Which formula is used to calculate Cerebral Perfusion Pressure (CPP)?

Cerebral Perfusion Pressure (CPP) is a crucial parameter that reflects the net blood flow to the brain, ensuring it receives adequate oxygen and nutrients. The correct formula to calculate CPP is attained by subtracting Intracranial Pressure (ICP) from Mean Arterial Pressure (MAP).

This is because CPP is directly influenced by the relationship between these two pressures. MAP represents the average blood flow pressure in the arteries, while ICP pertains to the pressure within the skull exerted by brain tissue, blood, and cerebrospinal fluid.

When ICP is elevated, it can compress cerebral blood vessels, hindering blood flow to the brain. Therefore, subtracting ICP from MAP provides a clearer picture of the actual perfusion pressure available to perfuse brain tissues. If the CPP drops too low, it indicates that the brain is not receiving sufficient blood flow, which can lead to ischemia and neurological deficits.

In this context, other formulas, including adding or multiplying MAP and ICP, do not accurately reflect the necessary relationship for assessing perfusion pressures in the brain.