Beneficial effects of the HFNC system have been assessed based on 3 physiologic conditions: decreased dead space, a high concentration of inspiratory oxygen, and positive pressure in the oro-laryngeal cavity.Studies have shown that it improves oxygenation in various perioperative settings such as the apneic patients, patients with respiratory failure , and patients undergoing bronchoscopy
High-flow nasal cannula (HFNC) is a device that delivers10 to 70 L min-1 of heated, humidified 100% oxygen via nasal route. It provides positive airway pressure, decreases dyspnea, decreases the work of breathing, and improves comfort