# Mean arterial pressure

**Mean arterial pressure** is the average value of blood pressure during one heart cycle.

## Calculation of mean arterial pressure[edit | edit source]

The mean arterial pressure value cannot be calculated as the arithmetic mean of the systolic and diastolic pressure values. The main reason for the difficulty of such a calculation is the duration of diastole, which is about twice as long as the duration of systole. For this reason, the mean arterial pressure value is **closer to the diastolic pressure value**.

In **physiological blood pressure **values (120/80 mmHg) the mean arterial pressure value is **93,3 mmHg**.

For an accurate calculation, it would be necessary to know the **detailed course of arterial pressure values** during the entire cardiac cycle. This condition is partially only met during **invasive measurements**. For this reason, relations using the fact that SAT depends significantly on the value of systolic and diastolic pressure are used to estimate mean arterial pressure:

*The mean arterial pressure (SAT) can be calculated as the sum of one-third of the systolic pressure (ST) and two-thirds of the diastolic pressure (DT)*.

*Another calculation for mean arterial pressure is the sum of diastolic pressure (DT) and one-third pulse pressure (PT)*.

*The pulse pressure value can be calculated as the difference between systolic and diastolic pressure.*

In practice, it should be borne in mind that these calculations are **valid** in situations where the pressure curve has a **physiological course**. If blood pressure values are significantly modified by a pathological process (affecting, for example, a vessel wall or blood viscosity), the actual mean arterial pressure value may differ from the value calculated using the above relations.

## References[edit | edit source]

### Related articles[edit | edit source]

### Source[edit | edit source]

- ŠVÍGLEROVÁ, Jitka.
*Střední arteriální tlak*[online]. The last revision 18. 2. 2009, [cit. 12.11.2010]. <https://web.archive.org/web/20160306065550/http://wiki.lfp-studium.cz/index.php/Střední_arteriální_tlak>.

- KITTNAR, Otomar, et al.
*Lékařská fyziologie.*1. edition. Praha : Grada, 2003. 790 pp. ISBN 978-80-247-3068-4.

- TROJAN, Stanislav, et al.
*Lékařská fyziologie.*4. edition. Praha : Grada, 2003. 771 pp. ISBN 80-247-0512-5.