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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

Total Peripheral Resistance (TPR) is represented mathematically by the formula:

R = ΔP/Q^[2]

R is TPR. ΔP is the change in pressure across the systemic circulation from its beginning to its end. Q is the flow through the vasculature (equal to cardiac output)

In other words:

Total Peripheral Resistance = (Mean Arterial Pressure - Mean Venous Pressure) / Cardiac Output

Therefore, Mean arterial pressure can be determined from:^[3]

MAP=(CO\cdot 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 $DP$ :^[4]^[5]^[6]

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 65 and 110 mmHg.^[7] MAP may be used similarly to Systolic blood pressure in^{[clarification needed]} for target blood pressure. Both have been shown advantageous targets for sepsis, trauma, stroke, intracranial bleed, and hypertensive emergencies.^[8]

If the $MAP$ falls below this number for an appreciable time, vital organs will not get enough Oxygen perfusion, and will become hypoxic, a condition called ischemia.

References

^ 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. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
^ Total peripheral resistance, Wikipedia
^ Cardiovascular Physiology Concepts: Mean Arterial Pressure, Richard E. Klabunde, Ph.D
^ Template:GeorgiaPhysiology
^ Cardiovascular Physiology (page 3)
^ http://www.clinicalreview.com Physiology Review
^ impactEDnurse (May 31, 2007). "mean arterial pressure". impactednurse.com. Retrieved 2013-12-12.
^ Magder SA (2014). "The highs and lows of blood pressure: toward meaningful clinical targets in patients with shock". Crit Care Med. 42 (5): 1241–51. PMID 24736333.

External links

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[pmid18451345-1] 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. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)

[2] Total peripheral resistance, Wikipedia

[3] Cardiovascular Physiology Concepts: Mean Arterial Pressure, Richard E. Klabunde, Ph.D

[4] Template:GeorgiaPhysiology

[5] Cardiovascular Physiology (page 3)

[6] ttp://www.clinicalreview.com Physiology Review

[7] tEDnurse (May 31, 2007). "mean arterial pressure". impactednurse.com. Retrieved 2013-12-12.

[8] Magder SA (2014). "The highs and lows of blood pressure: toward meaningful clinical targets in patients with shock". Crit Care Med. 42 (5): 1241–51. PMID 24736333.

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@@ Line 42: / Line 42: @@
 <math>MAP</math> is considered to be the [[perfusion pressure]] seen by [[Organ (anatomy)|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. <math>MAP</math> is normally between 70 and 110 [[mmHg]].<ref>{{cite web | last = impactEDnurse | title = mean arterial pressure | publisher = impactednurse.com   | date = May 31, 2007 | url = https://web.archive.org/web/20131212030722/http://www.impactednurse.com/?p=329 | accessdate = 2013-12-12 }}</ref> MAP may be used similarly to Systolic blood pressure in{{huh?|date=March 2015}} for target blood pressure. Both have been shown advantageous targets for sepsis, trauma, stroke, intracranial bleed, and hypertensive emergencies.<ref>{{cite journal | author=Magder SA | title=The highs and lows of blood pressure: toward meaningful clinical targets in patients with shock. | journal=Crit Care Med.  | year=2014 | volume=42 | issue=5| pages=1241-51| doi= | pmid=24736333}}</ref>
+It is believed that a <math>MAP</math> that is greater than 60 [[mmHg]] is enough to sustain the organs of the average person. <math>MAP</math> is normally between 65 and 110 [[mmHg]].<ref>{{cite web | last = impactEDnurse | title = mean arterial pressure | publisher = impactednurse.com   | date = May 31, 2007 | url = https://web.archive.org/web/20131212030722/http://www.impactednurse.com/?p=329 | accessdate = 2013-12-12 }}</ref> MAP may be used similarly to Systolic blood pressure in{{huh?|date=March 2015}} for target blood pressure. Both have been shown advantageous targets for sepsis, trauma, stroke, intracranial bleed, and hypertensive emergencies.<ref>{{cite journal | author=Magder SA | title=The highs and lows of blood pressure: toward meaningful clinical targets in patients with shock. | journal=Crit Care Med.  | year=2014 | volume=42 | issue=5| pages=1241-51| doi= | pmid=24736333}}</ref>
 If the <math>MAP</math> falls below this number for an appreciable time, vital organs will not get enough Oxygen perfusion, and will become [[Hypoxia_(medical)|hypoxic]], a condition called [[ischemia]].

Revision as of 23:54, 30 August 2015

Calculation

Estimation

Clinical significance

See also

References

External links