title: Alveolar nitric oxide concentration reflects peripheral airway obstruction in stable asthma.
abstract: OBJECTIVE
  Increased fraction of exhaled nitric oxide (FeNO) has been shown to reflect airway inflammation in asthma. Central airway NO flux (J'awNO; nL/s) and peripheral airway/alveolar NO concentration (CANO; ppb) can be calculated separately. CANO has been reported to reflect small airway inflammation. The aim of the present study is to correlate CANO levels with clinical and physiological parameters in patients with stable asthma.
  
  
  METHODS
  Seventy-three well-controlled asthmatics (mean age 61) were enrolled. Measurement of FeNO (at 50, 100, 150 and 200 mL/s) and pulmonary function test were performed. J'awNO(TMAD) and CANO(TMAD) were calculated and corrected by the trumpet shape of the airway tree and axial back-diffusion (TMAD).
  
  
  RESULTS
  CANO(TMAD) was significantly correlated with forced expiratory flow between 25-75% of the forced vital capacity (FVC) (FEF(25 -75)), FEF(25 -75) percentage of the predicted value (%pred), forced expiratory flow at 50% of the FVC (FEF(50)) and FEF(50) %pred (R = -0.39 P = 0.002, R = -0.29 P = 0.02, R = -0.39 P = 0.001, R = -0.29 P = 0.02, respectively). CANO(TMAD) was positively correlated with age (R = -0.45 P = 0.0002) and weakly correlated with duration of asthma (R = -0.27 P = 0.03). Forced expiratory volume in 1 s/FVC was negatively correlated with CANO(TMAD), J'awNO(TMAD) and FeNO 50 mL/s. Among these, correlation between forced expiratory volume in 1 s/FVC and FeNO 50 mL/s was the strongest (R = -0.34 P = 0.004).
  
  
  CONCLUSIONS
  CANO(TMAD) may be a more specific marker of peripheral airway obstruction than FeNO and J'awNO(TMAD) in stable asthma.
authors.affiliation: Department of Laboratory Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan. fujisawa@hama-med.ac.jp
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Fujisawa
authors.forename: Hideki
authors.initials: H
authors.lastname: Yasui
authors.forename: Taisuke
authors.initials: T
authors.lastname: Akamatsu
authors.forename: Dai
authors.initials: D
authors.lastname: Hashimoto
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Enomoto
authors.forename: Naoki
authors.initials: N
authors.lastname: Inui
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Masato
authors.initials: M
authors.lastname: Maekawa
authors.forename: Takafumi
authors.initials: T
authors.lastname: Suda
authors.forename: Kingo
authors.initials: K
authors.lastname: Chida
mesh_terms: D000402:Airway Obstruction / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D001249:Asthma / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism; D045853:Exhalation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis*; D011237:Predictive Value of Tests; D011650:Pulmonary Alveoli / Q000378:metabolism*; D012129:Respiratory Function Tests / Q000379:methods; D012720:Severity of Illness Index; D014797:Vital Capacity
chemical_list: D009569:Nitric Oxide