Effect of breathing re-training on end-tidal carbon-di-oxide in patients with asthma: a systematic review and meta-analysis

Objective: The review aims to determine the effect of breathing re-training on End-tidal carbon-di-oxide (ETCO₂) in patients with asthma. Data sources: A systematic search of articles was performed in PubMed, Cochrane, PEDro, Scopus, and Ovid databases from their inception till May 2022. Study selections: Studies were included if the patients were clinically diagnosed with mild-moderate asthma. Randomized controlled trials that monitored ETCO₂ as a primary or secondary outcome were included. Studies were examined for potential risk of bias using the Revised Cochrane risk of bias tool by two independent reviewers. Results: Eight articles were included. The trials used various techniques like Buteyko, Papworth, Biofeedback, and holistic approach. Quantitative analysis was conducted to examine the effects on ETCO₂ at various time points. A significant large effect was seen on ETCO₂ following breathing re-training post-treatment, 3 and 6 months post-intervention. Conclusion: There is moderate evidence for a significant effect of breathing re-training on ETCO₂ in the short and long term in patients with asthma. However, high-quality randomized controlled trials using standardized measurement of ETCO₂ are required to evaluate the effects of different breathing re-training techniques.