How is mean arterial pressure (MAP) commonly approximated?

• A. MAP ≈ (Systolic − Diastolic)/3
• B. MAP ≈ (Systolic + Diastolic)/3
• C. MAP ≈ (Systolic + 2×Diastolic)/3
• D. MAP ≈ Diastolic

Answer: (C)

Mean arterial pressure is the time-weighted average of arterial pressure over a cardiac cycle, and diastole lasts longer than systole, so diastolic pressure contributes more to that average. The standard practical estimate uses diastolic pressure plus a portion of the pulse pressure (pulse pressure = systolic − diastolic). This gives MAP ≈ Diastolic + (Systolic − Diastolic)/3, which simplifies to MAP ≈ (Systolic + 2 × Diastolic)/3. Equivalently, it’s Diastolic plus one-third of the pulse pressure. This weighting captures the longer diastolic interval and provides a simple, accurate approximation for normal to moderately abnormal pressures. The other forms either ignore the systolic contribution, weight the pressures equally, or only take a third of the pulse pressure without adding the diastolic baseline.