What is Mean Arterial Pressure?

Mean Arterial Pressure (MAP) is a measure of the average blood pressure in the arteries during a single cardiac cycle. It represents the driving force that pushes blood through the circulatory system, delivering oxygen and nutrients to the body’s tissues.

Blood pressure consists of two main components: systolic pressure and diastolic pressure. Systolic pressure is the higher number and represents the pressure in the arteries when the heart contracts and pumps blood into the circulatory system. Diastolic pressure is the lower number and represents the pressure in the arteries when the heart is at rest between beats.

MAP is calculated by taking into account both systolic and diastolic pressures, recognizing that the heart spends more time in diastole than in systole. The formula for calculating MAP is:

MAP = diastolic pressure + 1/3 (systolic pressure – diastolic pressure)

The 1/3 factor represents the approximate time ratio spent in systole compared to diastole.

Why is MAP important? MAP is a crucial indicator of tissue perfusion, which refers to the delivery of blood to organs and tissues. It is especially important in ensuring an adequate blood supply to vital organs like the brain, heart, and kidneys. A MAP below normal levels can lead to inadequate tissue perfusion and may result in organ damage or dysfunction. On the other hand, high MAP can strain blood vessels and contribute to conditions such as hypertension and cardiovascular diseases.

Healthcare professionals often monitor MAP in critical care settings and during anesthesia to assess a patient’s cardiovascular status and ensure proper tissue perfusion.