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Abstract
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.
Introduction
Exercise intolerance in chronic obstructive pulmonary disease (COPD) is related to airflow, gas exchange, and systemic limitations [1], with exertional dyspnoea being the most common reported symptom [1], [2]. Pursed-lips breathing (PLB) is a ventilatory strategy frequently adopted spontaneously by patients with COPD to relieve dyspnoea [2], and its practice is widely taught in respiratory physical therapy and pulmonary rehabilitation programs to increase exercise tolerance [3], [4]. The American Thoracic Society describes PLB as nasal inspiration followed by prolonged expiration with lips partly closed [3], [5].
To date, six studies have reviewed the efficacy of PLB [6], [7], [8], [9] but only two were conducted systematically [8], [10] and one attempted to combine the results of these studies in a meta-analysis [10]. The systematic review published in 2009 investigated the effect of PLB at rest, showing that PLB leads to a decrease in respiratory rate (RR) and an increase in tidal volume and oxygen (weighted mean calculation) [8]. At the time, there were only two studies with submaximal exercise protocol that considered the effects of PLB during exercise. Based on their weighted mean analysis, it seemed that PLB had some effect on the reduction in RR and recovery time [8]. Holland et al. [10] aimed to determine the effects of breathing exercises, including PLB, on dyspnoea, exercise capacity, and health-related quality of life in COPD. The authors considered the long-term effects of PLB after 4, 8, or 12 weeks of breathing exercise training but they did not consider its acute effects.
Although PLB may reduce dyspnoea in patients with chronic respiratory diseases in clinical practice [6], [8], its ability to improve ventilatory response, dyspnoea, and exercise performance in patients with COPD remains unclear. Thus, the main objective of the current study was to perform a systematic review of crossover, randomized and quasi-randomized controlled trials that investigated the effects of acute use of PLB in exercise performance, dyspnoea, ventilatory parameters and oxygen saturation during exercise in patients with COPD.
Section snippets
Data sources and searches
The searches were performed by two investigators in PEDro, EMBASE, MEDLINE via OVID, and EBSCO from inception until the first week of May 2016. The search included keywords and variants that identified “chronic obstructive pulmonary disease”; “pursed-lips breathing”; and “exercise” (the search strategy is shown in Supplementary information). The search included scientific articles in English; Spanish; or Portuguese and published in peer-review journals. Hand-searches in the references of the
Results
A total of 8856 articles were identified in the database search (Fig. 1 of Supplementary information), 121 of which were selected according to title and had their respective abstracts reviewed. In addition, the hand search revealed one title. Based on the abstracts, 11 studies were eligible for a full review, and eight studies that fulfilled the inclusion criteria were selected [12], [13], [14], [15], [16], [20], [21], [22] (Table 1), providing 197 patients. All studies used a crossover design
Discussion
The current systematic review aimed to investigate the effects of acute use of PLB during exercise in patients with COPD. Eight studies were included [12], [13], [14], [15], [16], [20], [21], [22] but, their heterogeneity prevented a meta-analysis for all outcomes. The results indicate that the use of PLB during exercise is effective in reducing minute ventilation (V’E) and respiratory rate (RR). However, no statistical difference was found in the 6MWT distance. Therefore, there is insufficient
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