obstructive lung diseases.

Results

One hundred and seventy-four patients were included in the study, median age 70 years. Seventy-seven (44.3%) of the patients were oxygen responders. Borg dyspnea score improved by 1.4 (±1.4) units (P<0.0005) on oxygen. Median survival was 66 months with death occurring in 84 (48.2%) patients. Kaplan–Meier analysis revealed no survival difference between both responders and nonresponders (P=0.571). Cox regression analysis showed that more 6MWT desaturation, lower 6-minute walking distance on room air, male gender, lower hemoglobin, and body mass index were associated with higher mortality risk.

Conclusion

Acute exercise response to supplemental oxygen is not associated with long-term survival in patients with obstructive lung disease. This supports the use of ambulatory oxygen treatment for symptomatic purposes only.