Exhaled breath profiling enables discrimination of chronic obstructive pulmonary disease and asthma

Am J Respir Crit Care Med. 2009 Dec 1;180(11):1076-82. doi: 10.1164/rccm.200906-0939OC. Epub 2009 Aug 27.


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; FEV(1), 1.72 +/- 0.69 L), 20 patients with asthma (age, 35.4 +/- 15.1 years; FEV(1) 3.32 +/- 0.86 L), 20 nonsmoking control subjects (age, 56.7 +/- 9.3 years; FEV(1), 3.44 +/- 0.76 L), and 20 smoking control subjects (age, 56.1 +/- 5.9 years; FEV(1), 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).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adrenal Cortex Hormones / therapeutic use
  • Adult
  • Aged
  • Aged, 80 and over
  • Asthma / diagnosis*
  • Asthma / drug therapy
  • Biomarkers / analysis
  • Breath Tests / instrumentation*
  • Breath Tests / methods*
  • Cross-Sectional Studies
  • Exhalation*
  • Female
  • Forced Expiratory Volume
  • Humans
  • Male
  • Middle Aged
  • Pulmonary Disease, Chronic Obstructive / diagnosis*
  • Pulmonary Disease, Chronic Obstructive / drug therapy
  • Reproducibility of Results
  • Smoking
  • Volatile Organic Compounds / analysis
  • Young Adult


  • Adrenal Cortex Hormones
  • Biomarkers
  • Volatile Organic Compounds