Recommendations to protect respiratory function in Duchenne muscular dystrophy (DMD)

Tuesday, February 20, 2024

Respiratory Futures spoke to Cathy Turner from DMD Care UK Project Manager about recommendations to protect respiratory function in DMD. The guidelines were created by the DMD Care UK programme and endorsed by the British Thoracic Society (BTS). The guidelines were published in Thorax in December 2023.

Why are these guidelines so important for people with DMD?

DMD is a condition with which many clinicians, including those in respiratory medicine and critical care, may be unfamiliar. There are aspects of the condition relating to respiratory and cardiovascular presentations which may not be known about or are not well understood. Knowledge about acute presentations may, therefore, be very helpful for clinicians caring for people with DMD to appreciate what signs to look out for and what treatments may be indicated and effective.  For example, people with DMD are a group in whom non-invasive ventilation is highly effective both acutely and in the longer term. 

Ventilatory failure is inevitable in people with Duchenne Muscular Dystrophy.

In what ways are the signs of respiratory deterioration different in someone with DMD compared to someone without DMD?

Respiratory deterioration in DMD is often slowly progressive, and symptoms of sleep-disordered breathing, such as daytime sleepiness, may come on so gradually as not to be noticed.  Furthermore, signs such as breathlessness on exertion are limited due to other muscles being affected and exertion therefore is very limited.  Finally, many people with DMD are medicated with steroids, which can reduce signs of infection, including a chest infection.

How can people with DMD be supported if they are admitted to hospital with an acute respiratory issue?

An emergency healthcare plan can be extremely useful for people with DMD.  This sets out the background treatments (for example, Non-Invasive Ventilation), common presentations and advice for clinical teams, including treatments which must be available, the optimal location of care and which teams to contact for advice.

Non-invasive ventilation is a very effective treatment for acute ventilatory failure.  Secretion management and mobilisation is often a challenge and specialist respiratory physiotherapy teams have a central role to play during an acute admission.

The guideline warns against the use of high flow oxygen in people with DMD, why is this?

Patients at risk of long-term ventilatory failure are very sensitive to excess oxygen and it can precipitate ventilatory failure (under breathing). This is the case in patients with neuro muscular disease including people with DMD. As with any drug, it is important to give the right amount of oxygen rather than too little or too much and to monitor the effects with saturations and potentially blood gases. Any person with DMD who requires supplementary oxygen should be a significant concern to clinicians and they require urgent assessment, treatment and placement in a location which can appropriately meet their needs.
If a person with DMD meets the criteria for referral to a respiratory clinic, what should be done in terms of discharge or follow-up once they are stable or ‘well’?

Ventilatory failure is inevitable in people with DMD. Symptoms such as morning headaches, poorly refreshing sleep and daytime sleepiness are used to predict patients at particular risk of ventilatory failure. Similarly, people are at an increased risk of ventilatory failure when their vital capacity drops below 50% of predicted. These two groups of people require close follow-up, and even if they are stable, their heightened risk of ventilatory failure means that they should not be discharged from a specialist respiratory clinic and should continue to be under follow-up. Once a person with DMD is established and stable on non-invasive ventilation, they should continue to be followed up by a specialist respiratory clinic.

For more information on DMD and respiratory, read the Development of respiratory care guidelines for Duchenne muscular dystrophy in the UK: key recommendations for clinical practice, published in Thorax, December 2023.