|dc.description.abstract||Introduction: This dissertation aims to explore, in a clinical setting, the effectiveness of pursed lips breathing (PLB), in the management of dyspnoea in stable COPD.
Methodology: A mixed methodology that comprised a randomised controlled trial (RCT), a predominantly qualitative follow-up (FU) study and two measurement studies was used. The RCT intervention group was taught PLB at home over 8 weeks. Primary outcome measures were the Self Report Chronic Respiratory Disease Questionnaire (CRQ-SR) dyspnoea and mastery domains and Endurance Shuttle Walk Test (ESWT). The FU study investigated the long-term experience of PLB in a subset of RCT participants through telephone interview, focus group and observation of PLB technique at home visit. Prior to the RCT a study using limits of agreement (LoA) methodology was conducted to investigate reliability of hand-held spirometric measurement of inspiratory capacity (IC) with a view to using it as an outcome measure. Following the RCT a retrospective analysis of data collected from the ESWT was performed comparing a 1-walk protocol with the published 2-walk protocol.
Results: Forty-one patients with COPD were recruited to the RCT (PLB n = 22, control n =19); mean age 68 years (SD 11), mean FEV1% predicted 47% (SD 15.80) and 13 were approached to participate in the FU; 11 of 13 agreed to telephone interview, 5 to attend the focus group and 6 to home visit. The median time since learning PLB was 17 months (6 - 23). The RCT found no statistically significant difference between groups in the primary outcome measures and in retrospect was insufficiently powered. Post hoc analysis found effect sizes for primary outcome measures were: CRQ-SR dyspnoea 0.05, CRQ-SR mastery 0.48 and ESWT 0.44. For secondary outcome measures the PLB group showed a significant (p = 0.02) improvement in oxygen saturation on ESWT. Long-term follow-up found 9 of 11 still used PLB, 8 reported definite benefit. Those using PLB used it for breathlessness with four themes identified: use of PLB with physical activity (8/11), to increase confidence and reduce panic (4/11), as an exercise (3/11), at night (3/11). Discontinuation of PLB (2/11) was due to no benefit. Hand-held spirometric measurement of IC found LoA for same-day IC measurement in healthy volunteers (n = 20) ± 0.630L (95%CI ± 0.255) and over 3 weeks (n = 11) ± 0.560L (95%CI ± 0.326). In COPD, same day LoA (n = 26) were ± 0.582L (95%CI ± 0.169) and over 6 weeks (n = 8) ± 0.486L (95%CI ± 0.302). Retrospective analysis of ESWT data identified that completion rates improved by 17% for the 1-walk protocol but that the ceiling-effect was 12.2% compared to 7.3% for the 2-walk protocol. LoA between protocols when measuring change over time (n = 31) was ±80% (95%CI 25.56); less than the difference described as "somewhat better" (113%) following pulmonary rehabilitation (PR) but greater than the m.c.i.d. of 68%.
Conclusions: LoA for IC exceeded the clinically significant reported 0.3L; the protocol tested here was not sufficiently reliable for use as an outcome measure. Analysis of ESWT data showed the 1-walk protocol was adequate for identify change in clinical practice but, for research purposes the 2-walk protocol should be retained. From the RCT learning PLB resulted in reduced physiological stress with respect to oxygen desaturation when performing ESWT compared to the control group. Long-term follow-up showed that, in severe COPD perceived benefits persisted in 62% of patients.||en_US