· · · Repository hosted by TU Delft Library

Background Eosinophilic inflammation in COPD is predictive for response to inhaled steroids. We hypothesized that inflammatory subtype in mild and moderately severe COPD can be assessed by exhaled breathmetabolomics. Methods Standardized sampling of exhaled compounds wasperformed using gas-chromatography and mass-spectrometry (GC-MS) and electronic nose (eNose) in 28 COPD patients (12/16 GOLD I/II). Differential cell counts, eosinophilic cationic protein and myeloperoxidase were measured in induced sputum. Relationships between compounds, eNose breathprints and sputum inflammatory markers were analyzedand ROC curves were constructed. Results Exhaled compounds were highly associated with sputum cell counts (9 compounds with eosinophils,20 with neutrophils:,p<0.01). Only two compounds (phenol, alkylatedbenzene) overlapped between eosinophilic and neutrophilic profiles.GC-MS and eNose breathprints were also associated with markers of inflammatory activity, in GOLD stage I (ECP: 19 compounds, p<0.01; eNose breathprint r=0.84, p=0.002) (MPO: 4 compounds p<0.01; eNose r=0.72, p=0.008). ROC analysis for eNose showed high sensitivity and specificity for inflammatory activity in mild COPD (ECP: AUC=1.00) (MPO: AUC=0.96). Conclusions Exhaled molecular profiles are closely associated with the type and activity of airways inflammation in mildand moderate COPD. This suggests that breath analysis can potentially be used for assessment and monitoring of airways inflammation inCOPD.

Abstract: An overview of the scientific literature in the medical field tells us that a large part of electronic nose applications is devoted to breath analysis. A network based study can help testing thevalidity of this strategy when using many different devices based on identical or different technologies, in view of a use in real clinical practice. The first step is the instrument calibration using aset of key-compounds. In this work a gas sensor array based on Quartz Micro Balance (QMB) transducers functionalized with metallo-porphyrins (ROTV e-nose), and a Cyranose are used simultaneously in a calibration experiment with three ad hoc selected compounds: ethanol, hexane and ethyl acetate, at concentration levels around 1 ppm. Thesetests have demonstrated that LODs down to tens of ppb are possible.Moreover, a mapping between the two instruments has been performed through the calculation of a model based on Cyranose data, and applied to the ROTV e-nose data, for the prediction of compound concentrations. This test has shown a good ability in concentrations prediction, with an error lower than 10 ppb.