Assessment and validation of bronchodilation using the interrupter technique in preschool children.
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.
Mele
Laura
L
Department of Pediatrics, University of Florence, Florence, Italy.
Sly
Peter D
PD
Calogero
Claudia
C
Bernardini
Roberto
R
Novembre
Elio
E
Azzari
Chiara
C
de Martino
Maurizio
M
Lombardi
Enrico
E
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
D001993:Bronchodilator Agents; D000420:Albuterol