CPP is defined as mean arterial pressure minus the greater of which values?

CPP is defined as mean arterial pressure minus the greater of which values?

• A. ICP
• B. CVP
• C. ICP or CVP
• D. MAP minus both ICP and CVP divided by 2

Answer: (C)

Cerebral perfusion pressure reflects the driving arterial pressure minus the back-pressure that opposes flow into the brain. The outflow/back-pressure is the higher of the intracranial pressure or the central venous pressure because either elevated ICP or elevated CVP will reduce the net gradient more. Therefore CPP is calculated as MAP minus the greater of ICP and CVP. This explains why subtracting only ICP or only CVP can misestimate CPP, and why using the maximum of the two captures the true perfusion pressure. If both are present, you still subtract the larger value because it most limits cerebral blood flow.

Cerebral perfusion pressure reflects the driving arterial pressure minus the back-pressure that opposes flow into the brain. The outflow/back-pressure is the higher of the intracranial pressure or the central venous pressure because either elevated ICP or elevated CVP will reduce the net gradient more. Therefore CPP is calculated as MAP minus the greater of ICP and CVP.

This explains why subtracting only ICP or only CVP can misestimate CPP, and why using the maximum of the two captures the true perfusion pressure. If both are present, you still subtract the larger value because it most limits cerebral blood flow.