Can heated high-flow nasal cannula be used to treat croup in children?

Heated High-Flow Nasal Cannula for Croup: Not a Standard Treatment

Heated high-flow nasal cannula (HFNC) is not established as a treatment for croup in children, and current guidelines do not support its use for this indication. The standard treatments for croup remain humidified air, nebulized racemic epinephrine for moderate-to-severe cases, and corticosteroids (dexamethasone 0.6 mg/kg) 1, 2, 3.

Why HFNC Is Not Recommended for Croup

Lack of Guideline Support

• The 1997 British Thoracic Society guidelines specifically address croup management and recommend nebulized adrenaline (0.5 ml/kg of 1:1000 solution) to avoid intubation and stabilize children prior to transfer to intensive care, with effects lasting only 1-2 hours 1.
• These guidelines make no mention of HFNC as a treatment modality for croup 1.
• The Paediatric Mechanical Ventilation Consensus Conference states there is insufficient data to recommend HFNC use in obstructive airway disease in pediatric populations, which would include croup 4, 5.

Mechanism Mismatch

• Croup is an upper airway obstruction at the level of the larynx and subglottic region, characterized by inspiratory stridor and a barking cough 2, 3, 6.
• HFNC primarily addresses lower airway and parenchymal lung disease by reducing work of breathing, providing PEEP, and eliminating nasopharyngeal dead space 1.
• The pathophysiology of croup (laryngeal and subglottic edema) is not effectively addressed by the mechanisms of HFNC 6.

Evidence-Based Treatment Algorithm for Croup

Mild Croup (No Stridor at Rest)

• Humidified air with at least 50% relative humidity in the child's room 3.
• Adequate hydration and fever control 2.
• Oral dexamethasone 0.6 mg/kg (or 0.15 mg/kg, which is equally effective) 3, 7.

Moderate-to-Severe Croup (Stridor at Rest, Respiratory Distress)

• Immediate treatment: Nebulized racemic epinephrine 0.5 mL of 2.25% solution diluted in 2.5 mL of saline 2, 3.
• Corticosteroids: Dexamethasone 0.6 mg/kg intramuscularly or intravenously (onset of action approximately 6 hours) 3, 7.
• Observation: Monitor for at least 2 hours after epinephrine administration for rebound airway obstruction 3.
• If supplemental oxygen is needed, use a mist tent with oxygen, not HFNC 3.

Hospitalization Criteria

• Children requiring two epinephrine treatments should be hospitalized 2.
• Stridor at rest, evidence of exhaustion, toxicity, or respiratory distress warrant admission 6.
• Signs of severe obstruction include agitation, air hunger, cyanosis, or exhaustion 6.

Critical Pitfalls to Avoid

Do Not Delay Proven Therapies

• Using HFNC instead of nebulized epinephrine in a child with moderate-to-severe croup could delay effective treatment and worsen outcomes 2, 3.
• The effect of racemic epinephrine is rapid (within minutes), whereas HFNC has no proven benefit in upper airway obstruction 1, 2.

Do Not Confuse HFNC Indications

• HFNC is appropriate for post-extubation support in infants ≥28 weeks gestation and ≥1000g, or for children at high risk of extubation failure 4, 5.
• HFNC may be considered for bronchiolitis or lower respiratory tract disease, but not for croup 8.

Recognize When to Escalate

• If a child with croup is not improving with standard therapy (humidified air, epinephrine, steroids), consider alternative diagnoses such as epiglottitis, retropharyngeal abscess, or foreign body aspiration 3, 6.
• Active airway intervention (intubation) is rarely required but may be life-saving if obstruction progresses despite treatment 6.

Bottom Line for Clinical Practice

Use the proven triad for croup: humidified air, nebulized racemic epinephrine for moderate-to-severe cases, and dexamethasone. HFNC has no established role in croup management and should not replace these evidence-based interventions 1, 2, 3. Reserve HFNC for its appropriate indications: post-extubation support, bronchiolitis, or other lower respiratory tract conditions where guidelines support its use 4, 5.