High-flow nasal cannula (HFNC) was developed to overcome conventional oxygen therapy limitations, allowing the delivery of 100% FiO2 heated and humidified oxygen with a flow up to 80 L/min. Research has been made to upgrade the interface, with the emergence of asymmetric nasal cannulas, to improve dead-space clearance. Main indications for HFNC treatment are acute hypoxemic respiratory failure, hypercapnic respiratory failure, postsurgical respiratory failure, and post-extubation respiratory failure. HFNC was associated with improved oxygenation, decreased need for airway intervention, and reduced procedure interruption in patients undergoing endoscopic procedures.