ICD-9 / Health Information

Mean arterial pressure

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From Wikipedia, the free encyclopedia

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.

Calculation

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$MAP\; =\; (CO\; \backslash times\; SVR)\; +\; CVP$, whereCardiovascular Physiology Concepts: Mean Arterial Pressure, Richard E. Klabunde, Ph.D

$CO$ is cardiac output

$SVR$ is systemic vascular resistance

$CVP$ is central venous pressure

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

Estimation

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At normal resting heart rates $MAP$ can be approximated using the more easily measured systolic and diastolic pressures, $SP$ and $DP$:http://www.nda.ox.ac.uk/wfsa/html/u10/u1002_03.htm:$MAP\; \backslash simeq\; DP\; +\; \backslash frac\{1\}\{3\}(SP\; -\; DP)$ or:$MAP\; \backslash simeq\; \backslash frac\{2\}\{3\}DP\; +\; \backslash frac\{1\}\{3\}SP$ MAP = x diastolic) + systolic / 3 or equivalently:$MAP\; \backslash simeq\; DP\; +\; \backslash frac\{1\}\{3\}PP$ 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 significance

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$MAP$ is considered to be the perfusion pressure seen by organs in the body. It is believed that a $MAP$ of greater than 60 mmHg is enough to sustain the organs of the average person under most conditions. 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.

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