Differential pressure is the difference between systolic and diastolic blood pressure, also known as pulse pressure; normal people’s right and left upper extremity blood pressure can have a difference of 5-10mmhg, lower extremity blood pressure is higher than the upper extremity of 20-40mmhg; a cardiac cycle, the average of each instantaneous arterial blood pressure, known as the mean arterial pressure; a rough estimate of the diastolic blood pressure plus 1/arterial pressure for the average arterial pressure. Increased pulse pressure (>40 mmhg) is seen in aortic valve closure insufficiency, hyperthyroidism, and aortic atherosclerosis in the elderly. Decreased pulse pressure (<30mmhg) is seen in aortic stenosis, heart failure, hypotension or shock, pericardial effusion, constrictive pericarditis, etc. The difference of blood pressure between upper limbs is more than 10mmhg, which is seen in multiple aortitis, thromboembolic vasculitis, congenital arterial malformation, etc. If the blood pressure of lower limbs is lower than that of upper limbs, it suggests that the arteries in the corresponding parts are narrowed or occluded, which is seen in aortic stenosis, occlusive arteriosclerosis, thoracic and abdominal aorta-type aortitis. If you feel unwell, you should go to the hospital in time and consult your physician for guidance.