Hypotension refers to a state where the systemic arterial pressure is lower than normal. The normal blood pressure has a wide range of variation, and varies greatly with age, physical condition, and environmental factors. Since hypertension often causes damage to important organs such as the heart, brain, and kidneys in clinical practice, it has received much attention. The World Health Organization has also clearly defined the standard for hypertension, but there is currently no unified standard for the diagnosis of hypotension. It is generally believed that an adult's limb arterial blood pressure lower than 12/8 kPa (90/60 mmHg) is hypotension. The vast majority of patients with hypotension (especially those with long-term chronic hypotension related to physical condition or genetics) do not have any discomfort in clinical practice, or only have non-specific symptoms such as dizziness, drowsiness, and fatigue. A small number of people (those with a sharp drop in blood pressure) have clinical symptoms mainly due to insufficient blood supply to the brain, such as dizziness, black eyes, and weak limbs, and may even experience syncope or shock.