Airway clearance techniques and evidence

ACTPhysiological principlesEvidencePragmatic approach in LAC
ACBTFlexible three phase cyclical technique of breathing control, TEE and FET
Enhances tidal volumes, collateral ventilation and expiratory airflow
Modification for use in LAC to ensure FET is optimised
Physiological background [32]
Bronchiectasis [34]
Cystic fibrosis [25]
No direct evidence
• Clinical experience in LAC demonstrates that caution may be required in FET to ensure balance of airway calibre with creation of equal pressure points
PEPA flow-regulated technique that has three effects: to increase lung volume (functional residual capacity and tidal volume (VT)), to reduce hyperinflation and to improve airway clearance. Positive pressure is then achieved by augmenting expiratory flow against this resistancePhysiological background [35]
COPD [39]
Cystic fibrosis [38]
TBM (improve expiratory airflow) [40]
No direct evidence
• Use in LAC to reduce airway closure during expiration and modify FET
• Caution to prevent airway collapse but not to cause limitation to expiratory airflow
OPEPPEP is applied by blowing out against a variable resistance that produces an oscillation in flow
Individuals breathe out to expiratory reserve volume (ERV) enabling a modulation of both pressure and flow
Physiological background [22]
Bronchiectasis [42]
Cystic fibrosis [45]
COPD [43]
No direct evidence
• Use in LAC with caution as oscillations may cause airway collapse and irritation in some patients
• If used comfortably, may have similar benefits to OPEP
HFCWOPatient wears an inflatable vest attached to a machine that creates positive and negative pressure changes through high-frequency air pulses at a set pressure and frequency. Displacement of the airway walls additionally disengages secretions, enhancing airflow and ciliary beatingPhysiological background [22]
Bronchiectasis [47]
Cystic fibrosis [49, 50]
COPD [48]
No direct evidence
• Clinical experience suggests this technique must be combined with FET (with relevant principles discussed for patients with LAC)
CPAPCreates a “pneumatic splint”, helping to prevent dynamic airways collapse as flow and effort increasePaediatric TBM [51]Extrapolation of knowledge from paediatric TBM although caution required as different conditions
• Clinical expertise/extrapolation of knowledge from use of PEP/high PEP
• Caution required as underlying pathology may be different

ACT: airway clearance technique; ACBT: Active Cycle of Breathing Technique; TEE: thoracic expansion exercise; FET: two forced expiration technique; LAC: large airway collapse; TBM: tracheobronchomalacia; PEP: positive expiratory pressure; OPEP: oscillating expiratory pressure; HFCWO: high-frequency chest wall oscillation; CPAP: continuous positive airway pressure.