Supplemental oxygen during pulmonary rehabilitation in patients with COPD with exercise hypoxaemia

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Abstract
BACKGROUND Supplemental oxygen in patients with chronic obstructive pulmonary disease (COPD) and exercise hypoxaemia improves exercise capacity and dyspnoea. However, the benefit of oxygen during pulmonary rehabilitation in these patients is still unknown. METHODS Twenty five patients with stable COPD (mean (SD) forced expiratory volume in one second (FEV1) 0.76 (0.29) l and 30.0 (9.89)% predicted, arterial oxygen tension (Pao 2) 8.46 (1.22) kPa, arterial carbon dioxide tension (Paco 2) 6.32 (1.01) kPa) and significant arterial desaturation on exercise (82.0 (10.4)%) were entered onto a pulmonary rehabilitation programme. Patients were randomised to train whilst breathing oxygen (OT) (n = 13) or air (AT) (n = 12), both at 4 l/min. Assessments included exercise tolerance and associated dyspnoea using the shuttle walk test (SWT) and Borg dyspnoea score, health status, mood state, and performance during daily activities. RESULTS The OT group showed a significant reduction in dyspnoea after rehabilitation compared with the AT group (Borg mean difference –1.46 (95% CI –2.72 to –0.19)) but there were no differences in other outcome measures: SWT difference –23.6 m (95% CI –70.7 to 23.5), Chronic Respiratory Disease Questionnaire 3.67 (95% CI –7.70 to 15.1), Hospital Anxiety and Depression Scale 1.73 (95% CI –2.32 to 5.78), and London Chest Activity of Daily Living Scale –2.18 (95% CI –7.15 to 2.79). At baseline oxygen significantly improved SWT (mean difference 27.3 m (95% CI 14.7 to 39.8) and dyspnoea (–0.68 (95% CI –1.05 to –0.31)) compared with placebo air. CONCLUSIONS This study suggests that supplemental oxygen during training does little to enhance exercise tolerance although there is a small benefit in terms of dyspnoea. Patients with severe disabling dyspnoea may find symptomatic relief with supplemental oxygen.