title: A Novel Method of Measuring Fractional Exhaled Nitric Oxide in Tracheostomized Ventilator-Dependent Children.
abstract: BACKGROUND
  The lower airway concentration of fractional exhaled nitric oxide (FENO) is unknown in children with chronic lung disease of infancy who have tracheostomy for long-term mechanical ventilation. We aimed to evaluate an online method of measuring FENOin a cohort of ventilator-dependent children with a tracheostomy and to explore the relationship between the peak FENOconcentration (FENOpeak) and the degree of respiratory support using the respiratory severity score.
  
  
  METHODS
  We conducted a prospective cross-sectional study in 31 subjects who were receiving long-term respiratory support through a tracheostomy. We measured the FENOpeak and FENOplateau concentration from the tip of the tracheostomy tube using a nitric oxide analyzer in subjects during a quiet state while being mechanically ventilated. We obtained 2 consecutive 2-min duration measurements from each subject. The FENOpeak, exhaled NO output (equal to the FENOpeak × minute ventilation), and pulmonary NO excretion (exhaled NO output/weight) were calculated and correlated with the respiratory severity score.
  
  
  RESULTS
  The median FENOpeak was 2.69 ppb, and the median FENOplateau was 1.57 ppb. The coefficients of repeatability between the 2 consecutive measurements for FENOpeak and FENOplateau were 0.74 and 0.59, respectively. The intraclass coefficient between subjects within the cohort was 0.988 (95% CI 0.975-0.994,P< .001) for FENOpeak and 0.991 (95% CI 0.982-0.996,P< .001) for FENOplateau. We found that the FENOpeak was directly correlated with minute ventilation, but we did not find a direct relationship between the FENOpeak concentration, exhaled NO output, or pulmonary NO excretion and respiratory severity score.
  
  
  CONCLUSIONS
  FENOpeak and plateau concentration can be measured online easily with a high degree of reliability and repeatability in infants and young children with a tracheostomy. FENOpeak concentration from the lower airway is low and influenced by minute ventilation in children receiving mechanical ventilation.
authors.affiliation: Children's Mercy Hospitals and Clinics, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri.
authors.forename: Vydehi R
authors.initials: VR
authors.lastname: Murthy
authors.affiliation: Children's Mercy Hospitals and Clinics, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri.
authors.forename: Hugo
authors.initials: H
authors.lastname: Escobar
authors.affiliation: Children's Mercy Hospitals and Clinics, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri.
authors.forename: Mike
authors.initials: M
authors.lastname: Norberg
authors.affiliation: Children's Mercy Hospitals and Clinics, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri.
authors.forename: Charisse I
authors.initials: CI
authors.lastname: Lachica
authors.affiliation: Children's Mercy Hospitals and Clinics, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri.
authors.forename: Linda L
authors.initials: LL
authors.lastname: Gratny
authors.affiliation: Children's Mercy Hospitals and Clinics, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri.
authors.forename: Ashley K
authors.initials: AK
authors.lastname: Sherman
authors.affiliation: Children's Mercy Hospitals and Clinics, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri.
authors.forename: William E
authors.initials: WE
authors.lastname: Truog
authors.affiliation: Children's Mercy Hospitals and Clinics, University of Missouri-Kansas City School of Medicine, Kansas City, Missouri. wmmanimtim@cmh.edu.
authors.forename: Winston M
authors.initials: WM
authors.lastname: Manimtim
mesh_terms: D001944:Breath Tests; D003430:Cross-Sectional Studies; D045853:Exhalation / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008168:Lung / Q000503:physiopathology; D008171:Lung Diseases / Q000503:physiopathology* / Q000628:therapy; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012129:Respiratory Function Tests / Q000379:methods*; D014139:Tracheostomy
chemical_list: D009569:Nitric Oxide
keywords: chronic lung disease of infancy; fractional exhaled nitric oxide; tracheostomy