Differential pressure is pulse pressure, and pulse pressure over 100mmHg in the elderly is more dangerous, and the cause needs to be identified in time for systematic treatment. The normal value of pulse pressure difference should be 30~60mmHg, if the pulse pressure difference increases significantly, more than 100mmHg is more dangerous, should be combined with the patient’s own symptoms and signs. It may be caused by hyperthyroidism, aortic valve insufficiency, atherosclerosis and other diseases, which need timely treatment. The cause of a small pulse pressure difference also needs to be identified. Common causes include aortic stenosis, pericardial effusion and severe heart failure. The difference in blood pressure between the upper and lower extremities should not exceed 5-10 mmHg. Multiple aortitis and congenital arteriovenous malformations can cause abnormalities. The difference in blood pressure between the upper and lower extremities should not exceed 20~40mmHg, and aortitis can lead to abnormalities. If you feel unwell, you should consult a doctor and take treatment under the guidance of a doctor.