Is clinical wheezing reliable as the endpoint for bronchial challenges in preschool children?
The present study was designed to compare the clinical finding of wheeze by auscultation with an objective evaluation by acoustic means at the endpoint of a bronchial challenge in preschool children. Challenges were undertaken using a tidal breathing method in 51 preschool children as part of the investigation of possible asthma. An electronic stethoscope was used for auscultation of each lung and for the simultaneous recording of the acoustic sonogram for analysis. In 24 children, the pediatrician determined that the challenge was positive, and in 22 of these, he heard wheezing at the endpoint of the challenge. In 2 children the challenge was considered positive, based on a modest fall in saturation. The acoustic record was scanned manually for presence of wheeze defined in terms of duration, and power spectrum without reference to auscultatory findings. In positive challenges, the mean wheeze rate was 28.1% (95% CI, 19.5-36.8%), while no wheeze was detected acoustically in negative challenges. Using a cutoff wheeze rate (duration of wheeze/duration of breath phase x100) of 10% for the whole group, clinical wheezing detected by the pediatrician had a sensitivity of 100% (no false negatives) and a specificity of 91%. In conclusion, the clinical observation of wheeze agrees very well with its detection by acoustic measurement at the endpoint of a bronchial challenge in preschool children.