Nasal High Flow respiratory support

Definition

Nasal High Flow (NHF): is heated, humidified and blended air/oxygen delivered via nasal cannula at flow rates that meet or exceed a patient’s peak inspiratory flow rate.

In this guideline the word Mokopuna is used to describe all children and young people.

Mokopuna receiving NHF can be managed on all wards within Starship Child Health.

Indications

1. NHF is a rescue therapy for mokopuna with hypoxaemic respiratory failure who are not responsive to optimised standard oxygen therapy or disease specific treatment and should be used when there is:

   • Hypoxaemia (SpO2 ≤ 92%) despite optimal oxygen therapy.
     Optimal oxygen therapy is defined as:
     Nasal cannula
     • ≤ 1-month maximum 1L/min
     • >1 month - < 2 years maximum 2L/min
     • ≥ 2 years maximum 4L/min
     Simple facemask oxygen
     • 4-10L/min for all ages (equivalent to 35-60%)

   • Severe respiratory distress
     

     

     Reference: Dalziel, S. Haskell, L. O'Brien, S et al (2022)

2. Mokopuna established on long term NHF under the guidance of the Respiratory Service.

3. Cardiac failure: The use of positive airway pressure in left ventricular heart failure has been shown to reduce the afterload of the left ventricle therefore improving cardiac output, tissue perfusion and reduction in cellular demand for oxygen. This improves feed absorption, and aids in weight gain in mokopuna with cardiac failure. Initiate with no supplemental oxygen - additional oxygen should be discussed with primary team.
   

   NHF can be initiated when there are NO signs of low cardiac output or cardiovascular instability.

4. Tracheomalacia or upper airway obstruction: NHF has the potential to generate airway-distending pressure and may be prescribed by ORL or Respiratory team for patients with these conditions. Initiate with no supplemental oxygen - additional oxygen should be discussed with ORL or respiratory SMO.

Contraindications

Unless specifically discussed and agreed by primary team SMO

• Facial anomalies or injury that preclude appropriate nasal cannula fit

• Base of skull fracture

• Existing air leak (pneumothorax or pneumomediastinum)

• Hypercapnic respiratory failure

• Active vomiting

• Bowel obstruction

Caution with high flow

• Apnoea

• Reduced level of consciousness

• Upper airway obstruction

• May cause gastric distension

Initiating NHF

• Except for NHF in bronchiolitis, the decision to initiate NHF on a ward should be made in consultation with the primary team SMO.

• Paediatric haematology/oncology patients have underlying diagnoses that lead to unpredictable trajectories of illness. There are multiple factors including often profound immunocompromise that impact them and their recovery. Haematology/oncology patients who require nasal high flow for any indication other than bronchiolitis will likely be experiencing failure of more than one body system and consequently should have NHF therapy established in the PICU setting. When the patient is showing signs of clinical stabilisation (i.e reduction in respiratory rate, heart rate and respiratory distress) and requires less than 40% FiO2, discussion with the primary team SMO and CCN/NUM should take place prior to agreement to transfer back to the ward setting.

• Initiation of NHF for mokopuna with cardiac failure will usually be done in the Paediatric Intensive Care Unit unless otherwise agreed by the clinical team. If a mokopuna previously transferred from PICU on NHF needs to be restarted after a period off, this can occur on ward 23B.

• Nursing staff are responsible for setting up and administering NHF.

Target flow rate

Reference: Franklin D, Babl FE, George S, et al (2023).

The flow rate for NHF is prescribed according to the above table for acute presentation or as prescribed by a respiratory specialist for children under the respiratory service.

Commencement of NHF

• If the mokopuna has an NG, secure the nasal cannula over the NG to enable easy removal of the nasal cannula

• Apply opsite over the hypafix tape securing the NG to improve adherence of the wiggle pads

• Secure nasal cannula on the child using wiggle pads, ensuring the cannula sit well into the nares.

• Aim for 80% occlusion, ensuring there is always a visible gap and that the cannula bridge does not touch the septum
  

  

• Unless otherwise documented:

  • Ensure AIRVO humidifier is set at 37°C invasive setting (or 34°C on Airvo 2 junior mode)

  • Start AIRVO flow rate at 5-10 L/min and increase to prescribed flow rate (or nearest equivalent) over a few minutes to allow patient to adjust to high flow:
    Airvo 3 flow rate can be set in 1 L/min increments up to 50 L/min (upper limit default selected for Starship)
    Airvo 2 flow rate can be set in 1 L/min increments to 25 L/min and then in increments of 5 L/min
    Airvo 2 flow rate greater than 25 L/min needs to use adult mode setting with Optiflow Junior 2+ XXL or adult Optiflow nasal cannula

Supplemental Oxygen

FiO2 is titrated by adjusting the oxygen flow rate at the wall flowmeter. The resulting changes in oxygen concentration will be displayed on the screen.

For respiratory conditions

• For mokopuna with SpO2 ≥85% and ≤ 92%:
  commence at room air (21% FiO2) and observe the mokopuna for 10 minutes
  If after 10 minutes, SpO2 remain ≤ 92%, oxygen is commenced using the wall oxygen flowmeter and titrated until SpO2>92%.

• For mokopuna with SpO2 <85%:
  commence NHF with oxygen using the wall oxygen flowmeter and titrate until SpO2 >92%

For non-respiratory conditions

• For mokopuna with cardiac failure initiate with no supplemental oxygen - additional oxygen should be discussed with primary team

• For mokopuna with signs of or potential for upper airway obstruction initiate with no supplemental oxygen - additional oxygen should be discussed with the primary team as a new or increased oxygen requirement could indicate new or worsening airway obstruction.

Equipment

Delivery of NHF for acute respiratory failure will usually be via the Airvo 3 (if available), while mokopuna on established home NHF therapy will be on their own Airvo 2 provided by Respiratory Physiology or ORL. In PICU NHF is delivered via a blender.

The Airvo 3 is ordered through the equipment pool. Stocks of consumables are kept on ward 23B, 25, 26B, PICU and CED (Children s Emergency Department) and can be sourced from there if NHF is needed on another ward.

Equipment required:

• Airvo 3 or Airvo 2

• Circuit: 900PT561 AirSpiral tube & chamber kit for AIRVO

• Nasal cannula appropriate for patient size and target flow rate

Minimum flow rate for adult cannula via Airvo 10L

• 1000mL bag of sterile water

• Double outlet oxygen flow meter 2 x 15 L/min

• Standard oxygen tubing to attach flowmeter to the Airvo

• WRJ112 Wiggle pad replacements for use with OJR416 & OJR418

• WJR114 Wiggle pad replacements for use with OJR520

• Tubing is changed every 14 days. Nasal cannula are changed every 7 days

• Use the date sticker in the set to record when change due

Nebulisers and Metered Dose Inhaler (spacer)

As NHF therapy is interrupted during nebuliser therapy, the benefit of NHF in mokopuna requiring frequent nebuliser therapy may not be realised and commencement of NHF should be carefully considered.

Where administration of medications via a nebuliser or spacer is prescribed, temporarily remove the high flow nasal cannula unless the mokopuna is unlikely to tolerate NHF disconnection, in which case apply the nebuliser mask over the nasal cannula. Do not reduce or change the Airvo flow rate.

Feeding

The decision to commence feeding either orally or via a NG is based on the severity of the respiratory distress, underlying medical condition and neurological status and is made by medical staff.

Some pēpi (babies) can continue to feed orally, but most will require feeding via NG tube.

Tamariki (children) can continue with oral intake as their condition allows and there are no contraindications.

Contraindications to oral feeds include but not limited to:

• Reflux

• Altered neurology

• History of or high risk for aspiration

• Hypotonia or muscle weakness

For pēpi and young tamariki consider inserting a NG tube to facilitate venting or decompression of air accumulated in the stomach.

If nil by mouth, the NG tube is placed on free drainage and aspirated with a syringe:

• at a minimum of 4 hourly

• signs of increasing respiratory distress

• If gastric distension is present

If feeding has commenced, the NG is capped for 30 minutes post feed and vented as above.

A closed decompression system may be used if available (e.g. Farrell system)

Documentation

• The decision and rationale for initiation of NHF should be recorded in the clinical record by the medical staff.

• The Airvo flow rate and supplemental oxygen should be prescribed on the National Medication Chart along with the target saturations

Monitoring

• Mokopuna receiving NHF for severe respiratory distress are at risk for treatment failure, necessitating endotracheal intubation and mechanical ventilation. Thus, close monitoring and frequent reassessment is an essential component of NHF. Caution with use outside PICU/HDU except for bronchiolitis.

• Most mokopuna will require continuous pulse oximetry, and observations will be as per observation and monitoring guideline

• In addition to NZPEWS the cannula positioning, connections and flow rates should be checked at minimum every hour.

• The PaR (Paediatric At Risk) NS should be notified of mokopuna who do not show signs of clinical stabilisation (reduction in respiratory rate, heart rate, respiratory distress and FiO2 below 40%) within 2 hours of commencement of NHF and/or as indicated by NZPEWS

• If mokopuna require an FiO2 of >40% to maintain their SpO2 > 92%, a PaR referral and PICU review is required with consideration for transfer to HDU or PICU

Stopping NHF

Oxygen is titrated to maintain target SpO2 with the aim to wean oxygen to 21% (i.e. no supplemental oxygen).

The decision to stop high flow differs according to the reason for initiation.

Patients under the General Paediatric service

When condition is improving, usually indicated by:

• Decreased work of breathing

• Normal or improved respiratory rate

• Return to normal cardiovascular parameters

• Maintaining SpO2 >92% for 4 hours on NHF without supplemental oxygen or improving with weaning oxygen <30% OR as requested by medical staff.

Remove the cannula and

• Continuously monitor Sp02 and record NZPEWS hourly for 2 hours.

• If not maintaining target saturations, initiate standard oxygen therapy by connecting the junior optiflow cannula to oxygen (as prescribed) with OPT014 Optiflow Junior Oxygen Tubing, or standard nasal cannula for older children.

• If unable to achieve target saturations despite optimised oxygen therapy, re start high flow and contact medical team.

Patients under the respiratory, cardiac or ORL service

The decision to stop high flow is made by the primary team SMO. The patient should continue to be monitored closely for signs of deterioration.

Cleaning

When NHF is no longer required, disconnect and dipose of the circuit and return the Airvo to the equipment pool for cleaning and disinfection.

Tracheostomy humidification

High flow cannot be delivered via a tracheostomy as it is an open system. An Airvo is used to deliver heated humidification via the tracheostomy and the flow rate is calculated differently by the respiratory physiologists. It is recorded on the NZPEWS chart as TH not HF.

 AIRVO Educational support

Website:
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Airvo 3 user guide
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