When High-Flow becomes too much: Are we Overusing HFNC in Acute Care?

High-flow nasal cannula (HFNC) works. It does.  In fact, some in the Respiratory world might even say it is the greatest advancement in Respiratory Care in the last dozen years or so.  Popularized through the pandemic when critical care resources were stretched like an old cracking rubber band, HFNC ‘saved the day’ in many cases by reportedly delaying the need for intubation and taking the stress off ICU’s who had a lack of ventilator access by: washing out patient dead space, promoting better gas exchange, providing a little PEEP (albeit uncontrolled PEEP) and being comfortable for patients.  RRT’s grew to love HFNC and rightly so!  It’s a great tool in the RRT’s toolbox for a multitude of patient care scenarios where someone is in acute and rapid decline.  But is there even a chance that maybe we’ve fallen head over heels too much with giving 70lpm?

Was HFNC created to replace conventional oxygen therapy (COT) devices?  We know the principal indications for HFNC include: treating patient desaturations due to ↑work of breathing (WOB) and air hunger, patients who have increasing difficulty expectorating due to thick, tenacious, copious secretions, HFNC can be used as a step down approach for post extubation respiratory support and occasionally even as a ‘break treatment’ for patients on BiPAP.  All of that makes incredible sense.  The ability to provide greater flow rates to support and reduce someone’s WOB, the provision of heated humidity to aid mucociliary clearance by breaking up all that thick, goupy phlegm in a critical pneumonia patient and the elevated level of support for post extubation and BiPAP ‘break times’ can’t be denied.  No one can argue that the tool of HFNC used under the right indications, in the right patient scenarios makes very clear sense.

But I wonder why it is then, that as I have more and more discussions with clinicians in acute care these days, that I’m hearing about HFNC being applied when a patient fails on 4-6lpm nasal cannula.  Large portions of entire provinces are starting to move to this care model and it’s making me wonder – ‘why’?  These patients are neither air hungry, nor filled to the brim with phlegm, but yet, are getting thrown on 70lpm flow anyway.  Why would we as Respiratory professionals be making this proverbial leap past many other choices for COT to go straight to this preference?

Like I mentioned earlier, the affection for HFNC is real as it ‘saved the day’ more times than probably any of us know when ICU’s / Hospitals didn’t have any more ventilators for their rapidly declining COVID patients.  There’s no doubt patients who should have been intubated and ventilated got treated on HFNC out of necessity, not preference, and while not being able to speak for every situation of course, it did a good job of sustaining people’s health in many critical moments.  You can’t help but fall in love with something like that, but there are other factors at play in the rise of popularity of HFNC.  RRT’s tend to love new tech.  Especially tech that worked in a crisis like the pandemic as well as HFNC did.  Now that we’re on the other side of the pandemic, RRT’s are very intimately familiar with the setup and use of HFNC; walk into any RT department these days and you’ll see the ‘army’ of HFNC setups, all lined up in rows, ready to be deployed, so there also might be a mentality of, “well, we’ve got all these here now, we may as well use ‘em!”  HFNC has also been promoted as an intervention that ‘delays the need for intubation’, and RRT’s have seen it work so well in acutely distressed patients that there might be a sense that HFNC can do no wrong – that putting every patient on HFNC is like an all encompassing blanket of care that I throw over my patient so it’s able to counter any bad outcome that may come their way. Plus, patient’s find it very comfortable in most circumstances.  So what’s not to love?

The answer is that there’s a lot to love. HFNC is the right tool for the right clinical situations under the indications we’ve stated above.  But does EVERY patient who desaturates on 6lpm nasal prongs REQUIRE heated high-flow therapy?

The quick answer is no.  HFNC was never developed to replace COT.  That would be excessive, overly aggressive, and possibly in some patient cases inappropriate.  It’s like driving a Ferrari as a grocery-getter… who does that?  But it’s happening more and more in respiratory circles, one could say almost blindly, and without reason or protocols to back it up.  Let me explain.

First, many hospital systems have expanded the use of HFNC faster than they have developed protocols for its initiation, management, escalation and discontinuation.¹  And when some form of protocols do exist, they often have major variations one from another in the metrics that guide management, escalation, and most importantly, liberation from HFNC.²  Potential consequences for not having a standardized approach in the management and liberation from HFNC could involve increased ICU/hospital stays, and increased costs and consumption of hospital resources.¹  An intensive therapy like HFNC shouldn’t be managed by ‘feel’, there should be well established protocols around when it is patient appropriate to start, manage and discontinue its use.  Currently, this often doesn’t exist in many centres.  The problem isn’t HFNC itself – it’s lack of governance around the therapy.

Let’s continue by unpacking some of the reasons that have been cited above.

“HFNC is convenient, easy to use and everyone knows how to use it”.  This statement may be true for RRT’s who became intimately familiar with HFNC during the pandemic, but this isn’t true for the greater body of healthcare professionals (HCP).  In fact, RRT’s in most cases are the only HCP’s that know how to setup, monitor and titrate HFNC, because the setup does require specific technical skills.  Because of this, once HFNC is initiated, that patient is rostered under the RRT team’s care, requiring regular follow-up shift after shift ( ie. Q4H, QID ), in some cases more often.  Because this responsibility solely falls to the RRT team, this effectively cuts out the other members of the HCP team who otherwise would participate in a patient’s timely oxygen titration.  If some of these patients are on HFNC who don’t really require it and would do just as well on other COT devices, this stretches the already tight RRT staffing resources.  Remember, RRTs cover patients in every care area, in every acute situation in the hospital.  Ask any RRT Manager and they’ll likely tell you post-pandemic: “I’m short staffed and the staff I do have are overwhelmed and approaching burn out.”  So why would we add to that already full RRT patient roster those who don’t really require this level of care?

What about the perception – stated or subconscious – that “HFNC is the ‘swiss army knife’ of Respiratory care” – that big ‘blanket’ we’ll throw over patients to mitigate any potential poor outcome, even delaying the need for intubation and ventilation better than COT?  Well, there’s a meta analysis from 2025 in the Journal of Intensive Medicine that sheds some interesting light here.³ Citing multiple recent studies there’s growing evidence that HFNC may provide little to no difference over COT to delay the need for intubation, or even in some cases, to reduce patient mortality.³   Certainly, there’s not the wide expanse of different patient outcomes for HFNC over COT that we’ve been all led to believe.

Additionally, there’s growing evidence that when HFNC is used outside of its primary indications, it could increase patient length of stay (LOS) by up to 30%, and raise the cost of treating each patient by up to 31%.⁴   Why would this be?  The study doesn’t completely come out and say why HFNC in these situations caused these increases, but it could be, in part, because only a limited number of HCP staff ( ie RRTs) are now able to titrate and manage the HFNC therapy, contributing to a slower titration than could be the case on COT involving the whole HCP team, because the RRT just won’t be able to get to bedside as frequently as someone like the floor nurse can to check on patients.  As mentioned earlier, a lack of liberation protocols for HFNC could also be a contributor here.¹ Another factor could be around mobilizing with a HFNC unit, heated humidifier and oxygen tank.  When it’s time to get your patient on HFNC up and moving with the Physiotherapist, this often requires the assistance of an RRT.  If the RRT isn’t available due to other more pressing patient situations and these schedules don’t co-ordinate, the patient potentially misses out.  This is much more cumbersome than if a patient were to mobilize on COT.  And we know all patients recover and have better outcomes when they are able to reliably mobilize.  Plus, patients on HFNC are often designated as ‘nothing by mouth’ (NPO) for a minimum set time due to increased fears of aspiration.  This will undoubtedly cause their nutrition to suffer if prolonged and could be causative around LOS increases.  If our patients are being placed on HFNC when they don’t really need to be, is it really helping them?

I could also speak to the amount of bulk oxygen used up by the large flow rates HFNC units demand, or the added plastic waste / patient of the HFNC setups vs. COT, or the fact that HFNC has been documented as dispersing aerosols more readily with greater velocities when used at flows >40lpm,^5,6 demanding extra care, possible patient quarantining, and extra use of PPE for HCP’s when HFNC is being used outside of its principal indications.  All of these concerns cost our hospitals more resources – both financially and personnel-wise.  But perhaps that’s another blog altogether.

And then there’s the added cost that this study cites.⁴ You don’t need a study to tell you that running HFNC is much more expensive than most COT devices.  This speaks to the whole, “well we bought all these HFNC units, we may as well use ‘em!”  And using HFNC inside its stated indications is of course appropriate, but when that usage creeps outside of those indications, your RRT dept is spending more money than it needs to.  Even putting the capital cost aside for a moment, the consumable costs alone associated with HFNC, the proprietary cannula, the heated circuit, the humidifier tub, even the water bag to feed the humidifier – all those costs add up to somewhere around $100/setup!^7,8  And how often does the setup need to be swapped out according to hospital protocols for fresh supplies?  Once a week?  HFNC it could be argued, when used outside of its stated indications, is an unnecessary resource drain for our healthcare institutions.  It’s staggering to me that in such a cost-conscious time we’re in regarding healthcare, that the large disparity in cost between HFNC and other alternative effective COT devices could be so overlooked.

What type of alternative therapy am I talking about?  Well, it’s been well documented that the traditional COT devices we’ve all grown up with since the 60’s – your Venturi Masks, Simple Masks and Non-Rebreather masks all make our patients hot and uncomfortable, and they’re also fraught with potential for errors – either in their setup or management and titration as your patient’s condition declines or improves.  We’re not talking about them.

Have you considered Oxy₂Mask for your patients? An innovative, tested and true over 20 years alternative to traditional oxygen masks. With its ability to provide a very wide range of FiO₂ – between 24-90% at 1-15+lpm of oxygen flow, Oxy₂Mask can provide effective oxygen therapy to a large portion of today’s patient population requiring supplemental oxygen.  Our innovative patented disc diffuser creates concentrated oxygen vortices that forms a ‘concentrated oxygen cloud’ effect that intentionally pours out of the diffuser, directed at the patient’s airway for effective delivery.  This oxygen delivery method and broad FiO₂ delivery capacity make Oxy₂Mask one of the easiest to use devices on the market.  Whether your patient is improving or declining, simply adjust the flow metre to titrate the patient’s oxygen saturations levels to their prescribed target range.

The open design of Oxy₂Mask allows exhaled CO₂ to be more easily removed from the mask, minimizing the potential risk of CO₂ rebreathing, making Oxy₂Mask one of the safest oxygen delivery products your patients could use today.  Getting rid of CO₂ so efficiently means that Oxy₂Mask does not have a mandatory minimum flow rate like other traditional masks employ, making it again, easy to use and less error prone for your HCP’s.

Oxy₂Mask’s open design also means it is likely to be one of the most comfortable your patients will use.  Patients won’t get as hot, sweaty or claustrophobic as wearing traditional devices, and they can easily drink, take oral medications or a bronchodilator treatment, and be heard by those at bedside much easier than if traditional COT devices were employed.  More comfort likely translates to better patient compliance with Oxy₂Mask, and that can only be a good thing for possible patient outcomes.

Oxy₂Mask is not like any other means of COT on the market today.  It’s a game changer!  For patient safety, for patient comfort and compliance, for clinician workflow optimization, and for appropriate clinical situations – Oxy₂mask fills that gap between when regular nasal cannula has failed, and if and when a patient’s decline progresses to requiring more aggressive measures such as BiPAP, HFNC or intubation and ventilation.

High-flow nasal cannula therapy works.  It does.  But it works best under the indications it was intended for.  The right tool for the right situation.  No clinical creep.  Before you reach for an overly aggressive, costly means of therapy when your patient just no longer tolerates nasal cannula, there’s an alternative you might consider… Oxy₂Mask!

1. High-Flow Nasal Cannula Liberation; Freeman H et al; CHEST 2025;168,1152-1161
2. Implementing High-Flow Nasal Oxygen Therapy in Medical Wards: a Scoping Review to Understand Hospital Protocols + Procedures; Thomas T et al; Int. J. Environ. Res. Public Health 2024, 21, 705
3. High flow nasal cannula is the reference treatment in Acute Hypoxemic Respiratory Failure: CON; Kemoun G et al; Journal of Intensive Medicine 2025 Vol 5 pg 230-236
4. Variation and Outcomes of Hospital-Level High-Flow Nasal Cannula Usage Outside of Intensive Care; Winer J. et al; Hospital Pediatrics 2022 DOI: 10.1542/hpeds.2022-006660
5. Airborne particle dispersion by high flow nasal oxygen: an experimental and CFD analysis; Crowley C et al; PLoS ONE JAN 2022; 17-1-e0262547
6. High-flow nasal cannula for COVID-19 patients: risk of bio aerosol dispersion; Li J, Fink JB, Ehrmann S. ; Eur Respir J 2020; 56: 2003136 [https://doi.org/10.1183/13993003.03136-2020]
7. The clinical effectiveness and cost-effectiveness of heated humidified high-flow nasal cannula compared with usual care for preterm infants: systematic review and economic evaluation; Fleeman N, et al. Southampton (UK): NIHR Journals Library; 2016 Apr. (Health Technology Assessment, No. 20.30.) Chapter 5, Cost-effectiveness results.
8. High-Flow Nasal Cannula & Respiratory Therapy Equipment Buyer Guide (2026); MedEquip Directory website; https://www.medequipdirectory.com/guides/high-flow-nasal-cannula-respiratory-therapy-equipment-buyer-guide/