The human rib cage moves to allow the lungs to expand and contract, movement that is essential to breathing. But while many of us take this repeated expansion and contraction for granted, such movement is dependent on two main factors: the action of intercostal muscles (muscles situated between the ribs), and air pressure differences between the atmosphere and the lungs.
Coughing plays a very important role in clearing the airways of mucus and other secretions, for better overall respiration.
Infants and children with spinal muscular atrophy (SMA) types 1 and 2 — the two most serious forms of this disease — often have weaken muscles, which may lead to chronic hypoventilation and low peak cough flows, with subsequent impaired chest clearance. These problems can result in pneumonia, atelectasis (complete or partial collapse of a lung) and altered gas exchange (an incomplete exchange if CO2 and O2 in the lungs).
Why is coughing difficult for people with SMA?
Because children with SMA have weak intercostal muscles, the diaphragm is the main muscle used for breathing. As a result, these children often have underdeveloped lungs, suffer from hypoventilation (short, rapid breaths not long enough to exchange CO2 for O2), and cannot cough with sufficient force to clear their lungs of secretions.
In children with SMA, lung disease is of primary concern, and a main cause of morbidity. Poor lung clearance can lead to recurrent chest infections and potential recurrent hospitalizations, as well as a reliance on antibiotics and inhalation therapies.
A visit to a pulmonologist is essential right after a diagnosis with SMA. This specialist helps families, after a thorough patient evaluation, with creating a plan of adequate and essential techniques to successfully loosen lung secretions and to improve cough.
Cough assist devices and SMA
A cough assist device can be a useful for both airway clearance (the removal of secretions that prevent air from easily entering or leaving the lungs) and lung expansion.
This device uses a positive air pressure that rapidly changes to negative pressure, assisting the patient with coughing. When the child breathes in, the machine provides air (positive pressure) to expand the lungs; when breathing out, the machine rapidly creates a sucking force (negative pressure), helping to remove air from the lungs.
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