Mean arterial pressure

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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.

Contents

1 Calculation
2 Estimation
3 Clinical significance
4 See also
5 References
6 External links

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, $SP-DP$

It's slightly less than the value half way between systolic and diastolic pressure because systole is shorter than diastole, so you put the diastole twice

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.

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. http://stroke.ahajournals.org/cgi/pmidlookup?view=long&pmid=18451345.
^ 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
^ 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

Cardiovascular system, physiology: cardiovascular physiology

Heart

Volumes	Stroke volume = End-diastolic volume – End-systolic volume Cardiac output = Heart rate × Stroke volume Afterload · Preload Frank–Starling law of the heart · Cardiac function curve · Venous return curve Aortic valve area calculation · Ejection fraction · Cardiac index

Dimensions	Fractional shortening = (End-diastolic dimension – End-systolic dimension) / End-diastolic dimension

Interaction diagrams	Cardiac cycle · Wiggers diagram · Pressure volume diagram

Tropism	Chronotropic (Heart rate) · Dromotropic (Conduction velocity) · Inotropic (Contractility) · Bathmotropic (Excitability) · Lusitropic (Relaxation)

Conduction system / Cardiac electrophysiology	Cardiac action potential (Atrial action potential, Ventricular action potential) · Effective refractory period · Pacemaker potential · EKG (P wave, PR interval, QRS complex, QT interval, ST segment, T wave, U wave) · Hexaxial reference system

Chamber pressure	Central venous pressure/right atrial pressure → Right ventricular pressure → Pulmonary artery pressure → Pulmonary wedge pressure/left atrial pressure → Left ventricular pressure → Aortic pressure

Other	Ventricular remodeling

Vascular system/
Hemodynamics

Blood flow	Compliance · Vascular resistance (Total peripheral resistance) · Pulse · Perfusion

Blood pressure	Pulse pressure (Systolic - Diastolic) · Mean arterial pressure Jugular venous pressure Portal venous pressure

Regulation of BP	Baroreflex · Kinin–kallikrein system · Renin–angiotensin system · Vasoconstrictors/Vasodilators · Autoregulation (Myogenic mechanism, Tubuloglomerular feedback, Cerebral autoregulation) · Paraganglia (Aortic body, Carotid body, Glomus cell)

M: HRT

anat/phys/devp

noco/cong/tumr, sysi/epon, injr

proc, drug (C1A/1B/1C/1D), blte

M: VAS

anat(a:h/u/t/a/l,v:h/u/t/a/l)/phys/devp/cell/prot

noco/syva/cong/lyvd/tumr, sysi/epon, injr

proc, drug(C2s+n/3/4/5/7/8/9)

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