BACKGROUND: High-flow nasal cannula (HFNC) is a safe, well-tolerated, and 
noninvasive method of respiratory support that has seen increasing use in the 
care of children with respiratory distress. High-flow nasal cannula may be able 
to prevent intubations in infants and children with respiratory distress.
OBJECTIVE: The objective of this study was to determine the clinical and patient 
characteristics that predict success or failure of HFNC therapy in children 
presenting to the pediatric emergency department (PED) with respiratory 
distress.
DESIGN/METHODS: A retrospective cohort review was conducted of all children 
younger than 2 years evaluated in 2 PEDs between June 2011 and September 2012 
who received HFNC therapy within 24 hours of initial triage. Data extraction 
included clinical variables, demographic variables, and patient outcomes. 
Therapy failure was defined as the clinical decision to intubate a patient after 
an antecedent trial of HFNC. Multivariable logistic regression was performed to 
identify factors associated with intubation following HFNC.
RESULTS: Four hundred ninety-eight cases meeting criteria for inclusion were 
identified. The most common final diagnosis was acute bronchiolitis (n = 231, 
46%), followed by pneumonia (n = 138, 28%) and asthma (n = 38, 8%). Of the 498 
patients, 42 (8%) of patients failed therapy and required intubation following 
HFNC trial. Risk factors associated with HFNC failure were triage respiratory 
rate greater than 90th percentile for age (odds ratio [OR], 2.11; 95% confidence 
interval [CI], 1.01-4.43), initial venous PCO2 greater than 50 mm Hg (OR, 2.51; 
95% CI, 1.06-5.98), and initial venous pH less than 7.30 (OR, 2.53; 95% CI, 
1.12-5.74). A final diagnosis of bronchiolitis was observed to be protective 
with respect to intubation (OR, 0.40; 95% CI, 0.17-0.96).
CONCLUSIONS: In infants with all-cause respiratory distress presenting in the 
PED, triage respiratory rate greater than 90th percentile for age, initial 
venous PCO2 greater than 50 mm Hg, and initial venous pH less than 7.30 were 
associated with failure of HFNC therapy. A diagnosis of acute bronchiolitis was 
protective with respect to intubation following HFNC. This finding may help 
guide clinicians who use HFNC by identifying a patient population at higher risk 
of failing therapy.