pH in Expired Breath Condensate of Patients with Inflammatory Airway Diseases

Abstract

Endogenous airway acidification, as assessed by pH in expired breath condensate, has been implicated in asthma pathophysiology. We measured pH in breath condensate of patients with inflammatory airway diseases in stable condition and examined its relationship with the inflammatory process (as assessed by differential cell counts in induced sputum), oxidative stress (as assessed by H(2)O(2) and 8-isoprostane), and nitric oxide metabolism (as assessed by total nitrate/nitrite). We studied 40 patients with bronchial asthma (20 with moderate disease, forced expiratory volume in 1 second 60 [10]% SD predicted), 20 patients with bronchiectasis, 20 patients with chronic obstructive pulmonary disease (COPD), and 10 normal subjects. Mean (95% confidence intervals) pH values were significantly lower in patients with COPD and bronchiectasis compared with patients with asthma and control subjects (7.16, 7.09-7.23 and 7.11, 7.04-7.19 versus 7.43, 7.35-7.52 and 7.57, 7.51-7.64, respectively, p < 0.0001). Patients with moderate asthma had significantly lower values compared with mild and control subjects. In patients with COPD and bronchiectasis, the values of pH were significantly correlated with both sputum neutrophilia and oxidative stress. Respectively, in patients with moderate asthma, a significant correlation was observed between pH and sputum eosinophilia, total nitrate/nitrite, and oxidative stress. The pH of the expired breath condensate might be a simple, noninvasive, inexpensive, and easily repeatable procedure for the evaluation of the inflammatory process in airway diseases.

Respiratory heat and moisture loss is associated with eosinophilic inflammation in asthma

“…These two markers vary in their response to inhaled steroid treatment [30,31]. EBC pH has previously been reported to correlate with sputum eosinophils in asthma by KOSTIKAS et al [32]. Important differences in the present study are that EBC samples were not deaerated prior to testing and the subjects had more severe asthma.…”

Exhaled Breath Condensate pH Assays

“…Normal values of gas-standardized ("CO 2 -free") EBC pH have been reported from multiple investigators and range between 7.5 and 8.1 (3,8,9,(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). In our normative database from 404 subjects, the mean pH was 7.83, and the median pH was 8.0 (12).…”

pH modulates the activity and synergism of the airway surface liquid antimicrobials β-defensin-3 and LL-37

“…Although a reduced ASL pH might be important for initiating S. aureus infection at the onset of CF lung disease, the variety of ASL antimicrobials, their varied properties, and interactions between them leave much uncertainty. In addition to CF, ASL pH may be abnormally reduced in asthma (76), chronic obstructive pulmonary disease (77), and acute respiratory distress syndrome (78). Acidic conditions can also be found at sites of infection outside airways, including in peritoneal fluid, pleural fluid, cerebral spinal fluid, and abscesses.…”