Impact of Initial High Flow Nasal Cannula Flow Rates on Clinical Outcomes in Children with Bronchiolitis

Purpose: Our aim was to evaluate the impact of the initial high flow nasal cannula (HFNC) flow rate on clinical outcomes in children with bronchiolitis.

Methods: This secondary analysis of retrospective data included children <2 years who required HFNC for bronchiolitis between 10/01/2018-04/20/2019, and following implementation of a revised institutional bronchiolitis pathway between 10/01/2021-04/30/2022. The new pathway recommended weight-based initiation of HFNC at 1.5-2 L/kg/min. We evaluated the effect of low (<1.0 L/kg/min), medium (1-1.5 L/kg/min) and high (>1.5 L/kg/min) HFNC flow rates on need for positive pressure ventilation (PPV), intensive care unit (ICU) transfer, HFNC treatment time, and hospital length of stay (LOS).

Results: The majority of the 885 included children had low initial flow rates (low [n = 450, 50.8%], medium [n = 332, 37.5%] and high [n = 103, 11.7%]). There were no significant differences in PPV (high: 7.8% vs. medium: 9.3% vs. low: 8.2%, p = 0.8) or ICU transfers (high: 4.9% vs. medium: 6.0% vs. low: 3.8%, p = 0.3). The low flow group had a significantly longer median HFNC treatment time (High: 29 [18, 45] vs. medium: 29 [16, 50] vs. low: 39 [25, 63], p < .001) and hospital LOS (High: 41 [27, 59] vs. medium: 42 [29, 66] vs. low: 50 (39, 75), p < .001). Logistic and linear regression models did not demonstrate any associations between HFNC flow rates and PPV or hospital LOS.

Conclusions: Initial HFNC flow rates were not associated with significant changes in clinical outcomes in children in children with bronchiolitis.