Question 17

a)    List the indications, contraindications, uses and adverse effects of high-flow nasal cannulae (HFNC).    (40% marks)

b)    Critically evaluate the use of HFNC use in adult ICU patients.    (60% marks)

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College answer

Not available.


The wording of this SAQ might have confused some people, as some trainees would have found it difficult to find the subtle difference between the indications for high flow nasal oxygen and the uses of high flow nasal oxygen. 

Fortunately, this question is a mutant hybrid offspring of Question 2 from the first  paper of 2013  and Question 3 from the first paper of 2017, which means the candidates should have been well prepared for it. Thus:


  • For hypoxic respiratory failure, especially due to pneumonia
  • For hypercapnic respiratory failure (though the evidence is weaker)
  • Where NIV is poorly tolerated or inappropriate (eg. oesophageal surgery)
  • Where intubation is not appropriate
  • Apnoeic oxygenation pre-intubation



  • Overdistension of the alveoli, and barotrauma
  • Discomfort associated with the device, its flow or the high temperature/humidity
  • Nasal mucosal damage due to high flow
  • Pressure areas due to the device
  • Failure to achieve the desired effect because of mouth-breathing
  • Overabundance of secretions (Velasco et al, 2014) - though some might view this as a desired effect
  • Epistaxis
  • Time-wasting (delaying the inevitable intubation)
  • Aspiration of food or upper airway secretions
  • Aspiration of circuit condensation water (there's no evidence that this causes pneumonia, but people complained about it in a survey of paediatric ICUs conducted by Manley et al, 2012)

"Critically evaluate" in 6 minutes or less, omitting elements already covered in the preceding question and stripping a more comprehensive answer down to some kind of bare metal:

  • Rationale:
    • ​​​​​Pharyngeal dead space washout
    • Improved oxygenation by PEEP effect (minor though it may be)
    • Improved oxygenation by oxygen dilution reduction (at high resp rates)
    • Benefits of humidification
    • Increased comfort
  • Advantages:
    • ​​​​​​​Appropriate where NIV and intubation are not
    • Allows high FiO2 otherwise impossible to safely achieve
    • Allows high flow rates of gas, beneficial in patients with increased respiratory effort
  • Limitations:
    • ​​​​​​​​​​​​​​The patient must be able to protect their airway
    • The nose and base of skull must be intact and uninjured
    • Avoided in upper GI surgery (risk to anastomosis)
    • PEEP is not measured, and is completely unpredictable
    • Intubation may be delayed; the outcome may be worse.
  • Evidence:


Groves, Nicole, and Antony Tobin. "High flow nasal oxygen generates positive airway pressure in adult volunteers." Australian Critical Care 20.4 (2007): 126-131.

Ricard, J. D. "High flow nasal oxygen in acute respiratory failure." Minerva Anestesiol 78.7 (2012): 836-841.

Locke, Robert G., et al. "Inadvertent administration of positive end-distending pressure during nasal cannula flow." Pediatrics 91.1 (1993): 135-138.

O’Brien, Bj, J. V. Rosenfeld, and J. E. Elder. "Tension pneumo‐orbitus and pneumocephalus induced by a nasal oxygen cannula: Report on two paediatric cases." Journal of paediatrics and child health 36.5 (2000): 511-514.

Corley, Amanda, et al. "Oxygen delivery through high-flow nasal cannulae increase end-expiratory lung volume and reduce respiratory rate in post-cardiac surgical patients." British journal of anaesthesia (2011): aer265.

Boyer, Alexandre, et al. "Prognostic impact of high-flow nasal cannula oxygen supply in an ICU patient with pulmonary fibrosis complicated by acute respiratory failure.Intensive care medicine 37.3 (2011): 558-559.

Stéphan, François, et al. "High-flow nasal oxygen vs noninvasive positive airway pressure in hypoxemic patients after cardiothoracic surgery: a randomized clinical trial.JAMA (2015).

Miguel-Montanes, Romain, et al. "Use of high-flow nasal cannula oxygen therapy to prevent desaturation during tracheal intubation of intensive care patients with mild-to-moderate hypoxemia*." Critical care medicine 43.3 (2015): 574-583.

Kang, Byung Ju, et al. "Failure of high-flow nasal cannula therapy may delay intubation and increase mortality." Intensive care medicine 41.4 (2015): 623-632.

Frat, Jean-Pierre, et al. "High-Flow Oxygen through Nasal Cannula in Acute Hypoxemic Respiratory Failure." New England Journal of Medicine (2015).

Vourc’h, Mickaël, et al. "High-flow nasal cannula oxygen during endotracheal intubation in hypoxemic patients: a randomized controlled clinical trial.Intensive care medicine (2015): 1-11.

Patel, A., and S. A. R. Nouraei. "Transnasal Humidified Rapid‐Insufflation Ventilatory Exchange (THRIVE): a physiological method of increasing apnoea time in patients with difficult airways." Anaesthesia 70.3 (2015): 323-329.

Hathorn, C., et al. "S68 The Hi-flo Study: A Prospective Open Randomised Controlled Trial Of High Flow Nasal Cannula Oxygen Therapy Against Standard Care In Bronchiolitis." Thorax 69.Suppl 2 (2014): A38-A38.

Parke, Rachael L., Shay P. McGuinness, and Michelle L. Eccleston. "A preliminary randomized controlled trial to assess effectiveness of nasal high-flow oxygen in intensive care patients." Respiratory Care 56.3 (2011): 265-270.

Vourc’h, Mickaël, et al. "High-flow nasal cannula oxygen during endotracheal intubation in hypoxemic patients: a randomized controlled clinical trial." Intensive care medicine 41.9 (2015): 1538-1548.