The cornerstone of COPD is a chronic inflammation leading to narrowing of the small airways and thus impairment of lung function. Spirometry, the most frequently used pulmonary function test for diagnosing and monitoring disease, mostly reflects obstruction of the larger airways. The single breath N2-test, however, is more sensitive to identify the regional heterogeneity of bronchial airflow obstruction in the small airways, a main site of injury in COPD.~The aim of this study is to evaluate whether there is a correlation between the sbN2-test, markers in exhaled air and the inflammatory cells in the small airways.~This protocol describes a cross-sectional, explorative trial in at least 16 patients with COPD (up to GOLD III) and 8 patients without COPD who are scheduled for surgical resection for primary lung cancer. Immunohistological methods will be used to characterize the airways (large and small) inflammation pattern in macroscopically normal tissue containing small and large airways collected from sites distant from the tumor. Inflammatory markers will be measured in exhaled breath (exhaled breath condensate, exhaled NO) and be correlated to the sbN2 test. Breath patterns before and after lung cancer surgery will be assessed by the electronic nose and differential mobility spectrometry.~We hypothesize that the sbN2-test and inflammatory markers in exhaled breath reflect changes at peripheral tissue level. Therefore the results of the present study would lead to validation of these non-invasive tools for studies into the pathogenesis of obstructive lung disease, to increased knowledge about the relationship between airway inflammation and small airways obstruction, and may provide further support for the small airways as a specific target for inhaled drug delivery.
Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality worldwide and is characterized by fixed airflow obstruction. The cornerstone of the disease is chronic inflammation leading to narrowing of the small airways and thus impairment of lung function. Compared to spirometry, the single breath N2-washout-test is more sensitive to identify the regional heterogeneity of bronchial airflow obstruction in the small airways.~The aim of this study is to evaluate whether there is a correlation between the sbN2-test, markers in exhaled air and the inflammatory cells in the small airways.