Nasal High-Flow Therapy during Exercise in Patients with Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis.

Several studies have evaluated the effect of nasal high-flow (NHF) therapy to enhance exercise performance and tolerance in patients with chronic obstructive pulmonary disease (COPD); however, results are disparate. The aim of this systematic review and meta-analysis was to assess the effect of NHF therapy as an adjuvant to exercise training on functional exercise capacity in patients with COPD. An electronic search was performed in the following databases: PubMed, the Cochrane Central Register of Controlled Trials, the Physiotherapy Evidence Database, ScienceDirect, the Web of Science, OpenGrey, ClinicalTrials.gov, and European Respiratory Society and American Thoracic Society databases. Two authors independently selected relevant randomized trials (parallel-group or crossover design), extracted data, assessed the risk of bias, and rated the quality of the evidence. Eleven studies were included, involving 408 participants (eight full papers and three conference abstracts). Most studies had a high risk of bias or other methodological limitations. The use of NHF therapy during a single session increased functional exercise capacity (standardized mean difference, 0.36 [95% confidence interval (CI), 0.03 to 0.69];  = 0.03, heterogeneity [ = 83%]). When conference abstracts were included in the pooled analysis, the estimated effect did not change ( = 0.006). The use of NHF therapy throughout a pulmonary rehabilitation program (parallel-group randomized controlled trials) increased functional exercise capacity at 4-12 weeks compared with training without NHF therapy (standardized mean difference, 0.34 [95% CI, 0.00-0.68];  = 0.05, heterogeneity [ = 18%]). There is very-low-quality to low-quality evidence that NHF therapy improves functional exercise capacity. Patient responses to NHF therapy were highly variable and heterogeneous, with benefits ranging from clinically trivial to worthwhile.