Analysis of exhaled air for a rapid, sensible and specific diagnosis of COPD

Aim: Exhaled air contains volatile organic compounds (VOCs) produced during metabolic processes in both healthy and pathological conditions. The early diagnosis of COPD is complicated and the identification of specific metabolic profiles of exhaled air may provide useful indication to better identify the disease. The aim of this study was to validate the COPD detection capability of an electronic nose (EN). Methods: Exhaled air was tested in 34 subjects, 7 healthy and 27 former smokers with stable COPD. The specific exhaled VOCs were characterized using an EN and a solid phase micro-extraction associated to gas chromatography-mass spectrometry (SPME GC-MS). Results: The signals of EN sensors were higher in COPD patients than controls, accurately classifying the studied population in healthy subjects or COPD patients. Among the 37 VOCs identified by GC-MS, 2 (decane; decane, 6-ethyl-2-methyl-) were positively correlated and 7 (limonene; butylated hydroxytoluene; 2-propanol; benzene, 1,3,5-tri-tert-butyl-;hexane, 3-ethyl-4-methyl-; hexyl ethylphosphonofluoridate; 1-pentene, 2,4,4-trimethyl-) were negatively correlated with COPD. The logistic regression analysis carried out with these 9 VOCs produced a significant predictive model of disease. Conclusions: Our EN showed a high diagnostic accuracy and discrimination between control and COPD group. Therefore, it may represent a suitable tool for rapid, sensitive and specific characterization of COPD. Our data suggest that stable COPD patients are characterized by a peculiar VOCs fingerprint profile of the exhaled breath. The detection of these profiles with GC-MS or EN gives rise to a suitable tool for rapid, sensitive, and specific diagnosis of COPD.