Mean arterial pressure: Difference between revisions
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Revision as of 17:14, 9 August 2012
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
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
<math>MAP = (CO \times SVR) + CVP</math>, where[1]
- <math>CO</math> is cardiac output
- <math>SVR</math> is systemic vascular resistance
- <math>CVP</math> is central venous pressure
<math>CVP</math> is usually small enough to be neglected in this formula.
Estimation
At normal resting heart rates <math>MAP</math> can be approximated using the more easily measured systolic and diastolic pressures, <math>SP</math> and <math>DP</math>:[2]
- <math>MAP \simeq DP + \frac{1}{3}(SP - DP)</math>
or
- <math>MAP \simeq \frac{2}{3}DP + \frac{1}{3}SP</math>
MAP = [(2 x diastolic) + systolic] / 3
or equivalently
- <math>MAP \simeq DP + \frac{1}{3}PP</math>
where <math>PP</math> is the pulse pressure, <math>SP-DP</math>
At high heart rates <math>MAP</math> is more closely approximated by the arithmetic mean of systolic and diastolic pressures because of the change in shape of the arterial pressure pulse.[3]
Clinical significance
<math>MAP</math> is considered to be the perfusion pressure seen by organs in the body.
It is believed that a <math>MAP</math> of greater than 60 mmHg is enough to sustain the organs of the average person under most conditions.
If the <math>MAP</math> falls significantly below this number for an appreciable time, the end organ will not get enough blood flow, and will become ischemic.
See also
References
de:Mittlerer arterieller Druck