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

Study objectives: 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. Design: 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. Patients and methods: 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 B-4 concentrations (r = -0.5; p < 0.005). Conclusion: We conclude that the measurement of EBC pH may be useful in the evaluation of airway inflammation in children with asthma and CF.