Mean arterial pressure

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The mean arterial pressure (MAP) is a term used in medicine to describe a notional average blood pressure in an individual. It is defined as the average arterial pressure during a single cardiac cycle.

Contents

Calculation

MAP = (CO \times SVR) + CVP, where[1]

CVP is 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:[2][3]

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

or

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

MAP = [(2 x diastolic) + systolic] / 3


or equivalently

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

where PP is the pulse pressure, SPDP

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.

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

References

  1. ^ Cardiovascular Physiology Concepts: Mean Arterial Pressure, Richard E. Klabunde, Ph.D
  2. ^ Physiology at MCG 3/3ch7/s3ch7_4
  3. ^ Cardiovascular Physiology (page 3)

Wikipedia content modification information:

  • This page was last modified on 10 March 2008, at 22:35.

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