Respiratory muscle function in patients with neuromuscular disorders and cardiopulmonary diseases

Respiratory muscle dysfunction frequently occurs in patients with neuromuscular disorders, cardiopulmonary diseases and in patients in intensive care units. Respiratory muscle weakness and/or fatigue is responsible for dyspnoea, reduced exercise tolerance, nocturnal desaturation, and prolonged weaning from mechanical ventilation. Chronic respiratory muscle weakness may also be associated with poor quality of life and increased mortality. Patients with severe respiratory muscle weakness are at increased risk of respiratory failure due to respiratory infections, electrolyte imbalance, sedation or uncontrolled inspired oxygen therapy. Although respiratory muscle weakness is often seen in clinical practice, the consequences and the precise point at which respiratory muscle fatigue occurs remain elusive. This article reviews the pathophysiology of respiratory muscle weakness and fatigue, and therapeutic interventions for enhancing respiratory muscle function in patients with neuromuscular and cardiopulmonary diseases.