Critically evaluate the use of High Flow Nasal Prongs (HFNP) in adult ICUs.
Definition & Equipment:
Variable FiO2 high flow (20L/min or more), humidified and heated to 37oC applied by specific nasal
cannulae. The cannulae are soft, and have a wide aperture; such that the gas velocity is less for a
given flow than conventional cannulae; this aids in patient tolerance.
• Varied and has become common and widespread
• Hypoxaemic respiratory failure of any cause
• Post extubation
• Maintenance of oxygenation during procedures (intubation, bronchoscopy,
TOE, GI endoscopy)
• May be used in hypercapnic respiratory failure as reduces dead space; less
evidence in this group
• Oxygen therapy in treatment limitation / palliation / not for intubation settings
Rationale & Physiologic Advantages:
• High flow “washes” dead space
• Mechanical splinting of nasopharynx prevents supraglottic collapse
• Small amount of CPAP with effects on work of breathing
• Well tolerated generally, and therefore
• Consistent oxygenation
• Known and titratable FiO2; potentially reduces periods of hypoxia and hyperoxia
• Humidification may be of benefit in reducing epithelial injury in patients with hyperpnoea
• PEEP is variable and difficult to measure
• PEEP drops to ~2 cmH2O when mouth open
• More costly and more complex to set up than standard nasal cannulae
• Local trauma, discomfort and pressure areas
• Gastric distension
• Secretions block cannulae
• May delay intubation and lead to worse outcomes
• Excessive PEEP may cause PTX in neonates
• NEJM Study; Frat et al (France) 2015 (DOI: 10.1056/NEJMoa1503326)
o NIV vs FMO2 vs HFNP
o No change in intubation rates
o Mortality advantage over NIV and face mask O2
o Favourable editorial at the time
• Other studies:
o Some have shown decreased re-intubation rates
o THRIVE as pre-oxygenation may be better than RSI
o Delays intubation (Kang, 2015)
o o THRIVE (Anaesthesia, Pateal, 2015) Mean apnoea time in difficult intubations 14min,
but PREOXYFLOW (Vour’ch, 2015) lowest SpO2 no better than high flow face mask
o Post extubation HFNP x24h equivalent to NIV (Hernandez, JAMA 2016)
Summary statement and personal practice opinion.
Additional Examiners Comments:
Many candidates failed to list the indications for this therapy and the knowledge of the evidence and patient groups studied was poor.
Question 2 from the first paper of 2013 asked for indications, contraindications and complications of high flow nasal prong therapy. To cover all bases, the High Flow Nasal Prongs revision chapter was written to answer Question 2 as if it were a "critically evaluate" style SAQ. Then, in this paper, that effort was justified by an actual "critically evaluate" SAQ.
Rationale for the use of high flow nasal prongs (HFNP)
Limitations of HFNP and contraindications to their use
Potential adverse events associated with HFNP
Evidence in the literature:
Parke et al (2011): one of the first studies comparing HFNP and standard high-flow face mask
FLORALI trial (2015): multicenter open-label trial, 310 patients
PREOXYFLOW (2015): multicenter open-label trial,124 patients
THRIVE (2014): observational case series of 25 patients with difficult airways
S68 Hi-Flo study (2014): Randomised controlled trial of 72 babies under 18 months of age
BiPOP (2015): Multicenter, randomized trial in 830 post-op cardiothoracic patients
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.