Mean Arterial Pressure Calculator

Estimates the average blood pressure obtained during one cardiac cycle.

In the text below the calculator there is more information on the formula used, the blood pressure classification and on tissue perfusion.


The mean arterial pressure calculator determines the average blood pressure during one contraction and rest period (in a cardiac cycle) based on systolic and diastolic pressure.

This provides a measure of tissue perfusion and blood flow in the circulatory system.

The accuracy of the estimation depends on the accuracy of the measurement of the two blood pressures.


The mean arterial pressure (MAP) formula accounts for cardiac output (CO), systemic vascular resistance (SVR) and central venous pressure (CVP).

MAP = (CO x SVR) + CVP

However, in practice, because of the two blood pressures being readily available in most charts, the following formula is used:

MAP = DBP + 1/3 PP (where PP = SBP – DBP)

This can also be written as:

MAP = 2/3 DBP + 1.3 SBP


Systolic pressure (SP):*
Diastolic pressure (DP):*
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Steps on how to print your input & results:

1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.


 

Mean Arterial Pressure formulas

As a measure of blood flow and tissue perfusion, the mean arterial pressure can be determined through two different methods.

The first to be described is the one present in the mean arterial pressure calculator, that accounts for two variables, systolic and diastolic blood pressure, where:

■ SBP (normal values 90 – 120 mmHg) is consistent with the forces that sends blood from the ventricle through to the arteries.

■ BDP (normal values 60 – 80 mmHg) is consistent with the blood pressure remaining in the arteries in between heart contractions.

It starts from: MAP = DBP + 1/3 PP (where PP = SBP – DBP).

Given the above it can also be written as: MAP = DBP + 1/3 (SBP – BDP).

This is turn evolves into: MAP = 2/3 DBP + 1/3 SBP.

The second method is more exact but requires laboratory testing in order to obtain the variables. In this case, MAP takes into account cardiac output (CO), systemic vascular resistance (SVR) and central venous pressure (CVP).

Therefore the formula is: MAP = (CO x SVR) + CVP.

 

MAP interpretation

The sum of two thirds DBP and one third SBP are considered to be a better indicator of blood flow than just the SBP because it accounts for the diastole as well. It can help clinicians set targets of blood pressure in order to improve therapy adhesion and outcomes in hypertension, stroke recover or other conditions.

The normal MAP is considered to be between 70 and 110 mmHg. Values above 60 indicate adequate tissue perfusion. In some cases, such as in stroke or sepsis, the threshold for adequate perfusion moves slightly higher, to 65 mmHg.

MAP values below 60 mmHg indicate that tissue perfusion is likely to be impaired and there is risk of ischemia. Some of the ways to address this clinically include hydration or certain medication (vasopressor, inotrope or vasodilator).

There are two minimal accepted blood pressure values to ensure adequate perfusion to the vital organs: systolic BP needs to be higher than 90 mmHg and diastolic BP needs to be higher than 60 mmHg.

Maintaining adequate levels of tissue perfusion is essential in sustaining cellular processes, it basically brings nutrition to the cells through blood and if the blood doesn’t circulate properly, ischemia occurs.

Hypertension, diabetes mellitus, obesity, lack of exercise are amongst the causes of impaired perfusion.

 

Blood pressure classification

The following table compares the systolic and diastolic pressure values with the thresholds for hypotension, normal range and the various degrees of hypertension severity, according to the American Heart Foundation:

Category SBP mmHg DBP mmHg
Hypotension < 90 < 60
Desired 90–119 60–79
Prehypertension 120–139 80–89
Stage 1 hypertension 140–159 90–99
Stage 2 hypertension 160–179 100–109
Hypertensive emergency  >180  >110
Isolated systolic hypertension  >140 < 90
 

References

1. Magder SA. The highs and lows of blood pressure: toward meaningful clinical targets in patients with shock. Crit Care Med. 2014; 42(5): 1241-51.

2. Klabunde R. (2011) Cardiovascular Physiology Concepts 2nd ed. Lippincott Williams & Wilkins.

3. Dillon DJ, Dougan N. Simultaneous measurement of mean arterial pressure with reference to both the phlebostatic axis and middle cranial fossa in the calculation of cerebral perfusion pressure. Br J Anaesth. 2016; 117(2):268-9.


App Version: 1.0.1

Coded By: MDApp

Specialty: Cardiology

System: Cardiovascular

Objective: Determination

Type: Calculator

No. Of Variables: 2

Abbreviation: MAP

Article By: Denise Nedea

Published On: March 15, 2017 · 11:02 AM

Last Checked: March 15, 2017

Next Review: March 9, 2018