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Children – Breathing

Children – Breathing

Last reviewed October 2024

The muscle weakness caused by SMA can affect the muscles for breathing. Breathing (respiratory) problems may be common for children who are unable to sit without support (usually diagnosed with SMA Type 1) and children who are able to sit but not walk. They are rare for children who are able to walk.

What happens and why?

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 your child has 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 your child to cough and clear mucus (secretions) from their lungs
  • Mean their 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 your child to take in enough oxygen while they are asleep.

There are different ways of helping to manage breathing challenges. Your child’s clinical team will assess your child and, if needed, will involve respiratory specialists in their care. They will have a full discussion with you.

Chapter 6 Breathing (Respiratory and Pulmonary Care) of the Family Guide to the 2017 International Standards of Care for SMA (SoC) summarises the key recommendations that were made then. Although this provides a useful reference point, a 3-year project is now underway to update all these standards for the UK. Any updates to this advice will be published once this area of care has been reviewed by the SMA Care UK > project. Your child’s clinical team will be up to date with any changes.

If your child has been recently diagnosed, you may also find helpful information in whichever of these SMA UK guides is the ‘best fit’ for your child:

Lisa Edel (Specialist Respiratory Physiotherapist) talks to SMA UK host Martyn Sibley about Cough Assist for Younger Children:

Dr Elaine Chan (Consultant Respiratory Paediatrician) and Gary Rendle (Non-Invasive Ventilation Clinical Nurse Specialist) talk to Martyn Sibley about Non-Invasive Ventilation for Younger Children, including the potential benefits, why it might be needed and what assessments are involved. They also look at a machine and explain how it works:

 

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.