High flow nasal cannula system or nasal high flow oxygen is an oxygen delivery device which administers heated, humidified high flow oxygen with concentrations from 21% to 100% and with a flow rate up to 60 L/min in adults. It generates many physiologic effects to respiratory system with a lot of clinical applications. Indeed, greater comfort and tolerance, more effective oxygenation, and improved breathing pattern with increased tidal volume and decreased respiratory rate and dyspnea has constantly been detected. Therefore, it can be used to improve cardiogenic pulmonary edema and hypoxemic respiratory failure of any cause, postoperatively, during post-extubation, as well as for palliative car
