Neuro - anesthetic implications

Question 1

Average CBF in adults

Answer 1

750 mL/min (15-20% of CO)

Question 2

Rate of CSF production

Answer 2

15-20 mL/hr

Question 3

total volume of CSF in system

Answer 3

150 mL

Question 4

Spinal cord and brain blood supply

Answer 4

often have redundancy

Question 5

Only artery of spinal chord that is not redundant

Answer 5

Artery of Adamkiewicz (Enters SC at T7 and suplies lumbosacral section)

Question 6

SCPP level recomendations

Answer 6

> 40

Question 7

Most important extrinsic factor influencing autoregulation

Key regulator or CBF

Answer 7

PaCO2

Question 8

Intracranial HTN

Answer 8

sustained ICP 20-25 mmHg or higher

*some texts say 15 mmHg

Question 9

Nitrous with neuro?

Answer 9

NO

Question 10

Volatiles and neuro

Answer 10

give 0.5 MAC because all volatiles interfere with autoregulation

Question 11

Ketamine a vasoconstrictor/vasodilator?

Answer 11

vasodilator and should be avoided

Question 12

Circulatory steal phenomenon

Answer 12

arterioles in ischemic areas are maximally dilated and will not respond to vasodilators

so other vessels vasodilate and get blood instead

Question 13

Fluid management: avoid

Answer 13

1. dextrose
2. hespan
3. dextran

use NS

Question 14

What agents are associated with isoelectric EEG changes?

Answer 14

1. propofol
2. isoflurane
3. thiopental

Question 15

Somatasensory evoked potentials (SSEP) monitors

Answer 15

ascending pathway (peripheral to brain)

tells us if there is an intact pathway from peripheral to spinal cord

Question 16

SSEP anesthetic considerations

Answer 16

1. Need goo mAP for good signals
2. 0.5 MAC because SSEP is decreased with volatiles

*communicate what you give because monitoring is happening

Question 17

Motor evoked potentials (MEP)

Answer 17

Monitors descending pathway, represents integrity of autonomic areas of spinal cord

stim applied to different areas, usually with TOF

Question 18

Motor evoked potentials (MEP) anesthetic consideration

Answer 18

1. No muscle relaxant during case
2. affected by hypothermia, hypoxia, hypotension

Question 19

BRainstem auditory evoked potentials (BAEP) does what?

Answer 19

monitor 8th cranial nerve during surgery that puts auditory nerve at risk

Question 20

Visual Evoked Potentials (VEP) does what?

Answer 20

Monitors visual pathways from retina via optic nerve

Question 21

what is the LEAST (barely) sensitive to anesthetics?

Answer 21

BAEP (brainstem auditory evoked potentials)

Question 22

What is the MOST sensitive to anesthetic agents?

Answer 22

VEP (Visual evoked potentials)

Question 23

Sensitivity to anesthetics in orders (evoked potential procedures)

Answer 23

VEP>MEP>SSEP>BAEP

Question 24

Craniotomy induction/intubation consideration

Answer 24

smooth and gentle! Don’t want to stimulate

Question 25

What is very common after craniotomy?

Answer 25

PONV

Question 26

Craniotomy emergence considerations

Answer 26

Smooth wake up (dont want to stimulate) - prevent bucking/coughing want quick emergence for early neuro assessment

Question 27

MAP decreases (positioning)

Answer 27

decreases 0/7mm Hg/cm above heart (or 1.5mm Hg / inch)

Question 28

In sitting procedures, MAP should be at

Answer 28

head level

Question 29

Venous embolism and sitting

Answer 29

20-40% incidence rate do not use nitrous

Question 30

Most sensitive monitor for Venous air embolism

Answer 30

TEE (invasive) pre-cordial doppler (non invasive)

Question 31

Earliest sign of Venous air embolism

Answer 31

Sudden drop in ETCO2 then overall decompensation

Question 32

Main treatment goal of venous air embolism

Answer 32

Stop entrainment of air!

Question 33

Steps in venous air embolism treatment:

Answer 33

1. Notify surgeon, floods field with NS 2. Give 100% O2 3. Place pt in L Lateral position with head down (Durant maneuver) 4. aspirate air from R atrium if you have central line

Question 34

Postoperative vision loss risk

Answer 34

prone spinal surgeries

Question 35

Prevention postoperative visual loss

Answer 35

1. appropriate position 2. avoid eye compression 3. MAP 60-70 to maintain BF to eyeballs

Question 36

Once patient is positioned in sterotactic brain procedure (3D imaging):

Answer 36

do not touch patient

Question 37

Ketamine and surgery to control seizures

Answer 37

avoid - activates seizures

Question 38

The only truly reliable neuro exam for craniotomy is

Answer 38

an awake patient allows for intra op speech, motor and sensory testing

Question 39

Inclusions for awake craniotomy (3):

Answer 39

1. normal airway exm 2. able to lie still for extended period of time 3. cooperative

Question 40

Risk of transphenoidal hypophysectomy procedures

Answer 40

massive hemorrhage (via nose)