Mean arterial pressure is the average of arterial blood pressure during a cardiac cycle. Mean arterial pressure provides a more accurate picture of the functional status of the heart and blood vessels and is clinically abbreviated as MAP. cardiac cycle refers to the process that the cardiovascular system undergoes from the start of one heartbeat to the start of the next. When the heart is diastolic, the internal pressure decreases and venous blood flows back into the heart, while when the heart is systolic, the internal pressure increases and blood is pumped to the arteries. Each systole and diastole of the heart constitutes a cardiac cycle. The primary clinical significance of mean arterial pressure is to reflect the function of the heart and the resistance of the peripheral arteries. If the mean arterial pressure is too low, it will cause a decrease in blood supply to organs, especially to vital organs such as the brain and heart. If the mean arterial pressure is elevated, it will cause cardiac insufficiency, heart failure, cerebral hemorrhage and other diseases. The normal value of mean arterial pressure in normal adults is between 70-102 mmHg and greater than 60 mmHg to ensure the blood supply to vital organs. Mean arterial pressure is calculated in two ways: (1) systolic pressure plus twice the sum of diastolic pressure divided by three; (2) diastolic pressure plus one-third of the pulse pressure difference (pulse pressure difference = systolic pressure – diastolic pressure). Only a sustained and steady reduction in mean arterial pressure can better prevent target organ damage.