Airway clearance techniques explained in a simple way

1. Principles of Airway
clearance
P. Madhan Kumar

2. Outline
• Importance of airway clearance techniques
• Mucociliary clearance factors
• Airway clearance physiology
• Airway clearance techniques

3. Importance of airway clearance techniques
• Therapy should be started before development of lung disease.
• Airway clearance techniques improves mucociliary clearance.
• Decreases mucus plugging and removes the secretions containing inflammatory
cells and by products.
• Removes the bacteria and there by decreasing the inflammation.

4. Factors impairing mucociliary clearance
• Quantity and viscosity of mucus
• Size of bronchi and bronchiolar aperture
• Ciliary beat frequency
• Shear force by the airflow

5. Airway clearance physiology
• Mucus is produced by bronchial glands in the bronchi and goblet cells in bronchioles.
• Factors which decide clearance of mucus from airways.
– The elastic recoil pressure is affected by thoracic expansion and lung compliance
– The bronchial wall stability is determined by cartilage and elastic resistance

6. Airway clearance
techniques

7. Airway clearance techniques
• Postural drainage and percussion *
• Active cycle of breathing techniques*
• Autogenic drainage
• Positive expiratory pressure
• Oscillating positive expiratory pressure*
• High frequency chest compression*
• Intrapulmonary percussive ventilation
• Exercise
* Will be demonstrated

8. Cough - Mechanism
Increased intrapulmonary pressure build up behind the glottis
Glottis opens
Supramaximal expiratory and turbulent airflow
High linear velocity (high kinetic energy)
• However ,sometimes clearance of secretions from terminal airways may be not be
complete due to collapse ,as there is minimal cartilage.

9. Huff coughing
• Forced expiratory maneuver
• Initiated from mid to low lung volumes – With partial open glottis
• Creates a shearing force which clears secretions during the prolonged expiration.

10. Postural drainage with percussion - Mainstay of Rx
• Gravity to enhance mucus movement to
the larger airways.
• At different positions, ventilation to
different part of lung will vary.
• Redistribution of ventilation can alter the
airway patency and movement of
particles
• Adjunct used : Percussion and vibration
techniques.

11. Postural drainage and percussion - Mainstay of Rx
• Percussion:
Increases intrathoracic pressure
Transmitting vibration through the chest wall
Loosening the secretion
• Drawbacks in Percussion (In some
children)
– Discomfort, pain, hypoxemia, arrhythmia &
bronchospasm
– Worsening of underlying GERD

12. Active cycle of breathing technique(ACBT)
• It is a forced expiration technique.
• Thoracic expansion gets air in behind the
secretion to loosen it.
• The increase in air flow decreases the
viscosity of the mucus
• These sequential steps aid in clearing
secretions

13. Autogenic drainage –For older children who can
understand instructions
• Involves breathing at different lung volumes to
improve secretion clearance.
• Patient is trained to breathe at low volume, then
mid lung volume, then full capacity followed by
forced expiration and huffing
• Phases:
– Unstick: Low lung volume
– Collect: Mid lung volume
– Evacuate: Forced expiration
• Slow inspiration provides optimal
humidification, warming of the inspired air and
decreased turbulent airflow which prevent
coughing.

14. Oscillating positive expiratory pressure (Micro
cough) -Eg acapella
• Combines positive expiratory pressure with
high frequency oscillations (5 to 25 cmH20).
• Breaking mucus bond and decreases viscosity
• Decreases the dynamic collapsibility of the
unstable airway
• Oscillation may enhance Ciliary beat
frequency

15. Oscillating positive expiratory pressure (Micro
cough)
• Principle :
The airflow causes the rocker to move in one direction.
The rocker, counterweighted by the magnet, moves back
into its original position with a see-saw action
Causing the vibration and resistance to airflow which is
then transmitted to the lungs.
This resistance to the airflow will help keep airways open
to get air behind the mucus and help it move upwards
The vibration will help to loosen secretions from airways
and move them up more easily for effective clearance.

16. High frequency chest compression - VEST
• Increases tracheal mucus clearance by 240-
340%
• Frequency of 5 – 25 Hz
• It causes 2-3 l/s of expiratory flow
• Decreases mucus viscoelasticity
• Principle:
Increased mucociliary clearance is made possible
by increasing the expiratory flow
Moves centrally

17. Exercise
Exercise mode Program specifics Outcome
Running 30 min, three times a week for 3
months
Increased peak VO2
Increased peak working capacity
Decreased heart rate
Cycling 3 – 13 Weeks Increased peak VO2
Treadmill 12 Weeks Increased peak VO2
Swimming Increased peak VO2
Stair stepping 12 Months Increased peak working capacity
Multimodal Jog, Swimming, Cycling Increased peak VO2
Decreased blood lactate
Increased peak working capacity
VO2 – Oxygen consumption

18. Reference
• Text book:
– Cystic fibrosis by Hodder Arnold
• Reference:
– Sontag MK, Quittner AL, Modi AC , et al; Investigators and Coordinators of the Airway
Secretion Clearance Trial. Lessons learned from a randomized trial of airway secretion
clearance techniques in cystic fibrosis. Pediatr Pulmonol 2010; 45 (3) 291-300
– McIlwaine MP, Alarie N, Davidson GF , et al. Long-term multicentre randomised controlled
study of high frequency chest wall oscillation versus positive expiratory pressure mask in
cystic fibrosis.Thorax 2013; 68 (8) 746-751
– Pryor JA. Physiotherapy for airway clearance in adults. Eur Respir J 1999; 14 (6) 1418-1424