New Technique to Analyze the Breath Sound Spectrum in Children with Asthma

Abstract

Objective: Breath sound parameters have been reported as useful biomarkers for evaluating the airway condition.

Methods: The reliability of breath sound analysis using an improved method was investigated. Eighty-three asthmatic children were included in the present study. After adjusting the 0 level based on the background noises of the breath sound spectrum, the total area under the curve of the dBm (A_T), the roll-off from 600-1200 Hz (Slope), the ratio of the third and fourth area to the A_T (A₃/A_T and B₄/A_T), and the ratio of power and frequency at 50% and 75% of the highest frequency (RPF₇₅ and RPF₅₀), were evaluated before and after β₂ agonist inhalation. Spirography and the forced oscillation technique were also used to evaluate all subjects.

Results: Using the new method, A₃/A_T, B₄/A_T, RPF₇₅ and RPF₅₀, were significantly increased after β₂ agonist inhalation. The increase in A₃/A_T and B₄/A_T were significantly correlated with the increase in FEV₁ and FEE_25-75, and the increase in RPF₇₅ was reversibly correlated with that in R5-R20.

Conclusions: The spectrum curve indices using the adjusted 0 level can indicate bronchial dilation with β₂ agonist inhalation. These parameters may be useful for the assessment of bronchial reversibility in asthmatic children.