TABLE 1

Airway clearance studies in bronchiectasis

First author [ref.]	Design	Duration	Subjects (n)	Intervention	Outcome measures
Munoz [35]	Randomised controlled trial	1 year	44	ELTGOL	Sputum: volume, purulence, colour, microbiology Respiratory function testing: FEV₁ HRQoL: SGRQ Cough-related QoL: LCQ Dyspnoea: mMRC Exercise capacity: 6MWT Exacerbations: frequency, time to first exacerbation Systemic inflammation: venous blood Adherence: self-report diary Adverse events: SpO₂, Borg scale for dyspnoea
Munoz [35]	Randomised controlled trial	1 year	44	Placebo (stretches)
Arif [49]	Randomised controlled trial	4 weeks	60	Antibiotics	Sputum: quantity Respiratory function testing: PEF Dyspnoea: Modified Borg scale Pulse oximetry: SpO₂ Other: auscultation
				Chest PT
				Antibiotics and chest PT
Tsang [41]	Randomised controlled trial	<1 week	15 (acute exacerbation)	PD + breathing + cough	Sputum: wet weight Respiratory function testing: FVC, FEV₁, PEF Patient perception: Likert scale (ease and effectiveness of ACT)
				Flutter + breathing + cough
				Breathing + cough
Herala [50]	Randomised controlled trial	Unclear	15	Thoracic compression Bubble PEP	Transcutaneous partial pressure of carbon dioxide
Nicolini [45]	Randomised controlled trial	15 days	37	HFCWO	Sputum: volume, cell count^# Respiratory function testing: FEV₁, FVC, TLC, RV, MIP, MEP HRQoL: CAT Cough-related QoL: breathing, cough and sputum scale Dyspnoea: mMRC Gas exchange: PaO₂, PaCO₂ Systemic inflammation: C-reactive protein
				Conventional chest PT
				Control (medical therapy)
De Souza [51]	Randomised crossover	10 days	40	Flutter	Sputum: wet and dry weight, adhesiveness, purulence Respiratory function testing: impulse oscillometry Dyspnoea: MRC Patient perception: Likert scales (acceptability, tolerance, difficulty of expectorating sputum) Pulse oximetry: SpO₂, heart rate
				Thoracic compression with deep breathing
				Control (tidal volume breathing)
Silva [42]	Randomised crossover	<2 weeks	40	Flutter	Sputum: wet and dry weight Patient perception: Likert scale (acceptance, tolerability of ACT)
Silva [42]	Randomised crossover	<2 weeks	40	Lung flute
Tambascio [52]	Randomised crossover	10 weeks	17	Flutter	Sputum: adhesiveness, purulence, mucociliary transport, displacement in simulated cough machine, contact angle measurement, inflammatory analysis, microbiology
Tambascio [52]	Randomised crossover	10 weeks	17	Flutter (PEP only)
Herrero-Cortina [43]	Randomised crossover	5 weeks	31	AD	Sputum: wet weight Respiratory function testing: FEV₁, FEV₁% pred, FVC, FVC % pred, FEF_25–75% Cough-related QoL: LCQ Pulse oximetry: SpO₂, heart rate Patient perception: Likert scale (preference for ACT) Adverse events: pulse oximetry, heart rate
				ELTGOL
				Temporary PEP (Uniko)
Semwal [44]	Randomised crossover	1 day	30	ADA	Sputum: volume, wet weight Respiratory function testing: PEF Dyspnoea: Modified Borg Pulse oximetry: SpO₂ Other: Respiratory rate Patient perception: VAS (comfort of ACT)
Semwal [44]	Randomised crossover	1 day	30	Acapella
Svenningsen [53]	Randomised crossover	6 weeks	29 (15 COPD, 14 bronchiectasis)	Aerobika	Respiratory function testing: FEV₁% pred, FVC % pred, FEV₁/FVC HRQoL: SGRQ Exercise capacity: 6MWT Patient perception: patient evaluation questionnaire (cough frequency, dyspnoea, ease in bringing up sputum)
Svenningsen [53]	Randomised crossover	6 weeks	29 (15 COPD, 14 bronchiectasis)	Usual care
Figueiredo [33]	Randomised crossover	9 days	8	Flutter	Sputum: volume Respiratory function testing: Impulse oscillometry (FOT)
Figueiredo [33]	Randomised crossover	9 days	8	Flutter sham
Guimarães [54]	Randomised crossover	24 days	10	ELTGOL	Sputum: dry weight Respiratory function testing: FVC, FEV₁, FEV₁/FVC, FEF_25–75%, IC, VC, TLC, RV
				Flutter
				Control (sitting)
Tambascio [34]	Randomised crossover	9 weeks	18	Flutter	Sputum: mucociliary relative transport velocity, displacement in a simulated cough machine and contact angle measurement
Tambascio [34]	Randomised crossover	9 weeks	18	Flutter (PEP only)
Murray [30]	Randomised crossover	7 months	20	Acapella Choice	Sputum: 24 h sputum volume, microbiology Respiratory function testing: FEV₁, FVC, FEF_25–75%, MIP, MEP HRQoL: SGRQ Cough-related QoL: LCQ Exercise capacity: incremental shuttle walk test Adherence: diary Adverse events: diary (haemoptysis, increased use of short-acting bronchodilator)
Murray [30]	Randomised crossover	7 months	20	No chest PT
Syed [55]	Randomised crossover	<2 days	35	ACBT with PD Conventional chest PT (percussion, vibrations,	Sputum: wet weight Respiratory function testing: FVC, FEV₁, FEV₁/FVC Patient perception: VAS (comfort of ACT)
Syed [55]	Randomised crossover	<2 days	35	PD, coughing, breathing)
Patterson [56]	Randomised crossover	10–12 days	20 (acute exacerbation)	Acapella DM or DH with PD	Sputum: volume/weight Respiratory function testing FEV₁, FEV₁% pred, FVC, VC, PEF Dyspnoea: Borg scale, 15-count breathlessness score Pulse oximetry: SpO₂ Patient symptoms: Interview-Based Questionnaire Patient adherence: diary and weekly phone calls Patient perception: preference
Patterson [56]	Randomised crossover	10–12 days	20 (acute exacerbation)	Usual ACT (ACBT, PEP, huffs, nil)
Patterson [57]	Randomised crossover	2 days	20	Acapella DH and DM with PD	Sputum: weight Respiratory function testing: FEV₁, FEV₁% pred, FVC, FVC % pred, PEF, PEF % pred Dyspnoea: 15 count breathlessness score Pulse oximetry: SpO₂ Patient perception: questionnaire (preference) Other: number of coughs
Patterson [57]	Randomised crossover	2 days	20	ACBT (including percssion, vibrations and PD)
Thompson [58]	Randomised crossover	4 weeks	17	ACBT	Sputum: weight Respiratory function testing: PEF HRQoL: Chronic Respiratory Disease Questionnaire Dyspnoea: Borg scale duration of airway clearance session Patient perception: preference
Thompson [58]	Randomised crossover	4 weeks	17	Flutter
Antunes [59]	Randomised crossover	8 weeks	13	Conventional chest PT (percussion with vibrations, PD) Flutter	Sputum: wet and dry weight Respiratory function testing: FVC, FEV₁, PEF Pulse oximetry: SpO₂, heart rate Other: respiratory rate
Antunes [59]	Randomised crossover	8 weeks	13
Sutton [60]	Randomised crossover	4 days	8	PD + FET Control (sitting)	Sputum: wet weight Respiratory function testing: FEV₁, FVC Other: radio aerosol clearance
Sutton [60]	Randomised crossover	4 days	8	with nebulised saline and nebulised terbutaline
Uzmezoglu [61]	Randomised comparative	4 weeks	40	Flutter ACBT with PD	Sputum: change in sputum production Respiratory function testing: FEV₁ % pred, FVC % pred, FEV₁/FVC, PEF % predicated HRQoL: SF-36 Dyspnoea: Modified Borg, MRC Patient symptoms: questionnaire
Uzmezoglu [61]	Randomised comparative	4 weeks	40
AbdelHalim [46]	Randomised comparative	2 weeks	30 (acute exacerbation)	ACBT + PD Conventional PT (PD	Sputum: wet volume, microbiology Respiratory function testing: FEV₁, FVC, MMEF, FEV₁/FVC QoL: LCQ Dyspnoea: mMRC Gas exchange: PaO₂, PaCO₂, P_A–aO₂ Adverse events: not defined
AbdelHalim [46]	Randomised comparative	2 weeks	30 (acute exacerbation)	+ diaphragmatic breathing + percussion)
Ramos [62]	Randomised comparative	4 days	22	PD + coughing PD + percussion +	Sputum: wet and dry weight, viscoelasticity
				coughing
				PD + huff
				Control (coughing)
Eaton [63]	Prospective randomised comparative	7 days	37	Flutter ACBT ACBT + PD	Sputum: wet weight, volume Respiratory function testing: FEV₁% pred, FVC % pred Dyspnoea: Borg scale Pulse oximetry: SpO₂ Patient perception: Likert scales (acceptability and tolerability, preference)


Svenningsen [64]	Randomised comparative	3 weeks	30	Aerobika	Respiratory function testing: FEV₁, FVC, D_{LCO_sb} Exercise capacity: 6MWT HRQoL: SGRQ Imaging: CT, MRI Patient perceptions: patient evaluation questionnaire
Svenningsen [64]	Randomised comparative	3 weeks	30	Health control
D’Abrosca [65]	Retrospective cohort study	Minimum 10 days of ACT (4-year data collection period)	162 (97 COPD, 65 bronchiectasis)	Temporary PEP (Uniko)	Respiratory function testing: FEV₁, FEV PaO₂% pred, FVC, FVC % pred, FEV₁/FVC, FEF_25–75%, FEF_50% Gas exchange: PaO₂
D’Abrosca [65]	Retrospective cohort study	Minimum 10 days of ACT (4-year data collection period)	162 (97 COPD, 65 bronchiectasis)	PEP (mask) during a pulmonary rehabilitation programme
Grillo [66]	Prospective Cohort study	∼2 weeks	90 (32 stable, 32 exacerbation, 26 control)	Usual ACT (type of ACT not defined): stable Usual ACT (type of ACT not defined): exacerbation Healthy control	Respiratory function testing: LCI, FEV₁, transfer factor for CO, CO transfer coefficient

ELTGOL: slow expiration with the glottis open in lateral posture; FEV₁: forced expiratory volume in 1 s; HRQoL: health-related quality of life; SGRQ: St George's Respiratory Questionnaire; QoL: quality of life; LCQ: Leicester Cough Questionnaire; mMRC: modified Medical Research Council Questionnaire; 6MWT: 6-min walk test; SpO₂: oxygen saturation measured by pulse oximetry; PT: physiotherapy; PEF: peak expiratory flow; PD: postural drainage; FVC: forced vital capacity; ACT: airway clearance technique; PEP: positive expiratory pressure; HFWCO: high frequency chest wall oscillation; TLC: total lung capacity; RV: residual volume; MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure; CAT: COPD assessment tool; PaO₂: arterial oxygen tension; PaCO₂: arterial carbon dioxide tension; MRC: Medical Research Council Scale; AD: autogenic drainage; FEF_25–75%: forced expiratory flow at 25–75% of FVC; VAS: Visual Analogue Scale; FOT: forced oscillatory technique; IC: inspiratory capacity; VC: vital capacity; ACBT: active cycle of breathing technique; DM: <definition>; DH: <definition>; FET: forced expiratory technique; SF-36: Short Form 36; MMEF: maximal mid-expiratory flow; P_A–aO₂: alveolar–arterial oxygen tension difference; D_{LCO_sb}: single breath diffusing capacity of the lung for carbon monoxide; CT: computed tomography; MRI: magnetic resonance imaging; LCI: lung clearance index. ^#cell count (white blood cells, red blood cells, neutrophils and lymphocytes).