What CPP level is generally considered adequate to maintain cerebral blood flow?

• A. 30–40 mmHg
• B. 90–100 mmHg
• C. 60–70 mmHg
• D. 40–50 mmHg

Answer: (C)

Cerebral perfusion pressure is the pressure that drives blood flow to the brain, calculated as mean arterial pressure minus intracranial pressure. The brain can auto-regulate blood flow over a range, but when CPP falls too low, brain tissue becomes ischemic; when CPP is kept high without excessive intracranial pressure, perfusion improves but you risk edema if pressures are too high. In most adults, keeping CPP around 60–70 mmHg provides enough gradient to maintain cerebral blood flow while avoiding the risks of markedly high pressures. Values in the 30–40 or 40–50 mmHg range are typically insufficient to guarantee adequate perfusion, while 90–100 mmHg would raise systemic pressures and potentially worsen intracranial dynamics without extra perfusion benefits beyond the 60–70 range.