Airway clearance techniques: overview and choice

1Why airway clearance is needed

Healthy airways clear mucus by the mucociliary escalator (cilia sweep a thin mucus layer upwards) and by coughing. Airway clearance techniques (ACTs) are needed when:

• there is too much mucus, or it is too thick (bronchiectasis, cystic fibrosis, COPD with chronic bronchitis, chest infection);
• the cilia work poorly (smoking, cystic fibrosis, ciliary dyskinesia, dry gas through a tracheal tube);
• the cough is weak or painful (neuromuscular disease, after surgery, sedation).

Aims: remove mucus, reduce infections and the "vicious cycle" of infection and inflammation, improve ventilation and gas exchange, reduce cough and breathlessness, and improve quality of life.

2Classification

• Breathing techniques: active cycle of breathing technique (ACBT), forced expiration technique and huffing, autogenic drainage, directed or assisted cough.
• Gravity and manual techniques: postural drainage, percussion, vibration, shaking.
• Positive expiratory pressure devices: PEP mask, oscillating PEP (Flutter, Acapella), bottle PEP.
• Mechanical devices: chest wall oscillation vest, intrapulmonary percussive ventilation, cough assist (insufflation–exsufflation), IPPB.
• Exercise (increases ventilation and loosens mucus).
• Adjuncts: hydration and humidification, nebulised saline (normal or hypertonic), mucolytics, bronchodilator before treatment.
• Suction when the patient cannot cough secretions out.

3Application, advantages and disadvantages (S19, W24)

4Choosing a technique

• No single technique is best for everyone (BTS/ACPRC 2009); short-term studies show they all help clear sputum. Choose by the patient's age, condition, ability, preference and what they will actually keep doing.
• Children: infants need modified postural drainage, gentle percussion and active play; older children PEP, bubble PEP and ACBT.
• Unstable airways or wheeze with forced breaths: autogenic drainage, PEP.
• Weak cough: assisted cough, cough assist, suction.
• Order with medicines: bronchodilator → mucoactive drug (for example hypertonic saline) → airway clearance → inhaled antibiotic or steroid.
• Review the technique regularly; adjust frequency during exacerbations.

5Mucus removal in chronic respiratory disease (7 marks in W19)

1. Assess: daily sputum amount and colour, how easily it comes up, X-ray or CT (which lobes), breathlessness, previous techniques.
2. Prepare the mucus: enough fluids; humidified or nebulised saline if sputum is thick; bronchodilator first in reactive airways.
3. Daily routine: one main technique (ACBT, autogenic drainage or oscillating PEP), in a gravity-assisted position for the worst lobe if tolerated; 10–30 minutes, once or twice a day.
4. Exacerbation plan: increase to 2–3 times a day; early medical review for antibiotics.
5. Exercise: regular aerobic exercise as part of pulmonary rehabilitation.
6. Pelvic floor: ask about urine leakage with coughing (common in women) and teach pelvic floor contraction before huffs and coughs.
7. Review: outcome measures such as sputum weight, cough or bronchiectasis quality-of-life scores, exacerbation count.

6Indications of bronchial hygiene therapy (3 marks in W25)

• Large amounts of sputum (classically more than about 25–30 mL a day) or difficulty clearing it.
• Mucus plugging with lobar or segmental collapse.
• Weak or painful cough: neuromuscular disease, after surgery, sedated or ventilated patients.
• Chronic suppurative lung disease (bronchiectasis, cystic fibrosis) as a daily routine.

7Exam corner

Past questions (MUHS, 2016–2026)

• 7-mark questionsVarious airway clearance techniques: application, advantages and disadvantages of each (S19). Mucus removal techniques in chronic respiratory disease (W19). Various airway clearance techniques (W24).
• 3-mark questionThree indications of bronchial hygiene therapy (W25).

Answer skeleton: "various airway clearance techniques", 7 marks

1. [1] Why: mucociliary clearance and cough fail; aims of ACTs.
2. [1] Classification list.
3. [4] The comparison table for 5–6 techniques.
4. [1] Choosing: no single best technique; patient factors; order with medicines.