title: Assessment and validation of bronchodilation using the interrupter technique in preschool children.
abstract: OBJECTIVE
  To determine and validate a cut-off value for bronchodilation using the interrupter resistance (Rint) in preschool children.
  
  
  METHODS
  Rint was measured in 60 healthy children (age range 2.7-6.4 years) before and after salbutamol inhalation (200 microg). Four potential methods for assessing BDR were evaluated: percent change from baseline, percent change of predicted values, absolute change in Rint, and change in Z-score. These cut-off values, determined as the fifth percentile of the healthy group, were applied to children referred for the assessment of recurrent wheezing, classified on the basis of acute symptoms and/or abnormal chest examination into symptomatic (n = 60, age range 2.9-6.1 years) and asymptomatic (n = 60, age range 2.5-5.7 years) groups.
  
  
  RESULTS
  The cut-off values for bronchodilation calculated in healthy children were: -32% baseline; -33% predicted; -0.26 kPa L(-1) sec; and -1.25 Z-scores. Assessing BDR in children with a history of wheezing by either a decrease in absolute Rint or a decrease in Z-score gave sensitivity, specificity, negative predictive value, and positive predictive value all >80% for detecting children with current respiratory symptoms.
  
  
  CONCLUSIONS
  Both a decrease in Rint > or =0.26 kPa L(-1) sec and a decrease in Z-score of > or =1.25 are appropriate for assessing BDR in preschool children with a history of recurrent wheezing. As Z-score is a more general solution, we recommend using a change in Z-score to determine BDR in preschool children. Further longitudinal studies will be required to determine the clinical utility of measuring BDR in managing lung disease in such children.
authors.affiliation: Department of Pediatrics, University of Florence, Florence, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Mele
authors.forename: Peter D
authors.initials: PD
authors.lastname: Sly
authors.forename: Claudia
authors.initials: C
authors.lastname: Calogero
authors.forename: Roberto
authors.initials: R
authors.lastname: Bernardini
authors.forename: Elio
authors.initials: E
authors.lastname: Novembre
authors.forename: Chiara
authors.initials: C
authors.lastname: Azzari
authors.forename: Maurizio
authors.initials: M
authors.lastname: de Martino
authors.forename: Enrico
authors.initials: E
authors.lastname: Lombardi
mesh_terms: D000403:Airway Resistance; D000420:Albuterol; D001249:Asthma / Q000175:diagnosis; D001980:Bronchi / Q000187:drug effects / Q000503:physiopathology*; D001993:Bronchodilator Agents; D002648:Child; D002675:Child, Preschool; D003371:Cough / Q000175:diagnosis; D005260:Female; D006801:Humans; D008297:Male; D012135:Respiratory Sounds / Q000175:diagnosis* / Q000187:drug effects / Q000503:physiopathology
chemical_list: D001993:Bronchodilator Agents; D000420:Albuterol