Respiratory muscle fatigue.

Respiratory muscle fatigue is caused by excessive effort relative to the strength and endurance of the respiratory muscles. It can be manifested by reductions in respiratory drive (central fatigue), by impaired neuromuscular transmission (transmission fatigue), by decreased contractility (contractile fatigue), or by a combination of these factors. Respiratory muscle fatigue probably contributes to the difficulties some patients have with weaning from mechanical ventilation, the symptoms of exercise intolerance and dyspnea in chronic lung disease, and CO2 retention. Therapy depends on a reduction in the required level of respiratory effort and/or an improvement in respiratory muscle strength and endurance.