Mean arterial pressure can be estimated using which of the following formulations?

• A. MAP equals pulse pressure.
• B. MAP equals heart rate times SV.
• C. MAP is the average arterial pressure across the cycle and can be estimated as diastolic pressure plus one-third pulse pressure.
• D. MAP equals systolic minus diastolic.

Answer: (C)

Mean arterial pressure is the average pressure in the arteries over a full cardiac cycle, and it isn’t just the midpoint between systolic and diastolic pressures because the heart spends more time in diastole than in systole. A practical and widely used estimate is diastolic pressure plus one-third of the pulse pressure (where pulse pressure is the difference between systolic and diastolic pressures). This weighting reflects the longer diastolic interval, so the average pressure sits closer to diastolic pressure while still accounting for the systolic rise. For example, if SBP is 120 and DBP is 80, the pulse pressure is 40, and the MAP ≈ 80 + 40/3 ≈ 93 mmHg. The other formulations describe different quantities: pulse pressure alone, cardiac output (heart rate × stroke volume), or systolic minus diastolic, none of which equal MAP.