Category: Critical Care
Keywords: acute respiratory failure, hypercapnia, hypercarbia, COPD, AE-COPD, noninvasive ventilation, high flow nasal cannula (PubMed Search)
Posted: 10/7/2025 by Kami Windsor, MD
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Q: Can you use high flow nasal cannula (HFNC) to manage acute hypercapnic respiratory failure?
A: It probably depends.
Background: While we now frequently utilize HFNC as an initial therapy for most acute hypoxic respiratory failure, its appropriateness in managing acute respiratory failure with hypercarbia has historically been opposed. With more recent data indicating that HFNC may be as good as noninvasive ventilation (NIV) for management of hypercapnia as well, this seemed like a good time to point out a few things:
The RENOVATE trial was a larger multicenter randomized noninferiority trial looking at HFNC vs NIV in all-comer acute respiratory failure, summarizing that HFNC was noninferior in the primary composite outcome of death + intubation at 7 days.
BUT this conclusion is not clearly supported in the smaller COPD (or acute cardiogenic pulmonary edema) subgroup:
What does seem to be clear across studies that HFNC has the capacity to clear some CO2 and is by and large better tolerated than facemask NIV.
Bottom Line: For mild-moderate acute COPD exacerbations with patient intolerance or exclusion criteria for NIV therapy, trialing HFNC is a reasonable option. For patients with severe acute or acute on chronic hypercapnia, as indicated by a [pseudo-arbitrary] pH < 7.25 and PaCO2 >70-80, noninvasive ventilation should be your go-to… or be ready to promptly intubate if/when the high flow fails.
