Mean arterial pressure

From Wikipedia, the free encyclopedia
  (Redirected from Mean Arterial Pressure)
Jump to: navigation, search

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.

Calculation[edit]

Total Peripheral Resistance (TPR) is represented mathematically by the formula:

R = ΔP/Q[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]

MAP = (CO \cdot SVR) + CVP

where:

Estimation[edit]

At normal resting heart rates MAP can be approximated using the more easily measured systolic and diastolic pressures, SP and DP:[4][5][6]

MAP \simeq DP + \frac{1}{3}(SP - DP)

or equivalently

MAP \simeq \frac{2}{3}(DP) + \frac{1}{3}(SP)

or equivalently

MAP \simeq \frac{(2 \times DP) + SP}{3}

or equivalently

MAP \simeq DP + \frac{1}{3}PP

where PP is the pulse pressure, SP-DP

At high heart rates MAP is more closely approximated by the arithmetic mean of systolic and diastolic pressures because of the change in shape of the arterial pressure pulse.

Clinical significance[edit]

MAP is considered to be the perfusion pressure seen by organs in the body.

It is believed that a MAP that is greater than 60 mmHg is enough to sustain the organs of the average person. MAP is normally between 70 to 110 mmHg[7]

If the MAP falls below this number for an appreciable time, vital organs will not get enough Oxygen perfusion, and will become hypoxic, a condition called ischemia.

See also[edit]

References[edit]

External links[edit]