10 January, 2007

Airway Clearance

There are a number of approaches to getting rid of excess mucus if coughing is exhausting or not effective.

The texture of the lungs is something like a very large kitchen sponge about 25-30cm long (10-12 inches). Each comprises millions of air cells or sacs. However, in the lungs these air sacs (alveoli) are the end points in a dense network of tiny tubes that join up with bigger tubes that eventually join up with the trachea, the main breathing tube that joins the back of your throat to your lungs. The airways are the breathing tubes that connect up the air sacs.

You need to apply pressure to squeeze out the water from a wet kitchen sponge. Similarly you have to apply pressure to the lungs to expel excess mucus and clear your airways. Applying direct pressure or force to your lungs is just not feasible!

The two other kinds of pressure are used in airway clearance.

Gravitational force
By lying on your side or face down with a pillow under your stomach or hips the mucus will drain down from the base of your lungs towards the trachea where it can be more easily coughed up. This is called Postural Drainage


  • You may notice a cough-full of mucus arises after you’ve bent down to put on your socks and shoes or to get something out of a low drawer.

It takes a long time to drain a wet sponge placed on the draining board of the kitchen sink. Likewise used on its own, gravity is a fairly ineffective means of clearing the airways because the finest tubes in the lungs are so narrow.

Often postural drainage is combined with vibration, by someone else repeatedly clapping or firmly patting the person on the back using the cupped hand and forearm for 5-10 minutes. Correctly done this causes vibrations in the chest which are transferred to the airways and to the mucus in them. The “banging” or “chest clapping” is known as Percussion (like the percussion section of a band or orchestra). Chest shaking or vibration while placing hands on your chest might also be carried out while you breathe out.

  • Percussion is a little like hitting the bottom of a tomato sauce bottle to get the last of the sauce out.
  • Shaking a rain-soaked umbrella shows how vibration can result in wet surfaces letting go of their excess fluid.

Postural Drainage and Percussion (together) are frequently called Chest Physiotherapy, or might even be shortened to Physiotherapy. Chest physiotherapy has been a long established and widely used method of moving mucus, although newer approaches are taking over, especially ones which people can do for themselves rather than requiring an assistant.

Some people with chronic lung disease also find the newer methods more comfortable than lying in a face-down position, which sometimes worsens gastro-oesophageal reflux or brings about lower oxygen saturation.

Postural drainage has also been combined with breathing exercises (see below).

Air pressure
Air - a mixture of gases - flows from a place of higher pressure to a place of lower pressure, until the pressure is equalised – provided there are no barriers to the free movement of the air. This principle forms the basis of such things as aerosol cans and our daily weather!

Example: If you blow up a balloon, you increase the pressure inside the balloon, in comparison with the normal air pressure outside the balloon. When you let go the mouth of the balloon, compressed air molecules inside the balloon rush out until the air pressure inside the balloon is similar to that outside.

Likewise, special breathing techniques, which systematically modify the air pressure inside your lungs, can encourage mucus to move out of your lungs.

Breathing techniques
You can expand all the air sacs in your lungs by simply taking a number of deep breaths, holding your breath briefly with each. When you let go of the breath, the mucus is encouraged to move in the direction of the air – up towards your mouth. By following the deep breaths with a few huffs (or forced expirations) the mucus will move up the larger airways until they are high enough up to cough out the rest of the way. Huffs are rather like loudly whispering the word “hough” (rhymes with cough) or like forcefully blowing out a candle.

A particular pattern of combining these breathing techniques is the basis of the Active Cycle of Breathing Technique (ACBT), developed by New Zealand pulmonary physiotherapist Jennifer Pryor in the 1970s and now used quite widely in Australia.

Most physiotherapists - and all pulmonary physiotherapists - have been trained to teach this technique to people who have trouble getting mucus up. It is simple to learn, safe and takes only 15-20 minutes.

It involves a special pattern of three different types of breathing:
  • relaxed normal breathing expanding the abdomen when you breathe in,
  • deep breaths which are held for a few seconds, and
  • huffing or forced expiration, described above.

More information about this technique can be found from your physiotherapist or at:
Keeping your lungs clear - Lung Foundation Australia
Active Cycle of Breathing - rather cheesey YouTube video

ACBT has been combined with postural drainage in the head-down position at various angles, but this has no advantages over ACBT done lying horizontally and is certainly less comfortable (Cecins, et al 1999[1]). The angle makes no difference to the amount of mucus produced - so you may as well be comfortable.

Autogenic Drainage was developed in Belgium and involves related breathing and air pressure principles.
It uses breaths of different sizes to perform different roles:
  • unsticking the mucus,
  • collecting the mucus in particular sections of the lungs and
  • evacuating the mucus.
Autogenic drainage can be adapted to each person’s particular lung and mucus problems. The technique is said to be less likely to cause uncontrolled coughing than others.

Autogenic Drainage is not as widely available in Australia as ACBT and is said to take longer than ACBT to learn and practice correctly. Consult a pulmonary physiotherapist if you wish to learn Autogenic Drainage or click here

Positive Expiratory Pressure (PEP)
Positive expiratory pressure involves breathing out against some form of resistance. The back pressure that builds up in your lungs helps open up all the smaller airways, enabling the mucus to get moving. This is important in damaged lungs where airways may tend to collapse.
PEP is also thought to encourage mucus trapped behind a mucus plug to find an alternative escape route.

Examples of pressure against breathing out:
  • Purse your lips and breathe out through the narrower opening
  • Try blowing bubbles by breathing out through a straw standing in a large glass or plastic bottle of water. If you add more water it is harder to blow bubbles. When you reduce the water level it gets easier. The water exerts a stronger pressure against your out-breath than simply breathing out through your mouth normally. Deeper water exerts more pressure.

Various gadgets have been developed to produce either a constant or variable resistance when you breathe out through them. A physiotherapist can advise which is suitable for you.

They include:
  • Constant resistance: PEP breathing mask which fits over the mouth and nose with PEEP valves of various resistances (eg Astra), Pari™ (PEP in a nebuliser)
  • Variable or oscillating resistance: Acapella ®, Flutter®, R-C Cornet®
The vibrating or oscillating positive pressure is thought to improve mucus clearance in much the same way as Percussion by setting up vibrations in the mucus.

However, these devices are not magic bullets. They must be used correctly and regularly; and they don’t work for everyone. Pressure and oscillation settings must be adjusted to the level which is right for each person.

The devices can help some people use their breath more effectively to move the mucus. All require instruction - the leaflet enclosed with the product is usually not enough. You may not find them at your local pharmacy, although a physiotherapist will be aware of suppliers in your area and can demonstrate how to use them.

Getting air into all parts of your lungs helps move mucus. One of the most effective ways of ensuring this is to exercise enough to get breathless, and the best exercise for people with lung disease is walking. You may notice you cough up mucus immediately after you finish your regular walk, or during a rest break in the course of your walk. This shows you just how effective walking is in moving mucus – in addition to its many other benefits.

It is recommended that people with chronic lung disease walk for 20-30 minutes, 4-5 times a week – every day if possible. If you have not exercised like this for a long time or you have other health problems, you may need to:
  • check with your doctor whether this is suitable for you and
  • ask for referral to a pulmonary rehabilitation program to get you started in a safe and gradual way
This section comes at the end for a reason. At present the most that medication can do is help thin out the mucus or open up the airways as much as possible. You will still have to do something to get the thinner mucus up and out of your open airways using one or more of the techniques described.

Medication however may be needed in specific situations: People with cystic fibrosis produce particularly sticky mucus which is always difficult to clear - even when you drink plenty of water. If your doctor has advised you to limit your fluid intake or you are unable to exercise, you may need to take mucus-thinning drugs (mucolytics), perhaps just for a short period during an exacerbation or acute infection.

Ask your doctor or pharmacist about mucolytics suitable for you. Some are available without prescription, such as bromhexine hydrochloride, sold in Australia as Bisolvon Chesty tablets. They come in a number of forms – as tablets or liquid you swallow, as a liquid for use in a nebuliser, or as an inhaled powder. Salt solution (saline) - either normal strength, or stronger - can be used in a nebuliser to thin out your mucus. If you do not use a nebuliser ask your pharmacist or pulmonary physiotherapist.

If you have a respiratory infection – acute or chronic – it is unwise to take any over-the-counter cough mixture - unless you have discussed it carefully with your doctor. Some cough medicines suppress your cough which may be dangerous if you have a chest infection.

Some new drugs are under development to control the production of mucus.

People with chronic lung disease may regularly take
  • bronchodilators (relievers which relax the smooth muscles lining the airways, opening them up);
  • corticosteroids (preventers) which reduce inflammation or swelling in the airways, preventing them from getting narrower.
They are often taken using an inhaler or “puffer”. Both groups of drugs have the effect of making the airways as open as possible, making it easier to move mucus.

If you take these medications it is recommended to use them before any of the airway clearance techniques described above – chest physiotherapy, breathing techniques, walking. This will enable you to get the maximum benefit possible.

Which airway clearance technique?
There is no evidence that proves that one of these techniques is better than all the others - apart from there being no particular angle to do postural drainage (mentioned above).
Reviews of airway clearance research suggest that you should do what works for you and what you can see yourself doing as often as needed.

Airway Clearance Guidelines

Keep up the fluids: Always drink plenty of water (at least 2 litres a day) to keep your mucus as thin as possible, unless your doctor has directed you to limit your fluid intake for some other health reason. Avoid caffeine drinks as these tend to dehydrate. When it’s cold you might prefer warm water. Saline or hypotonic saline nebulisers can also help thinning sticky hard to shift mucus.

Walk for 20-30 minutes a day 4-5 times a week. If this is currently too difficult, ask your doctor to refer you for pulmonary rehabilitation. When you are unwell walk a slightly shorter distance and pause to rest more often.

Practise one of these airway clearance techniques regularly – particularly when mucus clearance continues to bother you - even if you walk regularly and drink plenty of water. Also remember to practise one of these techniques during an acute infection or exacerbation when you have extra mucus.

In the early stage of pneumonia airway clearance may be ineffective. Resume your airway clearance technique once you can feel that the mucus is starting to move.

When there is a medical reason why you cannot walk (other than breathlessness) practice one of these airway clearance techniques regularly.

Monitor your mucus
Work out how often you need to use these techniques by listening to your body.

Increased mucus could be making your breathlessness worse than usual. Discuss with your doctor whether temporary airway inflammation or narrowing might also be contributing to your breathlessness.

Visit your doctor if your mucus changes colour – gets darker, particularly if you begin to feel unwell, very tired, more breathless than usual or have a temperature (see box at right).

More information
Your physiotherapist, especially those who specialise in pulmonary disease, (called respiratory therapist in USA). Ask the Australian Physiotherapy Association to recommend one in your area. The local cystic fibrosis association may be able to help you find a suitable physiotherapist.
Your general practitioner
Your respiratory physician or “chest doctor” 

Ref [1] Cecins NM, Jenkins SC, Pengelly J, Ryan G. The Active Cycle of Breathing Techniques – to Tip or not to Tip? Respiratory Medicine, 1999, 93 (9): 660-665.


Anonymous said...

Excellent guidelines for people with lung disease
Nebulised Normal or Hypertonic Saline has been invaluable for me & is worth considering to assist mucous clearance

Anonymous said...

Thank you so much for this hugely helpful posting. Happy New Year from Wales, UK !

Tasos said...

When people with mild / moderate bronchiectasis should see the doctor? when the colour of phlegm turn greenish or when the quantity of phlegm is increasing? I was told that I should see the doctor when my phegm turns green and take antiviotics. Is it correct? Assumng not much fatigue or fever.?
Please help

Anonymous said...

Hi Jenny, I just want to thank you very much for all the information you've provided :D)