O2 not helpful in overall QOL in COPD with exertional hypoxia

Clinical Question

Does supplemental oxygen during exertion improve exercise tolerance in patients with chronic obstructive pulmonary disease who have normal oxygen saturation at rest but who desaturate with exertion?

Bottom Line

Using supplemental oxygen during exertion improves exercise tolerance in patients with chronic obstructive pulmonary disease (COPD) who have normal oxygen saturation at rest but desaturate with exertion, but has no effect on overall quality of life. (LOE = 2b)


Nonoyama ML, Brooks D, Guyatt GH, Goldstein RS. Effect of oxygen on health quality of life in patients with chronic obstructive pulmonary disease with transient exertional hypoxemia. Am J Respir Crit Care Med 2007;176:343-349.  [PMID:17446339]

Study Design







Outpatient (any)


A Cochrane review has found that supplemental oxygen provides long-term benefit when given to patients with COPD with resting hypoxia. However, many clinicians give oxygen to patients with COPD who are not hypoxic at rest, but who desaturate with activity. These authors conducted a series of 27 N-of-1 trials in such patients to obtain objective data on the potential benefit of supplemental oxygen. In the evidence-based medicine hierarchy, the strongest evidence of therapeutic benefit to an individual patient comes from an N-of-1 trial. In this kind of study, individual patients, masked to whether they are receiving active or inactive treatment, serve as their own control. The patients in this study had exertional dyspnea enough to effect daily activity and oxygen saturation of 88% or less while walking for 6 minutes on room air. The treatment consisted of 2 weeks of inhaled oxygen (2 L/min) or air bottled to resemble oxygen and deliver 21% oxygen. The order of the treatment intervals was randomly assigned (concealed allocation). The patients were asked to use the inhaled gas for at least 1 hour daily during activity that typically caused dyspnea. The researchers assessed the endurance and quality of life for each patient using validated instruments. Of 38 patients enrolled, only 27 completed the study. Although patients receiving oxygen increased their endurance by approximately 2.5 minutes and increased the distance they could travel in 6 minutes, there was no overall increase on quality of life. Only 2 of the 27 patients experienced a clinically important increase in quality of life.