Respiratory Muscle Insufficiency in Neuromuscular Disorders

Acute ventilatory failure is a frequent occurrence in many neuromuscular disorders. It may appear at the onset of the disease, as in the acute inflammatory stage of poliomyelitis, in the Guillain-Barre syndrome, or in an episode of myasthenia gravis. Many neuromuscular disorders can also lead to chronic respratory insufficiency, which often contributes significantly to the cause of the death. Respiratory failure in these conditions is not simply due to the direct effect of weakness of the respiratory muscles leading to inability to inflate the lungs and alveolar hypoventilation. A variety of additional pathogenic mechanisms are important [1]. These include 1 alterations in the mechanical properties of the lung and chest wall, 2 inability to cough and impaired clearance of secretions, 3 dysfunction of the “respiratory centers”, and 4 ventilation-perfusion inhomogeneity.