Lung sound analysis in infants with risk factors for asthma development

BACKGROUND AND OBJECTIVES: Using a lung sound analysis, the prognosis of asthma was investigated in infants with risk factors for asthma development by a long‐term observation. METHODS: A total of 268 infants were included (median age: 8 months old). The lung sound parameters (the ratio of the third and fourth area to the total area under the curve [A(3)/A(T) and B(4)/A(T)], and the ratio of power and frequency at 50% and 75% of the highest frequency [RPF(50) and RPF(75)]) were evaluated at the first visit. At 3 years old, using a questionnaire, we examined the relationship between the lung sound parameters and risk factors of asthma development. RESULTS: Among the 268 infants, 175 infants were in good health and 93 had a history of acute respiratory infection (ARI) within 7 days at the first visit. Among the 3‐ to 12‐month‐old infants with an ARI, the A(3)/A(T), B(4)/A(T) values in those with a history of asthma/asthmatic bronchitis, atopic dermatitis, and atopy were smaller than in the infants without such histories. Among the 13‐ to 24‐month‐old infants with an ARI, the A(3)/A(T) and B(4)/A(T) values in those with a wheezing history were larger than in the infants without such a history. CONCLUSIONS: The characteristics of the lung sounds in infants with risk factors for asthma development were demonstrated over long‐term follow‐up. Lung sound analyses may be useful for assessing the airway condition of infants.