Changes in the Breath Sound Spectrum with Bronchodilator Inhalation in Asthmatic Children with Long-term Management.

Using a commercially available breath sound analyzer, the airway reversibility in asthmatic children during healthy periods was investigated.
Fifty samples of 34 children with asthma (median age, 11 years; range, 6-16 years) who visited our hospital and whose lung function was normal were included. The breath sound parameters, the frequency limiting 99% of the power spectrum (F) and spectrum curve indices, the total area under the curve of the dBm data (A/A and B/A) and the ratio of power and frequency at 50% and 75% of the highest frequency of the power spectrum (RPF and RPF) were evaluated before and after β agonist inhalation.
The values of spectrum curve indices were significantly increased after β agonist inhalation. The changes in these parameters were more marked than the changes in the FOT parameters. The changes in A/A and B/A were significantly related to two FOT parameters: R5-R20 and X5.
Our study suggested that significant changes in breath sound parameters were present in asthmatic children during the period of good control. A breath sound analysis may be useful for assessing the airway condition of asthmatic children during long-term management.