Final_Brain Flashcards
CPP
= MAP - ICP
Autoregulation
ability of brain to maintain CBF at constant levels despite changes in CPP
When CPP is increased, arterial ____ occurs
constriction
When CPP is decreased, arterial ____ occurs
dilation
rapid lowering of BP in HTN patients can cause
cerebral ischemia
Changes in CMRO2 usually leads to _____
same direction changes in CBF
VA effect on CBF and CMRO2
CBF: dose-dependent increase
CMRO2: decrease
*different from norm “CBF-CMRO2 coupling”
VA effect on ICP: most to least
Increases ICP
Des > Sevo, Iso
VA effect on CBF: most to least
Increases CBF
Des > Sevo > Iso
VA effect on CMRO2: most to least
Decreases CMRO2
Iso > Des/Sevo
How to offset VA effect on CBF?
Arterial hypocapnea helps to minimize increases in CBF
Normal CPP
50-150 mmHg
poor mans way to calculate CPP
substitute ICP for CVP
CPP=MAP-CVP
Brain receives how much cardiac output
15%
or 750 mL/min
CMRO2 of brain
3mL O2/g brain tissue/min
- 50mL/min
- 18-23% of total body O2 consumption
Hypocapnea can effect cerebral blood flow how?
acutely decrease: CBF, CBV, ICP
1 mmHg increase in PaCO2 = ______ CBF
15 mL/min
As _____ returns to normal, hypocapnea is no longer effective at decreasing CBF, CBV, ICP
CSF pH
PaO2 effect on CBF?
Decreased PaO2:
-Increases cerebral vasodilation + CBF
Only effects CBF when PaO2 < 50 mmHg
Nitrous Oxide effect on brain
increases ICP
Ketamine effect on brain
cerebral vasodilator
Propofol effect on brain
cerebral vasoconstrictor
Opioid effects on brain
cerebral vasoconstrictor