Mean arterial pressure
The mean arterial pressure (MAP) is a term used in medicine to describe an average blood pressure in an individual.[1] It is defined as the average arterial pressure during a single cardiac cycle.
Calculation
Mean arterial pressure can be determined from:[2]
- <math>MAP = (CO \times SVR) + CVP</math>
where:
- <math>CO</math> is cardiac output
- <math>SVR</math> is systemic vascular resistance
- <math>CVP</math> is central venous pressure and 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>:[3][4][5]
- <math>MAP \simeq DP + \frac{1}{3}(SP - DP)</math>
or equivalently
- <math>MAP \simeq \frac{2}{3}(DP) + \frac{1}{3}(SP)</math>
or equivalently
- <math>MAP \simeq \frac{(2 \times DP) + SP}{3}</math>
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.
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> that is greater than 60 mmHg is enough to sustain the organs of the average person.
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
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- ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
- ↑ Cardiovascular Physiology Concepts: Mean Arterial Pressure, Richard E. Klabunde, Ph.D
- ↑ Physiology at MCG 3/3ch7/s3ch7_4
- ↑ Cardiovascular Physiology (page 3)
- ↑ http://www.clinicalreview.com Physiology Review