Breath sound analyses of infants with respiratory syncytial virus acute bronchiolitis

Abstract

Introduction:The reliability of a breath sound analysis using an objective method in infants has been reported.Objective: Breath sounds of infants with respiratory syncytial virus (RSV) acute bronchiolitis were analyzed via a breath sound spectrogram to evaluate their characteristics and examine their relationship with the severity. Subjects and Methods:We evaluated the inspiratory and expiratory breath sound parameters of 33 infants diagnosed with RSV acute bronchiolitis. The sound powers of inspiration and expiration were evaluated at the acute phase and recovery phase of infection. 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 as well as the expiration-to-inspiration sound ratio in the mid-frequency (E/I MF) was increased in the acute phase and decreased during the recovery phase.The E/I MF was inversely correlated with the SpO 2 and positively correlated with the severity score. Conclusion:In infants with RSV acute bronchiolitis, the sound power of respiration was large at the acute phase, significantly decreasing in the recovery phase. In 61% of participants, nonuniform, granular bands were shown in the low-pitched region of the expiratory spectrogram.

Clinical application of a lung sound analysis in infants with respiratory syncytial virus acute bronchiolitis

“…In this study, we were able to obtain data from age‐matched control infants and were able to demonstrate the specificity of acute bronchiolitis. RSV acute bronchiolitis is probably characterized by the presence of specific narrowing of the peripheral airways due to thick sputum and severe epithelial damage 13 . One of the points of this study is whether or not lung sound analysis can help distinguish between bronchiolitis and non‐bronchiolitis in infants, and we were indeed able to demonstrate the potential utility of this method.…”

“…Wheezes is thought to be a sound originating from the bronchi that occurs when air of respiration passes through the narrowing part, and rhonchi is thought to be a sound of vibration mainly by viscous sputum in the airways due to the air flow 27 . In our previous study, we reported that the rhonchi of acute bronchiolitis pointed out by the attending physician was recognized as a non‐uniform, belt‐like pattern in the lung sound spectrogram (Figure 1a), such as bands that look like a series of particles in the low range 13 . Low‐tone intermittent sounds that occur continuously at very short intervals possibly heard as rhonchi.…”

“…Each of these four items was divided into four stages from none, mild, moderate and severe, and assigned 0–3 points. We evaluated the total points of this score in each patient 13 …”

“…The sounds were displayed as a sound spectrogram. The point on the lung sound spectrogram that showed the maximum frequency (Hz) during inspiration or expiration was used for the sound spectrum analysis 8,13 …”

“…The other interesting result is that rhonchi was found to be more frequent than wheezes in the RSV acute bronchiolitis (58% vs. 34%) as in the previous report. 13 It has been reported that wheezes and rhonchi have different origin mechanisms. Wheezes is thought to be a sound originating from the bronchi that occurs when air of respiration passes through the narrowing part, and rhonchi is thought to be a sound of vibration mainly by viscous sputum in the airways due to the air flow.…”