Breath condensate pH in children with cystic fibrosis and asthma: a new noninvasive marker of airway inflammation?

The noninvasive assessment and monitoring of airway inflammation could be important in respiratory disease. The pH of exhaled breath condensate (EBC) is a promising marker. Although pH has been measured in the EBC of adults with inflammatory airway diseases, no study has measured this in children. This study aimed to assess whether there is a change in pH in the EBC of children with cystic fibrosis (CF) and asthma, and to try to determine whether pH could be used as a marker of airway inflammation. Furthermore, the relationships among EBC pH, severity of disease, and oxidative stress were studied. We studied 20 children with CF (mean [± SEM] age, 7 ± 3 years), 20 children with asthma (mean age, 7 ± 2 years), and 15 age-matched healthy children (mean age, 7 ± 2 years). The pH of EBC was measured using a pH meter. Measurements and results: Lower pH values were observed in the EBC of children with CF and asthma compared to control subjects (mean pH, 7.23 ± 0.03 and 7.42 ± 0.01 vs 7.85 ± 0.02, respectively). Furthermore, relationships among EBC pH, severity of asthma, and the presence of an infective exacerbation of CF was found. There was a negative correlation between exhaled pH and exhaled leukotriene B4 concentrations (r = -0.5; p < 0.005). We conclude that the measurement of EBC pH may be useful in the evaluation of airway inflammation in children with asthma and CF