Physiometric Response to High-Flow Nasal Cannula Support in Acute Bronchiolitis

OBJECTIVES: To describe the rate of high-flow nasal cannula (HFNC) nonresponse and paired physiometric responses (changes [∆] in heart rate [HR] and respiratory rate [RR]) before and after HFNC initiation in hospitalized children with bronchiolitis.

METHODS: We performed a single-center, prospective descriptive study in a PICU within a quaternary referral center, assessing children aged ≤2 years admitted for bronchiolitis on HFNC from November 2017 to March 2020. We excluded for cystic fibrosis, airway anomalies, pulmonary hypertension, tracheostomy, neuromuscular disease, congenital heart disease, or preadmission intubation. Primary outcomes were paired ∆ and %∆ in HR and RR before and after HFNC initiation. Secondary outcomes were HFNC nonresponse rate (ie, intubation or transition to noninvasive positive pressure ventilation). Analyses included χ², Student’s t, Wilcoxon rank, and paired testing.

RESULTS: Of the 172 children studied, 56 (32.6%) experienced HFNC nonresponse at a median of 14.4 (interquartile range: 4.8–36) hours and 11 (6.4%) were intubated. Nonresponders had a greater frequency of bacterial pneumonia, but otherwise no major differences in demographics, comorbidities, or viral pathogens were noted. Responders experienced reductions in both %ΔRR (−17.1% ± 15.8% vs +5.3% ± 22.3%) and %ΔHR (−6.5% ± 10.5% vs 0% ± 10.9%) compared with nonresponders.

CONCLUSIONS: In this prospective, observational cohort study, we provide baseline data describing expected physiologic changes after initiation of HFNC for children admitted to the PICU for bronchiolitis. In our descriptive analysis, patients with comorbid bacterial pneumonia appear to be at additional risk for subsequent HFNC nonresponse.