Standardisation of Measurements in Exhaled Breath and Exhaled Breath Condensate.

Background of the study: Measurement of inflammatory markers (IM) in exhaled breath and exhaled breath condensate (EB(C)) is a very interesting and useful non-invasive new technique to evaluate airway inflammation. This technique is helpful for diagnostic and monitoring purposes in both children and adults with chronic lung disease. The hypothesis of the present study is that standardisation not only increase the reproducibility of measurements but will also enlarge the possibility to detect differences between healthy and diseased subjects. Objective of the study: 1. to investigate the influence of various factors on the concentration of markers in EB(C); parameters on a subject level (e.g. breathing pattern, nose clip, inspiratory filter, saliva contamination, physical exertion), on an apparatus level (cleaning procedures, temperature of the condenser tube, environmental conditions, buffer bags), and on a measurement/analysis level (sampling time, storage time, storage temperature, protein inhibitor or bovine serum albumine) can be discriminated. 2. to assess whether the reproducibility of measurements in EB(C) can be increased by analysing with ellipsometry, lyophilization or by standardising for exhaled volume, sampling time, or dilution factor. 3. to investigate whether differences in inflammatory markers (IM) in EBC between healthy and diseased subjects will increase by specific EB(C) sampling from more distal airways. Children with asthma, cystic fibrosis (CF), primary ciliary dyskinesia (PCD), bronchopulmonary dysplasia (BPD), and lower respiratory tract infections (LRTI) will be included. Study design: Part I: Cross-sectional study assessing the random influence of presence or absence of various factors on the concentration of IM in EB(C); Part II: A short-term prospective study on reproducibility during five consecutive days; Part III: A cross-sectional comparative study in several groups of children (healthy, asthma, CF, PCD, BPD, LRTI); Study population: Study part I and II are performed in healthy adult volunteers. Study part III is performed in healthy children and in children with asthma, CF, PCD, BPD, and LRTI aged 2-16 years. Primary study parameters/outcome of the study: Study part I: Concentration of IM in EB(C). Study part II: Reproducibility as assessed by coefficients of variations of IM in EB(C). Study part III: Concentration of IM in EB(C) from more distal and more proximal airways.