Cardiology
Mean Arterial Pressure (MAP)
Average arterial pressure across the cardiac cycle.
Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.
Background
Mean arterial pressure (MAP) is the average pressure in the arteries across a complete cardiac cycle and is a key determinant of organ perfusion. Because diastole occupies a larger proportion of the cardiac cycle than systole, MAP is weighted towards the diastolic pressure rather than being a simple average. It is commonly estimated as (systolic + 2 × diastolic) / 3. MAP is widely used in critical care, anaesthesia and sepsis, where a perfusion target guides resuscitation.
Interpreting the result
A MAP of roughly 65 mmHg or above is a commonly used threshold for adequate organ perfusion in critically ill adults, while a value below this is often taken as a sign of inadequate perfusion that warrants intervention. The 65 mmHg figure is a general target, not an absolute rule: individual patients — for example those with chronic hypertension — may need a higher MAP to perfuse vital organs. MAP reflects perfusion pressure better than systolic pressure alone, particularly in shock states.
Worked example
A patient with a blood pressure of 90/50 mmHg has an estimated MAP of (90 + 2 × 50) / 3 ≈ 63 mmHg. This sits just below the common 65 mmHg target and would prompt review of fluid status and perfusion in a critically ill patient.
Pearls / pitfalls
- The (SBP + 2×DBP)/3 formula is an approximation; invasive arterial monitoring gives a more accurate MAP in unstable patients.
- A "normal" systolic pressure can coexist with a low MAP if the diastolic pressure is low (for example in vasodilatory shock).
- The 65 mmHg target is a starting point — patients with long-standing hypertension may require a higher MAP to maintain organ perfusion.
- MAP is a perfusion-pressure surrogate, not a direct measure of blood flow or tissue oxygen delivery.
Evidence & validation
The MAP target of around 65 mmHg in sepsis resuscitation is supported by randomised trial data and is embedded in the Surviving Sepsis Campaign guidance, with higher individualised targets considered for chronically hypertensive patients.
Frequently asked questions
How is MAP calculated?
A common estimate is MAP ≈ (systolic + 2 × diastolic) / 3. The diastolic value is weighted more heavily because the heart spends more of each cycle in diastole.
What MAP is considered adequate?
A MAP of about 65 mmHg or above is the usual threshold for adequate organ perfusion in critically ill adults. This is a general target rather than a fixed rule.
Why use MAP instead of systolic pressure?
MAP better reflects the pressure driving blood through organs across the whole cardiac cycle. Systolic pressure alone can be misleading, especially in shock.
Does everyone need the same MAP target?
No. The 65 mmHg figure is a default; patients with chronic hypertension may need a higher MAP to perfuse their organs, and targets are individualised.
Is the formula accurate in unstable patients?
It is an approximation. In critically ill or rapidly changing patients, invasive arterial line monitoring provides a more reliable MAP.
References
- DeMers D, Wachs D. Physiology, Mean Arterial Pressure. StatPearls. 2023.
- Evans L, et al. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock. Crit Care Med. 2021.
Related calculators
Need a calculator we don't have — or a custom tool?
We build evidence-led clinical calculators, dashboards and reference tools for teams.