Cerebral perfusion pressure

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Cerebral perfusion pressure (CPP) is the pressure gradient between the systemic blood pressure (MAP) and the intracranial pressure (ICP) . It is expressed by the following equation:

CPP = MAP - ICP

CPP corresponds to the pressure necessary to pump blood from the aorta into the cranial compartment. It demonstrates also that blood flow and perfusion to the brain depends upon adequate blood pressure.

In normal conditions, the systemic blood pressure is much greater than intracranial pressure resulting in an adequate cerebral perfusion pressure (> 60 mmHg) . A decrease in CPP can be a result of:

a drop in MAP (e.g. systemic hypotension)
a rise in the ICP without a compensation in the systemic blood pressure (see more on Monro-Kellie hypothesis): intracranial hypertension