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The mean arterial pressure (MAP) is a term used in medicine to describe an average blood pressure in an individual.^{[1]} It is defined as the average arterial pressure during a single cardiac cycle.
Total Peripheral Resistance (TPR) is represented mathematically by the formula:
R = ΔP/QA^{[2]}
R is TPR. ΔP is the change in pressure across the systemic circulation from its beginning to its end. Q is the flow through the vasculature (equal to cardiac output)
In other words:
Total Peripheral Resistance = (Mean Arterial Pressure  Mean Venous Pressure) / Cardiac Output
Therefore, Mean arterial pressure can be determined from:^{[3]}
where:
At normal resting heart rates can be approximated using the more easily measured systolic and diastolic pressures, and :^{[4]}^{[5]}^{[6]}
or equivalently
or equivalently
or equivalently
where is the pulse pressure,
At high heart rates is more closely approximated by the arithmetic mean of systolic and diastolic pressures because of the change in shape of the arterial pressure pulse.
is considered to be the perfusion pressure seen by organs in the body.
It is believed that a that is greater than 60 mmHg is enough to sustain the organs of the average person. is normally between 70 to 110 mmHg^{[7]}
If the falls below this number for an appreciable time, vital organs will not get enough Oxygen perfusion, and will become ischemic.

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