Calculate cerebral perfusion pressure with BP 100/70, CVP 20 mm Hg, and ICP 15 mm Hg. CPP is:

Calculate cerebral perfusion pressure with BP 100/70, CVP 20 mm Hg, and ICP 15 mm Hg. CPP is:

• A. 60 mm Hg
• B. 65 mm Hg
• C. 70 mm Hg
• D. 75 mm Hg

Answer: (A)

Cerebral perfusion pressure is the pressure gradient that drives blood flow to the brain. It is calculated as mean arterial pressure minus intracranial pressure (CPP = MAP − ICP). First, turn the blood pressure into MAP. For a BP of 100/70, MAP ≈ (SBP + 2×DBP)/3 = (100 + 2×70)/3 = 240/3 = 80 mm Hg. Then subtract the intracranial pressure: CPP = 80 − 15 = 65 mm Hg. The value 60 mm Hg would result from subtracting central venous pressure (80 − 20), not ICP. The standard CPP calculation uses ICP, so the CPP here is 65 mm Hg.

Cerebral perfusion pressure is the pressure gradient that drives blood flow to the brain. It is calculated as mean arterial pressure minus intracranial pressure (CPP = MAP − ICP).

First, turn the blood pressure into MAP. For a BP of 100/70, MAP ≈ (SBP + 2×DBP)/3 = (100 + 2×70)/3 = 240/3 = 80 mm Hg.

Then subtract the intracranial pressure: CPP = 80 − 15 = 65 mm Hg.

The value 60 mm Hg would result from subtracting central venous pressure (80 − 20), not ICP. The standard CPP calculation uses ICP, so the CPP here is 65 mm Hg.