The size range of central aspiration negative pressure is related to the patient’s condition and age. The negative pressure of aspiration for adults is between 40-53kpa, for children it needs to be between 30-40kpa, and for the elderly it is between 35-45kpa. The negative pressure of aspiration is mainly to protect the trachea and airway mucosa through negative pressure when aspiration is performed on patients, and the pressure should not be too small when central aspiration is performed. The negative pressure of suction should be selected according to the patient’s condition. If the patient is suffering from serious heart disease, the negative pressure of suction should be appropriately reduced to avoid the increase of pressure on the heart caused by suction. If the patient’s condition is mild, the negative pressure of suction can be adjusted up appropriately to clear the airway in time to ensure smooth breathing, and the equipment should be cleaned and disinfected during the process of suction to avoid cross infection.