Background: Bronchiolitis is the most common reason for hospitalization and frequent cause of viral infection. This study aimed to determine the risk factors for severe bronchiolitis in children admitted through the emergency department at Sultan Qaboos University Hospital in Oman. Methods: A retrospective chart review was conducted among children <2 years of age with acute bronchiolitis between January 2015 and December 2018. Patients' demographics and clinical information were collected from the electronic hospital information system. Severe bronchiolitis is defined as a child requiring non-invasive ventilation (NIV) or mechanical ventilation (MV). Results: A total of 857 charts were reviewed and 684 met the inclusion criteria, where 86% of the patients were hospitalized. Mean corrected age was 5.08 ± 4.70 months and 59% were male. Out of all admitted children, 111 (19%) required NIV or MV. Two patients died. Children with severe disease had prolonged length of stay in days (10.2 vs. 4.4, p < 0.001). Using multivariate logistic regression analysis, the study identified severe outcomes to be independently associated with corrected age (<3 months) (OR 1.84, 95% Cl 1.12-3.03), chronic disease (OR 3.24, 95% Cl 1.79-5.86), O2 saturation (≤92%) (OR 4.12, 95% Cl 2.57-6.60), PCO2 (≥45) (OR 2.72, 95% Cl 1.67-4.45), C-reactive protein (≥20) (OR 1.86, 95% Cl 1.13-3.04), and abnormal chest X-ray findings (OR 1.88, 95% Cl 1.20-2.94). Conclusion: This study identified six variables as predictors of severe bronchiolitis. The younger and sicker children associated with comorbidities are more likely to have severe outcomes.

Keywords: Bronchiolitis, emergency medicine, non-invasive ventilation, mechanical ventilation, Oman.