Respiratory compromise is the major cause of morbidity and mortality in spinal muscular atrophy (SMA). These children may have decreased respiratory function, underdeveloped lungs, and difficulty coughing and clearing secretions.1,2

Children with spinal muscular atrophy demonstrate a wide range of respiratory compromise3

Respiratory compromise in children with infantile-onset (consistent with Type I) spinal muscular atrophy may be differentiated into 3 categories3 :

  1. Infants ≤5 months of age who require both continuous ventilatory support and non-oral nutritional support
  2. Infants with ineffective cough who develop acute respiratory compromise during upper respiratory tract infections and require non-oral nutritional support before 24 months of age
  3. Infants who do not develop respiratory compromise or who do not require non-oral nutritional support until after 24 months of age (approximately 10% of all children with infantile-onset spinal muscular atrophy)  

Ventilatory support provided in the home can range from noninvasive ventilation (e.g., nasal mask) to invasive ventilation (e.g., permanent airway, such as a tracheostomy tube)4

POTENTIAL BENEFITS

CONSIDERATIONS

NON-INVASIVE VENTILATION (NIV)

POTENTIAL BENEFITS

  • Non-invasive
  • Helps prepare for respiratory failure, prevents/minimises chest wall distortions and relieves shortness of breath1
  • Focus is on correcting gas exchange and reducing the work of breathing1

CONSIDERATIONS

  • NIV recommended in all symptomatic infants and in non-sitters prior to signs of respiratory failure1
  • NIV interfaces should be filled by skilled physiotherapists using at least two interfaces with different skin contact points1
  • CPAP is an alternative option for younger patients for short-term use to maintain resting lung volume1
    • May cause fatigue1

COUGH ASSIST MACHINE (Insufflator-exsufflator)

POTENTIAL BENEFITS

  • Non-invasive
  • Primary mode of airway clearance1
  • No significant risk of pneumothorax in most patients1
  • May be used with an oronasal mask3

CONSIDERATIONS

  • Should be made available to all non-sitters and introduced proactively based on cough effectiveness or peak cough flow1
  • Insufflation and exsufflation pressures should be gradually increased to 30-40 cm H2O of positive or negative pressure respectively, or increased to maximum tolerated pressure1
  • Potential risk of aerophagia and gastric distention1
  • May be intimidating for both parents/carers and children
  • Full cooperation is uncommon before 2 years of age3

TRACHEOSTOMY (Invasive ventilatory support requiring long-term airway)

POTENTIAL BENEFITS

  • Potentially life-prolonging
  • Option in selected patients if NIV fails or is insufficient1

CONSIDERATIONS

  • Invasive
  • Permanent
  • Potential ethical issues1
  • May fail to improve quality of life and prolong suffering1
  • Increases airway secretions3
  • Impedes speech development3
  • Decision to undertake tracheostomy should be based on individual’s clinical status, prognosis and quality of life1
    • In close discussion with the patient’s family1
Muscular Atrophy

The clinical spectrum of SMA is highly variable and requires comprehensive medical care involving multiple disciplines.1