When we breathe in our inspiratory muscles act as bellows to expand our lungs and pull in oxygen. The most important inspiratory muscle is the diaphragm. This is a dome-shaped muscle below the lungs. SMA causes the weakens the inspiratory muscles and decreases lung volume.

Breathing out the waste gas (carbon dioxide) from the lungs is known as expiration. This does not need particularly strong muscles, but coughing does.

If you have breathing problems, it is often due to having a weak cough and only being able to take in smaller breaths. Everyone is affected differently. But weak breathing muscles can:

• Make it difficult for you to cough and clear mucus (secretions) from your lungs
• Mean your lungs can’t get rid of enough of the waste gas produced by breathing. This includes carbon dioxide. When the levels of carbon dioxide in your blood are increased, this is known as ‘hypoventilation’.
• Make it difficult for you to take in enough oxygen while you are asleep.

The SoC recommend that people who are ‘sitters’ or ‘non-sitters’ should have a physical examination to check their breathing at least once every six months. At these appointments a spirometer machine is used to measure the strength of a person’s cough.

If you have trouble sleeping at night, or have headaches, this may mean you are not breathing well at night. If so, you should have an overnight sleep study. This may be at home with a small clip on your finger. This measures and records levels of oxygen in your blood. If it is in hospital, small sensors are attached to your face, head, arm and chest. They monitor you overnight. You usually also have a blood test.

These tests results will help your clinician discuss whether you need any intervention to help manage your breathing and what the possible options are. You should be seen by a respiratory specialist.

If you do not have a respiratory specialist and are worried about your breathing,  talk to your GP and ask for a referral to a respiratory specialist.

There are different ways to help manage breathing problems, depending on what your team assess is right for you.

If you have a weak cough,  it is difficult  to clear mucus and other secretions from your lungs. This makes you more vulnerable to chest infections.

Options that you may already use or that your team may discuss with you include:

• Chest physiotherapy to keep you comfortable and help clear secretions from your chest. Anyone providing your personal care would be trained to do this. You would be advised how often is best for you.
• Cough assist is the name often given to a mechanical insufflator – exsufflator machine. This helps to clear secretions from your lungs. If it is something that would help you and you could use it yourself you will be trained to do so.  Anyone providing personal care would also be trained.

Though this webinar was targeted at teenagers it gives a useful explanation  of cough assist and what it is like to use:

• A suction machine helps remove any excess secretions. If you need this, your physio or another member of your healthcare team would talk to you about why and when you should use it. They will train anyone providing your personal care.
• Non-invasive ventilation (NIV), is a machine with a mask providing gentle pressure to breathe against. This helps to keep your lungs inflated longer. It can help you get rid of carbon dioxide and take in more oxygen, making breathing easier. The mask is individually fitted for you by a respiratory specialist. When your breathing triggers the ventilator, it delivers a supported breath in. As you start to breathe out, the machine cycles into exhalation, allowing you to breathe out normally. BiPAP is one example of an NIV machine.
• Medication (mucolytics) can be used to break down secretions, but they are not recommended for long term use.
• Antibiotics aren’t recommended by the SoC as a way of trying to prevent chest infections (prophylactic use) but the medical team will have a ‘low warning’ threshold for when you should start them.

SMA UK has been involved in advocating for access to cough assist machines for some years now. For example, in 2021 we joined the MND Association in advocating for wider routine availability in Derbyshire. Access has improved but there are still regional variations.

If you need to argue your case, you may find it helpful to make the following points that we have used in previous submissions.

Please note – we are not medically qualified, nor are we researchers – the views and points expressed here reflect the questions and experiences of people with SMA who contact us for support and information and who share their views and experiences with us.  

• It is SMA UK’s experience that across the UK, more children and adults have had access to cough assist equipment since initial research by Chatwin and Simonds in 2003¹.
• The British Thoracic Society acknowledges the lack of robust evidence but still recommends use of cough assist equipment for children² and adults with neuromuscular weakness.
• The 2017 International Standards of Care for SMA3,4,5 (SoC) is the consensus of highly respected international clinical experts. They outline minimum care provision for individuals with SMA:

“Their working groups identified the aspects that constitute optimal care but considering that some of the recommendations may not be easily applicable in centres or countries with less resources, an effort was made to identify assessments or interventions that constitute the minimal care that families should expect to find in any neuromuscular centre.” 

The SoC recommend that:

• All children and adults with SMA should be seen by a specialist neuromuscular multi-disciplinary team, including respiratory specialists.
• Assessment and monitoring by the respiratory specialist, experienced in SMA should be regular and ongoing.
• Where indicated by clinical assessment, proactive introduction of cough assist is recommended for ‘non-sitters’ (unable to sit) and ‘sitters’ (able to sit but not walk).
• Sitters may have a clinical classification of SMA Type 1, SMA Type 2 or SMA Type 3 ‘Non-sitters’ would be likely to have a clinical classification of SMA Type 1.

• Further robust study evidence for the provision of a cough assist machine is difficult to achieve:
  • SMA is a rare condition – it is difficult to find the numbers of comparable individuals needed to provide a large sample with control groups.
  • Cough Assist is currently being used by many with SMA in the UK so it would be difficult to set a clinical trial baseline.
  • If a control arm was required, it would be difficult to justify and recruit to a trial for use of equipment which is already recommended in the international SoC for SMA.
• It is commonly stated that “Most coughs clear up within three weeks and do not require any treatment”. This is not the case for people with SMA who, due to muscle weakness, are unable to cough effectively and can experience very rapid progression to severe chest infection leading to severe breathing difficulties and hospitalisation.
• The experience of families and adults of regular use of cough assist is that it has a positive role in:
  • Maintaining optimum chest physio routines
  • Reducing time spent on effective chest physio (also see Chatwin and Simonds 2009)⁶
  • Increasing strength and capacity of lungs
  • More effectively moving secretions from lungs on a regular basis
  • Increasing ability to fight a chest infection if one does occur
  • Increasing feelings of well-being and confidence when respiratory function is maintained at a stable level
  • Decreasing severity of chest infections if they do occur
• The “Right to Breathe” report (2015)⁷ concluded that not providing cough assist is a false economy. The cost of the equipment compared to one week’s stay in ICU is minimal. A link to this report, plus background information, is detailed on MDUK’s website (see reference 7 below).

Though the Individual Funding Request application provides a possible route for provision, SMA UK is concerned that this should not replace routine provision in view of:

• The time and resources each application takes
• The focus and effort that already overstretched clinicians and families would need to put towards any application
• The waiting time increase which could be detrimental to individuals
• The risk of developing a severe chest infection while waiting that would result in hospitalisation and threaten life
• The burden on the clinician to prove exceptional clinical need, when Standards of Care 2017 recommend cough assist is a minimal intervention for those with SMA (sitters / non-sitters)
• Family already juggling 24-hour care and emotional stress of caring together with an ever-present prospect of life-threatening chest infections
• Families feeling that they must fight for a piece of equipment that has already been agreed by SMA experts as essential and which have been seen to improve individuals’ and families’ quality of life.
• Individuals potentially missing out on eligibility for, or experiencing delayed access to, newly emerging drug treatments and clinical trials which require as inclusion criteria that they adhere to the Standards of Care.

References:

1. Chatwin M et al. Cough Augmentation with mechanical Insufflation / Exsufflation in Patients with Neuromuscular Weakness. Eur Respir J: March 2003; 21(3) 502-508

2. BTS Guidelines for respiratory management of children with neuromuscular weakness (January 2014) 

3. Wang CH, Finkel RS, Bertini ES, Schroth M, Simonds A, Wong B, Aloysius A, Morrison L, Main M, Crawford TO, Trela A; Participants of the International Conference on SMA Standard of Care (2007) Consensus statement for standard of care in spinal muscular atrophy. J Child Neurol 22: 1027-1049.

4. Richard S. Finkel, et al., Diagnosis and management of spinal muscular atrophy: Part 2: Pulmonary and acute care; medications, supplements and immunizations; other organs systems; and ethics, Neuromuscular Disorders (2017), doi: 10.1016/j.nmd.2017.11.004

5. The Family Guide to the International Standards of Care 2017

6. Michelle Chatwin and Anita K Simonds; The Addition of Mechanical Insufflation/Exsufflation shortens airway-clearance sessions in neuromuscular patients with chest infection (November 2009). Respiratory Care 54 (11) 14731479.

7. Muscular Dystrophy UK publication available through the link at the bottom of this page: Right to Breathe; Access to Respiratory Care for people with a neuromuscular condition (2015)

At the 4th International Scientific Research Congress in April 2024, Kim Kant-Smits (University Medical Centre, Utrecht, Netherlands), a paediatric physical therapist and PhD student, presented research looking into the impact of exercising the breathing muscles in SMA. See the Breathing muscle training in SMA tab on the Congress Report page.