Blood Pressure - What is MAP ?

[jmcruz]

Dear Sirs,

My electronic blood pressure measure device, as 4 types of readings: Systolic Pressure (SP), Diastolic Pressure (DP), Pulse Rate and MAP.

The first three I know what they are, but the fourth, MAP, measured in mm Hg, what is it ? – Is it Medium Arterial Pressure ? – If, so, why isn’t it the average of SP and DP ?

What is the importance of this measure and what are the reference values for MAP ? (I read, once, in Internet, that Medium Arterial Pressure above 140 mm Hg was a medical emergency, is it?) – Since limit  values for DP are < 90 mm Hg (reference <= 85 mm Hg) and for SP are < 140 mm Hg (reference <= 130 mm Hg), what are the recommend, limit and risk values for MAP ?

About pulse rate, should values in rest about 80 – 90 bpm could be considered normal for a 36 years old male (1,75 m and 66-67 kg).

Can only anxiety (without physical exercise) raise the pulse up to 120 – 130 bpm ? – And, could these high rates be maintained for a 1 – 6 hours period without serious risks for the heart ?

Best regards,

José Cruz

[CCF-M.D.-CRC]

Dear Jose,
Mean Arterial Pressure (MAP) is the average pressure that occurs over the entire course of the blood pressure cycle and is calculated by (2XSBP + DBP) divided by 3.  This is a measure that takes into account both the peak and valley and is useful in monitoring patinets especially in acute settings.  Its use in long term monitoring is less useful but it should be around 80 mHg.  

Normal pulse is 60 to 100 so 80 to 90 would be in the normal range.  Anxiety does not usually cause resting heart rates in the 130's for a hour or more so I would look for other potential causes such as high thyroid or heart arrhythmias.

[stillkicken]

Could someone please explain how MAP could be calculated by SBP*2+DBP/3 and normal be around 80? since normal BP is supposed to be 120 over 80, that would be a MAP of 106.666...., would that not be considered very high?  I personally have not looked into MAP, but the formula the Dr. gave just made no sence to me.   could someone please elaborate on this matter.

[jmcruz]

Dear friend,

That kind of question is exactly the same that I want to make also to the doctor, but I hadn't yet the opportunity in this forum (always displaying the page that there is no room for further questions in the day). I think that you are absolutely right; or the formula is wrong or the reference values are wrong. Even if the formula was (2DP+SP)/3, a normal pressure of 120/80, would give 93,3 mm Hg and that's not in the 80's range.

[jmcruz]

Look what I find:

MEAN ARTERIAL PRESSURE - The average value for arterial pressure. MAP may be calculated using the following equation: [systolic BP + 2(diastolic BP)] / 3

But, also for this formula, I think 80's range is low

[sherry williams]

The good doctor was not saying that 80 is a normal MAP.  He said 80-90 is a normal pulse rate.  In healthy young persons, 100 to 140 mmHg systolic and 60 to 90 mmHg diastolic is considered a normal B/P.  Abnormal findings: systolic pressure PERSISTENTLY above 140; diastolic pressure above 90.  When either the systolic pressure is 160 or more or the diastolic is 115 or above , the elevation is considered severe.  Blood pressure varies with age, sex, altitude, muscular development, and physical and mental stress.  Mean blood pressure is half of the sum of systolic and diastolic values.  For a normal person in good health is about 100 mmHg

[jmcruz]

I agree with you in what regards to the value of 100 mmHg, but assuming the formula (2DP+SP)/3, as a ponderated mean,and not only the simple arithmetic mean (DP+SP)/2

[jmcruz]

I agree with you in what regards to the value of 100 mmHg, but assuming the formula (2DP+SP)/3, as a ponderated mean,and not only the simple arithmetic mean (DP+SP)/2

[sherry williams]

Mean Arterial Pressure
MAP = (1/3) (SBP - DBP) + DBP

Here is yet another formula I found.

[sherry williams]

Extrinsic influences on arteriole tone maintain mean arterial blood pressure


Extrinsic control of arteriole radius is influenced by neural and hormonal mechanisms, of which activity in the sympathetic nervous systems is the most important. In contrast to localized changes in blood flow caused by intrinsic controls, extrinsic control mechanisms produce widespread changes in arteriolar resistance.


Recall that F = DP / R


This formula can be applied to the entire circulation as for a single vessel, with F being the cardiac output, DP being the mean arterial pressure and R being the total peripheral resistance, most of which is generated in the arteriole system. Thus


Mean arterial pressure = Cardiac output ´ Total peripheral resistance


The total peripheral resistance generated collectively by the arterioles is thus the main factor maintaining mean arterial pressure. In a sense, the arterioles act as a dam, keeping pressure high in the arterial system, so that all tissues can be provided with an adequate blood flow should they demand it.

[sabrina]

My heart races a lot (its gone up to 180 bpm!!) In anxiety, what is the maximum heart that is considered within the normal range for a panic attack?? Can it exceed 140 bpm?? My episodes last for 15mins sometimes to an hour.  Its really scarey! WHat heart arrhythmias could be causing my heart to race so muc, ventricular or atrial?

What is the relationship between a fast heart and BP.   My BP is usually low.  But my heart rate fluctuates a lot and so does my BP! What does this mean??

Thanks,
Sabrina

[Lee534]

I am really confused with this MAP.  Will some Cardiologist please give us, once and for all the right formula.  And then explain what it means.  and what the results should be for a healthy heart and BP?????? lee534

[Joep2]

A related discussion, MAP was started.