High-Flow Nasal Oxygen Therapy vs Oxygen via a Venturi Mask

Nasal High-Flow Versus Venturi Mask Oxygen Therapy After Extubation. Effects on Oxygenation, Comfort, and Clinical Outcome

Maggiore SM, Idone FA, Vaschetto R, et al
Am J Respir Crit Care Med. 2014;190:282-288

Study Summary

A recent trial published in the American Journal of Respiratory and Critical Care Medicine compared high-flow oxygen (HFO) therapy with oxygen administration via a Venturi mask after extubation. The investigators hypothesized that HFO would improve both the PaO₂ and the PaO₂/FiO₂ ratio.

The trial was randomized, although for obvious reasons it could not be blinded. Their hypothesis was confirmed: PaO₂/FiO₂ was higher at 24, 36, and 48 hours, whereas the PaO₂ was higher at 36 hours. The secondary outcomes were even more impressive. There were fewer changes to noninvasive positive airway pressure ventilation and fewer endotracheal reintubations in the HFO group.

At first glance, it seems difficult to believe that a trial with only 100 patients could show such a dramatic difference in the need for endotracheal reintubation. After all, HFO is generally thought of as oxygen therapy with 2-3 cm H₂O of positive end-expiratory pressure (PEEP) caused by high flow rates. Is it reasonable to expect that a small amount of PEEP could provide this benefit over a Venturi mask? Perhaps the lack of blinding biased the physicians who were caring for the patients?

A closer look at the physiologic response to treatment and the additional benefits from HFO indicate the effect was probably real. HFO reduced the pCO₂ and respiratory rate, and the patients who used it experienced less discomfort from the interface. In a literature review^[1] cited by the authors, HFO has been shown to induce CO₂ washout from the nasopharynx, and the humidification system on the device is far more sophisticated than the standard water reservoirs typically used with a Venturi mask. The combination of increased comfort and reduced CO₂ can lead to a dramatic decrease in work of breathing.

Viewpoint

None of this is novel, of course, but it's nice to see a trial showing real-world application in the intensive care unit. At our hospital, we've gone to this system and anecdotally achieved impressive results -- more so in avoiding intubation than in support after extubation. This trial makes me think that we should expand our use of HFO. It should also remind us that patient comfort, especially in the setting of respiratory instability, is critically important to reducing work of breathing and avoiding failure.

Cite this: Aaron B. Holley. High-Flow Nasal Oxygen Therapy vs Oxygen via a Venturi Mask - Medscape - Sep 18, 2014.

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