Acute respiratory failure: nonintubation assist methods for the acutely deteriorating patient

Noninvasive ventilation is strongly recommended in acute hypercapnic respiratory failure, whereas high-flow nasal oxygen therapy could be an alternative in de novo respiratory failure.

High-flow nasal oxygen may improve the outcome of patients de novo respiratory failure as compared with standard oxygen. Its success within 2 h after initiation is well predicted by a ROX index (ratio of SpO2/FiO2 to respiratory rate) greater than 4.88, as failure when less than 3.85 at 12 h after initiation. However, the superiority of high-flow nasal oxygen to standard oxygen has not been confirmed in immunocompromised patients. Although noninvasive ventilation may be deleterious through barotrauma in patients with de novo respiratory failure, its use seems to be an optimal strategy for preoxygenation before intubation in preventing severe hypoxemia in most hypoxemic patients. In mild hypoxemic patient, high-flow nasal oxygen may be more efficient than bag-valve mask in preventing severe adverse events. After anesthetic induction further positive-pressure ventilation can better secure intubation procedure than absence of ventilation.

Despite the growing use of high-flow nasal oxygen, new studies are needed to confirm its superiority to standard oxygen in de novo respiratory failure and others causes of acute respiratory failure in place of standard oxygen.