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

Background: 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. Objective: 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. Data Sources: 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. Data Extraction: 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. Synthesis: 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]; P = 0.03, heterogeneity [I2 = 83%]). When conference abstracts were included in the pooled analysis, the estimated effect did not change (P = 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]; P = 0.05, heterogeneity [I2 = 18%]). Conclusions: 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.