11. Cerebral Physiology Flashcards
Dominant Jugular vein
65% Right
Circle of Willis
Anterior circulation from Internal carotids (x2)
Posterior from basilar artery
CSF production and absorption
Produce by choroid plexus. Reabsorbed by arachnoid granules
CSF production 450 ml/ day
CSF volume 150 ml
Cerebral blood flow
50 ml/100mg/min
PO2 in brain veins
40 mmHg
CBF and CMR. Grey vs white matter
Grey matter x 4 vs white
CBF autoregulated from ….
How much time take in case of rapid change in arterial pressure
From 70 - 150 MAP
Takes 3-4 min in case of rapid change (transient decrease in CBF)
Anesthetic drugs that increase CMR
Ketamine NO2
1 degree Celsius change CMR
6 - 7%
Autoregulation MAP and hypocapnia
More influence from Hypocapnia compared to MAP
The limit for an attenuated response of PCO2
25 mmHg
In case of hypotension (<66%) CO2 response
is abolished
In general, a decrease in CO2 affects CBF …
Decreases CBF
Lower limit autoregulation
From 33 as high as 108
In general, a decrease in MAP affects CBV …
Increase CBV to maintain flow
CBF and CBV
They run in parallel
CBV less magnitude in change compared to CBF
Ketamine CBF MAP CMR
Increases all
Drugs that decrease CBF and CMR
Thiopental the most
Prop > Etom > Dex > Fent > Diaz > Morph
Vasodilation potency of vapors
Halo > Enof > Dexf > Isof > Sevo
Scoline valid for RSI in TBI?
Yes. No changes in ICP (1 mg/kg)
What to use to control seizures in status epilepticus?
Iso
Use of mild Hypothermia
32-34, 24 h max
For cardiac arrest. For GCS <7
When restored normotension in patient with cerebral ischemia
ASAP. 70-80 MAP
MAC and CBF / CMR
0.5 Decrease both
1 CBF unchanged. CMR suppression
> 1 Decrease CMR, increase CBF
MAP at CBF 25mg/100ml/min
25 mmHg
CBF for EEG supression
15 ml/100mg/min
CBF thresholds
< 20 Ischemia
< 15 penumbra
6-10 Irreversible damage
Vasopressors and CBF
Nor / Phenylep No changes
Alpha 1 Midodrine increase velocity
Most powerful predictor after ischemia
Glucose levels
How to decrease rebound edema
Loop D (Bumetamide)
