Abstract
Introduction: The reliability of breath sound analysis using an
improved method in infants has been reported.
Objective: Breath sounds of infants with respiratory syncytial
virus (RSV)-induced acute bronchiolitis were analyzed to evaluate their
specificity and examine their relationship with the severity.
Subjects and methods: We evaluated the inspiratory and
expiratory breath sound parameters of 33 infants (median age=2 months
old) diagnosed with RSV-induced acute bronchiolitis. The sound powers of
inspiration and expiration and the spectrum curve indices (ratio of the
third and fourth area to the total area under the curve and ratio of the
power and frequency at 50% and 75% of the highest frequency were
evaluated at the acute phase and recovery phase. Furthermore, the
relationship between the breath sound parameters and the clinical
severity of acute bronchiolitis was examined.
Results: Analyses of the breath sound spectrogram showed that
the power of expiration at the acute phase was large, and was the
expiration-to-inspiration sound power ratio in a mid-frequency range
(E/I MF), with values decreased in the recovery phase. Data of the
inspiratory sound spectrum curve showed the improvement of airway
stenosis during the recovery period. Furthermore, there were significant
relationships between the E/I MF and SpO2 and the
severity score of acute bronchiolitis.
Conclusion: In RSV-induced acute bronchiolitis, specificity of
breath sounds was observed in the expiration sound and the reversible
airway stenosis was evaluated. Breath sound analyses are expected to be
useful for the diagnosis and clinical evaluation of the severity of
acute bronchiolitis.