title: Characterization of exhaled particles from the human lungs in airway obstruction.
abstract: BACKGROUND
  Human breath contains small particles that might be useful for the noninvasive diagnosis of lung disease. In this study, the impact of airway obstruction on particle emission was investigated.
  
  
  METHODS
  Particle number flux and particle size distribution were measured for healthy nonsmokers (n=16), healthy smokers (n=13), patients with chronic obstructive pulmonary disease (n=28, GOLD stage I-IV), and patients with asthma before and after methacholine challenge (n=10). The measurements were carried out using a condensation nucleus counter (TSI 3760) and a laser spectrometer (PMT LASAIR II-110).
  
  
  RESULTS
  Particle number per breath showed high intrasubject reproducibility. However, there was a large intersubject variability in the number of emitted particles on the order of two magnitudes, with no influence of airway obstruction on emission level. Methacholine-induced airway obstruction, in subjects with allergic asthma, did not change the number of exhaled particles, when compared with prechallenge values. For the droplet size distribution averaged per breath, there was no difference between healthy subjects and subjects with airway obstruction.
  
  
  CONCLUSIONS
  Airway obstruction does not change the number flux or size distribution of particles in exhaled breath. The high intersubject variability of particle emission supports the concept of online determination of aerosol properties (primarily number flux, during exhaled breath) during breath condensate sampling to properly normalize the results of biochemical analysis. As high dilution and variable dilution are the main challenges of biomarker assessment in exhaled breath condensate, this normalization procedure would significantly add to the value of the technique.
authors.affiliation: 1 Fraunhofer Institute for Toxicology and Experimental Medicine , Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research, 30625 Hannover, Germany .
authors.forename: Katharina
authors.initials: K
authors.lastname: Schwarz
authors.forename: Heike
authors.initials: H
authors.lastname: Biller
authors.forename: Horst
authors.initials: H
authors.lastname: Windt
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Koch
authors.forename: Jens M
authors.initials: JM
authors.lastname: Hohlfeld
mesh_terms: D000328:Adult; D000336:Aerosols; D000368:Aged; D001249:Asthma / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D015415:Biomarkers / Q000378:metabolism*; D001944:Breath Tests; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D016022:Case-Control Studies; D045853:Exhalation; D005260:Female; D006801:Humans; D008168:Lung / Q000378:metabolism* / Q000503:physiopathology*; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D010316:Particle Size; D011237:Predictive Value of Tests; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D015203:Reproducibility of Results; D012907:Smoking / Q000009:adverse effects / Q000378:metabolism / Q000503:physiopathology; D055815:Young Adult
chemical_list: D000336:Aerosols; D015415:Biomarkers; D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride
keywords: COPD; airway monitoring; asthma; biomarker; exhaled breath condensate; exhaled particles; pulmonary function