Description of the Clinical Course and Severity Score Progression in Critically Ill Children with Acute Bronchiolitis on High-Flow Nasal Cannula Support

Background and Objective: Bronchiolitis is one of the main causes of morbidity and mortality in children. High-flow nasal cannulas (HFNCs) are an alternative for managing moderate to severe cases. Our aim was to describe the outcomes in critically ill children with bronchiolitis who receive HFNC support. Materials and Methods: This was a retrospective cohort study of critically ill children who had bronchiolitis and received HFNC support while hospitalized in the pediatric intensive care unit (PICU) between January 2013 and January 2020. The primary outcome was deterioration in the Wood-Downes scale. Secondary outcomes included length of hospitalization, duration of oxygen therapy, SpO2/FiO2, and the ROX index (respiratory rate – oxygenation). Results: During this period, 2,390 children were admitted, 87 of whom had bronchiolitis and met the inclusion criteria. The median age was 4.4 months (IQR: 2.4 – 8.6). In 87.3% of cases there was no worsening in the scale with the use of HFNCs. In the group that worsened, 79.3% had moderate and 20.7% severe bronchiolitis on admission, and they had a higher rate of congenital heart disease (p=0.03), chronic respiratory diseases (p=0.03) and neurological (p=0.05) diseases. At 12 hours, this group had a lower SpO2/FiO2 (< 180) and ROX index (< 4.0). None of the patients required mechanical ventilation. Conclusion: The use of HFNCs in children with moderate to severe bronchiolitis was associated with a modified clinical course, avoiding mechanical ventilation even in risk groups. SpO2/FiO2 and ROX index 12-hour cut-off points suggestive of patients with a delayed response to HFNC support were identified.