Heated, humidified high-flow nasal cannula (HFNC) is commonly used for respiratory support in children. Prior observations have associated HFNC use before intubation with increased mortality among children with immunocompromising conditions (ICC). The study summarized here aimed to describe the rate of HFNC failure, defined as subsequent intubation, and to develop a bedside score associated with HFNC failure in this high-risk pediatric population.
This investigation was a single-center, retrospective cohort study. It included patients aged 0 to 26 years with immunocompromising conditions who received HFNC between 2021 and 2023. The abstract reports a total sample of 93 subjects meeting inclusion criteria. No additional details about inclusion/exclusion criteria, baseline diagnoses, or specific immunocompromising etiologies are provided in the abstract.
The authors developed a novel index named the FLOX score to quantify HFNC support relative to patient size and oxygen requirement. The FLOX score is calculated as:
FLOX = (flow in Liters/minute) / weight (kg) * FiO2
This formula combines the delivered HFNC flow rate, the patient’s body weight, and the fractional inspired oxygen (FiO2) to produce a single value intended to reflect the intensity of noninvasive respiratory support.
Among the 93 included subjects, 44 patients (47.3%) experienced HFNC failure, defined as progression to intubation. The median duration of HFNC use across the cohort was 18.7 hours, with an interquartile range (IQR) of 6.0 to 40.4 hours. The abstract does not provide further breakdown by age, underlying diagnosis, or reason for initiation of HFNC.
Median FLOX scores were higher among patients who ultimately failed HFNC compared with those who did not. Significant differences in median FLOX were observed at several time points after HFNC initiation: at initiation (p = 0.04), at 2 hours (p = 0.03), at 4 hours (p = 0.05), and at 6 hours (p = 0.05).
Using a threshold of FLOX ≥ 0.20, the authors report adjusted odds ratios for HFNC failure as follows:
The abstract indicates these associations were adjusted for acuity, though specific covariates used for adjustment are not detailed in the abstract.
PICU mortality in the cohort was reported as 14% (n = 13). The abstract links higher rates of HFNC failure with higher mortality but does not provide stratified mortality rates by FLOX score or by HFNC success versus failure beyond this overall figure.
In this single-center cohort of children and young adults with immunocompromising conditions treated with HFNC, nearly half failed HFNC and required intubation. The authors propose the FLOX score as a simple bedside metric—incorporating HFNC flow, patient weight, and FiO2—that was higher among patients who failed HFNC. A FLOX ≥ 0.20 was associated with significantly increased adjusted odds of HFNC failure at initiation and at 2, 4, and 6 hours after starting HFNC.
These findings suggest the FLOX score could help identify patients at increased risk of intubation early during HFNC therapy, potentially informing closer monitoring or earlier escalation of care in immunocompromised pediatric patients.
The abstract specifies that this was a single-center, retrospective study but does not report additional limitations (for example, external validation, sample heterogeneity, or adjustment variable details) within the abstract text. Details on study limitations, calibration or discrimination metrics for the FLOX score, and external validation were not provided in the source abstract.