Intro to Neuro Anesthesia PPT

Question 1

How much does the adult brain weigh?

Answer 1

1350gm (2% of tbw)

Question 2

What is CBF? (flow)

Answer 2

45-55 ml/100g/min

Question 3

How do you calculate CBF?

Answer 3

CBF= CPP/CVR

Question 4

How much of your cardiac output goes to the brain?

Answer 4

12-15%

Question 5

what is the CMRO2 of the brain?

Answer 5

3/5ml/100g/min (20% of total O2 consumption)

Question 6

How do you calculate CPP?

Answer 6

CPP=MAP-ICP

Question 7

What is CVR? (flow)

Answer 7

1.5-2.1 mmHg/100g/min/ml

Question 8

How do changes in the CBF change CMRO2?

Answer 8

They are directly coupled.

Question 9

What happens to CMRO2 when you sleep?

Answer 9

it decreases

Question 10

For every 1 degree celsius decrease in body temp below 37 how is CBF effected?

Answer 10

decreases 7%

Question 11

How do volatile anesthetics effect CMRO2?

Answer 11

reduces it

Question 12

Rank different induction medications in order of decreasing CMRO2….

Answer 12

thiopental>etomidate>propofol

Question 13

What MAP is required to maintain CBF?

Answer 13

70-150

Question 14

What is the Myogenic Hypothesis?

Answer 14

transient changes in CBF (3-4 min) due to rapid changes in MAP. Most likely due to direct changes in the tone of the vascular smooth muscle.

Question 15

Neurogenic innervation includes

Answer 15

cholinergic, adrenergic, serotonin, and vasoactive intestinal peptide.

Question 16

Neurogenic influence is greatest on?

Answer 16

large cerebral arteries.

Question 17

How does HCT and viscosity effect CBF?

Answer 17

decreases CBF when HCT is >55%

Question 18

What type of pt are we concerned with high HCT?

Answer 18

smokers

Question 19

In case you didn’t do my Nag questions….

what is an astrocyte?

Answer 19

support, metabolic function, nutritive functions

Question 20

ependymal cells

Answer 20

lines cavities of the CNS and makes up the walls of the ventricles

Question 21

microglia cells

Answer 21

phagocytosis

Question 22

oligodendrocytes

Answer 22

insulation for axons- myelin sheath in brain and spinal cord

Question 23

schwann cells

Answer 23

insulation- myelin sheath in peripheral nervous system

Question 24

Tell me about the BBB

Answer 24

effective isolation for the brain and spinal cord, tight junctions between cells.

Question 25

What portions of the brain are exempt from the BBB?

Answer 25

area postrema, pituitary gland, pineal gland, choroid plexus, and parts of the the hypothalamus

Question 26

VAAs and increased CBF rank em

Answer 26

halothane>>enflurane>desflurane=idoflurane>sevoflurane

Question 27

How does N2O effect the brain?

Answer 27

increases CBF, ICP, and CMRo2

Question 28

How does Ketamine effect PaCO2, CBF and ICP without controlled ventilation?

Answer 28

increased!!!!

Question 29

How do you minimize the effects of ketamine?

Answer 29

give it with another sedative or anesthetics and with controlled ventilation

Question 30

What do benzos and barbs do to CMRO2 and CBF?

Answer 30

reduce them in a dose dependent fashion

Question 31

Do narcs effect CBF and CRMO2?

Answer 31

NOPE

Question 32

Why do NDMR matter for the brain?

Answer 32

only poor effect is from histamine release.

Question 33

What does succs do for the brain?

Answer 33

increases ICP in light pts. increases CBF for cerebral activation from muscle spindle apparatus try and defasiculate if going to RSI

Question 34

4 determinants of CBF

Answer 34

brain (12%), intracellular water (78%), CSF (~75ml), and blood (~50ml). total is 1200-1500ml

Question 35

What is the normal range of ICP?

Answer 35

5-15

Question 36

What is considered intracranial HTN

Answer 36

sustained ICP >15-20

Question 37

What happens when ICP is over 30?

Answer 37

CBF progressively decreases ->ischemia -> cerebral edema -> increased ICP-> CBF decreases-> more ischemia -> more edema..... vicious cycle.

Question 38

In elevated ICP- what happens to the CSF?

Answer 38

CSF volume will decreases- or translocate to the spinal compartment.

Question 39

What are some signs of ICP?

Answer 39

``` NV HTN Bradycardia Personality changes Altered LOC Altered patterns of breathing Papilledema ```