Overview/Definition
Definition:
• High-flow nasal cannula (HFNC) therapy delivers heated, humidified oxygen at flow rates exceeding patient's peak inspiratory flow demand through nasal cannula interface
Provides respiratory support between conventional oxygen therapy and non-invasive ventilation, offering physiological benefits including PEEP effect, improved oxygenation, and reduced work of breathing.
Epidemiology:
• Increasingly utilized in pediatric intensive care units and emergency departments with growing evidence base supporting efficacy in bronchiolitis, pneumonia, and respiratory failure
Usage rates vary by institution but studies show 20-40% of children with moderate respiratory distress receive HFNC therapy as first-line respiratory support.
Age Distribution:
• Most commonly used in infants and young children (1 month-5 years) with bronchiolitis, pneumonia, or post-operative respiratory support
Neonatal applications include post-extubation support and primary respiratory failure
School-age children and adolescents less commonly require HFNC but may benefit in specific circumstances.
Clinical Significance:
• High-yield topic for DNB Pediatrics and NEET SS examinations focusing on appropriate patient selection, optimal settings, monitoring parameters, and escalation criteria
Essential for understanding respiratory support modalities, physiological effects, and evidence-based management protocols in pediatric critical care.
Age-Specific Considerations
Newborn:
• Neonatal HFNC typically uses lower flow rates (1-8 L/min) with careful monitoring for complications
Nasal cannula sizing critical to avoid excessive pressure and trauma
Higher risk of gastric distension and feeding difficulties
Close monitoring for apnea episodes
Consider CPAP if frequent desaturations or high FiOâ‚‚ requirements.
Infant:
• Peak population for HFNC use, particularly with bronchiolitis (RSV season)
Flow rates typically 1-2 L/kg/min with maximum flows 6-12 L/min depending on size
Excellent tolerance compared to CPAP masks
Allows continued feeding and parent interaction
Monitor for nasal trauma from prolonged use.
Child:
• School-age children (2-12 years) can cooperate with HFNC therapy and communicate comfort levels
Higher flow rates possible (up to 20-30 L/min) based on weight and clinical response
Alternative interfaces (high-flow masks) may be preferred in some children
Better understanding of therapy purpose aids compliance.
Adolescent:
• Adolescents may prefer HFNC over CPAP interfaces due to comfort and ability to communicate
Flow rates approach adult ranges (up to 50-60 L/min) based on weight and response
Consider patient preference in interface selection
May transition more readily to adult ventilation approaches if escalation needed.
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Clinical Presentation
Symptoms:
• Respiratory distress with tachypnea, increased work of breathing, oxygen desaturation <90-92%
Feeding difficulties in infants, irritability, sleep disruption
Signs of respiratory failure: altered mental status, fatigue, inability to maintain adequate oxygenation with conventional oxygen therapy
Response to HFNC typically seen within 1-4 hours.
Physical Signs:
• Moderate respiratory distress with nasal flaring, subcostal and intercostal retractions, use of accessory muscles
Tachycardia, tachypnea for age, hypoxemia requiring supplemental oxygen
Auscultatory findings depend on underlying pathology (wheeze, crackles, decreased air entry)
Improvement in work of breathing typically evident with effective HFNC.
Severity Assessment:
• Mild respiratory distress: minimal retractions, maintaining oxygen saturation >90% with low-flow oxygen, feeding adequately
Moderate distress: obvious work of breathing, requiring FiOâ‚‚ >0.4 to maintain saturation, some feeding difficulties
Severe distress: significant retractions, high oxygen requirements, unable to feed, risk of respiratory failure.
Differential Diagnosis:
• Underlying conditions requiring HFNC support include bronchiolitis, pneumonia, asthma exacerbation, post-operative respiratory depression, acute respiratory distress syndrome
Distinguish from conditions requiring immediate intubation (complete airway obstruction, cardiopulmonary arrest) or those unlikely to respond to HFNC (severe pneumothorax, massive hemoptysis).
Diagnostic Approach
History Taking:
• Rapid assessment of respiratory distress onset, progression, associated symptoms
Underlying medical conditions, recent procedures, medication history
Feeding and activity tolerance changes
Response to previous oxygen therapy or respiratory support
Family history of respiratory conditions or genetic syndromes.
Investigations:
• Arterial or capillary blood gas if respiratory failure suspected (pH, pCO₂, pO₂ assessment)
Chest X-ray to identify underlying pathology and rule out pneumothorax
Viral studies if bronchiolitis suspected
Basic metabolic panel if prolonged illness or poor oral intake
Continuous pulse oximetry monitoring.
Normal Values:
• Target oxygen saturation 92-98% for most pediatric patients (90-95% may be acceptable in bronchiolitis)
Normal pH 7.35-7.45, pCOâ‚‚ 35-45 mmHg
Flow rate effectiveness typically requires flows >patient's minute ventilation (roughly 2-3 times respiratory rate × tidal volume)
Adequate humidification temperature 34-37°C.
Interpretation:
• HFNC success indicators: improved work of breathing within 1-4 hours, decreased respiratory rate, improved oxygen saturation with lower FiO₂, ability to feed and interact appropriately
Failure indicators: worsening respiratory distress, increasing oxygen requirements, rising COâ‚‚ levels, hemodynamic instability requiring escalation to CPAP or intubation.
Management/Treatment
Acute Management:
• Initial HFNC settings: flow rate 1-2 L/kg/min (minimum 2 L/min), FiO₂ to maintain target saturation, temperature 34-37°C, appropriate nasal cannula size (nares occlusion <50%)
Gradual titration based on clinical response
Monitor closely for first 2-4 hours for improvement or need for escalation.
Chronic Management:
• Weaning protocol: reduce FiO₂ first to ≤0.4, then reduce flow rates by 25-50% increments as tolerated
Transition to conventional oxygen therapy when flow rates <2-4 L/min and FiOâ‚‚ <0.4
Some patients may require prolonged HFNC support for chronic conditions or home therapy in select cases.
Lifestyle Modifications:
• During HFNC therapy: maintain adequate nutrition and hydration, position for comfort (usually upright), continue medications as prescribed, monitor for complications
Family education on equipment, signs of improvement or deterioration
Minimize disruptions to allow rest and recovery.
Follow Up:
• Continuous monitoring during acute phase with vital signs, work of breathing assessment, oxygen saturation
Daily evaluation of weaning potential
Post-discharge follow-up within 24-48 hours if sent home on oxygen
Long-term follow-up for underlying conditions that required HFNC support.
Age-Specific Dosing
Medications:
• HFNC flow rates by weight: <10kg: 1-8 L/min (typically 1-2 L/kg/min), 10-20kg: 6-20 L/min, 20-40kg: 15-35 L/min, >40kg: 25-50 L/min
FiOâ‚‚ titrated to maintain SpOâ‚‚ 92-98%
Temperature setting 34-37°C with 100% relative humidity
No specific medications for HFNC therapy itself.
Formulations:
• HFNC equipment includes heated humidifier, flow generator, heated circuit, and appropriately sized nasal cannula
Cannula sizing: nares occlusion <50% to avoid excessive pressure
Oxygen blender for precise FiOâ‚‚ control
Monitoring equipment includes pulse oximetry, respiratory rate monitoring, work of breathing assessment tools.
Safety Considerations:
• Monitor for complications: nasal trauma, gastric distension, pneumothorax (rare), equipment malfunction
Ensure proper cannula sizing and positioning to avoid pressure necrosis
Temperature monitoring to prevent thermal injury
Backup oxygen delivery method available
Trained staff for troubleshooting and escalation.
Monitoring:
• Continuous monitoring: pulse oximetry, respiratory rate, work of breathing assessment using validated scales
Vital signs every 2-4 hours initially, then every 6 hours when stable
Daily assessment of cannula fit and nasal integrity
Blood gas analysis if clinical deterioration or high FiOâ‚‚ requirements persist.
Prevention & Follow-up
Prevention Strategies:
• Prevent respiratory failure through early recognition and intervention for underlying conditions
Optimize treatment of bronchiolitis, pneumonia, asthma to prevent progression to respiratory failure
Maintain immunizations to prevent vaccine-preventable respiratory illnesses
Hand hygiene to prevent nosocomial infections.
Vaccination Considerations:
• Ensure up-to-date immunizations including influenza, pneumococcal, and RSV prophylaxis (palivizumab) for high-risk infants
COVID-19 vaccination for eligible children and household contacts
Healthcare worker immunizations important for infection control in HFNC patients who may have prolonged hospitalizations.
Follow Up Schedule:
• During HFNC therapy: continuous monitoring with formal assessments every 4-8 hours
Weaning trials when clinically appropriate, typically after 24-48 hours of stability
Post-therapy monitoring for 4-6 hours before discharge consideration
Outpatient follow-up within 24-48 hours after discontinuation.
Monitoring Parameters:
• Clinical improvement indicators: decreased work of breathing, improved feeding tolerance, normalization of vital signs, reduced oxygen requirements
Objective measures: respiratory rate trending toward normal for age, oxygen saturation stable on lower FiOâ‚‚, improved activity and interaction levels
Family comfort with child's condition.
Complications
Acute Complications:
• Immediate complications: gastric distension from excessive flow or incorrect cannula sizing, nasal trauma from improperly fitted cannula, pneumothorax (rare but serious), equipment malfunction leading to inadequate support
Patient discomfort leading to removal of cannula and clinical deterioration.
Chronic Complications:
• Prolonged HFNC use may lead to nasal septum irritation, chronic nasal dryness despite humidification, dependency on therapy delaying weaning
Equipment-related issues: circuit condensation leading to infection risk, skin breakdown from cannula or tubing pressure
Delayed recognition of treatment failure.
Warning Signs:
• HFNC failure indicators: worsening work of breathing despite adequate settings, increasing oxygen requirements (FiO₂ >0.6-0.8), rising CO₂ levels, hemodynamic instability, inability to tolerate feeds, altered mental status, equipment intolerance requiring frequent adjustments.
Emergency Referral:
• Immediate escalation needed for: respiratory arrest, severe hemodynamic instability, HFNC failure with worsening respiratory status, suspected pneumothorax, equipment malfunction in critically ill patient
Emergency intubation equipment should be readily available for all HFNC patients.
Parent Education Points
Counseling Points:
• Explain HFNC as supportive therapy that helps child breathe more easily while underlying condition improves, not a cure but a "breathing helper." Discuss typical duration (usually 1-5 days for most conditions), expected improvements, and weaning process
Address concerns about child's comfort and ability to interact.
Home Care:
• Hospital-based therapy typically, though home HFNC possible for select chronic patients
During therapy: child may eat, drink, play quietly, sleep comfortably
Nasal cannula should stay in place but child can move head normally
Signs of improvement: less labored breathing, better appetite, more alertness and interaction.
Medication Administration:
• Continue all prescribed medications while on HFNC therapy
Nebulized medications can usually be given through the HFNC circuit or by temporary interruption
Oral medications and feeds typically well-tolerated
Notify staff of any medication allergies or adverse reactions during therapy.
When To Seek Help:
• Notify medical team immediately for: child appears more tired or difficult to wake, increased breathing difficulty, blue discoloration of lips or face, frequent removal of nasal cannula by child, decreased urine output, refusal to eat or drink for >12 hours
Trust parental instincts if child "doesn't look right."