Mean arterial pressure (MAP) is the average pressure that pushes blood through your arteries over one heartbeat. Doctors use it, more than the blood pressure reading alone, to judge whether the organs are being perfused. This calculator gives the MAP, the pulse pressure, its share of the systolic value and, if you add cardiac output, the systemic vascular resistance.
How the calculation works
- Pulse pressure = systolic − diastolic
- MAP = diastolic + (systolic − diastolic) ÷ 3
- Pulse pressure share = pulse pressure ÷ systolic × 100
- Systemic vascular resistance = 80 × (MAP − central venous pressure) ÷ cardiac output
Example
A blood pressure of 120/80 mmHg gives a pulse pressure of 40 mmHg and a MAP of 93 mmHg, in the normal range. The pulse pressure is 33 % of the systolic value. With a central venous pressure of 5 mmHg and a cardiac output of 5 L/min, the resistance is 80 × 88.3 ÷ 5 = 1,413 dyn·s/cm⁵, a little above the usual 800 to 1,200.
Why it matters
MAP is the number that tells clinicians whether blood flow to the brain and kidneys is secure, which is why it is a target in sepsis and shock. For people at home, a rising pulse pressure over the years is a hint of arterial stiffness worth discussing with a doctor.
Good to know
This calculator is for general information and does not diagnose anything. Home readings vary with posture, stress, caffeine and cuff size. Resistance needs a measured cardiac output, normally from a hospital monitor. Ask a clinician to interpret any reading that worries you. A single measurement is a snapshot: blood pressure changes through the day, so several readings taken at rest, at the same time of day, give a better picture than one. Seek urgent help for a very low reading with dizziness, confusion or fainting.
Related tools
The cerebral perfusion pressure calculator subtracts intracranial pressure from the MAP, the cardiac output calculator gives the flow figure, and the shock index calculator compares heart rate with systolic pressure.