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Changes in functional residual capacity during exercise in patients with exercise-induced asthma
Bulletin Europeen De Physiopathologie Respiratoire
|November 1, 1981
Summary
Exercise-induced asthma patients showed increased functional residual capacity (FRC) during exercise, correlating with post-exercise airflow obstruction. A sympathomimetic drug did not alter these responses in a follow-up test.
Area of Science:
- Respiratory Physiology
- Exercise Physiology
- Pulmonary Medicine
Background:
- Exercise-induced asthma (EIA) is a common condition characterized by bronchoconstriction following physical exertion.
- The underlying physiological mechanisms contributing to EIA, particularly changes in lung volumes, require further elucidation.
- Understanding these mechanisms is crucial for developing effective management strategies.
Purpose of the Study:
- To investigate the changes in functional residual capacity (FRC) during exercise in individuals with a history of EIA.
- To explore the relationship between FRC changes during exercise and post-exercise airflow limitation.
- To assess the impact of a sympathomimetic drug on FRC and spirometric responses during exercise in EIA responders.
Main Methods:
- Forty-eight patients with EIA history underwent standardized exercise tests at controlled ambient conditions (18-20°C, 45-55% RH).
- Functional residual capacity (FRC) was measured using a rebreathing technique during the initial minutes of exercise (25-50 W).
- Post-exercise spirometry assessed forced expiratory volume in one second (FEV1); five responders underwent a second test after sympathomimetic drug administration.
Main Results:
- Nineteen patients (responders) exhibited a significant increase in FRC during exercise (p < 0.025).
- A significant negative correlation was observed between the rise in FRC during exercise and the subsequent fall in FEV1 (r = -0.429, p < 0.005).
- In responders, FRC remained elevated between two exercise tests separated by 4 hours, even after spirometry normalized; a second exercise challenge did not alter spirometry or FRC.
Conclusions:
- The study suggests that increased FRC during exercise is a characteristic response in some individuals with EIA.
- The correlation between FRC changes and airflow obstruction indicates a potential link between lung volume dynamics and EIA severity.
- Distinct mechanisms may underlie the observed changes in FRC and maximal expiratory flow during exercise-induced bronchoconstriction, suggesting a complex pathophysiology.