title: Expiratory flow rate, breath hold and anatomic dead space influence electronic nose ability to detect lung cancer.
abstract: BACKGROUND
  Electronic noses are composites of nanosensor arrays. Numerous studies showed their potential to detect lung cancer from breath samples by analysing exhaled volatile compound pattern ("breathprint"). Expiratory flow rate, breath hold and inclusion of anatomic dead space may influence the exhaled levels of some volatile compounds; however it has not been fully addressed how these factors affect electronic nose data. Therefore, the aim of the study was to investigate these effects.
  
  
  METHODS
  37 healthy subjects (44 ± 14 years) and 27 patients with lung cancer (60 ± 10 years) participated in the study. After deep inhalation through a volatile organic compound filter, subjects exhaled at two different flow rates (50 ml/sec and 75 ml/sec) into Teflon-coated bags. The effect of breath hold was analysed after 10 seconds of deep inhalation. We also studied the effect of anatomic dead space by excluding this fraction and comparing alveolar air to mixed (alveolar + anatomic dead space) air samples. Exhaled air samples were processed with Cyranose 320 electronic nose.
  
  
  RESULTS
  Expiratory flow rate, breath hold and the inclusion of anatomic dead space significantly altered "breathprints" in healthy individuals (p < 0.05), but not in lung cancer (p > 0.05). These factors also influenced the discrimination ability of the electronic nose to detect lung cancer significantly.
  
  
  CONCLUSIONS
  We have shown that expiratory flow, breath hold and dead space influence exhaled volatile compound pattern assessed with electronic nose. These findings suggest critical methodological recommendations to standardise sample collections for electronic nose measurements.
authors.affiliation: Department of Pulmonology, Semmelweis University, 1/C Dios arok, Budapest 1125, Hungary. andras.bikov@gmail.com.
authors.forename: Andras
authors.initials: A
authors.lastname: Bikov
authors.forename: Marton
authors.initials: M
authors.lastname: Hernadi
authors.forename: Beata Zita
authors.initials: BZ
authors.lastname: Korosi
authors.forename: Laszlo
authors.initials: L
authors.lastname: Kunos
authors.forename: Gabriella
authors.initials: G
authors.lastname: Zsamboki
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Sutto
authors.forename: Adam Domonkos
authors.initials: AD
authors.lastname: Tarnoki
authors.forename: David Laszlo
authors.initials: DL
authors.lastname: Tarnoki
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Losonczy
authors.forename: Ildiko
authors.initials: I
authors.lastname: Horvath
mesh_terms: D000328:Adult; D000368:Aged; D062485:Breath Holding; D001944:Breath Tests / Q000379:methods*; D062609:Electronic Nose; D005260:Female; D005540:Forced Expiratory Flow Rates; D064368:Healthy Volunteers; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012126:Respiratory Dead Space; D012907:Smoking; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D055549:Volatile Organic Compounds