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Advance in EM

Optimising Preoxygenation: NIV vs HFNC

Dr LAM Chun Wai Justin

Resident, A&E, Princess Margaret Hospital

Intubating a critically ill patient is a high-risk, high-pressure moment. When someone’s oxygen levels are severely compromised, every second counts. That’s when preoxygenation plays a pivotal role. It extends safe apnoeic time and helps minimise the potential adverse risks of intubation, particularly in high-risk populations such as patients with obesity or limited physiological reserve. Conventional methods including non-rebreathing masks and bag-valve masks are sometimes just insufficient. Luckily, novel techniques such as non-invasive ventilation (NIV) and high-flow nasal cannula (HFNC) offer promising alternatives.



NIV: Positive Pressure, Positive Results


Enter the PREOXI trial, a large-scale multi-centre RCT with 1,301 critically ill patients recruited from 24 EDs and ICUs in the U.S.. This trial showed that preoxygenating with BiPAP (bilevel positive airway pressure) reduces hypoxaemia rates nearly in half, down to 9% compared to 19% using a standard oxygen mask, and without bumping up aspiration risk. (1) 


Another study in ICU supports the use of the pressure support (PS) mode with PEEP, showing it performs better than non-rebreathing masks at keeping the arterial O2 level up. (2) However, another RCT failed to show any major difference in organ protection when NIV was used. (3)



HFNC: The Hands-Free Hero


HFNC is like the “hands-free” preoxygenation gadget.(8) It delivers oxygen continuously during apneic phase, even during laryngoscopy, and doesn't need to be removed mid-procedure. (4, 5, 7, 8) 


Multiple RCTs in ICU found that HFNC holds its own against non-rebreathing and bag-valve masks, offering similar lowest oxygen saturations during intubation (4, 5, 6, 7, 8), maintaining O2 during the apneic phase (7), and lowering the odds of scary complications like deep desaturation, shock, or cardiac arrest. (4, 8)


A meta-analysis also gave HFNC a high-five for being non-inferior to the standard care, even showing shorter ICU stays and fewer cases of severe hypoxaemia. (9)


NIV vs HFNC: The Showdown


So, which one is better: NIV or HFNC?


The FLORALI-2 trial, a multi-centre randomised open-label trial in 28 ICUs in France, tried to settle the score. Spoiler alert: it’s not that simple.


In patients with acute hypoxaemic respiratory failure, both approaches performed similarly in terms of preventing severe desats or complications. (10)


But secondary analyses suggest NIV may have an edge in patients with moderate-to-severe hypoxaemia thanks to its combo of high FiO₂ and PEEP that keeps those alveoli open and ready for action. (11) 


Digging deeper, a subgroup analysis of the same trial showed that in obese patients, NIV didn’t really outperform HFNC. (12) A network meta-analysis also found NIV reduced desaturation more effectively than conventional methods and HFNC. (13) For HFNC, open mouths during respiratory distress might also reduce its PEEP-like benefit. (14)


In the end, both NIV and HFNC seem better than the traditional methods, and neither appears to be better or worse on mortality. (13) A systematic review suggests NIV probably reduces hypoxaemia more reliably than HFNC, and might even lead to fewer serious adverse events. (15)


The Dream Team? Combining HFNC and NIV


Why choose one when you can have both? In OPTINIV trial, patients got both HFNC and NIV (with PS and PEEP), and they had better oxygen saturation than those with NIV alone, without more complications or ICU deaths. (16)


What is Holding Us Back?


Our emergency clinicians are still hesitant to use NIV or HFNC for some reasons.


1. Availability of Equipment


Many emergency departments just don’t have the right equipment. That said, some conventional mechanical ventilators used for mechanical ventilation after intubation can provide NIV too. One case series showed that patients stayed safe and hypoxia-free using NIV delivered by a portable machine. (17) HFNC can be readily initiated with a dedicated device.


2. Aspiration Anxiety


There is a worry that NIV could up the risk of aspiration. Evidence from both a systematic review and the PREOXI trial showed no evidence of an increased risk of aspiration with NIPPV compared with alternative preoxygenation methods (1, 15)


Final Take


NIV and HFNC have emerged as game-changers of optimising preoxygenation before intubation. Whether used alone or together, they help us make the whole intubation process a little less risky. Hope that they become the initial tools for preoxygenation in every emergency department. 


Reference

  1. Gibbs KW, Semler MW, Driver BE, Seitz KP, Stempek SB, Taylor C, Resnick-Ault D, White HD, Gandotra S, Doerschug KC, Mohamed A, Prekker ME, Khan A, Gaillard JP, Andrea L, Aggarwal NR, Brainard JC, Barnett LH, Halliday SJ, Blinder V, Dagan A, Whitson MR, Schauer SG, Walker JE Jr, Barker AB, Palakshappa JA, Muhs A, Wozniak JM, Kramer PJ, Withers C, Ghamande SA, Russell DW, Schwartz A, Moskowitz A, Hansen SJ, Allada G, Goranson JK, Fein DG, Sottile PD, Kelly N, Alwood SM, Long MT, Malhotra R, Shapiro NI, Page DB, Long BJ, Thomas CB, Trent SA, Janz DR, Rice TW, Self WH, Bebarta VS, Lloyd BD, Rhoads J, Womack K, Imhoff B, Ginde AA, Casey JD; PREOXI Investigators and the Pragmatic Critical Care Research Group. Noninvasive Ventilation for Preoxygenation during Emergency Intubation. N Engl J Med. 2024 Jun 20;390(23):2165-2177.

  2. Baillard C, Fosse JP, Sebbane M, Chanques G, Vincent F, Courouble P, Cohen Y, Eledjam JJ, Adnet F, Jaber S. Noninvasive ventilation improves preoxygenation before intubation of hypoxic patients. Am J Respir Crit Care Med. 2006 Jul 15;174(2):171-7.

  3. Baillard C, Prat G, Jung B, Futier E, Lefrant JY, Vincent F, Hamdi A, Vicaut E, Jaber S. Effect of preoxygenation using non-invasive ventilation before intubation on subsequent organ failures in hypoxaemic patients: a randomised clinical trial. Br J Anaesth. 2018 Feb;120(2):361-367.

  4. Miguel-Montanes R, Hajage D, Messika J, Bertrand F, Gaudry S, Rafat C, Labbé V, Dufour N, Jean-Baptiste S, Bedet A, Dreyfuss D, Ricard JD. Use of high-flow nasal cannula oxygen therapy to prevent desaturation during tracheal intubation of intensive care patients with mild-to-moderate hypoxemia. Crit Care Med. 2015 Mar;43(3):574-83.

  5. Vourc'h M, Asfar P, Volteau C, Bachoumas K, Clavieras N, Egreteau PY, Asehnoune K, Mercat A, Reignier J, Jaber S, Prat G, Roquilly A, Brule N, Villers D, Bretonniere C, Guitton C. High-flow nasal cannula oxygen during endotracheal intubation in hypoxemic patients: a randomized controlled clinical trial. Intensive Care Med. 2015 Sep;41(9):1538-48.

  6. Chua MT, Ng WM, Lu Q, Low MJW, Punyadasa A, Cove ME, Yau YW, Khan FA, Kuan WS. Pre- and apnoeic high-flow oxygenation for rapid sequence intubation in the emergency department (the Pre-AeRATE trial): A multicentre randomised controlled trial. Ann Acad Med Singap. 2022 Mar;51(3):149-160.

  7. Simon M, Wachs C, Braune S, de Heer G, Frings D, Kluge S. High-Flow Nasal Cannula Versus Bag-Valve-Mask for Preoxygenation Before Intubation in Subjects With Hypoxemic Respiratory Failure. Respir Care. 2016 Sep;61(9):1160-7.

  8. Guitton C, Ehrmann S, Volteau C, Colin G, Maamar A, Jean-Michel V, Mahe PJ, Landais M, Brule N, Bretonnière C, Zambon O, Vourc'h M. Nasal high-flow preoxygenation for endotracheal intubation in the critically ill patient: a randomized clinical trial. Intensive Care Med. 2019 Apr;45(4):447-458.

  9. Jhou HJ, Chen PH, Lin C, Yang LY, Lee CH, Peng CK. High-flow nasal cannula therapy as apneic oxygenation during endotracheal intubation in critically ill patients in the intensive care unit: a systematic review and meta-analysis. Sci Rep. 2020 Feb 26;10(1):3541.

  10. Frat JP, Ricard JD, Quenot JP, Pichon N, Demoule A, Forel JM, Mira JP, Coudroy R, Berquier G, Voisin B, Colin G, Pons B, Danin PE, Devaquet J, Prat G, Clere-Jehl R, Petitpas F, Vivier E, Razazi K, Nay MA, Souday V, Dellamonica J, Argaud L, Ehrmann S, Gibelin A, Girault C, Andreu P, Vignon P, Dangers L, Ragot S, Thille AW; FLORALI-2 study group; REVA network. Non-invasive ventilation versus high-flow nasal cannula oxygen therapy with apnoeic oxygenation for preoxygenation before intubation of patients with acute hypoxaemic respiratory failure: a randomised, multicentre, open-label trial. Lancet Respir Med. 2019 Apr;7(4):303-312.

  11. L'Her E, Deye N, Lellouche F, Taille S, Demoule A, Fraticelli A, Mancebo J, Brochard L. Physiologic effects of noninvasive ventilation during acute lung injury. Am J Respir Crit Care Med. 2005 Nov 1;172(9):1112-8.

  12. Rodriguez M, Ragot S, Coudroy R, Quenot JP, Vignon P, Forel JM, Demoule A, Mira JP, Ricard JD, Nseir S, Colin G, Pons B, Danin PE, Devaquet J, Prat G, Merdji H, Petitpas F, Vivier E, Mekontso-Dessap A, Nay MA, Asfar P, Dellamonica J, Argaud L, Ehrmann S, Fartoukh M, Girault C, Robert R, Thille AW, Frat JP; REVA Network. Noninvasive ventilation vs. high-flow nasal cannula oxygen for preoxygenation before intubation in patients with obesity: a post hoc analysis of a randomized controlled trial. Ann Intensive Care. 2021 Jul 22;11(1):114.

  13. Fong KM, Au SY, Ng GWY. Preoxygenation before intubation in adult patients with acute hypoxemic respiratory failure: a network meta-analysis of randomized trials. Crit Care. 2019 Sep 18;23(1):319.

  14. Nishimura M. High-Flow Nasal Cannula Oxygen Therapy in Adults: Physiological Benefits, Indication, Clinical Benefits, and Adverse Effects. Respir Care. 2016 Apr;61(4):529-41.

  15. Pitre T, Liu W, Zeraatkar D, Casey JD, Dionne JC, Gibbs KW, Ginde AA, Needham-Nethercott N, Rice TW, Semler MW, Rochwerg B. Preoxygenation strategies for intubation of patients who are critically ill: a systematic review and network meta-analysis of randomised trials. Lancet Respir Med. 2025 Mar 20:S2213-2600(25)00029-3.

  16. Jaber S, Monnin M, Girard M, Conseil M, Cisse M, Carr J, Mahul M, Delay JM, Belafia F, Chanques G, Molinari N, De Jong A. Apnoeic oxygenation via high-flow nasal cannula oxygen combined with non-invasive ventilation preoxygenation for intubation in hypoxaemic patients in the intensive care unit: the single-centre, blinded, randomised controlled OPTINIV trial. Intensive Care Med. 2016 Dec;42(12):1877-1887.

  17. Grant S, Khan F, Keijzers G, Shirran M, Marneros L. Ventilator-assisted preoxygenation: Protocol for combining non-invasive ventilation and apnoeic oxygenation using a portable ventilator. Emerg Med Australas. 2016 Feb;28(1):67-72.



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