Abstract
Background: Exercise intolerance is the hallmark of fibrosing interstitial lung diseases (FILD), but the role played by the respiratory muscles is controversial.
Objective: To measure the inspiratory and expiratory muscle strength, chest wall synchrony and inspiratory endurance in FILD patients.
Methods: For 16 FILD patients and 14 healthies we measured, at rest, volitional and non-volitional inspiratory and expiratory strength. During a maximal cycle test, we measured inspiratory and expiratory accessory muscle activity (electromyography), chest wall synchrony (inductive pletysmography) and inspiratory endurance using the tension-time index (TTi) with gastric and esophageal catheters.
Results: The volitional and non-volitional inspiratory and expiratory strength were similar between the groups. From rest to strenuous exercise, inspiratory and expiratory muscles were significantly more activated in patients. Patients and volunteers presented similar chest wall synchrony. Patients presented higher inspiratory TTi at rest and during exercise (p<0.01)(figure1) with the inspiratory to total time of the breathing cycle ratio similar to volunteers.
Conclusion: In FILD patients, respiratory muscle weakness and chest wall movement asynchrony don´t cause exercise intolerance. However, a lower inspiratory endurance due to a lower inspiratory force reserve is a probable cause.
- Copyright ©ERS 2015
