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Clinical Guidelines (Nursing)

High flow nasal prong (HFNP) therapy

  • Introduction


    Definition of Terms





    Special Considerations 

    Companion Documents


    Evidence Table



    Humidified high flow nasal prong (cannula) therapy is a form of non-invasive respiratory support which has been compared to continuous positive airway pressure (CPAP). HFNP may act as a bridge between low flow oxygen therapies and Nasal CPAP (NCPAP), reducing the need for NCPAP/intubation. At high flows of 2 litres per kilogram per minute, using appropriate nasal prongs, a positive distending pressure may be achieved. The high flows and humidification improve functional residual capacity and mucocililary clearance of secretions thereby reducing work of breathing. The high flows may also affect pulmonary and systemic circulation which is an important consideration when applying HFNP therapy to children with cardiac disease.
    HFNP is an aerosol generating procedure (AGP), a patient’s clinical requirement for HFNP should be balanced against the risk of aerosolization. 


    The aim of this guideline is to describe the indications and procedure for the use of High Flow Nasal Prong (HFNP) therapy within The Royal Children’s Hospital Melbourne

    This guideline does not refer to the management of HFNP in the neonatal patient.  Please refer to the Newborn Intensive Care Unit

    Definition of terms

    • HFNP: High Flow Nasal Prong therapy as measured by a flow rate of 2 L/kg/min up to 12kg, plus 0.5 L/kg/min for each kilogram thereafter (to a maximum flow of 50 LPM.) HFNP should not to be confused with humidified nasal prong oxygen.
    • FiO2: Fraction of inspired oxygen.
    • SpO2: Arterial oxygen saturation measured via pulse oximetry
    • High flow: High flow systems are specific devices that deliver the patient's entire ventilatory demand, meeting, or exceeding the patients Peak Inspiratory Flow Rate (PIFR), thereby providing an accurate FiO2. Where the total flow delivered to the patient meets or exceeds their Peak Inspiratory Flow Rate the FiO2 delivered to the patient will be accurate.  
    • Low flow: Low flow systems are specific devices that do not provide the patient's entire ventilatory requirements, room air is entrained with the oxygen, diluting the FiO2.
    • Peak Inspiratory Flow Rate (PIFR): The fastest flow rate of air during inspiration, measured in litres per second.
    • NGT: Nasogastric tube
    • NJT: Nasojejunal tube
    • EBM: Expressed Breast Milk
    • CPAP: Continuous Positive Airway Pressure
    • BPAP: Bilevel Positive Airway Pressure
    • NPA: Nasopharyngeal airway


    • The prevention of, or relief from, hypoxaemia with respiratory distress due to bronchiolitis or pneumonia.
    • HFNP therapy in the patient with bronchiolitis may be considered where there is continuing hypoxemia (SpO2<90%) and signs of moderate to severe respiratory distress despite standard low flow nasal prong oxygen therapy.
    • Respiratory support to infants and children with chronic lung disease. 
    • Weaning therapy from mask CPAP or BPAP

    There is provision for use of HFNP therapy on patients in mild respiratory distress or who exhibit signs of increasing oxygen requirements in order to prevent further deterioration.

    Indications - Koala ward only

    • Respiratory distress from congestive heart failure.
      • Including cyanotic and acyanotic congenital heart disease
    • Respiratory support post extubation and mechanical ventilation.


    • Critically ill infants and children requiring immediate higher level of respiratory support i.e. NIV or invasive ventilation or decreased level of consciousness.
    • Upper airway obstruction
    • Central apnoea
    • Asthma
    • Blocked nasal passages/choanal atresia 
    • Trauma/surgery to nasopharynx 
    • Pneumothorax


    • The decision to initiate HFNP therapy must be made in consultation with the bed card Consultant
    • Any patient who does not exhibit signs of clinical stabilization, as described below, within 2 hours of commencement of HFNP therapy should be reviewed by PICU outreach service.
    • Any patient who does not exhibit signs of clinical stabilization with 4 hours of commencement of HFNP should be considered for transfer to the PICU.
    • The RCH Oxygen Nursing Clincal Practice Guideline should be consulted with regards to FiO2 delivered and target SpO2 ranges.

    Management: Acute/Ongoing

    • Secure nasal cannula on patients using supplied “Wiggle pads,” ensuring the prongs sit well into the nares.
    • Nasal prongs should not completely occupy the nares. 
    • Start the high flow nasal cannula system in room air ie. 21% oxygen
    • Once prescribed flow rate is reached assess requirement for supplemental oxygen.

    Flow rate

    Flow rate for HFNP Therapy is the same for all patients regardless of medical condition

    • ≤12Kg: 2 L/kg/minute
    • >12Kg: 2 L/kg/minute for the first 12kg + 0.5L/kg/minute for each kg thereafter (max flow 50 L/min)
    • Increase flow to the prescribed rate over a few minutes, or as tolerated.
    • Where supplemental oxygen is required, titrate FiO2 to the minimum amount required in order to maintain target SpO2.

    There is a difference in oxygen requirements of children with cyanotic congenital heart disease and balanced circulation compared to general medical patients. In such patients HFNP therapy is generally used with an FiO2 of 0.21 (i.e. room air), or a low increased fraction of oxygen (≤30%).

    Approval should be sought with the Cardiac Consultant or PICU consultant before oxygen therapy is commenced for a patient with cyanotic congenital heart disease.


    • Abdominal distension. 
    • Pressure areas. 
    • Blocked HFNP due to secretions. 
    • Pneumothorax. 

    Supplemental Oxygen

    Oxygen therapy should be commenced if: 

    • SpO2 is persistently less than 90% (PaO2 less than 80mmHg) in patients without cyanotic heart disease.
    • <91% in premature and newborn neonates 
    • SpO2 is persistently less than patient’s acceptable limit in the patient with cyanotic heart disease, generally <70% (PaO2 less than 37mmHg)

    Reduction or cessation of oxygen therapy. 

    Oxygen therapy should be reduced or ceased if: 

    • SpOis ≥ 90% in patients without cyanotic heart disease.
    • The child with cyanotic heart disease reaches their baseline SpO2
    • Patients requiring FiO2 greater than 0.50 (50% oxygen) should be reviewed by PICU with consideration for transfer to the PICU. 
    • Cardiac patients requiring FiO2 greater than 0.30 (30% oxygen) should be reviewed by PICU with consideration for transfer to PICU


    Because flows used are high, heated water humidification is necessary to avoid drying of respiratory secretions and for maintaining nasal cilia function.
    Airvo humidifier setting at 34° C non-invasive setting. 

    Nursing care: Nutrition/Hydration

    • All patients on HFNP therapy must have a nasogastric tube inserted prior to the commencement of therapy due to the risk of abdominal distension. 
      • Do not feed during the initial 2 hours following commencement of HFNP therapy.
      • Once stable on high flow the infant should be assessed as to whether they can tolerate oral feeds.
      • Some infants can continue to feed orally, but many require feeding via the nasogastric tube.
      • If oral feeding is not tolerated, commence 2 hourly NG bolus feeds with EBM or formula as appropriate, reduce total volume to 2/3 maintenance.
      • Consider continuous NG feeds if not tolerating bolus feeds. 
      • Infants who do not clinically stabilize within 2 hours or who do not tolerate NGT feeds should have an I.V. inserted to receive hydration. 
      • Aspirate the NGT for air 2-4 hourly. 
    • Oral and nasal care must be performed 4 hourly. 
    • Note nasal prongs are in correct position and no pressure areas to nares. 
    • Gentle suction as required to keep nares clear. 

    Where an infant clinically improves, oral feeds can commence:

    • HFNP therapy should be turned down to LOW FLOW, see the Oxygen Delivery Clinical Guideline.
    • Oxygen should be titrated to maintain target SpO2
    • After a maximum of 20 minutes, oral feeds/breast feed should be stopped and HFNP therapy recommenced at previous settings.

    Oral feed should be ceased and HFNP therapy recommenced if child clinically deteriorates during feeding.

    Patient monitoring

    Observation and patient clinical assessment and documentation should occur hourly at a minimum.  Adjustment of frequency of patient observation and assessment should occur in response to clinical condition.

    Continuous monitoring of SpOand HR until clinically stable 

    • Monitor patient for response in 
      • Respiratory rate 
      • Heart rate 
      • Respiratory Distress (Work Of Breathing) 
      • SpO2

    Within 2 hours it should be possible to reduce the FiO(where required) and signs of clinical stabilization should be seen 

    • FiO2 required to maintain SpO2 in the target range should decrease to <40%. 
    • Heart rate should reduce by 20% or to within normal range. 
    • Respiratory rate should reduce by 20% or to within normal range. 
    • Signs of respiratory distress should improve. 

    Seek medical review if any of the following occurs: 

    • Patient is not stabilizing as described above. 
    • Degree of respiratory distress remains unchanged, or worsens. 
    • Hypoxaemia persists despite oxygen therapy. 
    • Requirement for >50% oxygen in patients without cyanotic heart disease
    • Requirement for >30% oxygen in patients with cyanotic heart disease


    • For the patient with cardiac disease, heart failure and respiratory failure have similar clinical manifestations. HFNP therapy may mask signs of heart failure, therefore consider other tests, such as ECHO, ECG to understand child’s cardiac function.
    • If a high FiO2 is used, oxygen saturation may be maintained in an infant despite the development of hypercarbic respiratory failure.
    • If there is rapid deterioration of oxygen saturation or marked increased work of breathing, a chest x-ray should be done to exclude a pneumothorax. 
    • Do blood gas analysis when clinically indicated but remember that blood taking can further upset an infant.  If in doubt discuss with consultant paediatrician, or PICU

    Sometimes an infant commenced on HFNP will be more distressed because of the discomfort of the therapy.  This is sometimes interpreted as indicating a deterioration requiring escalation of therapy.  However sometimes such infants will be just as stable, or even more settled, simply on standard low flow 100% oxygen.  Deciding which children require escalation and which children would be better changed to standard flow 100% oxygen therapy requires judgement and sometimes a trial of standard oxygen.  This decision is best made by a doctor and nurse who have observed the child consistently since commencement of HFNP therapy.  Contact the Consultant Paediatrician or PICU Outreach if unsure.



    • RR, HR, SpO& WOB. 
    • Flow rate, FiO& humidifier temp.
    • Water level, rainout

    Ceasing HFNP therapy 

    When the child's clinical condition is improving as indicated by: 

    • Decreased work of breathing 
    • Normal or improved respiratory rate 
    • Return to normal cardiovascular parameters
    • Wean FiOto 21% then cease HFNP therapy. 
      • HFNP therapy should not be routinely weaned, just stopped

    Consider transfer to low flow nasal prong oxygen therapy where HFNP is no longer required but clinical requirement for oxygen persists.  Consult section on weaning oxygen on the Oxygen Nursing Guideline.

    Continue pulse oximetry monitoring for 30 minutes post cessation of HFNP therapy, perform vital sign observation, intermittent SpOmonitoring 30 minutes later, then hourly for 2 hours.

    Where cessation of HFNP therapy is successful – usually known within 2 hours of stopping - continuous pulse oximetry monitoring may be discontinued.

    Unless contraindicated, an attempt to wean oxygen or stop HFNP flow should be made at least once per shift.


    • Patients transferred to  the wards on HFNP from the Emergency Department or PICU/NNU must show clinical stabilization as detailed under ‘Patient monitoring’ prior to transfer occurring.
    • Patients transferred to Koala Ward from the PICU must show clinical stabilization on HFNP therapy with FiO2 <30% as detailed under ‘Patient monitoring’ prior to transfer occurring
    • Consideration for transfer to PICU is clinically indicated if patient on HFNP therapy have reached the maximum target of FiO2 requirement. (≥50%  or >30% cyanotic cardiac patients) 

    Special Considerations

    Infection Control

    • Should an aerosol generating procedure be undertaken on a patient under droplet precautions then increase to airborne precautions by donning N95/P2 mask for at least the duration of the procedure.


    • The AIRVO 2 Humidifier requires cleaning and disinfection between patients. 
    • Follow the instructions in the disinfection kit manual

    Companion documents


    Evidence table

    Click here to view the evidence table.  

    Please remember to read the disclaimer.

    The development of this nursing guideline was coordinated byThe development of this clinical guideline was coordinated by John Kemp, Clinical Support Nurse and Respiratory CNC, with the help of Lauren Davis, RN, Danielle Smith, NUM, and Rebecca McGrath, Clinical Nurse Specialist, all from Sugar Glider Medical Care, along with Dr Ed Oakley, Dr Micheal Cheung, Dr. Trevor Duke, and approved by the Nursing Clinical Effectiveness Committee. Updated June 2021.  

    Special thanks to Annabelle Santos and Bernie Attard, Clinical Support Nurses, Koala Ward