Physiotherapy for large airway collapse: an ABC approach

Lizzie J.F. Grillo; Georgie M. Housley; Sidhu Gangadharan; Adnan Majid; James H. Hull

doi:10.1183/23120541.00510-2021

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FIGURE 1
Flow-limiting segment in large airway collapse (LAC). a) Airway with LAC. The flow-limiting segment is limiting the expiratory airflow and/or creating unwanted turbulent airflow due to the invagination of the airway influenced by the equal pressure point theory and wave speed theory. P_pl: pleural pressure; P_alv: alveolar pressure. b) Normal airway. The equal pressure point (EPP) is kept proximal and promotes movement of expiratory airflow to enhance sputum clearance.
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FIGURE 2
Dynamic movements of equal pressure points in different examples of airway physiology. EPP: equal pressure point; FET: forced expiration technique; FLS: flow-limited segment.
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FIGURE 3
The Active Cycle of Breathing Technique.
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FIGURE 4
Visual representation of the physiological mechanism behind the positive expiratory pressure (PEP).
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FIGURE 5
Positive expiratory pressure (PEP) Mask (PEP/RMT© Henleys Medical Supplies, Welwyn Garden City, UK).

TABLE 1

Subjective and objective physiotherapy assessment for a patient with large airway collapse (LAC)

Subjective: Patient's description/report		Objective: Physiotherapist's observations/measurements
A: Airways
NASAL SYMPTOMS Blocked or runny nose Sinus pain Post-nasal drip Altered sense of smell AIRWAY CLEARANCE Technique completed Frequency and length of Rx Efficacy % adherence	COUGH Effectiveness/ease of clearance Triggers Dry/rattling/productive Feeling of airway closure SPUTUM Colour/consistency 24-h volume	NASAL SYMPTOMS Quality of secretions Throat clearing AIRWAY CLEARANCE Observed technique Impact of airway closure on clearance Observed effectiveness	COUGH Nature/sound, e.g. barking/honking sound SPUTUM Viscosity/colour of sputum Microbiology
B: Breathing
BREATHLESSNESS Symptoms Triggers Recovery techniques	VOICE/UA Voice changes, e.g. husky/strained/lost voice Closure/discomfort in throat BREATHING PATTERN Awareness of breathing pattern	BREATHLESSNESS Work of breathing Upper limb fixation Accessory muscle use S_pO₂ Auscultation	VOICE/UA Audible upper airway sounds Quality BREATHING PATTERN Completion of BPAT score -Upper chest versus lower chest -Nose–mouth breathing -Flow/air hunger/RR/rhythm
C: Capacity for exercise
EXERCISE ABILITY Frequency of exercise Intensity of exercise Time spent on exercise Type of exercise Symptoms with exercise -cough/airway closure General physical activity levels Barriers to exercise Use of oxygen/NIV/CPAP for exercise		EXERCISE TESTING 6MWT 1 min STS Ax with and without CPAP/NIV Cough/SOB/WOB/S_pO₂ Breathing pattern changes during exercise UA SYMPTOMS Observed adaptations to breathing Audible airway collapse
Other Ax
SLEEP Quality/duration Epworth sleep score NIV/CPAP history +/− use		OUTCOME MEASURES VAS: ease of clearance/airway closure Dyspnoea-12 BPAT MRC grading Leicester cough questionnaire (LCQ)

Rx: treatment; S_pO₂: oxygen saturation measured by pulse oximetry; Ax: assessment; UA: upper airway; NIV: noninvasive ventilation; CPAP: continuous positive airways pressure; RR: respiratory rate; SOB: shortness of breath; 6MWT: 6-min walk test; 1 min STS: 1-min sit-to-stand test; BPAT: breathing pattern assessment tool; WOB: work of breathing; VAS: visual analogue scale; MRC: Medical Research Council.

TABLE 2

Airway clearance techniques and evidence

ACT	Physiological principles	Evidence	Pragmatic approach in LAC
ACBT	Flexible 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
PEP	A flow-regulated technique that has three effects: to increase lung volume (functional residual capacity and tidal volume (V_T)), to reduce hyperinflation and to improve airway clearance. Positive pressure is then achieved by augmenting expiratory flow against this resistance	Physiological 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
OPEP	PEP 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
HFCWO	Patient 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 beating	Physiological 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)
CPAP	Creates a “pneumatic splint”, helping to prevent dynamic airways collapse as flow and effort increase	Paediatric 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.

Supplementary Materials

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Supplementary material 00510-2021.SUPPLEMENT