The more you know, the more you can do How Duchenne muscular dystrophy affects lung function As life expectancy of patients with Duchenne muscular dystrophy (DMD) has increased over the past few decades, 1,2 respiratory health has become increasingly important to its overall management. This brochure is intended to help you understand how DMD affects the respiratory system and become an active care partner. BreatheDuchenne.com
DMD and respiratory function Most people are diagnosed with DMD aged around 5 when breathing is normal. 3,4 But as DMD progresses and the respiratory muscles weaken, breathing and coughing become increasingly difficult. 5 This reduces the body s ability to clear the airways making them more susceptible to infection. 6 Stages of DMD and respiratory health Ambulatory (able to walk) Those that can walk are unlikely to have any serious respiratory problems. 5 However, gaining a good understanding of respiratory health and getting it regularly checked will be of great benefit in the future. Non-ambulatory (wheelchair users) Wheelchair users, whether part- or full-time, are at greater risk of respiratory issues and their respiratory health should be a priority. 5 For further information on the respiratory system and how it works, visit: BreatheDuchenne.com
Early complications and symptoms of Respiratory Function Decline People with DMD usually start to experience the early signs of respiratory weakening aged 10 20 years old. 7,8 They are often subtle and appear disconnected from the lungs. 5,9 These early symptoms are often related to sleep disorders such as sleep disordered breathing, obstructive sleep apnoea (OSA; the partial or complete blockage of the upper airways) and shallow breathing at night. 7 This is known as hypoventilation and can cause low blood oxygen and high carbon dioxide levels that have the potential to cause damage. 7 For further information on sleep disorders and monitoring tests, visit: BreatheDuchenne.com
Later complications and symptoms As DMD progresses, respiratory-related symptoms begin to appear. These symptoms, like not being able to cough hard enough, can also be subtle but may result in serious chest infections. 6 Ineffective cough and respiratory infections Coughing is the body s way of clearing mucus and other secretions from the lungs. 6 When the muscles weaken, the lungs can t take in as much air or generate enough force to clear the airways as they should. This can lead to blockages and repeated infections that can result in hospitalisations. 6,10 These infections in turn worsen respiratory muscle function leading to a vicious cycle of recurrent, ever-worsening chest infection and inflammation, ineffective cough and mucus retention. 6,11,12
Respiratory management in DMD Understanding respiratory health and being actively involved with the medical care team will help patients and their carers tackle any problems that arise in the future. Why it s important while still ambulatory (able to walk) An assessment by a specialised paediatric respiratory care physician should take place when the patient is approximately 4 6 years old and can still walk. 6 This will help with equipment familiarity and establish respiratory test values while their function is still good (known as a baseline value). This will help guide future treatment choices and will help detect and manage any potential problems early. Why it s important when non-ambulatory (wheelchair user) Evaluating respiratory function before problems arise lets doctors monitor progress and plan out the optimal treatment options to keep the lungs working as well as possible. 13,14 After the loss of the ability to walk, it can take a while before the signs and symptoms of respiratory decline become obvious. 4 Guidelines for measuring breathing 5 Once patients with DMD lose the ability to walk (become non-ambulatory), lose 20% of their lung function (function is at 80% FVC % predicted) or are 12 years old, they should be seen by a respiratory specialist twice a year. For further information on the guidelines for measuring respiratory function and other useful tests, visit: BreatheDuchenne.com
Take active care of respiratory function in DMD As life expectancy with DMD is increasing, more patients are experiencing age-related lung function decline 1,2 This can lead to infections that result in a vicious cycle of further lung function decline and ever worsening infections 6,11,12 It is therefore important to get your respiratory function assessed early and frequently to help guide future treatment choices to detect and proactively manage any potential problems 6 Further resources and support The following organisations provide resources and ways to connect with others in the DMD community for information and support: United Parent Projects Muscular Dystrophy (UPPMD) www.uppmd.org Muscular Dystrophy UK www.musculardystrophyuk.org Action Duchenne www.actionduchenne.org Duchenne UK www.duchenneuk.org Request specialist respiratory monitoring at least twice a year 5 1. Bello L, et al. Neurology 2015;85:1048 55. 2. Rall S & Grimm T. Acta Myol 2012;31:117 20. 3. Kinnett K, et al. PLoS Curr, 2015;7. 4. Bushby K, et al. Lancet Neurol, 2010;9:77 93. 5. Finder JD, et al. Am J Respir Crit Care Med, 2004;170:456 65. 6. Kravitz RM. Pediatrics, 2009;123(Suppl 4):S231 5. 7. Katz SL. Pediatrics 2009;123 Suppl 4:S222 5. 8. Ishikawa Y, et al. Neuromuscul Disord 2011;21:47 51. 9. Simonds AK. Eur Respir Rev 2013;22:325 32. 10. Dohna-Schwake C et al. Neuromuscul Disord, 2006;16:325 8. 11. Lo Mauro A & Aliverti A. Breathe (Sheff), 2016; 12:318 27. 12. Bach JR, et al. Am J Phys Med Rehabil, 1998;77:8 19. 13. Wagner KR, et al. Biochim Biophys Acta, 2007;1772:229 37. 14. Sharma GD. Pediatrics 2009;123(Suppl 4):S219 21. 0-D-0050-000418-V1-1 April 2018