# Mean arterial pressure

In medicine, the mean arterial pressure (MAP) is an average blood pressure in an individual during a single cardiac cycle.[1]

## CalculationEdit

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

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]

${\displaystyle MAP=(CO\cdot SVR)+CVP}$

where:

## EstimationEdit

At normal resting heart rates ${\displaystyle MAP}$  can be approximated using the more easily measured systolic and diastolic pressures, ${\displaystyle SP}$  and ${\displaystyle DP}$ :[4][5][6]

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

or equivalently

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

or equivalently

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

or equivalently

${\displaystyle MAP\simeq DP+{\frac {1}{3}}PP}$

where ${\displaystyle PP}$  is the pulse pressure, ${\displaystyle SP-DP}$

At high heart rates ${\displaystyle MAP}$  is more closely approximated by the arithmetic mean of systolic and diastolic pressures because of the change in shape of the arterial pressure pulse.

For a generalized formula of ${\displaystyle MAP}$ :

${\displaystyle MAP\simeq DP+0.01\times \exp(4.14-40.74/HR)(SP-DP)}$

Where HR is the heart rate.[7]

## Clinical significanceEdit

${\displaystyle MAP}$  is considered to be the perfusion pressure seen by organs in the body.

It is believed that a ${\displaystyle MAP}$  that is greater than 70 mmHg is enough to sustain the organs of the average person. ${\displaystyle MAP}$  is normally between 65 and 110 mmHg.[8] MAP may be used similarly to Systolic blood pressure in monitoring and treating[clarification needed] for target blood pressure. Both have been shown advantageous targets for sepsis, trauma, stroke, intracranial bleed, and hypertensive emergencies.[9]

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

## ReferencesEdit

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.
2. ^ Total peripheral resistance, Wikipedia
3. ^ Cardiovascular Physiology Concepts: Mean Arterial Pressure, Richard E. Klabunde, Ph.D
4. ^ Physiology: 3/3ch7/s3ch7_4 - Essentials of Human Physiology
5. ^ Cardiovascular Physiology (page 3)
6. ^ http://www.clinicalreview.com Physiology Review
7. ^ Moran D, Epstein Y, Keren G, Laor A, Sherez J, Shapiro Y. "Calculation of mean arterial pressure during exercise as a function of heart rate". Appl Human Sci. 14: 293–5. doi:10.2114/ahs.14.293. PMID 8591100.
8. ^ impactEDnurse (May 31, 2007). "mean arterial pressure". impactednurse.com. Archived from the original on December 12, 2013. Retrieved 2013-12-12.
9. ^ 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. doi:10.1097/ccm.0000000000000324. PMID 24736333.