Introduction High flow nasal cannula (HFNC) is commonly used as first step respiratory support in infants with moderate-to-severe acute viral bronchiolitis (AVB). This device, however, fails to effectively manage respiratory distress in about a third of patients, and data are limited on determinants of patient response. The respiratory rate-oxygenation (ROX) index is a relevant tool to predict the risk for HFNC failure in adult patients with lower respiratory tract infections. The primary objective of this study was to assess the relationship between ROX indexes collected before and 1 hour after HFNC initiation, and HFNC failure occurring in the following 48 hours in infants with AVB. Method: This is an ancillary study to the multicenter randomized controlled trial TRAMONTANE 2, that included 286 infants of less than 6 months with moderate-to-severe AVB. Collection of physiological variables at baseline (H0), and 1 hour after HFNC (H1), included heart rate (HR), respiratory rate (RR), fraction of inspired oxygen (FiO 2), respiratory distress score (mWCAS), and pain and discomfort scale (EDIN). ROX was calculated as SpO 2/FiO 2 to RR. Predefined HFNC failure criteria included increase in respiratory distress score or respiratory rate, increase in discomfort, and severe apnea episodes. The accuracy of ROX index to predict HFNC failure was assessed using receiver operating curve analysis. Result: HFNC failure occurred in 111/286 (39%) infants, and for 56 (50% of the failure) of them within the first 6 hours. The area under the curve of ROX indexes at H0 and H1 were, respectively, 0.56 (95% CI 0.48-0.63, p =0.14), 0.56 (95% CI 0.49- 0.64, p =0.09). HFNC failure was associated with higher mWCAS score at H1 (p<0.01) and lower decrease in EDIN scale during the first hour of HFNC delivery (p = 0.02), but none of the physiological variables were predictive of HFNC failure. Conclusion: In this study, neither ROX index, nor physiological variables usually collected in infants with AVB had early discriminatory capacity to predict HFNC failure.

Rationale: Noninvasive ventilation (NIV) is the first-line therapy in infants with bronchiolitis-related acute respiratory failure. However, there is a lack of data regarding weaning from NIV in this setting. Working hypothesis: This study aims to evaluate a nurse-driven weaning protocol in this homogenous population. Study design: A retrospective single-center study with pre-versus-post comparative design in a tertiary center. Methodology: Data from all infants aged ≤ 6 months admitted to the PICU during 2 seasons with a clinical diagnosis of bronchiolitis and requiring any type of noninvasive ventilatory support on admission, were analyzed. Main results: In total, 187 infants (95 with standard and 92 with nurse-driven protocols) were included; the median age was 47 (IQR 24-75) and 31 days (19-58) in patients at baseline and after the protocol implementation, respectively. There was no difference in terms of weaning failure between the two periods (11 (12%) versus 14 (15%), p=0.46). At baseline, the ventilatory support duration was 70 hours (IQR 54-104) versus 56 hours (IQR 29-83) during the nurse-driven protocol period (p=0.29). The PICU and hospital lengths of stay did not differ between the two periods. No complication related to NIV occurred in the two periods. Conclusions: In patients with bronchiolitis supported by NIV, the nurse-driven weaning management - as opposed to physician-driven - was not associated with a significantly higher proportion of weaning failure cases.