Exhaled nitric oxide measurements in a population sample of young adults

Am J Respir Crit Care Med. 1999 Mar;159(3):911-6. doi: 10.1164/ajrccm.159.3.9802108.


In epidemiologic studies of asthma there is a group with recent wheeze, but with no airway hyperresponsiveness (AHR), in whom it is unclear whether any significant airway abnormality exists. Exhaled nitric oxide (NO) has been proposed as a measure of airway inflammation. We measured exhaled NO in a population sample of 306 young adults who also underwent bronchial challenge with histamine or a bronchodilator test. Subjects blew into a 3-L Tedlar bag against a 2-mm-diameter resistance to close the soft palate and exclude nasal air. The NO content of expired gas from a single breath was analyzed by chemiluminescent analyzer. Exhaled NO was log-normally distributed in the population sample and duplicate measurements were highly reproducible (intraclass correlation coefficient = 0.98). Exhaled NO correlated significantly with airway responsiveness, measured as the dose-response ratio to histamine (r = 0.39, p < 0.001) and with peripheral blood eosinophils (r = 0.35, p < 0.001). Exhaled NO was significantly greater in asthmatic subjects (geometric mean, 22.2; 95% confidence intervals, 16.1 to 30. 7 ppb) than in normal subjects (7.8, 7.1 to 8.4, p < 0.001) or in subjects with wheeze but no AHR (8.8, 7.5 to 10.3, p < 0.001). We conclude that exhaled NO is log-normally distributed, is highly reproducible and discriminates well among subjects, suggesting that it is both a feasible and useful measurement for epidemiologic studies of asthma. The findings suggest that wheeze in the absence of AHR is unlikely to be associated with airway inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Asthma / diagnosis*
  • Asthma / physiopathology
  • Breath Tests*
  • Bronchial Hyperreactivity
  • Bronchial Provocation Tests
  • Child
  • Dose-Response Relationship, Drug
  • Follow-Up Studies
  • Forced Expiratory Volume
  • Histamine / administration & dosage
  • Humans
  • Nitric Oxide / analysis*
  • Reproducibility of Results
  • Respiratory Sounds


  • Nitric Oxide
  • Histamine