cerebral autoregulation
CPP = MAP - ICP
Aim: maintain constant cerebral blood flow match to metabolic demand across a range of blood pressures (50-170 as quoted values from passmed)
normal values
ICP waveform - 3 peaks/trifid:
- arterial pulsation
- intracranial compliance
- aortic valve closure
| Affected by: | Net effect | Mechanism |
|---|---|---|
| PaCO2 | ↑ PaCO2 = vasodilation → ↓ cerebral vascular resistance | ↓ periarteriolar pH → change in NOS activity → ↑ intracellular cGMP production → ↑ intracellular Ca availability |
| PaO2 | ↓ PaO2 → ↑ cerebral flow | ??? |
| K+ | ↑ K+ → ↑ cerebral flow | ??? |
Cerebral blood flow ↑ when metab demand is high