Clinical use of exhaled biomarkers in COPD

Exhaled breath analysis holds great promise as a diagnostic and investigative tool in COPD and is a new and rapidly expanding field of research in pulmonary disease. Generally speaking, exhaled breath analysis focuses on two areas: measurement of exhaled nitric oxide (ENO) and the detection of biomarkers in exhaled breath condensate (EBC). ENO measurement may not be as useful in COPD as in other pulmonary diseases, such as asthma, due to the lower levels of ENO found in COPD, although this is an area of ongoing research. Analysis of EBC for proinflammatory biomarkers is an area of great promise but its true value will not be realized until methods of collecting and analyzing EBC have been standardized. Once this is done, biomarkers detected in EBC may assist in the diagnosis of COPD, identification of preclinical disease, phenotyping of COPD patients, evaluation of response to therapies and defining the prognosis of individual patients. Identification of novel inflammatory mediators in EBC may cast new light on the pathogenesis of COPD and identify new therapeutic targets, which are badly needed in this disease.