Mod IX: General Effects of Anesthesia on the Brain + Clinical Therapies in Neuroanesthesia

Question 1

_{Effects of Anesthesia on the Brain - Generalizations}

How do Inhalation agents affect CBF and ICP?

Answer 1

Inhalation agents have a direct vasodilatory effects

→ ↑CBF which could lead to ↑ICP

Desflurane > Isoflurane > Sevoflurane

May negate impact of ↑ in CBF by hyperventilation

Question 2

_{Effects of Anesthesia on the Brain - Generalizations}

What’s inhalation agents order of decreasing vasodilatory effect on the brain? How can this effect ne negated?

Answer 2

Desflurane > Isoflurane > Sevoflurane

May negate impact of ↑ in CBF by hyperventilation

Question 3

_{Effects of Anesthesia on the Brain - Generalizations}

Why do inhalation agents ↓CMRO2?

Answer 3

They put the barin to sleep

Question 4

_{Effects of Anesthesia on the Brain - Generalizations}

What’s the effect of combning N2O with inhalation agents CBF, CMRO2, and ICP?

Answer 4

N2O when combined with inhalation agents ↑CBF, ↑CMRO2, ↑ICP

Used, but use with caution

Question 5

_{Effects of Anesthesia on the Brain - Generalizations}

How do Commonly used IV anesthetics affect CBF & CMRO2? What the exception to this rule?

Answer 5

Commonly used IV anesthetics ↓CMRO2 & ↓CBF

with the exception of Ketamine

Ketamine ↑CMRO2 & ↑CBF

Question 6

_{Effects of Anesthesia on the Brain - Generalizations}

Why are Cerebral effects of Muscle relaxants only secondary?

Answer 6

Muscle relaxants Do not cross the BBB

Cerebral effects are secondary

Question 7

_{Effects of Anesthesia on the Brain - Generalizations}

What were some negative effect of Atracurium that may be the reason why it’s no longer used?

Answer 7

Laudanosine a metabolite of Hoffmann elimination has caused seizures in lab animals

Has histamine release

Question 8

_{Effects of Anesthesia on the Brain - Generalizations}

What was a negative effect of Mivacurium (no longer used) when given rapidly IV push?

Answer 8

Has histamine release

Question 9

_{Effects of Anesthesia on the Brain - Generalizations}

How does Pancuronium affect CBF and ICP?

Answer 9

Can get ↑HR & BP → ↑CBF → ↑ICP

Question 10

_{Effects of Anesthesia on the Brain - Generalizations}

↑ CBF associated with ↑ICP after administration of Succinylcholine is secondary to:

Answer 10

Fasciculations

Question 11

_{Effects of Anesthesia on the Brain - Generalizations}

↑ CBF associated with ↑ICP after administration of Succinylcholine can be attenuated with

Answer 11

Pretreatment with nondepolarizing muscle relaxant

Question 12

_{Effects of Anesthesia on the Brain - Generalizations}

Despite ↑ CBF associated with ↑ICP after administration of Succinylcholine, why is it still the drug of choice for RSI?

Answer 12

↑ICP is modest & transient and

May be out weighed by need for rapid sequence intubation

Question 13

_{Effects of Anesthesia on the Brain - Generalizations}

Chart showing How common anesthetic agents affect CBF, CMRO2 and Direct Cerebral Vasodilation

Answer 13

_{Chart showing How common anesthetic agents affect CBF, CMRO2 and Direct Cerebral Vasodilation}

[No need to memorise]

Question 14

_{Clinical Therapies in Neuroanesthesia - Hypothermia}

What % of CMRO2 is decreased for each 1 degree Celsius decrease in temperature?

Answer 14

CMRO2↓ 7% for each degree ↓Celsius

Question 15

_{Clinical Therapies in Neuroanesthesia - Hypothermia}

Why is Mild hypothermia Not beneficial?

Answer 15

Higher incidence of bacteremia in hypothermic group

Question 16

_{Clinical Therapies in Neuroanesthesia - Hypothermia}

Why must hyperthermia be Avoided?

Answer 16

Increases CMRO2

Question 17

_{Clinical Therapies in Neuroanesthesia - Hyperglycemia}

What’s the Hypothesis regarding hyperglycemia?

Answer 17

The Hypothesis is that ↑ glucose results in ↑lactic acid production during ischemia

Question 18

_{Clinical Therapies in Neuroanesthesia - Hyperglycemia}

What solution must be used to treat hypoglycemia (<60 mg/dl)?

Answer 18

Dextrose solutions

Use dextrose solutions to treat hypoglycemia (<60 mg/dl)

Question 19

_{Clinical Therapies in Neuroanesthesia - Hyperglycemia}

Treat hyperglycemia (>150 mg/dl) with:

Answer 19

Insulin

Question 20

_{Clinical Therapies in Neuroanesthesia}

Why must hypotension, hypoxia, and hypercapnia be avoided in neuro anesthesia?

Answer 20

Hypotension can be detrimental due to ↓CPP

Question 21

_{Clinical Therapies in Neuroanesthesia - Hemodilution}

How would decreasing Hematocrit from 34% to 32% ↑CBF?

Answer 21

by decreasing blood viscosity →improved O2 delivery

Have not seen personally (on purpose anyway)

Question 22

_{Clinical Therapies in Neuroanesthesia}

Which methods could be used for Normalization of ↑ICP?

Answer 22

Hyperventilate to PaCO2 of 30 to 35 mmHg

(Careful with TBI)

↑HOB 300

Mannitol, Lasix

CSF drainage via ventriculostomy

Question 23

_{Clinical Therapies in Neuroanesthesia - Pharmacologic agents}

What are the only drugs shown to be effective for pharmacologic cerebral protection against ischemic damage in humans?

Answer 23

Barbiturates and Erythropoietin

Question 24

_{Clinical Therapies in Neuroanesthesia - Pharmacologic agents}

What are the benefits of Lidocaine in neuroanesthesia?

Answer 24

Decreases CMRO2

May reduce ischemia

Blocks hemodynamic response to laryngoscopy

Question 25

_{Clinical Therapies in Neuroanesthesia - Pharmacologic agents} What are the benefits of Propofol in neuroanesthesia?

Answer 25

↓CMRO2 & ↓CBF. May also ↓MAP, therefore ↓ CPP (bad)

Question 26

_{Clinical Therapies in Neuroanesthesia - Pharmacologic agents} How do Benzodiazepines affect CMRO2/CBF? How about the use of **flumazenil w/ inc ICP?**

Answer 26

↓CMRO2 & ↓CBF, but not as well as barbiturates **Do not give flumazenil to patients with ↑ ICP**

Question 27

_{Clinical Therapies in Neuroanesthesia - Pharmacologic agents} Although Etomidate does ↓CMRO2, CBF & ICP while maintaining cardiovascular stability and CPP, it is associated with which negative effects?

Answer 27

Causes adrenocortical suppression Myoclonic activity and seizures have occurred Nausea, vomiting and pain on injection

Question 28

_{Clinical Therapies in Neuroanesthesia - Pharmacologic agents} How does Nitrous oxide affect CBF, CMRO2, and ICP?

Answer 28

Cerebrovasodilatator = ↑CBF, CMRO2, and ICP ↑CBF attenuated by barbs, opioids, & hyperventilation

Question 29

_{Clinical Therapies in Neuroanesthesia - Pharmacologic agents} Which could attenuate increased CBF caused by Nitrous oxide

Answer 29

Barbs, opioids, & hyperventilation

Question 30

_{Clinical Therapies in Neuroanesthesia - Pharmacologic agents} Why must Nitrous oxide be avoid in pneumocephalus and in any surgery within 2 weeks of craniotomy if N2O was used?

Answer 30

Nitrous oxide is 32X more soluble in blood than nitrogen Diffuses into air-filled cavities **Discontinue immediately if air embolism suspected**

Question 31

_{Clinical Therapies in Neuroanesthesia - Pharmacologic agents} Why must Ketamine be avoided in neuro (unless you have no other option)?

Answer 31

Cerebrovasodilatator Marked ↑in ICP and CBF (60%) Seizures can occur Do not use in neuro