Which change would most likely decrease cerebral perfusion pressure?

Which change would most likely decrease cerebral perfusion pressure?

• A. Increase MAP
• B. Decrease ICP
• C. No change
• D. Increase ICP

Answer: (D)

Cerebral perfusion pressure is driven by the pressure gradient that pushes blood into the brain, calculated as CPP = MAP − ICP. Anything that increases intracranial pressure reduces this gradient, so cerebral blood flow and perfusion drop. Increasing ICP, while MAP remains the same, lowers CPP and risks ischemia. In contrast, increasing MAP would raise CPP if ICP stays constant, and decreasing ICP would raise CPP as well. No change keeps the gradient the same. For example, with MAP 90 and ICP 20, CPP is 70; if ICP rises to 50, CPP falls to 40.

Cerebral perfusion pressure is driven by the pressure gradient that pushes blood into the brain, calculated as CPP = MAP − ICP. Anything that increases intracranial pressure reduces this gradient, so cerebral blood flow and perfusion drop. Increasing ICP, while MAP remains the same, lowers CPP and risks ischemia. In contrast, increasing MAP would raise CPP if ICP stays constant, and decreasing ICP would raise CPP as well. No change keeps the gradient the same. For example, with MAP 90 and ICP 20, CPP is 70; if ICP rises to 50, CPP falls to 40.