RESEARCH ARTICLE Using the Electronic Nose to Identify Airway Infection during COPD Exacerbations

Background The electronic nose (e-nose) detects volatile organic compounds (VOCs) in exhaled air. We hypothesized that the exhaled VOCs print is different in stable vs. exacerbated patients with chronic obstructive pulmonary disease (COPD), particularly if the latter is associated with airway bacterial infection, and that the e-nose can distinguish them. Methods Smell-prints of the bacteria most commonly involved in exacerbations of COPD (ECOPD) were identified in vitro. Subsequently, we tested our hypothesis in 93 patients with ECOPD, 19 of them with pneumonia, 50 with stable COPD and 30 healthy controls in a cross-sec-tional case-controlled study. Secondly, ECOPD patients were re-studied after 2 months if clinically stable. Exhaled air was collected within a Tedlar bag and processed by a Cynar-ose 320 e-nose. Breath-prints were analyzed by Linear Discriminant Analysis (LDA) with “One Out ” technique and Sensor logic Relations (SLR). Sputum samples were collected for culture