Flush Rate Oxygen as a Makeshift HFNC

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ACEP Now: December 2025 (Digital)

FIGURE 3. Oxygen regulator in our trauma room. Note that the markings on the side stop at 15 liters per minute, but the sticker to the right of the regulator knob indicates a maximum flush rate of 60 to 80 liters per minute. Photo courtesy of Dr. Paul Jansson. (Click to enlarge.)

HFNC requires a dedicated device and typically requires a respiratory therapist for initiation, limiting its use for emergent hypoxemia or in out-of-hospital settings.¹³ If you are waiting for the RT to bring the HFNC, or if you don’t have HFNC at your institution, utilizing flush rate oxygen can approximate the therapy in a pinch. Most wall-mounted regulators have clearly demarcated lines showing the precise amount of oxygen delivered between 0 and 15 liters per minute but are well capable of delivering oxygen past this amount (Figure 3), often up to 60 of 80 liters per minute. At flow rates above 15 LPM, you will not be able to precisely control the flow (nor the FiO₂), but you can deliver more oxygen than typically delivered with conventional therapy and more closely match the minute ventilation of the patient. This can be used as a bridge to intubation or noninvasive ventilation,^14,15 but should not be utilized for long-term use as the equipment is not designed for the high flow of gas that you are putting through it. The lack of warming and humidification can also be irritating to the upper airway mucosa. Be sure to firmly attach the cannula or NRB mask to the regulator, otherwise it will pop off and make a ferocious noise that will terrify everyone in the room.

Paul S. Jansson, MD, MS, is the medical director of the emergency critical care center (EC3), director of operations for the division of critical care, and an assistant professor of emergency medicine and internal medicine at the University of Michigan.

References

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