Breath sound analyses of infants with respiratory syncytial
virus-induced acute bronchiolitis
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.