Airway Narrowing Common in Patients With RSV Acute Bronchiolitis

Airway narrowing could be found through lung sound analysis in patients who had respiratory syncytial virus (RSV) acute bronchiolitis, according to a study conducted in Japan and published in Pediatrics International.

Japan saw an outbreak of RSV in the summer of 2021, with a similar trend occurring in 2022. RSV acute bronchiolitis is often found in children 2 years and younger. Doctors found that the symptoms of acute bronchiolitis were not observed at all times, even when infants had a positive RSV antigen check. This study aimed to investigate “various parameters by lung sound analysis in all hospitalized patients with acute respiratory tract infection cause by RSV.”

An observational study took place from June 1, 2021, to December 31, 2022. Infants who were 2 years and younger who had a lung sound analysis while in the hospital were the focus of the study. Diagnosis of acute bronchiolitis came from previous reports, including diagnoses by pediatric specialists. All other respiratory infections due to RSV were grouped as patients with nonbronchiolitis. Severity of bronchiolitis was based on a clinical score based on respiratory rate, presence of expiratory wheeze, chest retraction, and SpO2 value. Lung sound analyses were done for all participants, and all while the participant was sitting.

There were 50 infants in this study with an RSV acute bronchiolitis diagnosis, with a median age of 7 months and 29 of whom were male, and 20 infants with a median age of 5 months who had diagnosed RSV acute respiratory tract infections. Forty of the infants with acute bronchiolitis had a fever, 46 had coughing, 65 had wheezes, and 20 had pneumonia based on an x-ray diagnosis. There were 38 age-matched children used as controls for comparison.

Expiratory sounds were visually larger on spectrogram in children with acute bronchiolitis and non-bronchiolitis compared with the controls. Low-pitched zonal bands were seen in many patients with acute bronchiolitis. Inspiratory sounds were significant lower in patients with RSV respiratory tract infections compared with controls.

There was no significant difference in the length of hospital stay between bronchiolitis and nonbronchiolitis patients. Log and severity score were found to have a correlation in patients with RSV respiratory tract infections. A chest auscultation was found to reveal wheezing in 17 and rhonchi in 29 patients who had bronchiolitis compared with 1 wheeze and 10 rhonchi in patients with nonbronchiolitis.

There were some limitations to this study. The number of patients with nonbronchiolitis was small, due to the study being conducted at a single institution. Answering whether acute bronchiolitis was induced by other viruses also was not possible.

The researchers concluded that RSV acute bronchiolitis is “probably characterized by the presence of specific narrowing of the peripheral airways due to thick sputum and severe epithelial damage.”

Reference

Ichinose M, Obara T, Shibata M, et al. Clinical application of a lung sound analysis in infants with respiratory syncytial virus acute bronchiolitis. Pediatr Int. 2023;65(1):e15605. doi:10.1111/ped.15605