Understanding Mean Arterial Pressure (MAP)

Wondering what mean arterial pressure (MAP) means? Have a good read to know about it, the issues that may be attached to it and the possible ways that can help you out!

Quick Summary

• Mean arterial pressure, often known as MAP, is generally calculated with respect to diastolic and systolic blood pressure.
• The measurements can also be taken with the help of a sphygmomanometer, oscillometric BP machine, or echocardiography.
• An increase or decrease in the MAP can indicate an underlying disease that should be treated immediately.

If you are suffering from blood pressure-related problems, you must have heard the term “mean arterial pressure”.

Usually, BP readings are taken with the help of a sphygmomanometer which indicates various measurements. These results are in the form of diastolic, systolic and mean arterial pressure.

The MAP, or mean arterial pressure, induces various effects on the body when it rises or falls too low. To know more about this blood pressure condition, read on!

MAP Or Mean Arterial Pressure

In the case of an automatic blood pressure monitor, one may notice systolic and diastolic blood pressure readings. Some of these readings include a number written in parentheses below or beside the standard blood pressure reading. This number that is written in parenthesis is referred to as the mean arterial pressure.

This MAP is the average arterial pressure during one cardiac cycle and is varied by the output and VSR or systematic vascular resistance.

This resistance is the width of a blood vessel that impacts the flow of the blood. It is generally harder for the blood to flow via a narrow artery. With the increase in the resistance in arteries, the BP also increases, whereas the flow of blood decreases.

How Is MAP Calculated?

MAP can be measured using a basic formula,

MAP= DP+ ⅓ (SP-DP),

Or MAP= DP + ⅓ (PP).

Here, DP indicates the diastolic blood pressure, SP indicates the systolic blood pressure, and PP indicates the pulse pressure.

This is the quickest means of calculating mean arterial pressure and is used in various clinical settings.

The basic step to measure blood pressure is by using a sphygmomanometer and then analysing it using a chart. After knowing these values, MAP can be calculated easily.

Another way to measure this is by using an oscillometric BP machine or echocardiography. Using echocardiography, one can evaluate the myocardium function and analyse the ejection fraction of left ventricular and cardiac output.

A new method for calculating the MAP from central aorta pressure has also been introduced. According to this,

MAP= DP+ [0.33 + (HR x 0.0012)] x [PP]

Here, HR stands for heart rate. This formula is in validation with the previous formula.

What Is The General MAP Range?

Generally, a human body needs a minimum of 60 mm Hg (or greater) to ensure that there is enough blood supply. Anything between 70 to 100 mm Hg is considered a normal MAP range.

A high MAP is defined as a reading greater than 100 mm Hg, indicating that there is excessive pressure in the arteries. This increased pressure can eventually result in blood clots or heart muscle damage, increasing the heart load.

How Can Increased MAP Affect The Body?

If the MAP is too high, it can lead to stress on the heart. This happens as it would need to work harder than regular to push against the pressure in the blood that is already elevated. This condition can lead to advanced heart disease, heart attack, blood clots and stroke.

If this elevation continues, the heart muscles enlarge and, in turn, decrease life expectancy.

How Can Low MAP Affect The Body?

A low map is defined as a reading under 60 mm Hg and can be life-threatening. In such conditions, the vital organs lack the nutrition they need for survival. This leads to shock and stress on the organs, cell deaths and damaged organ issues.

A low mean arterial pressure is a result of stroke, sepsis, trauma, or haemorrhage.

What Are The Factors That Affect MAP?

MAP is directly affected by the following factors:

• Heart rate,
• Blood pressure,
• Resistance to blood flow of the vessels,
• Cardiac output.

How To Manage Mean Arterial Pressure?

The arterial blood pressure is regulated by endocrine and neural mechanisms. It is further augmented by the exchange that takes place between the body’s fluid and vascular spaces. SNS controls neural functions with a minor role played by PNS that controls heart rate and local vascular beds.

An unusual MAP needs to be treated to solve the underlying problems in the body. The treatment of this condition depends upon the cause.

In the case of a low MAP, the treatment focuses on safely raising the blood pressure so that no organ damage takes place.

• Intravenous fluids or transfusion of blood is done to increase the blood flow.
• Vasopressors are used to tighten the blood vessels. These can increase the BP and allows the heart to beat or pump faster.

High MAP needs treatments that can help to lower overall blood pressure. This can be done using intravenous or oral nitroglycerin. These medications help to relax and widen the blood vessels, which also makes it easier for blood to reach the heart. 

Once this condition is under control, a doctor can continue to treat the underlying causes, which may involve:

• Causing breaks in stroke-causing blood clots.
• Adding stent into the coronary artery to allow it to stay open.

Conclusion

The mean arterial pressure is generally ignored by people when taking blood pressure readings. It is to be noted that this MAP reading is as important as the systolic or diastolic BP readings.

Any change in the MAP can indicate an underlying disease or problem. If not treated on time, these changes in the long can lead to severe cardiovascular problems.

Remember to contact a doctor if too high or low readings are observed.