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 (A1000 [dBm·Hz]) and the ratio of the A1000 to the total AUC at 100 Hz to the highest frequency of the dBm power spectrum (AT) (A1000/AT [%]) were measured before and after β2 agonist inhalation. Spirography and the forced oscillation technique were also used to evaluate all subjects. RESULTS: The value of A1000 was negatively correlated with the FEV1 (p=0.028). The increase in the ΔFEV1 was correlated with the decrease in the ΔA1000 (p=0.001) and the ΔA1000/AT (p=0.036). CONCLUSIONS: The A1000 indicates the airway condition, and the ΔA1000 and the ΔA1000/AT well describe the dilatation of the airways. These parameters are useful for the assessment of bronchial reversibility in asthmatic children.