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 [SpO212Kg: 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 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.
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.