Raised intracranial pressure may lead to hypertension. This is part of a cerebroprotective mechanism aiming to maintain cerebral perfusion pressure (CPP) of 60-70 mmHg.

CPP = MAP – ICP (if ICP > JVP)

CPP = MAP – JVP (if ICP < JVP)

MAP - Mean arterial pressure (mmHg)

ICP - Intracranial pressure (mmHg)

JVP - Jugular venous pressure (mmHg)

From this equation, it can be seen that a patient with raised ICP of 20 mmHg, requires a MAP of at least 90 mmHg to achieve CPP of 70 mmHg. In this case, reducing MAP below 90 mmHg will be detrimental.