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Cerebral Perfusion Pressure Calculator (CPP = MAP − ICP)

Calculate cerebral perfusion pressure from mean arterial pressure (measured or from systolic and diastolic) and intracranial pressure in mmHg or cmH₂O, against the 60–70 mmHg brain trauma target.

Mean arterial pressure

Systolic blood pressure

Diastolic blood pressure

Measured MAP (if entered directly)

Intracranial pressure (ICP)

ICP unit

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How it works

CPP = MAP − ICP · MAP ≈ DBP + (SBP − DBP) ÷ 3 · ICP in cmH₂O ÷ 1.36 = mmHg. Brain Trauma Foundation (2016): CPP target 60–70 mmHg; treat ICP above 22 mmHg.

Cerebral perfusion pressure is the pressure gradient that drives blood through the brain: mean arterial pressure minus intracranial pressure (or jugular venous pressure if higher). When ICP rises after a head injury, hemorrhage or edema, CPP falls and the brain risks ischemia. The Brain Trauma Foundation guidelines (4th edition, 2016) recommend a CPP target of 60–70 mmHg in severe traumatic brain injury and treating ICP above 22 mmHg; pushing CPP above 70 mmHg with fluids and vasopressors increases the risk of respiratory failure. For accuracy the arterial transducer should be zeroed at the level of the tragus (foramen of Monro) when calculating CPP.

Worked example

A ventilated patient with traumatic brain injury has a blood pressure of 130/70 mmHg and an ICP of 20 mmHg. MAP = 70 + (130 − 70) ÷ 3 = 90 mmHg, so CPP = 90 − 20 = 70 mmHg — within the 60–70 mmHg target, with ICP below the 22 mmHg treatment threshold.

Sources: Carney N et al. Guidelines for the Management of Severe Traumatic Brain Injury, Fourth Edition. Neurosurgery 2017;80:6–15 · Brain Trauma Foundation — TBI guidelines

Frequently asked questions

What is a normal cerebral perfusion pressure?

In healthy adults CPP is roughly 60–80 mmHg. In severe traumatic brain injury the Brain Trauma Foundation target is 60–70 mmHg, and values under 50 mmHg are associated with ischemia.

What is a normal intracranial pressure?

About 5–15 mmHg in adults lying flat. Sustained ICP above 22 mmHg after brain injury is the treatment threshold in the 2016 Brain Trauma Foundation guidelines.

How do I convert ICP from cmH₂O to mmHg?

Divide by about 1.36 (1 mmHg = 1.36 cmH₂O). For example 27 cmH₂O ≈ 20 mmHg. This calculator converts automatically when you choose cmH₂O.

Why not keep CPP as high as possible?

Aggressive attempts to keep CPP above 70 mmHg with fluids and vasopressors increase the risk of acute respiratory distress syndrome without improving outcomes, which is why an upper target exists.

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Clinical decision tool for education and for use by trained clinicians alongside clinical judgement — not a diagnosis and not a substitute for medical assessment. Scores and cut-offs come from the cited validation studies and may not apply to every patient; follow local protocols.