Assisted Coughing


Philips Cough assist Device for airway clearance[1]

The cough assist helps to clear secretions by applying a positive pressure to fill the lungs, then quickly switching to a negative pressure to produce a high expiratory flow rate and simulate a cough.[2] It is known as ‘manual insufflation-exsufflation’ and can be applied via a mask, mouthpiece, endotracheal or tracheostomy tube.[3]

It is most useful in patients with an ineffective cough due to muscle weakness, in conditions such as muscular dystrophies, myasthenia gravis, SMA, Spinal cord lesions, MND etc.[4][5][6]

In conditions such as spinal cord injury or neuromuscular disease, an individual may require assistance to cough using manual techniques or a medical device.[7] [8]Manual assisted cough is the compression of the diaphragm by another person to replace the work of abdominal muscles in order to facilitate a cough. A medical device can be used to assist coughing effort by a positive pressure breath followed by a rapid change to negative pressure.[9]


  • A patient unable to clear secretions effectively due to muscle weakness
  • Peak cough flows of <180 L/min are unlikely to be effective at clearing secretions
  • Can be useful in preventing respiratory complications due to secretion retention and poor tidal volumes[10]

Clinical Presentation

  • Subjectively 'chesty'
  • Audible secretions at the mouth
  • Crackles heard on auscultation
  • Tactile fremitus
  • Hypoxemia
  • Non-productive cough
  • Poor inspiratory efforts


Manual assisted cough Cough assist device
Direct pressure should be avoided to rib fractures or surgical sites. Undrained pneumothorax

Frank haemoptysis


Facial fractures

CVS instability

Raised intracranial pressure (ICP)

Recent upper GI surgery

Lung abscess



Manual assisted cough Cough assist device
Immediately following surgery

Paralytic ileus

Rib fractures

Raised ICP

Undrained pneumothorax



Unstable spine

Oxygen dependency



Patient compliance

Airway obstruction



  • Cardiovascular instability
  • Coagulopathy
  • High Oxygen requirements
  • Asthma or air trapping
  • Full tummy!

Side Effects

  • Abdominal distension
  • Chest soreness
  • Fatigue
  • Oxygen desaturation

Setting Up the Cough Assist

  • Plug in the cough assist and ensure it is on a flat, stable surface
  • Set up the circuit – machine, filter, tubing, mask
  • Position patient as needed

First, set the expiratory pressure

  • Turn on the machine and set to MANUAL
  • Occlude the tubing with your gloved hand and push the manual control to EXHALATION   
  • Observe pressure gauge and adjust to the desired level using the main PRESSURE CONTROL

Next, set the inspiratory pressure

  • Inspiratory pressure matches the Expiratory pressure when the INHALE PRESSURE dial is turned to the far right.
  • To reduce the inhale pressure, occlude the tubing and push the manual control to the right (inhalation phase)
  • Gently turn the inhale pressure dial to the left. When fully to the left, it will be 50% of the set expiratory pressure
Guide to pressures:
Adult Up to 40 cmH2O
Age 5-12 20 – 30 cmH2O
Child<5 Up to 20cmH2O


Set the Flow Rate

  • The inhale flow rate can be adjusted for comfort and effectiveness. Turned to the left is maximum flow rate and to the right is slower

Finally, set the cycle timing

  • The cough assist can be used in Automatic or Manual modes.
  • Manual mode is operated by moving the switch from inhale to exhale manually, coordinating with the patient's breathing
  • Automatic mode allows the machine to cycle automatically through inspiration, expiration and pause


  • Gain consent
  • Carry out any chest physio techniques prior to cough assist to optimise treatment and position patient as indicated.
  • Explain the procedure and accustom patient to mask with machine off.
  • Switch the machine on and allow the patient to feel with their hand
  • Set pressures low to begin with (10-15cmH2O) to allow the patient to acclimatise
  • Choose manual or automatic mode and build up pressures as tolerated to gain adequate secretion removal. Always start with the inspiratory phase
  • Oxygen can be entrained via nasal specs or t-piece if needed.
  • Encourage patient to cough with the breath out
  • 5 breaths in and out at a time followed by 30-60 sec rest. Repeat up to 10 times as needed. Usually, 3-5 ‘cycles’ are enough to produce a cough
  • Cough assist is for intermittent use and should not be used for >5 mins
  • Observe post-treatment and reassess for improvement
  • Document treatment details and effects

Cough Assist Device Troubleshooting

Please also see non-invasive ventilation for more information on positive pressure devices



  2. Finder J. Overview of airway clearance technologies. July 2006. Available at: articles/2006-07_06.asp. Accessed August 12, 2007
  3. Bach JR. Mechanical insufflation/exsufflation: has it come of age? A commentary. Eur Respir J. 2003;21:385-386.
  4. Finder JD, Birnkrant D, Farber CJ, et al. Respiratory care of the patient with Duchenne muscular dystrophy: ATS consensus statement. Am J Respir Crit Care Med. 2004;170:456-465.
  5. Chatwin M, Ross E, Hart N, Nickol AH, Polkey MI, Simonds AK. Cough augmentation with mechanical insufflation/exsufflation in patients with neuromuscular weakness. Eur Respir J. 2003;21:502-508.
  6. Sancho J, Servera E, Vergara P, Marin J. Mechanical insufflation-exsufflation vs tracheal suctioning via tracheostomy tubes for patients with amyotrophic lateral sclerosis. Am J Phys Med Rehabil 2003;82(10750-753.
  7. Vianello A, Corrado A, Arcaro G, Gallan F, Ori C, Minuzzo M, Bevilacqua M. Mechanical insufflation-exsufflation improves outcomes for neuromuscular disease in patients with respiratory tract infections. Am J Phys Med Rehabil 2005;84:83-88.
  8. Garstang SV, Kirshblum SC, Wood KE. Patient preference for in-exsufflation for secretion management with spinal cord injury. J Spinal Cord Med 2000;23(2)80-85.
  9. 9.0 9.1 9.2 Harden, B. (2004). Emergency physiotherapy: An on-call survival guide. 1st ed. Edinburgh: Churchill Livingstone.
  10. Tzeng AC, Bach JR. Prevention of pulmonary morbidity for patients with neuromuscular disease. Chest. 2000;118:1390-1396.
  11. Miske LJ, Hickey EM, Kolb SM, Weiner DJ, Panitch HB. Use of the mechanical in-exsufflator in pediatric patients with neuromuscular disease and impaired cough. Chest. 2004;125:1406-1412.