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.