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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. It is known as ‘manual insufflation-exsufflation’ and can be applied via a mask, mouthpiece, endotracheal or tracheostomy tube.
In conditions such as spinal cord injury or neuromuscular disease an individual may require assistance to cough using manual techniques or a medical device. 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.
- 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
- Subjectively 'chesty'
- Audible secretions at the mouth
- Crackles heard on auscultation
- Tactile fremitus
- 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
Raised intracranial pressure (ICP)
Recent upper GI surgery
|Manual assisted cough||Cough assist device|
|Immediately following surgery
- Cardiovascular instability
- High Oxygen requirements
- Asthma or air trapping
- Full tummy!
- Abdominal distension
- Chest soreness
- 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 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 procedure and accustom patient to mask with machine off.
- Switch machine on and allow patient to feel with their hand
- Set pressures low to begin with (10-15cmH2O) to allow 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
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