Asthma should pay more attention to their lung function status. Acute asthma attacks are possible in environments with excessive allergen exposure, in viral infections, bacterial infections, excessive exercise, etc. Then the usual pulmonary function status of asthma patients is even more important. How to monitor the usual pulmonary function status of asthma patients relies on peak flow rate monitoring. The use of peak flow velocity monitoring has several considerations: 1. At a fixed point in time, because there are differences in lung function at different points in time. 2. Each blow before the marker code to zero, each blow 3 times (in order to avoid errors due to the method of blowing) to record the highest value. 3. blowing, the key is to use the maximum force, the fastest speed, try to blow in the first second 4. recording paper can be more copies before recording, because each instrument in only one record paper, run out of it. 5. Each person’s peak flow rate normal values are different, please contact your doctor before use, so that the doctor to give you your normal value.