[High-flow nasal oxygen in acute hypoxemic respiratory failure]. / Oxygénothérapie à haut débit nasal dans l'insuffisance respiratoire aiguë hypoxémique.

Although standard oxygen is the first-line therapy in patients with acute hypoxemic respiratory failure, high-flow nasal oxygen has gained major popularity in ICUs due to its simplicity of application, good comfort for patients, and efficiency in improving oxygenation. Physiological effects of high-flow oxygen therapy can limit the physiological consequences of acute hypoxemic respiratory failure and may mitigate the deleterious effects of high and prolonged inspiratory efforts generated by patients. Although clinical studies have reported a decreased risk of intubation with high-flow oxygen therapy as compared with conventional oxygen therapy, its benefits with regard to survival are uncertain. However, a more precise definition of acute hypoxemic respiratory failure including a classification of severity levels based on oxygenation levels is needed, the objective being to better compare the efficiency of different non-invasive oxygenation supports (conventional oxygen therapy, high-flow oxygen and non-invasive ventilation). Moreover, other clinical trials are needed to confirm the place and the benefit of these oxygenation supports, particularly high-flow nasal oxygen therapy, in acute hypoxemic respiratory failure, especially in the severe forms.

[Use of high-flow nasal oxygen therapy after extubation]. / Place de l'oxygénothérapie à haut débit en post-extubation.

The decision of extubation is difficult in ICUs because in case of reintubation mortality is particularly high. High-flow nasal cannula oxygen therapy (HFNC) and noninvasive ventilation (NIV) are two respiratory supports that help to improve oxygenation, to decrease work of breathing and to decrease the risk of reintubation in selected patients. In the ICU, HFNC seems effective in patient with mild hypoxemia at time of extubation (risk of reintubation<10%) while prophylactic NIV is particularly effective in patients at high-risk of extubation failure (risk of reintubation>20%). Patients older than 65 years, those with underlying chronic cardiac or respiratory disease, or with hypercapnia are patients at high-risk easily identified at time of extubation. The best oxygenation strategy for management of post-extubation respiratory failure is unknown. HFNC has never been assessed in this setting, and NIV may have deleterious effects in patients with post-extubation respiratory failure. In postoperative patients, standard oxygen is sufficient even after major planned surgery (risk of intubation<5%), but should probably be switched to HFNC in patients with hypoxemia (risk of intubation 10-15%) and further to NIV in patients with respiratory failure with hypoxemia and clinical signs of respiratory distress (risk of intubation 50%).