General Anesthetics

Question 1

Can you give sodium channel blockers as general anesthetic

Answer 1

NO! Heart has sodium channels -> will block them everywhere

Question 2

How to suppress CNS

Answer 2

activate GABA
NMDA receptor antagonists
glycine inhibition

Question 3

What drugs get to brain faster: lipophilic or lipophobic

Answer 3

lipophilic

Question 4

What does GA cause

Answer 4

muscle relaxation, loss of autonomic reflexes, analgesia, anxiolysis
reversible loss of sensation

Question 5

what does suppression of amygdala do

Answer 5

removes fear, anxiety, emotion, memory

Question 6

What happens if you suppress activity of medulla

Answer 6

medulla is vasomotor center -> will suppress cardiac and respiratory center -> only want to do this to a certain point

Question 7

Two types of GA

Answer 7

inhaled

IV

Question 8

what is balanced anesthesia

Answer 8

both inhaled and IV together

Question 9

properties of inhaled anesthetics

Answer 9

distribute well to all body parts
become concentrated in fatty tissue
CNS primary site of action

Question 10

At low concentrations, inhaled anesthetics act as

Answer 10

GABAa positive allosteric modulators (increase activity of GABA channels)

Question 11

At high concentrations, inhaled anesthetics act as

Answer 11

GABAa receptor agonists

Question 12

GABA agonist vs modulator

Answer 12

agonist increases duration of opening

modulator increases frequency of opening

Question 13

Four stages of anesthesia

Answer 13

stage 1: Analgesia - amnesia, euphora
stage 2: excitement - excitement, delirium, combative behavior
Stage 3: surgical anesthesia - unconsciousness, regular respiration, decreasing eye movement
Stage 4: medullary depression - respiratory arrest, cardiac depression and arrest, no eye movement

Question 14

primary site of action for GA

Answer 14

CNS

Question 15

What stage of anesthesia is the goal

Answer 15

stage 3, avoid stage 4 (in both inhaled and IV)

Question 16

Minimum alveolar concentration (MAC)

Answer 16

alveolar partial pressure (minimum concentration) of anesthetic vapor that is able to prevent motor responses to a surgical incision in 50% of patients (analogous to ED50)

Question 17

What happens when you increase MAC

Answer 17

increase partial pressure

Question 18

MAC is inversely/proportionately related to potency

Answer 18

inversely
LOW MAC = high potency and vice versa
potency = 1/MAC

Question 19

Wide or narrow TI for inhaled (isoflurane example)

Answer 19

narrow TI

TI = lethal pressure 50/MAC

Question 20

What dictates inhaled anesthetic potency

Answer 20

lipophilicity

Question 21

Greater lipophilicity equals

Answer 21

greater potency and greater rate of absorption

Question 22

What dictates rate of anesthetic induction

Answer 22

rate of gas absorbed into lungs

Question 23

Lower rate of absorption equals

Answer 23

faster anesthesia induction

Question 24

lower rate of absorption allows anesthetic to build up in alveoli, leading to

Answer 24

faster onset of anesthesia

Question 25

If gas remains in lungs then you get faster/slower rate of absorption

Answer 25

faster

Question 26

highly lipophilic inhaled agents do what

Answer 26

penetrate alveoli -> go to capillaries -> distribute to body -> not as much goes to the brain -> slower anesthetic induction

Question 27

low lipophilic inhaled agents do what

Answer 27

high concentration builds up in alveoli -> goes to blood -> goes to brain -> faster anesthetic induction

Question 28

Inhaled anesthetic agents

Answer 28

``` Nitrous oxide desflurane sevoflurane enflurane isoflurane halothane methoxyflurane ```

Question 29

Nitrous oxide

Answer 29

MAC = 1.01 | rapid onset and recovery

Question 30

desflurane

Answer 30

MAC = 0.06 | poor induction agent, rapid recovery

Question 31

sevoflurane

Answer 31

MAC = 0.02 | rapid onset and recovery

Question 32

enflurane

Answer 32

MAC = 0.0168 | medium rate of onset and recovery

Question 33

Isoflurane

Answer 33

MAC = 0.0114 | medium rate of onset and recovery

Question 34

Halothane

Answer 34

MAC = 0.0077 | Medium rate of onset and recovery

Question 35

Methoxyflurane

Answer 35

MAC = 0.0016 | very slow onset and recovery

Question 36

The lower the MAC

Answer 36

the more potent the agent

Question 37

The more potent the agent

Answer 37

the more lipophilic

Question 38

The more lipophilic the agent

Answer 38

the higher rate of absorption

Question 39

The higher the rate of absorption of the agent

Answer 39

the SLOWER the onset of anesthesia

Question 40

Balanced anesthesia

Answer 40

several anesthetic agents used simultaneously | allows physician to achieve potency and rapid induction/recovery in controlled manner

Question 41

What will mixture of nitrous oxide and isoflurane produce

Answer 41

NO = rapid induction Iso = potent NO will anesthetize pt quickly and Iso will ensure deep anesthesia simultaneous removal of the drugs will cause person to wake up (NO = rapid recovery) but be groggy (Iso = medium recovery)

Question 42

IV agents used for

Answer 42

rapid induction of anesthesia | administered with inhaled

Question 43

IV agents

Answer 43

ultra short acting -> barbiturates (thiopental) | Propofol: ultra-short, rapidly distributed and metabolized

Question 44

Barbiturates

Answer 44

ultra short acting high lipid solubility Thiopental and Methohexital

Question 45

Benzodizepines

Answer 45

-pams and -zolams | given to cause sedation, relaxation, amnesia prior to administration of other GA

Question 46

Do benzo's have faster or slower onset of action than barbs or propofol

Answer 46

Slower, but still adequate for surgical anesthesia

Question 47

What can benzo's be reversed by

Answer 47

flumazenil

Question 48

Propofol

Answer 48

powerful GABAa positive allosteric modulator (increases time channel open) ultra short, but rapidly distributed and metabolized -> faster recovery most commonly used IV anesthetic

Question 49

Opioid analgesics

Answer 49

fentanyl, sufentanil, alfentanil, and remifentanil are used in combo bind mu receptors in brain and spinal cord -> suppress midbrain/raffe nucleus

Question 50

which two opioids have rapid onset of action and can be used in combo with barbiturates as an anesthetic

Answer 50

Alfentanil and remifentanil