Exhaled breath condensate analysis: evaluation of a methodological setting for epidemiological field studies

The analysis of exhaled breath condensate (EBC) is a noninvasive method to determine airway inflammation. There is accumulating evidence that pH, nitrogen oxides (NOx), and leukotriene B4 (LTB4) are suitable markers of inflammatory airway diseases. It was the aim of the present pilot study to evaluate a protocol of EBC sampling and processing for epidemiologic field studies. EBC samples were repeatedly obtained by 16 healthy adults on each of four days over two consecutive weeks. The effects of sample collection (volume vs. time, with vs. without nose-clip) and sample processing on volume, pH, NOx, and LTB4 as well as within-day, between-day, and between-week reproducibility were assessed. We found that wearing a nose-clip had no significant effects on mediators. Sampling time was the major determinant of the volume. Reproducibility was fairly good. Storage at 4-6 degrees C for 24 h had no significant effects on NOx and LTB4 concentrations, but resulted in an increase of pH. In conclusion, wearing a nose-clip during EBC collection is not recommended in terms of convenience and compliance for repeated investigations. Samples for the analyses of NOx and LTB4 can be transported under usual conditions, but pH should preferably be determined at the workplace.