Chest Physiotherapy in the Well Child

Respiratory problems are the leading cause of acute illness and chronic disability in infants and children with spinal muscular atrophy (SMA). Among children with SMA type I and type II, respiratory issues are the most common cause of death. On the other hand, when started early, proactive, noninvasive respiratory care interventions can prolong the lives of children with SMA.1 As such, particular attention should be focused on providing consistent, high-quality chest physiotherapy starting as early as the initial diagnosis.

One of the major drivers of respiratory symptoms in children with SMA is respiratory muscle weakness. Affected children have extremely weak intercostal muscles with relatively preserved strength of the pulmonary diaphragm.2 Since the intercostal muscles are unable to oppose the action of the diaphragm, the chest wall and, by extension, the lungs cannot fully expand to accommodate inhalation. This lung pathophysiology has five main consequences2:

  • Impaired cough
  • Insufficient clearance of lower airway secretions
  • Hypoventilation during sleep 
  • Anatomical underdevelopment of the chest wall and lungs
  • Recurrent infections

Effective, chronic respiratory care has many facets. Pulse oximetry is especially important in children with SMA because typical signs of respiratory distress may not manifest due to diffuse chest muscle weakness. Thus, oxygen desaturation should be used to assess oxygen status and to infer respiratory competency.2 Likewise, heart rate is also suggestive—tachycardia may be an early sign of acute pulmonary illness. The rapid desaturation of sPO2 to 95% or less usually indicates atelectasis, mucus plugging, or agitation in the wake child, or hypoventilation and/or mucous plugging in the sleeping child.2

Airway-secretion mobilization and clearance is a fundamental component of chest physiotherapy. This can be accomplished through manual, mechanical or combination chest physiotherapy techniques combined with postural drainage. Children with SMA should receive manual cough assistance and/or the assistance of a mechanical insufflation/exultation device. While there are several devices available, current clinical evidence supports the use of CoughAssist.3

According to Dr. Mary K. Schroth, the University of Washington uses the following protocol for assisted coughing the combines manual and machine-assisted steps.

  1. CoughAssist: 4 sets of 5 breaths
  2. Oral suction to remove secretions
  3. Mobilize secretions manually or with a mechanical chest physiotherapy device
  4. CoughAssist: 4 sets of 5 breaths
  5. Oral suction to remove secretions
  6. Place the child in the Trendelenburg position for postural drainage for up to 20 minutes as tolerated
  7. CoughAssist: 4 sets of 5 breaths
  8. Oral suction to remove secretions

Infants with SMA type I may need these chest interventions performed twice per day when not acutely ill. On the other hand, children with SMA type II may only need these chest interventions when they show signs of having retained secretions. Lastly, children with SMA type III may only need cough assistance in certain situations, such as postoperatively, or during acute illness.

References

1. Lemoine TJ, Swoboda KJ, Bratton SL, Holubkov R, Mundorff M, Srivastava R. Spinal Muscular Atrophy Type 1: Are Proactive Respiratory Interventions Associated with Longer Survival? Pediatr Crit Care Med. 2012;13(3):e161-165. doi:10.1097/PCC.0b013e3182388ad1 

2. Schroth MK. Special Considerations in the Respiratory Management of Spinal Muscular Atrophy. Pediatrics. 2009;123 Suppl 4:S245-249. doi:10.1542/peds.2008-2952K 

3. Miske LJ, Hickey EM, Kolb SM, Weiner DJ, Panitch HB. Use of the Mechanical in-Exsufflator in Pediatric Patients with Neuromuscular Disease and Impaired Cough. Chest. 2004;125(4):1406-1412. 

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