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]

$MAP = (CO \times SVR) + CVP$

where:

• CO is cardiac output
• SVR is systemic vascular resistance
• CVP is central venous pressure and usually small enough to be neglected in this formula.

Estimation

At normal resting heart rates MAP can be approximated using the more easily measured systolic and diastolic pressures, SP and DP:^[3][4][5]

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

or equivalently

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

or equivalently

$MAP \simeq \frac{(2 \times DP) + SP}{3}$

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 significance

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. MAP is normally between 70 to 110 mmHg^[6]

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.

See also

• Blood pressure
• Hypertension
• Pulse pressure

References

1. ^ Zheng L, Sun Z, Li J, et al. (July 2008). "Pulse pressure and mean arterial pressure in relation to ischemic stroke among patients with uncontrolled hypertension in rural areas of China". Stroke 39 (7): 1932–7. doi:10.1161/STROKEAHA.107.510677. PMID 18451345. http://stroke.ahajournals.org/cgi/pmidlookup?view=long&pmid=18451345. 
2. ^ Cardiovascular Physiology Concepts: Mean Arterial Pressure, Richard E. Klabunde, Ph.D
3. ^ Physiology at MCG 3/3ch7/s3ch7_4
4. ^ Cardiovascular Physiology (page 3)
5. ^ http://www.clinicalreview.com Physiology Review
6. ^ impactEDnurse (May 31, 2007). "mean arterial pressure". impactednurse.com. http://www.impactednurse.com/?p=329. Retrieved 2010-12-25. 

External links

• Mean Arterial Pressure Calculator

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