How this calculator works
The usual bedside approximation subtracts intracranial pressure from mean arterial pressure. A negative calculated CPP is displayed as entered, rather than silently clamped. MAP and ICP must use compatible reference levels. Age-specific targets are deliberately not generated: this arithmetic cannot select adult or paediatric neurocritical care treatment. The result is an estimate for information only and is not medical advice.
Formula
CPP = MAP - ICP; MAP = CPP + ICP; ICP = MAP - CPP. Optional resting MAP ≈ (SBP + 2 DBP)/3.
Worked example
MAP 90 and ICP 15 mmHg give CPP 75 mmHg. A pressure of 120/75 gives estimated MAP 90 and the same CPP.
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Frequently asked questions
Why is there no age selector?
Age affects clinical targets, not this pressure-difference equation. No paediatric target is inferred.
Is estimated MAP interchangeable with invasive MAP?
No. The cuff-pressure approximation may differ from integrated arterial pressure.
Does this account for venous pressure?
No. The usual MAP minus ICP approximation may be inadequate when venous outflow pressure is unusually high.