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The mean arterial pressure (MAP) is a term used in medicine to describe a notional average blood pressure in an individual. It is defined as the average arterial pressure during a single cardiac cycle.

CalculationEdit

$MAP = (CO \times SVR) + CVP$, where[1]

$CVP$ is usually small enough to be neglected in this formula.

EstimationEdit

At normal resting heart rates $MAP$ can be approximated using the more easily measured systolic and diastolic pressures, $SP$ and $DP$:[2][3]

$MAP \simeq DP + \frac{1}{3}(SP - DP)$

or

$MAP \simeq \frac{2}{3}DP + \frac{1}{3}SP$

MAP = [(2 x diastolic) + systolic] / 3

or equivalently

$MAP \simeq DP + \frac{1}{3}PP$

where $PP$ is the pulse pressure, $SP-DP$

At high heart rates $MAP$ is more closely approximated by the arithmetic mean of systolic and diastolic pressures because of the change in shape of the arterial pressure pulse.

Clinical significanceEdit

$MAP$ is considered to be the perfusion pressure seen by organs in the body.

It is believed that a $MAP$ that is greater than 60 mmHg is enough to sustain the organs of the average person.

If the $MAP$ falls significantly below this number for an appreciable time, the end organ will not get enough blood flow, and will become ischemic.