Inspiratory muscle dysfunction as a cause of death in COPD patients.

Although fatigue of the inspiratory muscles has been well documented, its prevalence in patients with chronic obstructive pulmonary disease (COPD) and its influence on mortality are unknown, because of the lack of a simple, clinically available diagnostic test. The hypothesis and experimental evidence relating inspiratory muscle dysfunction to the development of hypercapnia and hypercapnic ventilatory failure are reviewed. Since a poor prognosis in COPD is associated with carbon dioxide retention, inspiratory muscle weakness and/or fatigue may have an association with survival in these patients.