What are the recommended High Flow Nasal Cannula (HFNC) settings for pediatric patients?

High-Flow Nasal Cannula Settings in Pediatric Patients

For pediatric patients requiring HFNC, use flow rates of ≥1 L/kg/min for infants up to 10 kg and ≥10 L/min for patients above 10 kg, delivered through heated humidified circuits, with FiO2 titrated to maintain SpO2 92-97%. 1, 2

Flow Rate Settings by Weight

Infants ≤10 kg

• Start at ≥1 L/kg/min as the minimum threshold to qualify as HFNC therapy 1
• Flow rates below 1 L/kg/min are considered conventional oxygen therapy, not HFNC 1, 3
• Evidence supports starting at 2 L/kg/min for infants with moderate-to-severe bronchiolitis, as this flow rate meets peak inspiratory flow demands and improves respiratory mechanics more effectively than 1 L/kg/min 4
• A randomized trial comparing 2 L/kg/min versus 3 L/kg/min found no benefit to the higher flow rate, with 3 L/kg/min causing more discomfort (43% vs 16%) and longer PICU stays (6.4 vs 5.3 days) 5

Patients >10 kg

• Start at ≥10 L/min as the minimum threshold 1, 3
• Titrate upward based on respiratory effort and patient comfort 3
• Maximum flows typically reach 60 L/min in older children 3

Essential Circuit Requirements

All HFNC must use heated humidification to meet the definition of HFNC therapy 1

• Set temperature between 34-37°C based on patient preference 3
• Higher temperatures provide optimal humidification 3
• Without heating and humidification at the specified flow rates, the therapy is classified as conventional oxygen, not HFNC 1

FiO2 Titration Targets

Standard Oxygenation Targets

• SpO2 92-97% for most pediatric patients 1, 2
• SpO2 ≥95% when breathing room air for healthy lungs 1
• Keep SpO2 ≤97% to avoid hyperoxia 1

Disease-Specific Targets

• For severe restrictive disease with PEEP ≥10 cmH2O equivalent: SpO2 88-92% 1, 2
• For patients with pulmonary hypertension: target normal pH and higher SpO2 1

Monitoring Parameters

Continuous Monitoring Required

• SpO2 via pulse oximetry in all patients on HFNC 2, 3
• Respiratory rate - should decrease with effective therapy 3
• Work of breathing - assess for accessory muscle use and patient comfort 3

Intermittent Assessment

• Arterial or capillary blood gases when necessary to assess response 2, 3
• Target pH >7.20, accepting permissive hypercapnia 2
• PCO2 35-45 mmHg for healthy lungs, higher PCO2 accepted for acute pulmonary patients 1

Titration Algorithm

Initial Setup

1. Flow rate: 2 L/kg/min for infants ≤10 kg; 10-15 L/min for patients >10 kg 1, 3, 4
2. Temperature: 37°C 3
3. FiO2: Titrate to achieve target SpO2 3

Flow Rate Adjustments

• Increase by 0.5-1 L/kg/min (or 5-10 L/min) for persistent increased work of breathing 3
• Decrease by 0.5-1 L/kg/min (or 5-10 L/min) for patient discomfort 3
• Quality improvement data shows higher initial flows (median 14.5 L/min vs 10 L/min) reduce HFNC failure rates (10% vs 17%) 6

FiO2 Adjustments

• Titrate in 5-10% increments to maintain target SpO2 3
• Wean FiO2 before weaning flow rate 6

Weaning Strategy

• Rapid weaning is safe and effective once patient stabilizes 6
• Protocol-driven weaning at 4.1 L/min/hour is faster than clinician-directed weaning at 2.4 L/min/hour, with lower failure rates 6
• When flow falls below HFNC thresholds (1 L/kg/min or 10 L/min), transition to conventional oxygen therapy 1

Critical Pitfalls to Avoid

Inadequate Initial Flow

• Starting too low (below 2 L/kg/min in infants) may not meet peak inspiratory flow demands, particularly in infants with high airway resistance 4
• Insufficient flow reduces PEEP effect and dead space washout 3

Excessive Flow in Young Infants

• Flows of 3 L/kg/min in young infants with bronchiolitis increase discomfort without improving outcomes 5
• Monitor for patient intolerance at higher flows 3

Delayed Escalation

• Recognize treatment failure early using predefined criteria: persistent tachypnea, increased work of breathing, worsening hypoxemia despite FiO2 >0.60 1, 3
• Delayed intubation is associated with worse outcomes 3

Interface and Circuit Issues

• Poor interface fit reduces effectiveness through air leaks 3
• Use appropriately sized nasal cannulas that do not occlude the nares 1
• Ensure heated humidification is functioning to prevent airway dryness 3

Oxygen Toxicity

• Avoid excessive FiO2 - titrate to target SpO2, not higher 3
• Prolonged exposure to high FiO2 causes oxygen toxicity 3

Special Considerations for Patients <10 kg

• Measure all ventilator parameters near the Y-piece in children <10 kg, as circuit compliance and dead space are proportionally more significant with small tidal volumes 7
• Minimize dead space by limiting added components between the interface and circuit 7
• Use double-limb circuits for any invasive ventilation 7