Library · Physiology
Mean arterial pressure
Make it clearer
Mean arterial pressure, or MAP, is not a separate number from the two you already know: it is the average pressure inside your arteries during one full heartbeat, counting both the part where the heart squeezes and the part where it rests.
Two things influence it. One is cardiac output, which is how much blood the heart pumps each minute. The other is systemic vascular resistance, which is how hard it is for that blood to get through all the arteries in the body. That resistance depends mainly on the radius of the vessels: it is the difference between watering with a wide hose and watering with a narrow one.
In practice it is estimated with a formula, using the blood pressure reading that was already taken: the diastolic pressure plus one third of the pulse pressure, which is the difference between the top number and the bottom one.
It tells you whether blood is really reaching the organs, not just whether it hits a high peak for an instant. When mean arterial pressure drops below 60 millimeters of mercury, that supply is no longer assured.
In brief
Mean arterial pressure is the average blood pressure over one full cardiac cycle, both systole and diastole.
The average of the whole cycle, not the peak.
Two things influence it: cardiac output and systemic vascular resistance.
That resistance depends mainly on the radius of the vessels: if they narrow, it rises.
It is estimated with a formula: the diastolic pressure plus one third of the pulse pressure.
Below 60 mmHg, perfusion of the vital organs is no longer assured.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Mean Arterial Pressure, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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