Hazards of intubation in the ICU: role of nasal high flow oxygen therapy for preoxygenation and apneic oxygenation to prevent desaturation.

Acute respiratory failure is one the most common motives for intensive care unit admission. Although results from recent studies with high flow nasal oxygen have challenged our current management of these patients, a substantial number of them will require invasive mechanical ventilation and tracheal intubation. Life-threatening hypoxemia is the most frequent complication of these intubations. Desaturations occur despite properly conducted preoxygenation. Hence, alternatives are warranted to improve oxygenation during intubation. Two phases may be distinguished: the actual preoxygenation period (whilst the patient is still breathing spontaneously) and the laryngoscopy that requires rapid sequence induction. Noninvasive ventilation improves preoxygenation and limits desaturation but oxygen supply is interrupted to allow for laryngoscopy. High flow oxygen is increasingly used to manage patients with hypoxemic acute respiratory failure and can be maintained during the intubation procedure with the advantage of pursuing oxygen supply during patient's apnea, thereby providing apneic oxygenation. Discrepant results on the superiority of high flow oxygen compared to conventional facemask preoxygenation to limit desaturation during intubation highlight key determinants of effective apneic oxygenation: patent upper airway (importance of jaw thrust), and sufficient and constant administration of oxygen (high flows of 60 L/min rather than 15 L/min). Studies comparing high flow oxygen to noninvasive ventilation are ongoing and will help clarify the indications of each technique. This paper aims to show the evidence on the potential high flow nasal oxygen bears to improve preoxygenation for intubation outside the operating room. A practical algorithm to decide which preoxygenation device to use is proposed.