Viscoelastic Properties of Bronchial Mucus After Respiratory Physiotherapy in Subjects With Bronchiectasis

Ex-vivo effects of intrapulmonary percussive ventilation on sputum rheological properties

Intrapulmonary percussive ventilation (IPV) has been postulated to enhance mucociliary clearance by improving tracheobronchial sputum rheological properties. The IPV effects on linear (viscoelasticity) and non-linear (flowing) rheological properties of 40 sputum samples collected from 19 patients with muco-obstructive lung diseases were investigated ex-vivo. Each sputum sample was split into 4 aliquots. These aliquots were independently placed in a circuit connected on one side to an IPV device and on the other side to a lung model that simulated spontaneous adult breaths. IPV was superimposed on simulated breathing. Three aliquots were exposed to a different IPV setting, modifying either percussion frequency or amplitude (4 Hz-200 L/min, 10 Hz-200 L/min, 10 Hz-140 L/min). One aliquot was only exposed to breathing (IPV was switched off, control condition). Each aliquot underwent 5 min of the pre-fixed mechanical stimulation before being recollected to proceed to rheological analysis. Neither percussion frequencies nor amplitudes had a significant impact on any sputum rheological properties studied. These results need to be confirmed in vivo.

Airway mucus in pulmonary diseases: Muco-adhesive and muco-penetrating particles to overcome the airway mucus barriers

Airway mucus is a complex viscoelastic gel that provides a defensive physical barrier and shields the airway epithelium by trapping inhaled foreign pathogens and facilitating their removal via mucociliary clearance (MCC). In patients with respiratory diseases, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), non-CF bronchiectasis, and asthma, an increase in crosslinking and physical entanglement of mucin polymers as well as mucus dehydration often alters and typically reduces mucus mesh network pore size, which reduces neutrophil migration, decreases pathogen capture, sustains bacterial infection, and accelerates lung function decline. Conventional aerosol particles containing hydrophobic drugs are rapidly captured and removed by MCC. Therefore, it is critical to design aerosol delivery systems with the appropriate size and surface chemistry that can improve drug retention and absorption with the goal of increased efficacy. Biodegradable muco-adhesive particles (MAPs) and muco-penetrating particles (MPPs) have been engineered to achieve effective pulmonary delivery and extend drug residence time in the lungs. MAPs can be used to target mucus as they get trapped in airway mucus by steric obstruction and/or adhesion. MPPs avoid muco-adhesion and are designed to have a particle size smaller than the mucus network, enhancing lung retention of particles as well as transport to the respiratory epithelial layer and drug absorption. In this review, we aim to provide insight into the composition of airway mucus, rheological characteristics of airway mucus in healthy and diseased subjects, the most recent techniques to study the flow dynamics and particle diffusion in airway mucus (in particular, multiple particle tracking, MPT), and the advancements in engineering MPPs that have contributed to improved airway mucus penetration, lung distribution, and retention.

Evaluation of outcome reporting in clinical trials of physiotherapy in bronchiectasis: The first stage of core outcome set development

INTRODUCTION

The aim of this study is to explore outcomes currently reported in physiotherapy trials for bronchiectasis and investigate the level of consistency in outcome reporting. This mapping of outcomes will be used to inform the development of a core outcome set (COS) for physiotherapy research in bronchiectasis. Outcomes reported in randomised clinical trials (RCTs) and RCT protocols were reviewed and evaluated. We included trials with physiotherapy as the main intervention, including pulmonary rehabilitation, exercise prescription, airway clearance, positive expiratory pressure devices, breathing training, self-management plans, and home exercise program. Medline, CINAHL, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL), and the physiotherapy evidence database (PEDro) were searched from inception using a prespecified search strategy. Records including adult patients with bronchiectasis were included. Outcomes were listed verbatim and categorised into domains based on a pre-specified system, frequency of reporting and sources of variation were inspected.

RESULTS

Of 2158 abstracts screened, 37 trials (1202 participants) and 17 trial protocols were identified. Eighteen different physiotherapy techniques were investigated. A total of 331 outcomes were reported. No single outcome was reported by all trials. The most reported outcomes were lung function (27 trials, 50%), health related quality of life (26 trials, 48.1%), and dyspnoea (18 trials, 33.3%). A list of 104 unique outcomes covering 23 domains was created. Trials focus on physiological outcomes, mainly those related to respiratory system functions. Outcomes related to functioning and life impact are often neglected.

CONCLUSION

Outcome reporting in physiotherapy research for bronchiectasis was found to be inconsistent in terms of choosing and defining outcomes. Developing a core outcome set in this area of research is needed to facilitate aggregation of future trial results in systematic reviews that will in turn inform the strength of evidence for the effectiveness of physiotherapy. Outcome choice should include all stakeholders, including patients.

TRIAL REGISTRATION

This study is registered in the PROSPERO registry under the number CRD42021266247.

Measuring airway clearance outcomes in bronchiectasis: a review

While airway clearance techniques (ACTs) are recommended for individuals with bronchiectasis, many trials have demonstrated inconsistent benefits or failed to reach their primary outcome. This review determined the most common clinical and patient-reported outcome measures used to evaluate the efficacy of ACTs in bronchiectasis. A literature search of five databases using relevant keywords and filtering for studies published in English, up until the end of August 2019, was completed. Studies included randomised controlled trials, using crossover or any other trial design, and abstracts. Studies were included where the control was placebo, no intervention, standard care, usual care or an active comparator. Adults with bronchiectasis not related to cystic fibrosis were included. Extracted data comprised study authors, design, duration, intervention, outcome measures and results. The search identified 27 published studies and one abstract. The most common clinical outcome measures were sputum volume (n=23), lung function (n=17) and pulse oximetry (n=9). The most common patient-reported outcomes were health-related quality of life (measured with St George's Respiratory Questionnaire, n=4), cough-related quality of life (measured with Leicester Cough Questionnaire, n=4) and dyspnoea (measured with Borg/modified Borg scale, n=8). Sputum volume, lung function, dyspnoea and health- and cough-related quality of life appear to be the most common clinical and patient-reported measures of airway clearance treatment efficacy.