Nasal high-flow therapy in ARDS

Simon Oczkowski, MD, MHSc, MSc, is an associate professor of medicine in the Division of Critical Care at McMaster University.

What is the role of nasal high-flow therapy (NHFT) in the treatment of acute respiratory distress syndrome (ARDS)?

That’s an interesting question. I get asked about the role of NHFT in ARDS fairly commonly. I think the biggest challenge with it is the definition of ARDS. Using the Berlin criteria requires that a patient be on ≥5 cm H₂O before you can diagnose it. And the challenge is if you have a patient who is not intubated and they’re on NHFT, we actually don’t know what the positive end-expiratory pressure (PEEP) that they’re on is.

The first fundamental question is, can you actually diagnose ARDS in patients on NHFT? Because I think this is something that needs to be worked out at more of a definition level. I don’t know if it’s really a question that it makes sense to ask in that regard. I think if we did have a definition of ARDS that you could apply in the setting of NHFT, what we’ve seen is that NHFT works very well in patients with severe hypoxic respiratory failure.

We all saw that during the pandemic. We had patients with coronavirus disease 2019 (COVID-19) with an 80% or 90% fraction of inspired oxygen (FiO₂); really severe. Even if you couldn’t formally diagnose them as ARDS, they would otherwise meet the criteria. What we found is that it [NHFT] seemed to work very well in those patients, especially with adjuncts like awake proning. In fact the randomized trials on awake proning, where the patient lies on their stomach, showed that with the combination of NHFT and awake proning, we could avoid intubating many patients and therefore not needing to put them on a ventilator, which during the high points of the pandemic was actually incredibly helpful.

To summarize, I’d say I don’t know how you diagnose ARDS in patients on NHFT, but I suspect that many patients we treat with NHFT have the same condition, and I suspect that NHFT would be a very helpful treatment, as we saw with COVID-19.