MAP, or mean arterial pressure, is a measurement of the average pressure in the arteries. The calculation to determine a person's MAP is based on blood pressure readings. This number needs to be high enough to supply blood to every capillary of every tissue in the body, a process known as perfusion.
MAP gives a better look at how well the heart can supply blood to bodily tissues. It is also used to calculate blood supply to other parts of the body, like the brain.
Mean arterial pressure is measured on most automatic blood pressure machines used in doctor's offices and hospitals. The machine measure both systolic and diastolic pressures and calculates MAP. Medical staff and laypersons can calculate it on their own as well.
Factors Affecting MAP
MAP has many factors that can affect it, including cardiac output, blood volume and total peripheral resistance. As the blood vessels dilate and constrict, or if they become occluded or partially blocked, blood pressure changes which will, in turn, affect MAP.
To calculate MAP, multiply the diastolic pressure by two and add this to the systolic pressure. Divide your result by three to obtain mean arterial pressure. You could also subtract diastolic from systolic and divide that number by three, then add the diastolic number to it. The reasoning behind giving more weight to the diastolic pressure is that the heart spends more time at rest than it does pumping blood.
Normal MAP Range
In order to perfuse vital organs and supply the body with the blood it needs, MAP should be at least 60. A normal map range is generally between 70 and 110.