Đo huyết áp. Hãy lưu lại chỉ số tâm thu và tâm trương. Hiệu áp là chênh lệch giữa chỉ số tâm thu và tâm trương.

I'm interested in that, but I only have a few mins. Can you give me at most the first 500 characters of a detailed explanation in English about that?
Taking a traditional blood pressure measurement with a blood pressure cuff, stethoscope, and analog sphygmomanometer can take some practice and requires instruction and experience. Some people visit automated machines at their local pharmacy in order to get their blood pressure taken.  It can be quite difficult to take your own blood pressure if you are using the traditional method. If possible, get a someone to help and take your blood pressure for you. When purchasing an at-home blood pressure