HFNC refers to a high-flow (8-80 L/min) therapy method that can continuously provide patients with adjustable and relatively constant high flow inhalation with oxygen concentration (21%~100%), temperature (31~37 ℃) and humidity. High flow humidified nasal oxygen therapy equipment mainly includes high flow nasal cannula machine, humidification treatment instrument, high-flow nasal congestion and connecting breathing tube. Combining the common domestic and international naming conventions, this consensus adopts "high flow humidified nasal oxygen therapy" or "high flow nasal cannula" for expression, which is abbreviated as HFNC in English.
The history of humans starting oxygen therapy can be traced back to the latter part of the 18th century, and the use of rubber-made nasal catheters for oxygen therapy began in the early 20th century. In 1987, the United States developed the oxygen therapy heating and humidification device MT-1000 with a maximum flow rate of 20 L/min, which was used in oxygen therapy for patients with cystic pulmonary fibrosis to promote the discharge of lower respiratory tract secretions. In the past 10 years, HFNC has entered a stage of rapid development and widespread clinical application. The international mainstream HFNC devices all use the working principle of non-invasive ventilator: air-oxygen mixing is carried out with an air-oxygen mixer, and the inhaled oxygen concentration (FiO2) is 21%~100%. The turbine is used to provide high-flow gas, and the inhaled gas is heated and humidified by the heating humidifier and pipeline heating guide wire used in the ventilator, and the temperature and oxygen concentration are dynamically adjusted by real-time monitoring of the temperature and oxygen concentration near the patient. In addition, some ventilator manufacturers have installed HFNC functions on invasive and non-invasive ventilators, further expanding the scope of clinical application of the ventilator, and this is also the direction of future development. The history of domestic HFNC is only about 5 years. It is innovated on the basis of imitating foreign HFNC in the early stage, forming its own characteristics in a short time, such as automatic adjustment and precise adjustment of FiO2 (21%~100%). The accuracy of temperature control can reach ±1℃, and the breathing circuit adopts disinfection-free air circuit technology.