(1211) A Novel Score for High-Flow Nasal Cannula Failure in Children With Immunocompromising Conditions

Introduction: High-flow nasal cannula (HFNC) use in children with immunocompromising conditions (ICC) is not well understood. While exposure to HFNC before intubation is associated with increased mortality in children with ICC, data regarding HFNC failure rate and predictors of failure in this population are not clear. HFNC criteria are now included in the possible pediatric acute respiratory distress syndrome (PARDS) definition, however this definition has not been explored in those with ICC. Therefore, we sought to describe the HFNC failure rate and the association of oxygenation markers with failure in children with ICC.

Methods: This was a single center, retrospective cohort study of children with ICCs who used HFNC between 2021-2023. HFNC failure was defined as intubation following HFNC. We sought to determine if possible PARDS was associated with HFNC failure. However, due to limitations of high SpO2 in our cohort, we investigated the association of the following model based on degree of HFNC support of Flow/Kg*FiO2 at HFNC initiation, 2, 4, and 6 hours with HFNC failure. Logistic regression was used.

Results: We included 93 subjects. HFNC failure rate was 48% (n=44). The median duration of HFNC was 19 hours (IQR:6, 40). The median PICU stay length was 6 days (IQR:3,15). For those that failed HFNC, Median Flow/kg*FiO2 was higher at initiation (p=0.04), 2 hours (p=0.03), 4 hours (p=0.05), and 6 hours (p=0.05). Using Liu’s index to define a high cutpoint of ≥ 0.20 at HFNC initiation, those with a high Flow/kg*FiO2 were more likely to fail HFNC. Adjusting for PRISM score, the odds of HFNC failure with a high Flow/kg*FiO2 (>0.20) were as follows: Initiation aOR=2.6 [(95%CI: 1.1, 6.1), p=0.03]; 2 hours of HFNC, aOR 3.2 [(95%CI: 1.8, 11.3), p=0.001]; 4 hours of HFNC, aOR=4.0 [(95%CI: 2.7, 17.3), p< 0.001]; and 6 hours of HFNC, aOR=2.5 [(95%CI: 2.0, 13.1), p=0.001]. There was a high rate of PARDS present on intubation (64%, n=28). Of those that failed HFNC, 23% (n=10) died in the PICU. All had PARDS present on intubation.

Conclusions: In children with ICCs, HFNC failure is high. Mortality is high in those who fail HFNC. High Flow/kg*FiO2 reflecting degree of respiratory support, is associated with increased odds of failing HFNC. These results should be explored in an external cohort for further validation.