Dynamic hyperinflation in patients with asthma and exercise-induced bronchoconstriction

Area of Science:

• Respiratory Medicine
• Exercise Physiology
• Pulmonary Function Testing

Background:

• Limited understanding of operative lung volumes during exercise in asthma patients with exercise-induced bronchoconstriction (EIB).
• Investigating dynamic hyperinflation (DH) and its relationship with exercise-induced airflow limitation.

Purpose of the Study:

• To compare DH prevalence in mild asthma patients with and without EIB versus healthy individuals.
• To correlate changes in end-expiratory lung volume (EELV) with postexercise airflow reduction.

Main Methods:

• Studied 122 stable mild asthma patients and 38 controls (>12 years).
• Measured baseline lung volumes and performed exercise bronchial challenge.
• Estimated EELV and end-inspiratory lung volume (EILV) during exercise using inspiratory capacity.

Main Results:

• DH was significantly more frequent in asthma patients with EIB (76%) compared to those without EIB (11%) and controls (18%).
• EELV increased during exercise in asthma patients with EIB, while it decreased in those without EIB and controls.
• Postexercise forced expiratory volume in 1 second reduction correlated with EELV increase, EILV increase, age, and baseline forced vital capacity.

Conclusions:

• Development of DH is frequent in asthma patients with EIB and correlates with postexercise bronchoconstriction intensity.
• DH may play a role in the development and severity of exercise-induced bronchoconstriction.