1. Duchenne Muscular Dystrophy: Pulmonary Management

2. Introduction Ambulant boys normally have few respiratory difficulties
Progressive loss of muscle strength leads to risk of respiratory complications over time:
Ineffective cough
Nocturnal hypoventilation
Sleep disordered breathing
Daytime respiratory failure
Staged progression: planned/proactive approach to respiratory care, aiming to prevent/manage these complications
Team to include a doctor and therapist skill in initiation/management of
Non-invasive ventilation and associated interfaces
Lung-volume recruitment techniques
Manual and mechanically assisted cough
Specific guidelines for respiratory care in DMD have also been published

3. Surveillance: Ambulatory
Minimal assessment to include pulmonary function
e.g. sitting Forced Vital Capacity (FVC) at least annually
Enables familiarity of patient with equipment
Allows care team to assess maximum respiratory function achieved

4. Surveillance: Non-ambulatory (clinic measurements)
Main need for pulmonary care is after loss of independent walking
[Figure 2, TLN p181]
Clinic measurements at least every 6 months
Sitting FVC
Peak cough flow
Oxyhaemoglobin saturation by pulse oximetry
Maximum inspiratory and expiratory pressures
Awake end-tidal CO2 level should be measured by capnography, if patient non-ambulatory and has any of
Suspected hypoventilation
FVC <50% prediceted
Current use of assisted ventilation

5. Surveillance: Non-ambulatory (home measurements)
[See Figure 3, TLN p181]

6. Family Awareness
Family should be aware of the symptoms of hypoventilation or a weak cough, which should be reported to medical caregivers
Prolonged, apparently minor upper respiratory infections (e.g. recovery from common colds is slow, with colds progressing to chest congestion and bronchitis often requiring antibiotic therapy)
More tiredness than is usual
Shortness of breath, difficulty catching breath or finishing sentences
Headaches all the time or in the morning
Sleepiness for no reason
Trouble sleeping, frequent waking from sleep, nightmares
Wakes trying to catch breath, or can feel heart pounding
Trouble paying attention
Family should keep copies of the latest breathing test results to show to attending doctors

7. Prevention of Problems
Immunisation with 23-valent pneumoccocal polysaccharide vaccine for patients ≥ 2 years
Annual immunisation with trivalent inactivated influenza vaccine for patients ≥ 6 months
Both can be given to patients on steroids, though immune response to vaccination may be diminished
Detailed information on immunisation indications, contraindications, and schedules can be obtained from national sources
It is essential to keep up to date with vaccination policies as they can change regularly according to new threats
If chest infection occurs, then in addition to manually and mechanically assisted cough, antibiotics should be prescribed early

8. Interventions
Specific interventions are dependent on the disease phase
Staged progression:
Volume recruitment/deep lung inflation techniques
Manual/mechanically assisted cough techniques
Nocturnal ventilation
Daytime ventilation
Tracheostomy

9. Step 1: Volume Recruitment & Deep Lung Inflation Techniques
By self-inflating manual ventilation bag, or mechanical insufflation/exsufflation
When FVC <40% predicted

10. Step 2: Manual and Mechanically Assisted Cough Techniques
Necessary when
Respiratory infection present and baseline peak cough flow < 270 L/minute
Baseline peak cough flow < 160 L/min or max expiratory pressure < 40cm water
Baseline FVC < 40% predicted or < 1.25 L in older teenagers/adults

11. Step 3: Nocturnal Ventilation
Indicated in patients who have any of
Signs/symptoms of hypoventilation (patients with FVC < 30% predicted are at especially high risk)
Baseline SpO2 <95% and/or blood or end-tidal Co2 >45 mm Hg while awake
An apnoea-hypopnoea index >10 per hour on polysomnography or four or more episodes of SpO2 <92% or drops in SpO2 of at least 4% per hour of sleep
Optimally, use of lung volume recruitment assisted cough techniques should always precede initiation of non-invasive ventilation

12. Step 4: Daytime Ventilation
In patients already using nocturnally assisted ventilation daytime ventilation is indicated for
Self-extension of nocturnal ventilation into waking hours
Abnormal deglutition due to dyspnoea, which is relieved by ventilator assistance
Inability to speak a full sentence without breathlessness and/or
Symptoms of hypoventilation with baseline SpO2 <95% and/or blood or end-tidal Co2 >45mm Hg while awake
Continuous non-invasive assisted ventilation (with mechanically assisted cough) can facilitate endotracheal extubation for patients who were intubated during acute illness or anaesthesia, followed by weaning to nocturnal non-invasive assisted ventilation if applicable

13. Step 5: Tracheostomy Indications for tracheostomy include
Patient and clinician preference
Patient cannot successfully use non-invasive ventilation
Inability of local medical infrastructure to support non-invasive ventilation
3 failures to achieve extubation during critical illness despite optimum use of non-invasive ventilation and mechanically assisted cough
The failure of non-invasive methods of cough assistance to prevent aspiration of secretions into the lung and drops in oxygen saturation below 95% or the patient’s baseline, necessitating frequent direct tracheal suctioning via tracheostomy

14. Surgery Lung function should be checked before surgery
DMD patients should never be given inhaled anaesthesia or succinylcholine

15. CAUTION: Supplemental Oxygen
In later stages of DMD, supplemental oxygen therapy should be used with caution
Can apparently improve hypoxaemia while masking underlying cause (e.g. atelactasis or hypoventilation)
Might impair central respiratory drive, exacerbating hypercapnia
If patient has hypoxaemia due to hypoventilation, retained respiratory secretions and/or actelectasis, then manual and mechanically assisted cough and non-invasive ventilatory support are necessary
Substitution of these methods by oxygen therapy is dangerous

16. References & Resources
The Diagnosis and Management of Duchenne Muscular Dystrophy, Bushby K et al, Lancet Neurology (1) & Lancet Neurology (2)
Particularly references, p
The Diagnosis and Management of Duchenne Muscular Dystrophy: A Guide for Families
TREAT-NMD website:
CARE-NMD website: