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    MAP
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    MAP

    Mean arterial pressure: formula, normal range, invasive measurement and the 65 mmHg target in shock.

    Mean arterial pressure (MAP) is the average pressure in the arteries over one heart cycle. It is the pressure that actually drives blood into the organs. Because the heart spends about two thirds of each cycle in diastole, MAP is closer to the diastolic than to the systolic value. Many automatic monitors show MAP in brackets. In intensive care it is the main blood-pressure target, because organ perfusion depends on it.

    Blood pressureOrgan perfusionIntensive care
    FormulaDBP + (SBP − DBP) / 3
    Typical healthy adult≈ 70–100 mmHg
    Organ perfusion at risk< 65 mmHg
    Example120/80 → MAP ≈ 93 mmHg
    Mean arterial pressure scale: below 65 organ perfusion at risk, 65 to 70 borderline, 70 to 100 typical, above 100 consistent with hypertension Mean arterial pressure (mmHg) Too low Shock, poor organ perfusion 65 Borderline 65–70 70 Typical ≈ 70–100 100 High Hypertension
    Figure 1. Mean arterial pressure zones. A MAP of at least 65 mmHg is the usual initial target in septic shock.

    How MAP is obtained

    MAP ≈ DBP + (SBP − DBP) / 3

    Oscillometric monitors measure MAP directly as the point of maximum cuff oscillation and then calculate systolic and diastolic values from it. In intensive care, MAP is measured continuously through an arterial catheter, usually in the radial artery. This invasive method is the reference standard for blood-pressure measurement.

    Clinical significance

    Organs such as the brain and kidneys keep their blood flow constant over a wide range of MAP (autoregulation). Below the lower limit, flow falls and organs become ischaemic. In septic shock, international guidelines recommend an initial MAP target of 65 mmHg with fluids and vasopressors. People with long-standing hypertension may need somewhat higher values. A persistently high MAP reflects hypertension and increases cardiovascular risk.

    Seek emergency care

    if low blood pressure comes with confusion, cold clammy skin, rapid pulse, fast breathing, little urine or fainting. These may be signs of shock.

    References

    1. Evans L, Rhodes A, Alhazzani W, et al. Surviving Sepsis Campaign: international guidelines for management of sepsis and septic shock 2021. Crit Care Med. 2021;49(11):e1063–e1143.
    2. McEvoy JW, McCarthy CP, Bruno RM, et al. 2024 ESC Guidelines for the management of elevated blood pressure and hypertension. Eur Heart J. 2024;45(38):3912–4018. doi:10.1093/eurheartj/ehae178

    This article is for general information and does not replace a consultation with a doctor. Measurements must be interpreted by a physician together with symptoms and other tests.

    Published on 11 February 2020