Small pulse pressure is caused by a decrease in systolic (high) pressure, while hypotension is a general term for lower than normal arterial pressure in the body circulation. Generally speaking, when the brachial blood pressure in adults is measured to be lower than 90/60 mmHg (12.0/0.8 kPa) according to conventional measurement methods, it can be called hypotension. Both symptoms are classified as pathological and physiological in origin. The symptoms often associated with both are also similar (dizziness, nausea, loss of appetite, shock, etc.). Therefore, diagnostic differentiation is required in clinical practice. A small pulse pressure: small pulse pressure is mostly caused by a decrease in systolic blood pressure (high pressure), of which there are physiological factors, but also pathological reasons. Belonging to the former systolic pressure decline is mostly seen in the body wasting or weak, the latter category is seen in shock, myocardial infarction, cardiac insufficiency, pericardial tamponade, hyperalgesia and other diseases. The organic lesions that cause the reduction of pulse pressure difference are also pericardial effusion, constrictive pericarditis, severe mitral stenosis, aortic stenosis. Second, hypotension: 1, physiological hypotension state is part of the healthy population, the blood pressure measurement has reached the standard of hypotension, but no conscious symptoms, after long-term follow-up, in addition to low blood pressure, the human system organs without ischemia and hypoxia and other abnormalities, and does not affect life. 2, pathological hypotension (1) primary hypotension disease: refers to the state of hypotension without obvious causes, such as physiological hypotension (somatic hypotension) and pathological hypotension (hypotensive disease). (2) Secondary hypotension: It refers to the lowering of blood pressure caused by a disease of an organ or system of the body. In most cases, hypotension occurs slowly and can gradually worsen, such as secondary to severe tuberculosis, malignant tumor, malnutrition, cachexia and other causes of hypotension, and its prevention and treatment is mainly for the original cause.