Abstract
Background Exercise-induced bronchoconstriction (EIB) is the temporary narrowing of the airways caused by physical exercise. Its exact pathophysiology is unclear; however acute changes in airways pH may play a role. Exhaled breath condensate (EBC) pH was suggested as a surrogate indicator for airway acid-base status, but its value is also affected by volatile molecules and respiratory droplet dilution.
Objective The aim of the study was to assess changes in EBC pH during exercise-induced bronchoconstriction.
Methods Twenty-two asthmatic patients who reported breathlessness following exercise and sixteen healthy individuals participated in the study. Lung function test was performed and exhaled breath samples were collected for pH, dilution factor and volatile compound pattern measurements (Cyranose 320) pre-exercise and at 0, 10, 20 and 30 minutes after physical exercise challenge. FENO was also measured before exercise.
Results EIB developed in 13 asthmatic subjects. In these patients, but not in the EIB-negative asthmatics (p=0.51), EBC pH reduced significantly during exercise (p=0.01). In addition, changes in EBC pH were related to the degree of bronchospasm only in the EIB-positive group (p=0.01, r=0.68). Exhaled volatile pattern altered (p<0.05) during exercise in all subjects (asthmatics and controls). EBC pH changes were not related to EBC dilution or volatile compound pattern alterations (p>0.05).
Conclusions The development of EIB was related to acute changes of EBC pH which suggest the role of airway pH decrease in the pathophysiology of EIB. Exercise-induced changes in exhaled biomarkers suggest methodological precautions to avoid physical exercise before performing exhaled breath tests.
- © 2014 ERS