High-flow nasal cannula effectiveness in acute bronchiolitis: a retrospective study

Introduction and Objectives: Acute bronchiolitis (AB) is a leading cause of hospital admission in pediatric patients. The main objective of this study was to evaluate the effectiveness of high-flow nasal cannula (HFNC) oxygen therapy in AB. Methods: Retrospective cohort study. Patients (1–24 months of age) admitted with AB in a tertiary hospital were included, comparing the periods before ('preHFNC:Apr/2018–Nov/2019) and after the introduction of HFNC ('postHFNC:Nov/2019–Apr/2022). The outcome measure of effectiveness was transfer to the intensive care unit (ICU). Effect measures were relative risk (RR), absolute risk reduction (RRA) and number needed to treat (NNT). Results: Of the 486 patients included, 196 were preHFNC and 290 were postHFNC. Of the latter, 46 (14.9%) required HFNC. Treatment with HFNC was associated with a significant reduction (p < 0.001) in respiratory rate, use of accessory muscles, wheezing and, consequently, an improvement in the WARM score. In the postHFNC period, there were fewer transfers to the ICU (21.4% vs. 13.8%, p = 0.027), with RR = 0.66, RRA = 7.6% and NNT = 13. In patients treated with HFNC, daycare attendance (p = 0.036; OR 91.7) and a higher WARM score 24 hours after HFNC (p = 0.009; OR 16.2) were predictors of transfer to the ICU (Hosmer-Lemeshow: x 2 = 0.82, p = 0.976). In the survival curve for time to ICU admission, preHFNC patients were transferred earlier (p = 0.013). None of the patients under HFNC required invasive ventilation. Discussion: The introduction of HFNC in the treatment of AB reduced the need for the ICU and was associated with a clinical improvement in several respiratory parameters. On the basis of the NNT, it is estimated that three to four ICU admissions were avoided in the postHFNC period.