Effects of acute use of pursed-lips breathing during exercise in patients with COPD: a systematic review and meta-analysis

Background Pursed-lips breathing (PLB) is a ventilatory strategy frequently adopted spontaneously by patients with chronic obstructive pulmonary disease (COPD) to relieve dyspnoea, and its practice is widely taught as a respiratory strategy to increase exercise tolerance. Objective To investigate the effects of acute use of PLB in exercise performance, dyspnoea, ventilatory parameters and oxygen saturation during exercise in patients with COPD. Data sources PEDro, EMBASE, MEDLINE via OVID, and EBSCO up to May 2016. Study selection Crossover, randomized and quasi-randomized controlled trials that studied PLB as a ventilatory strategy for patients with COPD during exercise. Data extraction and synthesis Data extraction included background characteristics of the research reports; participant characteristics; description of the analyzed variables and corresponding instruments; exercise protocol; exercise performance; outcomes and corresponding results; data for "responder" and "non-responder" outcomes. Results Eight studies were selected. The meta-analysis demonstrated that the use of PLB during exercise reduces minute ventilation and respiratory rate compared to exercise without PLB. No statistically significant differences were found in the 6-minute walk test distance. Limitations The sample characteristics, exercise protocols, and criteria for "responders" and "non-responders" differed among studies. Conclusion PLB is effective in reducing minute ventilation and respiratory rate during exercise in patients with COPD. It is still unclear who responds to PLB and how these responders benefit from its use. Further studies with better methodological quality are necessary to understand the implications of its acute use on the functional capacity and symptoms of patients with COPD. Systematic review registration number: PROSPERO CRD42015025903. (C) 2017 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.