The expiratory test is an examination method that performs respiratory muscle tone, expiratory flow rate, and repetitive breathing test and determines whether there is a respiratory system pathology based on the test results. It is also an important diagnostic basis for examining laryngeal muscle weakness. To check the spirometer, inject 1000 ml of air into the gelatinous air sac. turn the three-way switch and close the air sac so that the gelatinous interface is connected to the atmosphere. The subject is instructed to hold the gelatinous interface in the mouth, wear a nasal clip, switch to mouth breathing, and then do up and down exercises on a 25 cm high stool for 1 min (about 30 times each up and down). Examination process: 1. Subjects rested for 10 min before the test, and the test requirements were explained to them to obtain cooperation. Check and prepare the instruments and equipment for the test. 2.Check the spirometer and inject 1000ml of air into the gum air sac. turn the three-way switch and close the air sac so that the gum interface is connected to the atmosphere. The subject was instructed to mouth the gelatin interface, wear a nasal clip, switch to mouth breathing, and then do up and down exercise on a 25cm high stool for 1min (about 30 times each up and down). 3. When the exercise is finished, quickly turn the three-way switch after exhalation, so that the gum interface and the gel airbag are connected, and the subject breathes the air stored in the airbag for 20s, and finally does a big exhalation. Immediately turn the three-way switch to close the airbag access. 4. Take a sample from the gelatinous airbag and analyze it to determine the percentage of oxygen and carbon dioxide volume in the airbag. Measurement of respiratory muscle tone: Have the patient perform a forceful inhalation and exhalation using a pressure gauge. This test has a predictive value for the ability of mechanically ventilated patients to get off the machine. Expiratory flow rate measurement: The highest expiratory flow rate that can be achieved in the first 10 milliseconds after the subject inhales forcefully to the total lung volume and then does a maximal exhalation. The expiratory flow rate of both normal and asthmatic patients has a diurnal cycle, with the lowest value in the morning and the highest value in the afternoon, but the variation in normal subjects is small, and the fluctuation rate of expiratory flow rate is less than 10%; while the fluctuation rate of expiratory flow rate of asthmatic patients is more than 20%-30% or even 50%. Therefore, the measured expiratory flow rate of many patients is always higher or lower than the predicted value, with a range of deviations or variations from person to person, so it is recommended that the expiratory flow rate value used to evaluate treatment should be the patient’s personal best value. A consistent expiratory flow rate of 80% or more of the personal best value indicates good asthma control.