Clinical Application of High-pitched Breath Sound in Children with Asthma.

Objective: Breath sound parameters have been suggested to be a new biomarker of airway conditions in asthmatic patients. We investigated new breath sound parameters to determine their utility for evaluating asthmatic children.

Methods: Fifty-seven children (mean age, 9.0 years, 6-16 years) were included in the present study. The new breath sound parameters, the area under the curve (AUC)>1,000 Hz (A [dBm·Hz]) and the ratio of the A to the total AUC at 100 Hz to the highest frequency of the dBm power spectrum (A) (A/A [%]) were measured before and after β agonist inhalation. Spirography and the forced oscillation technique were also used to evaluate all subjects.

Results: The value of A was negatively correlated with the FEV (p=0.028). The increase in the ΔFEV was correlated with the decrease in the ΔA (p=0.001) and the ΔA/A (p=0.036).

Conclusions: The A indicates the airway condition, and the ΔA and the ΔA/A well describe the dilatation of the airways. These parameters are useful for the assessment of bronchial reversibility in asthmatic children.