An electronic nose in the discrimination of patients with asthma and controls.
BACKGROUND
Exhaled breath contains thousands of volatile organic compounds (VOCs) that could serve as biomarkers of lung disease. Electronic noses can distinguish VOC mixtures by pattern recognition.


OBJECTIVE
We hypothesized that an electronic nose can discriminate exhaled air of patients with asthma from healthy controls, and between patients with different disease severities.


METHODS
Ten young patients with mild asthma (25.1 +/- 5.9 years; FEV(1), 99.9 +/- 7.7% predicted), 10 young controls (26.8 +/- 6.4 years; FEV(1), 101.9 +/- 10.3), 10 older patients with severe asthma (49.5 +/- 12.0 years; FEV(1), 62.3 +/- 23.6), and 10 older controls (57.3 +/- 7.1 years; FEV(1), 108.3 +/- 14.7) joined a cross-sectional study with duplicate sampling of exhaled breath with an interval of 2 to 5 minutes. Subjects inspired VOC-filtered air by tidal breathing for 5 minutes, and a single expiratory vital capacity was collected into a Tedlar bag that was sampled by electronic nose (Cyranose 320) within 10 minutes. Smellprints were analyzed by linear discriminant analysis on principal component reduction. Cross-validation values (CVVs) were calculated.


RESULTS
Smellprints of patients with mild asthma were fully separated from young controls (CVV, 100%; Mahalanobis distance [M-distance], 5.32), and patients with severe asthma could be distinguished from old controls (CVV, 90%; M-distance, 2.77). Patients with mild and severe asthma could be less well discriminated (CVV, 65%; M-distance, 1.23), whereas the 2 control groups were indistinguishable (CVV, 50%; M-distance, 1.56). The duplicate samples replicated these results.


CONCLUSIONS
An electronic nose can discriminate exhaled breath of patients with asthma from controls but is less accurate in distinguishing asthma severities.


CONCLUSIONS
These findings warrant validation of electronic noses in diagnosing newly presented patients with asthma.
Dragonieri
Silvano
S
Department of Pulmonology, Leiden University Medical Center, Leiden, The Netherlands.
Schot
Robert
R
Mertens
Bart J A
BJ
Le Cessie
Saskia
S
Gauw
Stefanie A
SA
Spanevello
Antonio
A
Resta
Onofrio
O
Willard
Nico P
NP
Vink
Teunis J
TJ
Rabe
Klaus F
KF
Bel
Elisabeth H
EH
Sterk
Peter J
PJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000175:diagnosis*; D015374:Biosensing Techniques / Q000295:instrumentation*; D001944:Breath Tests / Q000295:instrumentation*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008875:Middle Aged; D009930:Organic Chemicals / Q000032:analysis*; D014835:Volatilization
D009930:Organic Chemicals