2.2, Study protocol
Breath sounds were measured at the time of hospitalization (acute phase)
and after discharge (recovery phase). The contents of the study were as
follows: (1) to examine the specificity of RSV-induced acute
bronchiolitis from the breath sound spectrogram, (2) to examine the
power of expiratory and inspiratory sounds17,18) and
to compare them between the acute phase and the recovery phase, (3) to
compare the various parameters of sound spectrum curve indices between
the acute phase and the recovery phase, and (4) to evaluate the
relationship between the various breath sound parameters and the
SpO2 values, the severity score of acute
bronchiolitis19) and the number of days of
hospitalization.
The diagnosis of acute bronchiolitis was made by more than two
specialists with pediatric licenses. They diagnosed acute bronchiolitis
according to previous reports 8, 20, 21), infants
younger than two years, who had respiratory symptoms and wheezes and/or
rhonchi and had decreased SpO2 and hyperinflation
findings on chest radiographs.
The clinical severity of acute bronchiolitis was based on the clinical
score of De Boeck, et al.19). Their score was
determined based on the SpO2 value, respiratory rate,
presence of expiratory wheezes/rhonchi and chest retraction. Each of
these four items was divided into four stages from none, mild, moderate
and severe, and assigned 0 to 3 points. We evaluated the total points of
this score in each patient.
All patients received equal treatment with oxygen administration,
humidification, removal of airway secretions and administration of
expectorants. Inhalation of β2-agonists and hypertonic
saline and treatment with systemic steroids were not performed. No
patients needed mechanical ventilation.