Background: Chronic obstructive pulmonary disease (COPD) is characterised by symptomatic dyspnoea and reduced exercise tolerance, in part as a result muscle weakness, for which inspiratory muscle training (IMT) may be useful. Excess mucus hypersecretion commonly coexists in COPD and may lead to reduce ventilation, further impacting on breathlessness. Devices for sputum clearance may be employed to aid mucus expectoration. This trial aimed to explore the effectiveness of a combined IMT and high-frequency airway oscillating (HFAO) device in the management of dyspnoea.
Methods: This was a double-blinded, randomised sham-controlled trial which recruited symptomatic patients with COPD. Patients were randomised to either a HFAO device (Aerosure) or sham device for 8 weeks, three times a day. The primary outcome was the Chronic Respiratory Questionnaire dyspnoea (CRQ-D) domain. Pre-specified subgroup analyses were performed including those with respiratory muscle weakness, excessive sputum and frequent exacerbators.
Results: 104 participants (68% men, mean (SD) age 69.75 years (7.41), forced expiratory volume in 1 s per cent predicted 48.22% (18.75)) were recruited to this study with 96 participants completing. No difference in CRQ-D was seen between groups (0·28, 95% CI -0.19 to 0.75, p=0.24), though meaningful improvements were seen over time in both groups (mean (SD) HFAO 0.45 (0.78), p<0.01; sham 0.73 (1.09), p<0.01). Maximal inspiratory pressure significantly improved in the HFAO group over sham (5.26, 95% CI 0.34 to 10.19, p=0.05). Similar patterns were seen in the subgroup analysis.
Conclusion: There were no statistical differences between the HFAO and the sham group in improving dyspnoea measured by the CRQ-D.
Trial registration number: ISRCTN45695543.
Keywords: perception of asthma/breathlessness; pulmonary rehabilitation; respiratory muscles.
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