Introduction Pursed lips breathing (PLB) at rest increases oxygen saturation and tidal volume and reduces respiratory rate. Used with exercise it shortens the recovery period, reduces end-exercise breathlessness and improves reported physical function measured by SF-36 (Roberts SE et al, 2009). This study aimed to explore, in a clinical setting, the effectiveness of PLB, in the management of dyspnoea in stable COPD.
Methods COPD patients referred to pulmonary rehabilitation (PR) were randomised to a control or PLB intervention group. Patients were visited twice at home over 8 weeks prior to starting PR. Each visit comprised a respiratory examination and provision of information on the PR programme; the intervention group were also taught PLB, instructed to practise this daily and to use the technique whenever troubled by breathlessness. Use of PLB was recorded in a home diary. Primary outcome measures were the Self Report Chronic Respiratory Disease Questionnaire (CRQ-SR) dyspnoea and mastery domains and the Endurance Shuttle Walk Test (ESWT). An a priori power calculation, for 80% power, was based on local PR data. Secondary outcome measures were change in Borg breathlessness, respiratory rate, heart rate and oxygen saturation on ESWT.
Results 41 patients with COPD were recruited (PLB n=22, control n=19); mean (SD) age 68 (11) years, mean (SD) FEV1% predicted 47 (15.80)%. There was no statistically significant difference between groups in the primary outcome measures and in retrospect the RCT was insufficiently powered. Post hoc analysis found effect sizes for primary outcome measures were: CRQ-SR dyspnoea 0.05, mastery 0.48 and ESWT 0.44. For secondary outcome measures unpaired t-test showed a significant (p=0.02) reduction in oxygen desaturation on ESWT in favour of PLB group.
Conclusion This study showed PLB practised over 8 weeks resulted in reduced physiological stress with respect to oxygen desaturation when performing a standardised endurance walk. Additionally it raises questions regarding use of a health related quality of life dyspnoea tool when investigating PLB. To date beneficial effect of PLB on dyspnoea related to exercise has only been shown using the Borg breathlessness score (Nield et al, 2007).