Cerebral blood flow
Some brain-specific figures:
- 1400g by weight
- 15% of cardiac output
- 20% of total basal oxygen consumption
NB:
- Total cardiac output = 5L/min
- Total basal oxygen consumption = 250mL/min
- O2 content of arterial blood = 20mL per 100mL blood
Cerebral blood flow (CBF)
CBF
= 15% of cardiac output
= 750mLs blood/min
= 50-54mLs/min/100g
Thus, O2 flux = 150mL O2/min delivered
Cerebral metabolic rate of oxygen consumption
(i.e. CMRO2)
CMRO2
= 20% of total basal oxygen consumption
= 50 mLs O2/min
= 3-3.5mLs O2/min/100g
NB:
- Grey matter uses 70mLs O2/min
- White matter uses 20mLs O2/min
O2 extraction ratio in brain
= CMRO2/O2 flux
= 50/150
= 33%