Respiratory Management and NIV

Information about respiratory assessment, breathing muscle weakness, Non-Invasive Ventilation (NIV), secretion management and assisted cough.

Assessment of Breathing Muscles

At most clinic visits you will be invited to perform one or more simple breathing tests (known as SVC, SNIP & PCF) which help us to monitor the strength of your breathing muscles. We will also ask you some questions about your breathing. Some questions will relate to issues which may not seem directly connected to your breathing, these include:

  • Sleep Quality

  • Appetite

  • Morning Headaches

Changes in these areas can be the result of a change in the strength of your breathing muscles. Assessing your breathing regularly allows us to detect changes early and thus offer treatment as soon as it might be useful for you.


SVC (Slow Vital Capacity)

A measure of how much air you can get in to your lungs. You will be asked to take a big breath in and then to blow it all out steadily into a machine via a mask. You will be asked to repeat the test 3 times but with a short rest in between each blow.

SNIP (Sniff Nasal Inspiratory Pressure)

A way of measuring how strong your inspiratory (breathing in muscles) muscles are. A small probe will be placed in one of your nostrils and you will be asked to sniff hard. Again, this test will be repeated 5-10 times but you will have a rest in between each sniff.

PCF (Peak Cough Flow)

A measure of how effective your cough is. You will be asked to take a big breath in and then cough as hard as you can into a peak flow meter via a mask. This test will be repeated 3 times with a rest in between each test.

What Treatment Options Are Available?

Non-Invasive Ventilation (NIV)

Weakness of the respiratory muscles can occur just as it does in other muscle groups (limbs, trunk, throat). Whilst we cannot stop this weakness we can offer mechanical support which improves your breathing and quality of life. This support is usually known as NIV.

NIV is a way of helping get a little more air in to your lungs as you breathe to ensure that you fill your lungs every time you breathe in (inhale) and thus are able to breathe out more effectively (exhale). This ensures that you move air in and out of your lungs (ventilate) as efficiently as possible and achieve appropriate levels of oxygen and carbon dioxide in your blood. Improved ventilation should result in an improvement in the symptoms associated with respiratory weakness.

NIV is provided by a small machine which acts like a small compressor, delivering air under some positive pressure to you every time you breathe. The air is delivered via a tube and a mask. The machine is portable (wt 4kg).

Research has shown that people with MND and weak breathing muscles who use NIV regularly have an imp

Our myBreathing website contains thorough information and guidance regarding NIV.

The website was created in collaboration with people living with MND and ALS who helped to turn research and clinical guidance into an educational resource relevant to everyday life. Hearing their experiences can help you make your own choice about the treatments on offer. myBreathing also offers an insight into using NIV.

Secretion Management

Many people with MND find that coughing and clearing thick secretions from their chest becomes difficult if their respiratory muscles get weaker. If this is becoming a problem for you, we can advise on how best to help thin these secretions to make it easier for you. There are a number of management options available, but among the first things you may want to try are:

  • ensuring you drink plenty to keep well hydrated

  • trying pineapple or other exotic fruit juice (they contain an enzyme which helps thin secretions)

  • trying a medication which thins mucous (Mucodyne)

Your doctor can also advise about the use of devices (breath stacking, mechanical insufflators-exsufflators) which help stimulate or simulate a cough and, if appropriate, supply the equipment and train you to use it.

Please speak to the care team if you experience any problems with secretion management.