Define cerebral perfusion pressure?

  • The net pressure gradient driving blood flow through the cerebral circulation which results in cerebral blood flow
  • It depends upon the mean arterial pressure (MAP), the intracranial pressure (ICP) and the central venous pressure (CVP) – many exclude CVP from the equation as its effects are usually negligible:

CPP = MAP – (ICP + CVP)

  • The normal CPP is 70–80 mmHg
  • A CPP of 30-40 mmHg is the threshold for critical ischaemia