Effect of continuous positive airway pressure on maximal exercise capacity in patients with obstructive sleep apnea: a systematic review and meta-analysis.

STUDY OBJECTIVES: Exercise capacity is impaired in obstructive sleep apnea (OSA). There are conflicting reports on the effect of CPAP on maximal exercise capacity. The objective of this review was to determine if there is a change in exercise capacity and anaerobic threshold following continuous positive airway pressure (CPAP) treatment in OSA patients.

METHODS: We conducted a systematic review and meta-analyses to summarize the changes in peak rate of oxygen uptake (V̇O₂peak) or maximum rate of oxygen uptake (V̇O₂max) and anaerobic threshold (AT) during cardiopulmonary exercise testing following CPAP intervention in patients with OSA. A systematic literature review was conducted to identify published literature on markers of V̇O₂ peak, V̇O₂ max and AT pre versus post CPAP using a web-based literature search of PubMed/MEDLINE, Embase, CINAHL and Cochrane review (CENTRAL) databases. Two independent reviewers screened the articles for data extraction and analysis.

RESULTS: The total search of all the databases returned 470 relevant citations. Following application of eligibility criteria, six studies were included in the final meta-analysis for V̇O₂ peak, two studies for V̇O₂ max, and five studies for AT. The meta-analysis showed a mean net difference in V̇O₂ peak between pre and post CPAP of 2.69 mL·kg-1 ·min-1 , p=0.02, favoring the treatment with CPAP. There was no difference in V̇O₂ max or AT with CPAP treatment (mean net difference 0.66 mL·kg-1 ·min-1 (0.78) and -144.98 mL·min-1 (p=0.20) respectively).

CONCLUSIONS: There is a paucity of high-quality studies investigating the effect of CPAP on exercise capacity. Our meta-analysis shows that V̇O₂ peak increases following CPAP treatment in patients with OSA, but we did not observe any change in V̇O₂ max or AT, Our findings should be considered preliminary and we recommend further randomized controlled trials to confirm our findings and to clarify the V̇O₂ adaptations with CPAP therapy.

CLINICAL TRIAL REGISTRATION: The study is registered on PROSPERO [ID number 138158] (www.crd.york.ac.uk).