Infants with bronchiolitis with high-flow nasal cannula in the paediatric ward. Is there a role for the ROXi (Respiratory rate–Oxygenation index) to predict transfer requirement to the PICU?

Introduction: The respiratory rate–oxygenation index (ROXi) has been shown to be a reliable tool to predict the risk for HFNC failure in adult patients with lower respiratory tract infections. In paediatrics, the reliability of this index to predict HFNC failure appeared mitigated. In specific population, such as infants with moderate to severe bronchiolitis hospitalized in paediatric ward with HFNC, its ability to predict transfer requirement to the PICU needs to be further evaluated. The main objective of this study was to evaluate the ability of the ROXI collected at initiation of HFNC in the paediatric ward to predict the need for PICU transfer and/or HNFC failure in cases of moderate to severe bronchiolitis. Methods: A retrospective review of patients aged 0 to 6 months with bronchiolitis who received HFNC within seven tertiary paediatric hospital over the last 5 epidemic seasons from 2018 to 2023 was conducted. Demographic, clinical, and biochemical variables were collected at admission and at the beginning of HFNC therapy support. Initial management and its evolution were described. Patients were compared depending on their transfer to the PICU during hospital stay. HFNC failure was defined as the need for Non-Invasive Ventilation. Multivariable regression analysis was used to determine parameters associated with transfer to the PICU and HFNC failure. Results: We included 383 infants in this multicentric study (median age 63 days [7; 192]). 76 patients (20%) requiring HNFC were finally transferred to the PICU with a median of 2 days after the hospitalization. Only 40 children (10%) benefited from ventilatory escalation and for children transferred to a PICU, only one patient was intubated. In our population, the optimal ROX index for prediction of PICU requirement and HNFC failure of 6.9 (sensibility 53.1% and specificity 79.8%) and 7.6 (sensibility 62.5% and specificity 66.8%), respectively. In the multivariate analysis, explanatory variables for both transfer to the PICU and HFNC failure were preterm birth, younger age (under 3-month-old), and mWCAS ≥ 3. Besides, SpO2 ≤ 92% at admission and hypotonia were considered as risks factor for transfer and HFNC failure, respectively Conclusion: HFNC appeared to be a safe tool for the management of moderate to severe bronchiolitis in the paediatric ward. However, it is necessary to identify patients for whom management remains safe in the paediatric ward, and in this context ROXi appears to be an interesting marker.