Characteristics of High Flow Nasal Cannula

Some people may have heard that High Flow Nasal Cannula oxygen therapy (HFNC) is useful, but they don't really understand it very well. As a professional manufacturer of medical equipment, Pigeon Medical will introduce the characteristics of HFNC to you.

1. Positive end expiratory pressure (PEEP) effect of HFNC

High Flow Nasal Cannula can maintain a certain level of PEEP and keep the alveoli open by delivering high-velocity gas, which is conducive to end-expiratory alveolar recruitment and gas-blood exchange. For patients with chronic obstructive airway disease, positive end-expiratory pressure helps to open the trapped small airways, which can improve the symptoms of carbon dioxide retention to a certain extent. However, it should be noted that the ventilation effect of HFNC requires the patient to close the mouth and perform nasal inhalation to ensure that the patient's mouth breathing will inevitably lead to unstable PEEP levels.

As the flow rate increases, the end-expiratory lung volume also increases, which means that the higher the flow rate, the greater the positive end-expiratory pressure generated. Studies have found that for every 10 L/min increase in flow rate, the positive end-expiratory pressure increases by 0.5-1 cmH₂O.

2. Physiological dead space erosion effect of HFNC

HFNC provides the patient with a constant and adjustable high-flow air-oxygen mixture to flush out the gas remaining in the anatomical void of the nasal cavity, oral cavity and pharynx at the end of the patient's expiration, which can significantly reduce the CO₂ content inhaled by the patient during the next inhalation. Secondly, the gas can be as high as 80L/min, which can meet the peak inspiratory flow rate required by the shortness of breath patient, and effectively relieve the symptoms of shortness of breath and breathing effort.

The higher the flow rate of the high-flow oxygen therapy setting, the better the flushing effect on the anatomical dead space.

3. HFNC can maintain the function of the mucociliary removal system

Compared with ordinary oxygen therapy, the use of HFNC machine can significantly reduce the dryness score of the patient's nose, mouth, and throat, help dilute sputum and expectoration, repair and maintain the structure and function of human respiratory epithelial cells and cilia, and improve patient comfort and reduce the incidence of lower respiratory tract infections.

As shown in the picture, the left picture shows the normal mucus-ciliary system under the electron microscope. (The transnasal high-flow oxygen therapy instrument comfortably delivers high-flow oxygen with the best humidity, so that the mucus-ciliary cleansing function is in the best state and maintains the sputum mobility, allowing sputum to be transported upwards and out of the airway, reducing the risk of respiratory infections.) The right picture shows the airway mucosa damaged by dry and cold gas.