The Royal Children's Hospital Melbourne

Nursing guidelines

High flow nasal prong (HFNP) therapy

Introduction
Aim
Definition of Terms
Indications
Contraindications
Initiation
Management: Acute
Flow rate
Humidification
Complications
Supplemental Oxygen
Patient Monitoring
Documentation
Nursing Care
Transfers
Ceasing HFNP therapy
Special Considerations
Cleaning
Companion Documents
Links
Evidence Table
References
Introduction

Humidified high flow nasal prong (HFNP) therapy is a form of non-invasive respiratory support. HFNP may act as a bridge between low flow oxygen therapies and CPAP, reducing the need for CPAP/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.
Please Note: HFNP therapy is an aerosol generating procedure (AGP), a patient’s clinical requirement for HFNP should be balanced against the risk of aerosolization. When HFNP therapy is required for a SCOVID or COVID patient, this should be carried out in a negative pressure room using Airborne Precautions which include personal protective equipment (PPE): P2 respirator (N95 mask); Eye protection (e.g. Eyewear, face shield); Long-sleeved gown; Gloves (non-sterile). If a negative pressure room is unavailable, AGPs may be performed in a single room without negative pressure ventilation with the door closed. Airborne precautions should be maintained for 30minutes after an AGP has been performed. The patient should be transferred to a negative pressure room as soon as possible. PPE including P2/N95 masks should be discarded following an aerosol generating procedure or discarded and replaced if contaminated with blood or body fluids.
Aim
The aim of this guideline is to describe the indications and procedure for the use of High Flow Nasal Prong (HFNP) therapy within paediatrics.
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

CPAP: Continuous Positive Airway Pressure
FiO₂: Fraction of inspired oxygen (%).
PaCO₂: The partial pressure of CO₂ in arterial blood. It is used to assess the adequacy of ventilation.
PaO₂: The partial pressure of oxygen in arterial blood. It is used to assess the adequacy of oxygenation.
SaO₂: Arterial oxygen saturation measured from blood specimen.
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. High flow in approved areas only. Consult your NUM if unsure.
Humidification is the addition of heat and moisture to a gas. The amount of water vapour that a gas can carry increases with temperature.
Hypercapnea: Increased amounts of carbon dioxide in the blood.
Hypoxaemia: Low arterial oxygen tension (in the blood.)
Hypoxia: Low oxygen level at the tissues.
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.
Tidal Volume: The amount of gas that moves in, and out, of the lungs with each breath, measured in millilitres (6-10 ml/kg).
Ventilation - Perfusion (VQ) mismatch: An imbalance between alveolar ventilation and pulmonary capillary blood flow.

Indications
Patients requiring respiratory support.
Acute respiratory distress associated with respiratory illness, hypoxaemia (SpO₂<90%) and/ or moderate to severe work of breathing
Respiratory distress in association with non-respiratory issues e.g., congestive cardiac failure, fluid overload
Post-operative respiratory support e.g., tonsillectomy & adenectomy (Ts&As)
Respiratory support to infants and children with chronic lung disease.
Weaning therapy from mask CPAP or BPAP
Contraindications
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
Blocked nasal passages/choanal atresia
Trauma/surgery to nasopharynx
Pneumothorax
Initiation
The decision to initiate HFNP therapy must be made in consultation with the bed card Consultant
Medical order placed within EMR
HFNP can be initiated in wards if clinically indicated
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 Clinical Guideline should be consulted with regards to equipment, set up, FiO₂ delivered and target SpO₂ ranges.
Management: Acute

Equipment and set up, check device settings match the EMR order
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.
Humidification

Water humidification is necessary to avoid drying of respiratory secretions and for maintaining nasal cilia function due to the high flow rate
Airvo humidifier setting at 34° C non-invasive setting.
Complications
Abdominal distension.
Pressure areas.
Blocked HFNP due to secretions.
Pneumothorax.
Possible hypotension
Supplemental Oxygen
When HFNP therapy is commenced to provide respiratory support for children with non-respiratory issues, supplemental oxygen should be used cautiously with a FiO₂ not greater than 0.3

In children with cyanotic congenital heart disease and balanced circulation, HFNP therapy is generally used with an FiO₂ of 0.21 (air) or a low increased fraction of oxygen (≤30%) The addition of supplemental oxygen requires approval from Cardiac or PICU Consultant

In children with clinical signs of upper airway obstruction (noisy breathing, tracheal tug, subcostal retractions, absence of tachypnoea) or potential obstruction e.g., post-op Ts & As on HFNP therapy should only receive FiO₂ 0.21 (air). The addition of supplemental oxygen requires approval from ENT or PICU Consultant.

Supplemental Oxygen therapy should be commenced for patients on HFNP who display hypoxaemia
SpO₂ is persistently less than 90% (PaO2 less than 80mmHg) in patients without cyanotic heart disease
SpO₂ is persistently less than patient’s acceptable limit in the patient with cyanotic heart disease, generally <70% (PaO₂ less than 37mmHg)
Where supplemental oxygen is required, titrate FiO2 to the minimum amount required to maintain target SpO₂.
Oxygen therapy should be reduced or ceased if:
SpO₂ is ≥ 90% in patients without cyanotic heart disease.
Child with cyanotic heart disease reaches their baseline SpO₂
Patient monitoring
Observation, 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 SpO₂ and 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 FiO₂ (where required) and signs of clinical stabilization should be seen
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.
FiO₂ required to maintain SpO₂ in the target range should decrease to <40%.
Seek medical / Outreach / After-hours 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 >40% oxygen in respiratory patients
Requirement for >30% oxygen in non-respiratory patients
Documentation
Document hourly:
RR, HR, SpO2 & WOB.
Flow rate, FiO2 & humidifier temp.
Water level, rainout.
Nursing care
Patients on HFNP therapy should have a strict fluid balance
Patients on HFNP should have a NGT for air decompression (unless contraindicated e.g. post op Ts&As)
Method of nutrition/ hydration should be based on severity of respiratory distress
Do not feed during the initial 2 hours following commencement of HFNP therapy.
Once stable the child should be assessed as to whether they can tolerate oral feeds.
Oral feed should be ceased if child clinically deteriorates during feeding.
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.
Check for pressure areas, nasal prongs are in correct position and saturation probe moved regularly
Gentle suction as required to keep nares clear.
Monitor for abdominal distention and aspirate NGT as clinically indicated
Cluster cares and minimal handling
Notes
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 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, PICU Outreach or After-hours if unsure.
Transfers
The Airvo requires main power and is not portable. Patients receiving HFNP therapy who require transfer must be escorted by a nurse or doctor. Patients on HFNP with oxygen therapy, can be transferred on low flow oxygen therapy with HFNP re-established as soon as possible. If unstable off HFNP, patients require escalation of care prior to transport.
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 FiO₂ to 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 Clinical Guideline.
Continue pulse oximetry monitoring for 30 minutes post cessation of HFNP therapy, perform vital sign observation, intermittent SpO2 monitoring 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 cease HFNP flow should be made at least once per shift.
Special Considerations
Cleaning
The AIRVO 2 Humidifier requires cleaning and disinfection between patients.
Follow the instructions in the disinfection kit manual.
Companion documents
RCH Nursing Guideline: Nursing assessment.
RCH Nursing Guideline: Nursing documentation.
Links

Oxygen delivery nursing guideline
PICU HFNP guideline
Bronchiolitis nursing guideline
Evidence table

Click here to view the evidence table.

Please remember to read the disclaimer.

The development of this clinical guideline was coordinated by John Kemp, Clinical Support Nurse and Respiratory CNC, Sugar Glider and the coordination of making this guideline hospital wide was done by Sophie Linton, CNC, Nursing Innovation; and approved by the Nursing Clinical Effectiveness Committee. Updated November 2021.