High-flow nasal cannula is superior to noninvasive ventilation to prevent reintubation?

In the ICU, when there is a do-not-intubate order, after extubation or lobectomy, during invasive diagnostic procedures such as bronchofibroscopy, and in other clinical situations, non-invasive ventilation (NIV) may be applied to enrich oxygenation before intubation. For acute exacerbation of COPD, acute cardiopulmonary edema, and respiratory failure in immunocompromised patients, NIV is strongly recommended because evidence shows that it reduces the mortality of such critically ill patients. There is no proof, however, that NIV reduces mortality for patients with other diseases. Because it recruits collapsed alveoli, increases end-expiratory lung volume, consequently improving oxygenation and decreasing the risk of lung injury due to atelectrauma, NIV appears to be beneficial. Unfortunately, patient discomfort limits administration of NIV, so it is usually applied for 4–7 hours a day (1). During periods when NIV support is withdrawn, end-expiratory lung volume may decrease and oxygenation might worsen. Such occurrences may explain why NIV fails to prevent re-intubation in patients with some types of respiratory failure. If it could be constantly applied until respiratory failure resolves to the point where support is no longer needed, NIV might be able to improve outcomes for more patients. By contrast, patients are far more tolerant of high-flow nasal cannula (HFNC), which can be applied for longer periods (2).