Characteristics of breath sound in infants with risk factors for asthma development

Background: Breath sound parameters have been suggested as biomarkers of the airway narrowing in children. Using a commercially available breath sound analyzer, the characteristics of the airway condition were investigated in infants with the risk factors for asthma development. Methods: A total of 443 infants (mean age, 9.9 months; range, 3–24 months) were included in the present study. The breath sound parameters of the frequency limiting 99% of the power spectrum (F99), the roll-off from 600 to 1200 Hz (Slope) and spectrum curve indices, the total area under the curve of the dBm data (A3/AT) and the ratio of power and frequency at 50% and 75% of the highest frequency of the power spectrum (RPF75 and RPF50), were evaluated. Using an ATS-DLD based original Japanese questionnaire, we examined the characteristics of airway condition of infants. Results: Finally, 283 infants in good health were included in the present study. The RPF75, RPF50, Slope and F99 in infants with positive results of allergy and atopic dermatitis were significantly increased more than those in the infants with negative result. Conclusions: Our data highlight the characteristics of breath sounds in infants with risk factors for asthma. The breath sound analysis may be useful for assessing the airways of infants for asthma development. Keywords: Asthma, Breath sound analysis, Infant, Risk factors, Sound spectrum