Exhaled breath condensate pH in patients with cystic fibrosis

Exhaled breath condensate (EBC) pH has been proposed as a useful, non-invasive marker of airway inflammation in pulmonary diseases. In this study we tested whether cystic fibrosis (CF) is associated with acidification of EBC, when pH is assessed by the CO2 gas standardization method. EBC was collected using two different devices (EcoScreen and R-Tube) in 46 stable CF patients during routine clinical visits and in 28 healthy controls. Mean EBC pH in CF patients and in healthy controls was similar (EcoScreen: CF patients: 6.38 +/- A 0.03 versus controls: 6.39 +/- A 0.03, p = 0.699; R-tube: CF patients: 5.94 +/- A 0.04 versus controls: 6.02 +/- A 0.03, p = 0.159). Inflammatory cell counts in spontaneously expectorated sputum obtained in a subset of patients (n = 20) showed no correlation with pH values. EBC samples collected with the R-tube were more acidic than those collected with the EcoScreen device (p < 0.001). Our data suggest that EBC pH does not discriminate between healthy controls and those with CF disease indicating that the clinical applicability of EBC pH measurements for assessing airway inflammation in CF is limited.