Non-invasive ventilation or high-flow oxygen therapy: When to choose one over the other?

It has been found that high-flow oxygen therapy (HFOT) can reduce mortality of patients admitted to intensive care unit (ICU) for de novo acute respiratory failure (ARF) as compared to non-invasive ventilation (NIV). HFOT might therefore be considered as a first-line strategy of oxygenation in these patients. The beneficial effects of HFOT may be explained by its good tolerance and by physiological characteristics including delivery of high FiO₂ , positive end expiratory pressure (PEEP) effect and continuous dead space washout contributing to decreased work of breathing. In contrast, NIV should be used cautiously in patients with de novo ARF due to high tidal volumes promoted by pressure support and that may potentially worsen pre-existing lung injury. Although recent studies have reported no benefit and even deleterious effects of NIV in immunocompromised patients with ARF, the experts have recommended its use as a first-line strategy. In patients with acute-on-chronic respiratory failure and respiratory acidosis, it has been clearly shown that NIV is the best strategy of oxygenation. However, HFOT seems able to reverse respiratory acidosis and further studies are needed to evaluate whether HFOT could represent an alternative to standard oxygen. Although NIV is recommended to treat ARF in post-operative patients or to prevent post-extubation respiratory failure in ICU, recent large-scale randomized studies suggest that HFOT could be equivalent to NIV. While recent recommendations have been established from studies comparing NIV with standard oxygen, new studies are needed to compare NIV versus HFOT in order to better define the appropriate indications for both treatments.