Neuromuscular Disease (British Thoracic Society Physiotherapy Guideline Development Group)
The diagnosis of Neuromuscular Disease covers a wide range of disorders that give rise to progressive muscular weakness. Common diseases in this category include motor neuron disease also known as amyotrophic lateral sclerosis in the USA, multiple sclerosis, spinal muscular atrophy, congenital myopathy, postpoliomyelitis and muscular dystrophies, the most common of these being Duchenne muscular dystrophy. They vary in age of onset, rates of progression and patterns of muscles involved.
Patients with neuromuscular disease may have a reduced Vital Capacity (VC) (the greatest volume of air that can be expelled from the lungs after taking the deepest possible breath) due to reduced inspiratory muscle strength, with resultant underventilation of lung units and microatelectasis (partial collapse of the lung that is only visible by microscope). The combination of loss of respiratory muscle strength, ineffective cough and decreased ventilation could lead to pneumonia, atelectasis (partial collapse of the lung), and respiratory insufficiency and failure. Additionally, the unstretched chest wall muscles shorten and stiffen due to the pathological process of disease and an inability to be worked through the full range. Such patients will frequently have an inadequate cough due to weakness in inspiratory and expiratory muscles.
Maximum insufflation capacity is the maximum volume of air that can be held with a closed glottis (the vocal apparatus of the larynx). This may be achieved via air stacking for the patient who can maintain a closed glottis. Air stacking involves consecutive inhalations, closing the glottis after each one, to create a maximum insufflation. Patient representatives report improvements in their perception of cough strength and secretion management when using unaided breath stacking. Performing maximal insufflation prior to coughing will increase inspiratory volume and consequently the expiratory flow and cough efficiency.
Subjects with a larger maximum insufflation capacity/VC difference consequently have a greater ability to clear airway secretions, thus decreasing the risk of pulmonary complications. Maximal insufflation to Inspiratory Capacity (IC) also provides a full range of movement to the lungs and chest wall. This technique performed 15 times three times daily increased maximum insufflation and subsequent peak cough flow when commenced in patients with neuromuscular disease and reduced Vital Capacity.
Physiotherapy encompasses more than ‘‘tipping and bashing’’ and the integrated approach of physiotherapy embraces a wide variety of techniques, including: breathing re-education, dyspnoea management, physical training and pulmonary rehabilitation, airway clearance, and non-invasive ventilation.