High Flow Nasal Cannula Oxygen Therapy ( HFNCT ) for Infants and Children ( not for use in NICU )

Publication: 13/08/2014  --
Last review: 23/01/2017  
Next review: 01/10/2019  
Clinical Guideline
ID: 3925 
Approved By: Trust Clinical Guidelines Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2017  


This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.

High Flow Nasal Cannula Oxygen Therapy (HFNCT) for Infants and Children (not for use in NICU)

Children may require respiratory support for many reasons.
Non-invasive respiratory support may reduce the frequency with which children require mechanical ventilation. Two modes are readily available:

  • Continuous Positive Airway Pressure (CPAP)
  • High Flow Nasal Cannula Oxygen Therapy (HFNCT)

To date there are no published good quality randomized controlled trials (RCTs) supporting the use of HFNCT in children. There are however, small RCTS and retrospective studies demonstrating that HFNCT may reduce the number of children admitted to PICU with bronchiolitis, and there is some evidence from early studies in infants to suggest that HFNCT may be as effective as CPAP whilst being simpler to administer1, 2 . Research is on-going and will inform our future practice.

The following is a guide aimed predominantly at the use of HFNCT for the management of infants and children with acute respiratory illness, WITHOUT pre-existing co-morbidity. There is a section at the end of the document for the management of children with pre-existing co-morbidity who may require a different approach. This approach should be discussed with the child’s named Consultant. This guide is not for use on the Neonatal Unit.

The decision to commence HFNCT should be made by a middle grade Doctor (Registrar) or above and the Consultant responsible should always be informed.

Vapotherm is the form of HFNCT used in Leeds Childrens Hospital, and in this document “Vapotherm” and “HFNCT” are used interchangeably.  Other forms of HFNCT are available and may have different advantages and disadvantages.

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Indications for the use of HFNCT

Consider additional respiratory support with HFNCT if, despite optimising treatment/other manoeuvres to optimise respiratory condition, two or more of the following are present:

  • Respiratory rate scoring 3 (amber) or more on PAWS
  • Apnoeas in infants less than 6 months of age with possible bronchiolitis
  • Bradypnoea or cyanotic episodes (with or without bradycardia) despite supplemental O2
  • Significantly increased respiratory effort including recession
  • Need for high oxygen flow rate via nasal prongs (max 2-4L/min depending on comfort and age of child), facemask (8-10L/min), or headbox (consider if requiring 50-60%)
  • Inability to achieve target saturations with, or to tolerate, other modes of oxygen delivery
  • PaCO2 8.5 kPa or more (in children without pre-existing chronic lung disease) on a capillary blood gas.
  • Rising PaCO2 (more than 2kPa from baseline)
  • Respiratory acidosis (pH 7.2 – 7.28, if pH less than 7.20 consider ventilation)

HFNCT should not be used as a routine oxygen delivery system for children due to its cost and the scarcity of machines.

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Special Considerations in the use of HFNCT

Patients in this group must be discussed with the Paediatric Consultant responsible for the patient before HFNCT is started as other options may be preferable.

  • Pre-existing lung disease/ Cardiac conditions
  • Neuromuscular disorders
  • Thoracic abnormalities
  • Patients with an initial pH< 7.2 who don’t meet other indications, (i.e. could this be something else such as a metabolic acidosis/sepsis)
  • Small neonates with apnoeas (consider sepsis)
  • Asthma – NOT standard therapy, therefore would need a discussion with PICU
  • Croup - NOT standard therapy, therefore would need a discussion with PICU

When starting a child on HFNCT, an appropriate clinical risk assessment needs to be made. Consider whether the child needs HDU/PICU/stabilization area or high dependency bed. Please consider staffing and equipment availability.

Standard nebulisers should not be used at the same time as HFNCT as it will prevent drug delivery. A device called an Aerogen nebuliser is required to enable drug delivery with HFNCT.

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Contraindications to the use of HFNCT

  • The need for intubation and/or mechanical ventilation as evidenced by the presence of:
    • Severe respiratory or cardiovascular instability and impending arrest
    • pH less than 7.20 and not improving with initial support
    • SpO2 less than 88% in maximal effective oxygen therapy
    • Exhaustion (decreasing respiratory rate, desaturations, apnoea and increasing heart rate or bradycardia may indicate fatigue)
  • Upper airway abnormalities that may make HFNCT, NCPAP, or Nasal Mask (NM)-CPAP ineffective or potentially dangerous (e.g., choanal atresia, cleft palate, tracheoesophageal fistula)
  • Pneumothorax
  • Burns to the face/ chest

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How it works

HFNCT is a system by which warmed and humidified high flow oxygen/air mixture is administered via nasal cannulae at flow rates more than 2 l/min 3. It can be used by trained staff to provide respiratory support for infants who would be considered for CPAP therapy.

HFNCT delivery systems work by producing gas flows that exceed patient inspiratory flow rates. This ensures that the patient inspires the intended gas composition and may provide other physiological benefits including:

  • Washout of nasopharyngeal dead space
  • Reduction in inspiratory resistance associated with gas flow through the nasopharynx
  • Improvement in respiratory mechanical parameters associated with gas temperature and state of humidification
  • Reduction in metabolic work associated with heating and humidification of gas
  • Provision of mild distending pressures3,4

It is not intended for use as a continuous positive airway pressure device, but rather as a high flow system to deliver conditioned (i.e. warmed and humidified) breathing gases.3

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  • More comfortable, with less risk of nasal trauma than with CPAP
  • Less nursing time required as easier to use than CPAP, not dependent on seal
  • Easier access to child than CPAP (and head box oxygen in infants)
  • Easier parental interaction with their child

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Potential Disadvantages

  • Unpredictable delivery pressures which are not measured (however the circuit pressure will always be significantly greater than pressure within the nasopharynx), 3 and there have been case reports of barotrauma. 5
  • The Vapotherm unit needs wall oxygen to operate and cannot therefore be used to transfer patients.
  • The Vapotherm unit has very limited battery and so should not be used in situations where power supply is unreliable.
  • Standard nebulisers should not be used at the same time as HFNCT as it will prevent drug delivery. A device called an Aerogen nebuliser is required to enable drug delivery with HFNCT.

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Set up

  • HFNCT is applied to children via nasal cannulae, and is attached to a continuous flow of warm, humidified air and oxygen.
  • It is intended as an open system, which allows for flushing of nasopharyngeal dead space.
  • Select appropriate sized nasal cannula for that child. These must not occlude more than 50% of the child’s nostrils
  • The mouth must not be held closed
  • Select appropriate circuit
    • There are 2 circuits available for HFNCT:
      • High flow circuit can deliver 5-40L flow
      • Low flow circuit can deliver 1-8L flow
    • Infant and Intermediate Infant cannulae can only be used with the low flow circuit which can be sourced from NICU or PICU.
  • Select the initial flow rate using the table below (higher flow rates may be used in babies younger than 2 months of age following PICU advice).
  • Stop feeds initially (See Fluid Management below)
  • See equipment and personnel requirements below

Nasogastric tubes:

  • Insert if required for feeding
  • Observe the child for gastric distension and pass an NG tube if it occurs. Leave on free drainage
  • Please use the LHP for NG feeding

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Start with FiO2 0.6 (60%) and the starting flow rate – weight related. (See table below).

Set target SpO2 for child (normally 92 -95%) may need to be lower in children with chronic lung disease or congenital heart disease.

Ensure nares are not occluded by more than 50%. They cannula can be sat below the nostrils.


Minimum Flow Rates

Starting Flow

Maximum Flow



Less than 3kg




Paediatric Small Cannula
(infant or intermediate cannula can be used)
Low flow circuit

Greater than or equal to 3kgs
but less than 4kgs




Paediatric Small Cannula
High flow circuit

Greater than or equal to 4kgs
but less than 8kgs





Paediatric small cannula
High flow circuit

Greater than or equal to 8kgs
but less than 12kgs




Paediatric small cannula
High flow circuit

Greater than or equal to 12kgs
but less than 20kgs




Paediatric/Adult small cannula
High Flow Circuit

Greater than or equal to 20kgs
but less than 30kgs




Paediatric/Adult small cannula
High Flow Circuit

Greater than or equal to 30kgs




Adult small cannula
High Flow Circuit

*For PICU review

Blood gases

  • Check a capillary gas before starting HFNCT
  • If pH less than 7.20 – consider if invasive ventilation/ PICU admission is required
  • pH 7.20 – 7.25 – start HFNCT. Observe closely. Repeat the gas within 1 hour and contact the on duty Consultant with the result
  • pH more than 7.25 and clinically improving on HFNCT – no need to repeat gas unless there is a change in the patient’s condition.

Supportive Care

  • Stop feeds initially; Start 80% maintenance IV fluids as per the fluids guideline
  • Consider prone positioning
  • Consider chloral hydrate 25mg/kg (max 1 gram four times a day), initially 6 hourly, in unsettled babies as chloral does not cause apnoeas in the majority of patients. Only use in children with normal or improving blood gases.
  • If the child is irritable then consider other causes e.g. hypoxia, hypercapnia, meningitis.
  • Do not administer chloral hydrate in small babies with apnoeas/ those with poor muscle tone or those with any other contra-indication to Chloral hydrate
  • Once stable/improving:
    • Consider nasogastric feeds after 4 hours of therapy if the patient is stable
    • Oral feeds can be considered in patients who have mild - moderate respiratory distress and are improving after discussion with the consultant.

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  • Continuous HR and SpO2 monitoring
  • Half hourly recording of RR, HR, SpO2, PAWS for the first 2 hours, with 4 hourly temperature, BP and AVPU score
  • 4 hourly observations once stable/improving
  • Fluid balance
  • Daily U&E if on IV fluids

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Assessment (see flowchart)

If SpO2 more than 95% or prescribed target range

  • Reduce FiO2 in 10% increments as tolerated until SpO2 in target range or greater than 95%. (Note once FiO2 is 40% (0.4) then consider reducing flow)
  • Review FiO2 with every set of observations at least (i.e. every 4 hours or more frequently if possible) and reduce accordingly.
  • If following reduction in FiO2 to 40%, SpO2 remains more than target range or greater than 95% and clinical observations and PAWS are stable after at least 2 hours of HFNCT, reduce flow by 2 litres per minute increments as tolerated, until SpO2 is in target range. Consider weaning at every set of observations.
  • If SpO2 remains more than target range or greater than 95% and flow rate has reached minimum weight-appropriate thresholds (see table), the child should have a trial off HFNCT on low flow oxygen (unless it was started for apnoeas or airway obstruction).
  • If target saturations are not maintained after flow or FiO2 are reduced then go back to previous settings.

Children should be weaned from HFNCT to other modes of oxygen therapy as soon as safely possible to ensure a supply of machines for other children who need them.

If SpO2 less than 92% or below prescribed target range

  • Temporarily increase FiO2 to 80% (0.8) and increase the flow by increments of 2 litres/minute up to the maximum (see table).
  • Urgent medical review
  • If SpO2 is still less than 92%, increase FiO2 to 1 (100%)
    • Urgent review of ABC and intervention as necessary
    • Check circuit and the position of the cannula
    • Exclude causes for failure including: nasal obstruction, pneumothorax, gastric distension leading to diaphragmatic splinting
    • If the situation is not resolved, discuss with consultant and call PICU for referral.
    • Some patients may be managed with high settings on a general ward with PICU supervision if duty paediatric consultant agrees.

Once condition stabilizes wean FiO2 as tolerated.

Success of treatment can be gauged by:

  • Reduction in frequency/ severity of apnoea
  • Reduction in oxygen requirement
  • Reduction in heart rate and respiratory rate within the first hour (but beware of fatigue!)
  • Improvement in respiratory acidosis
  • Reduction in work of breathing

Failure of treatment can be gauged by:

  • Increasing oxygen requirement
  • Unchanged / rising heart rate and respiratory rate
  • Failure to improve respiratory acidosis (pH <7.2)
  • An unchanged or increased work of breathing
  • SpO2 less than 92% at FiO2 more than 60% (0.6) and maximal weight-appropriate flow rate
  • Fatigue (falling respiratory rate with increasing heart rate; apnoeas; bradycardias; desaturations)

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If HFNCT is failing:

(pH less than 7.2, unable to maintain saturations in target range or increase in work of breathing):

  • Urgent review of ABC and intervention as necessary. Consider calling 2222.
  • Check, equipment, circuit and nasal cannulae position
  • Consider repeat chest X-ray  [Please link to CXR guidelines]
  • Consider complications:
    • Barotrauma; pneumothorax or subcutaneous emphysema
    • Sudden deterioration requiring immediate ventilation
    • Aspiration
    • Gastric distension and diaphragmatic splinting
    • Obstruction or irritation due to improper sizing of nasal cannulae
  • Review diagnosis, consider:
    • Nasal obstruction
    • Lung collapse/secretions (consider physiotherapy)
    • Pneumothorax
    • Gastric distension
    • Sepsis/metabolic/cardiac causes
  • Consultant Paediatrician review
  • PICU referral for further management
  • 2222

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Discontinuation of HFNCT

  • Need for IPPV
  • Intractable gastric distension and diaphragmatic splinting
  • Improvement, therefore able to wean
  • If no progress by day 3 (48 - 72hours):
    • discuss with Consultant
    • review diagnosis / co-morbidity

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Equipment and personnel requirements

  • Commercially available nasal prongs
  • Continuous flow air & oxygen gas source
  • HFNCT delivery device
  • Continuous pulse oximetry, with audible alarm settings
  • Suction source, suction regulator, and suction catheters
  • Resuscitation apparatus and masks of appropriate size

HFNCT can be used in Paediatric units where:

  • Nursing staffing levels are adequate to ensure initial 1 nurse to 2 patient ratio until the patient is stable.
  • Nursing staff have received training and are competent to care for patients with HFNCT
  • Adequate medical staff cover exists to ensure frequent review of patients on HFNCT

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Transfer of children on HFNCT from PICU to ward

When the decision has been made that a child is stable on HFNCT and well enough for discharge from PICU, then transfer to another ward within the hospital should be possible. The child will require respiratory support with PEEP for transfer. A Nurse and Doctor escort is necessary.

Once a child has arrived on the ward, the PICU Nurse and Doctor will stay with the child until HFNCT has re-commenced and the ward staff are happy with the child’s clinical condition.

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Transfer of children on HFNCT between children’s wards

Children on moderate flows and in less than 50% oxygen can be moved between wards temporarily off the Vapotherm. Patients made distressed with mask can be transferred on nasal cannula with a suction control unit adaptor. Children who need more support will need a medical escort who is capable of providing bag mask ventilation including PEEP.

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Complex patients

  • Patients who have underlying respiratory or neuromuscular comorbidity may not wean easily from high flow. These patients should be discussed with a respiratory consultant.
  • It is unreasonable to expect a child with chronic lung disease who requires oxygen at home to be weaned to less than 30% before going on to wall oxygen. It is therefore more important to wean the flow, as high flows cannot be used at home.
  • The smaller the child the greater the effect of PEEP.
  • Oxygen delivery to the lungs is determined by the product of tidal volume (which is dependent on the size of the child), FiO2 being delivered, and respiratory rate. When oxygen is delivered through a nasal cannula, the precise FiO2 is unknown. The actual concentration of oxygen delivered through a nasal cannula is a blend of nasally inhaled oxygen and room air entrained through the mouth and nose (Walsh et al, 2005).
  • Benaron et al, 1994, used complex mathematical models to suggest that very small babies receive different effective FiOdepending on weight, flow and inspired oxygen, that approaches 100% in small babies (less than 4kg) with a flow of more than 4l/min in 100% oxygen. However, infants on low flow who mouth-breathe will dilute their cannula flow and have lower than estimated effective FiO2, and infants who have nasal obstruction (partial or complete) will not actually receive/inhale the flow being provided through the cannula. This dilutional effect is reduced by high flow rates.
  • For example, a 4kg baby in a flow of 1l/min receiving 100% oxygen is getting an effective FiO2 of 41% oxygen. A 2kg baby with the same is getting 61% oxygen and a 6kg baby would be getting less than 41%.
  • Further a 4kg baby in a flow of 6l/min and 50% oxygen is getting an effective FiO2 of 50% as the flow fills the nasopharynx and deadspace. A 2kg baby on 2l/min and 50% oxygen is getting at least the same effective FiO2, 50%, depending on their clinical condition.
  • The tables used to make these calculations are available in the appendix.
  • Therefore for chronic lung disease children, we should reduce flow but may need to tolerate higher oxygen requirements (eg 40%)  when switching to low flow.
  • Patients with neuromuscular problems may be receiving an unmeasurable benefit from the PEEP effect of HFNCT. These patients may benefit from NIV if appropriate.
  • If a child cannot be weaned from HFNCT after 2 weeks, the patient should be discussed with PICU and the LTV team regarding converting them to NIV support.

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Top Tips for Vapotherm use

  • A green light means the machine is running, an orange light means the machine is in standby.  It may be necessary when you first set up, to press the run button twice, to ensure the machine starts.
  • Ensure that when connecting the delivery tube to the disposable water path that it is FULLY inserted i.e. both latches must click shut to prevent leaking.
  • Clamp the tube below the spike to the water bag prior to assembly.  When changing the water bag when the unit is in use, there is no need to stop the machine.  Just clamp the tube to the bag and switch it using non touch technique and then unclamp.  (Clean the spike with 70-90% isopropyl alcohol wipe in both instances as suggested by manufacturer)
  • The disposable water circuit can hold approximately 200 mls of water so may take a few minutes to fully fill initially.
  • Wait until the desired temperature set (usually 37 oC) is reached before placing the nasal cannula on the end of the patient delivery tube. (The flashing LED becomes steady to indicate that the set temperature is reached). This allows purging of condensation out of the system. It may take up to 2 minutes to reach the set temperature.
  • See suggested cannula sizes in table above, but ensure no more than 50% of nares is occluded. (If cannula are too large you can try to tape them slightly lower down face so that the prongs are sitting just below the nares.)
  • If you are unable to change the settings with the dial, check that the tubes connecting to the gases are inserted correctly (e.g. if the air is not connected properly, the display will not change from 100%, and similar if O2 not connected, it will say 21%)
  • The Vapotherm machine can be put into stand-by, but there is no off/on switch. To switch off completely you must disconnect from the power supply.
  • If there is a problem with the machine that you can’t seem to fix, then turning the machine off at the mains for a minute or two, disconnecting air and oxygen supply, and then restarting it may work!
  • Have a bag and mask in the room while the child is on Vapotherm in case of any machine malfunction or need for urgent moving of the patient. (e.g. in the event of fire)
  • If changing the circuit for any reason, assemble the circuit prior to disconnecting the machine from the patient. (The instruction manual will tell you to take the old circuit out first.)
  • Clamp the water supply when the machine is in standby mode for any length of time. If you don’t, this can damage the machine and may result in it needing changing. (Circuits cost £350 per box of 5!)
  • The circuits have a life of 30 days and must be replaced if still on the patient. Label the circuit with the assembly date and document in care plan.
  • Only setup a Vapotherm unit if definitely being used, not “just in case.”
  • If a patient is disconnected from the Vapotherm, then leave it running with the flow at 5l/min and FiO2 set at 21% (air).  If you turn the machine off completely, this will reset all the settings and the patient will need a new circuit.
  • If the machine is switched off completely to trial the patient off Vapotherm, then the circuit must be changed after 12 hours.  (It doesn’t need changing if the unit is left running therefore advisable to leave switched on during the trial off)
  • Keep plugged in at all times (when not in use) as this ensures the machine is at full charge. Full charge takes 2 hours.
  • The oxygen sensor described in the instruction manual will have already been fitted by medical physics.
  • If you press the mute button when no alarms are sounding, this puts the display into night mode (the display goes from bright to dim).

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Record: 3925
Clinical condition:

Respiratory deterioration

Target patient group:
Target professional group(s): Secondary Care Doctors
Allied Health Professionals
Secondary Care Nurses
Adapted from:

Evidence base

  1. Schibler A, Pham T M T, Dunster K R, Foster K, Barlow A, Gibbons K, Hough J L. Reduced intubation rates for infants after introduction of high-flow nasal prong oxygen delivery. Intensive Care Medicine. March 2011; 37:847-852
  2. McKiernan C, Chadrick Chua L, Visintainer P F, Allen H. High Flow Nasal Cannulae Therapy in Infants with Bronchiolitis. Journal of Pediatrics. 2010; 156: 634-8
  3. http://www.vtherm.com
  4. Dysart K, Miller TL, Wolfson MR, Shaffer TH. “Research in High Flow Therapy: Mechanisms of Action. Respiratory Medicine 2009: In press
  5. Hegde S, Prodhan P. Serious Air Leak Syndrome Complicating High-Flow Nasal Cannula Therapy: A Report of 3 Cases. Pediatrics.2013;131(3):e939-e944.
  6. Benaron D et al Maximizing the Stability of Oxygen Delivered Via Nasal Cannula. Arch Pediatr Adolesc Med. 1994;148:294-300
  7. Walsh et al. Oxygen Delivery Through Nasal Cannulae to Preterm Infants: Can Practice Be Improved? PEDIATRICS Vol. 116 No. 4 October 2005

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Approved By

Trust Clinical Guidelines Group

Document history

LHP version 1.0

Related information

This is a new guideline and comments are very welcome.

Please get in touch with either:

PICU Sister Sharon Coulson - sharoncoulson@nhs.net
PICU Sister Ann McDermott - ann.mcdermott2@nhs.net
Dr Christopher Smith (Paediatric Consultant) - christopher.smith11@nhs.net
Dr Chris Edwards (Paediatric Respiratory Consultant) - christopheredwards1@nhs.net
Dr Jo Lumsden PICU consultant) - jolumsden@nhs.net

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