Investigation of pH of the exhaled breath condensate in inflammatory lung diseases

Abstract

Investigation of inflammatory markers in the exhaled breath condensate (EBC) is a non-invasive method for evaluation and monitoring of bronchopulmonary inflammation. Endogenous oxidative processes in the airways can be evaluated by pH measurement in the EBC. We examined 153 healthy volunteers (of them, 51 smokers) and 615 patients with lung pathology (of them, 131 asthma (BA) patients, 205 COPD patients, 43 patients with bronchiectasis, 72 patients with idiopathic lung fibrosis (ILF), 142 pneumonia patients, and 42 cystic fibrosis patients). EBC was collected with ECoScreen equipment (Erich Jaeger, Germany) using a standardized method. The EBC pH was measured using the f32 PH-meter (Beckman, USA) with a glass microelectrode. The average ECB pH was 6.16 ± 0.52 in BA, 6.35 ± 0.56 in COPD, 6.13 ± 0.46 in bronchiectasis, 5.98 ± 0.30 in ILF, 5.96 ± 0.37 in pneumonia, and 6.35 ± 0.23 in cystic fibrosis. It was significantly lower than in the healthy volunteers (6.97 ± 0.31, р < 0.0001). In patients with exacerbation of BA and COPD ECB pH was considerably lower compared with those in stable condition. A reliable growth of pH was noted in pneumonia patients after treatment of the disease. There was a correlation between ECB pH and severity of fibrotic and inflammatory disorders of lung tissue according to HRCT (r = –0.62, p = 0.01), lung diffusing capacity (r = 0.51, p = 0.01), Tiffeneau index (r = 0.68, p = 0.004) in ILF. Therefore, the ECB pH is a distinct marker of the airway inflammatory severity in lung pathology. The ECB pH monitoring can assess the inflammatory activity and efficacy of anti-inflammatory therapy in lung diseases.