Mean arterial pressure

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

Calculation

Mean arterial pressure can be determined from:

<math>MAP = (CO \times SVR) + CVP</math>

where:

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

Estimation

At normal resting heart rates <math>MAP</math> can be approximated using the more easily measured systolic and diastolic pressures, <math>SP</math> and <math>DP</math>:

<math>MAP \simeq DP + \frac{1}{3}(SP - DP)</math>

or equivalently

<math>MAP \simeq \frac{2}{3}(DP) + \frac{1}{3}(SP)</math>

or equivalently

<math>MAP \simeq \frac{(2 \times DP) + SP}{3}</math>

or equivalently

<math>MAP \simeq DP + \frac{1}{3}PP</math>

where <math>PP</math> is the pulse pressure, <math>SP-DP</math>

At high heart rates <math>MAP</math> 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

<math>MAP</math> is considered to be the perfusion pressure seen by 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.

If the <math>MAP</math> 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

de:Mittlerer arterieller Druck sv:Medelartärtryck