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Exhaled Breath Profiling Enables Discrimination of Chronic Obstructive Pulmonary Disease and Asthma

¹ Department of Respiratory Medicine and ² Clinical Epidemiology and Biostatistics, Academic Medical Centre, University of Amsterdam, Amsterdam; ³ Department of Pulmonary Diseases, Haga Teaching Hospital Leyweg, Den Haag; and ⁴ Department of Respiratory Medicine, Albert Schweitzer Hospital, Dordrecht, The Netherlands

Correspondence and requests for reprints should be addressed to Niki Fens, M.D., Department of Respiratory Medicine, F5-260, Academic Medical Centre, University of Amsterdam, P.O. Box 22700, Amsterdam NL-1100 DE, The Netherlands. E-mail: N.Fens{at}amc.nl

Rationale: Chronic obstructive pulmonary disease (COPD) and asthma can exhibit overlapping clinical features. Exhaled air contains volatile organic compounds (VOCs) that may qualify as noninvasive biomarkers. VOC profiles can be assessed using integrative analysis by electronic nose, resulting in exhaled molecular fingerprints (breathprints).

Objectives: We hypothesized that breathprints by electronic nose can discriminate patients with COPD and asthma.

Methods: Ninety subjects participated in a cross-sectional study: 30 patients with COPD (age, 61.6 ± 9.3 years; FEV₁, 1.72 ± 0.69 L), 20 patients with asthma (age, 35.4 ± 15.1 years; FEV₁ 3.32 ± 0.86 L), 20 nonsmoking control subjects (age, 56.7 ± 9.3 years; FEV₁, 3.44 ± 0.76 L), and 20 smoking control subjects (age, 56.1 ± 5.9 years; FEV₁, 3.58 ± 0.78). After 5 minutes of tidal breathing through an inspiratory VOC filter, an expiratory vital capacity was collected in a Tedlar bag and sampled by electronic nose. Breathprints were analyzed by discriminant analysis on principal component reduction resulting in cross-validated accuracy values (accuracy). Repeatability and reproducibility were assessed by measuring samples in duplicate by two devices.

Measurements and Main Results: Breathprints from patients with asthma were separated from patients with COPD (accuracy 96%; P < 0.001), from nonsmoking control subjects (accuracy, 95%; P < 0.001), and from smoking control subjects (accuracy, 92.5%; P < 0.001). Exhaled breath profiles of patients with COPD partially overlapped with those of asymptomatic smokers (accuracy, 66%; P = 0.006). Measurements were repeatable and reproducible.

Conclusions: Molecular profiling of exhaled air can distinguish patients with COPD and asthma and control subjects. Our data demonstrate a potential of electronic noses in the differential diagnosis of obstructive airway diseases and in the risk assessment in asymptomatic smokers.

Clinical trial registered with www.trialregister.nl (NTR 1282).

Key Words: biomarkers • diagnosis • electronic nose • exhaled breath • volatile organic compounds

AT A GLANCE COMMENTARY Scientific Knowledge on the Subject Lung diseases can change the molecular mixture of exhaled air. Electronic noses are suitable for the recognition of molecular patterns and provide an exhaled breathprint. What This Study Adds to the Field Patients with chronic obstructive pulmonary disease and asthma can be distinguished by their breathprints of exhaled air. This shows the potential of electronic noses in the discrimination of obstructive airways diseases.

 

Related articles in AJRCCM:

Identifying Chronic Obstructive Pulmonary Disease and Asthma by Exhaled Breath Analysis: Does the (e)Nose Know?

Roberto F. Machado
AJRCCM 2009 180: 1038-1039. [Full Text]  

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				R. F. Machado Identifying Chronic Obstructive Pulmonary Disease and Asthma by Exhaled Breath Analysis: Does the (e)Nose Know? Am. J. Respir. Crit. Care Med., December 1, 2009; 180(11): 1038 - 1039. [Full Text] [PDF]