General Anesthetics

Question 1

what does general anesthesia do?

Answer 1

renders patient unresponsive to painful stimuli through loss of consciousness

Question 2

what are the five primary effects of general anesthetics?

Answer 2

unconsciousness
amnesia
analgesia
inhibition of autonomic reflexes
skeletal muscle relaxation

Question 3

what do general anesthetics do to the cardiovascular and respiratory systems?

Answer 3

cardiovascular depression
some: cardiac dysrhythmias
depress respiration

Question 4

why is balanced anesthesia used?

Answer 4

to achieve goal of safe, effective anesthesia and analgesia

Question 5

what are the four stages anesthesia?

Answer 5

awake/analgesia
excitement
surgical anesthesia
overdose: medullary paralysis

Question 6

what are the functional steps in anesthesia?

Answer 6

anesthetic induction
anesthetic maintenance
anesthetic recovery

Question 7

what is the main effect of general anesthetics?

Answer 7

inhibit synaptic transmission

Question 8

what are the main targets of anesthetics?

Answer 8

GABAa receptors
glutamate NMDA receptors
glycine receptors
K2P channels

Question 9

where does general anesthesia act?

Answer 9

in the brain

Question 10

what are the most sensitive regions to anesthesia?

Answer 10

thalamic sensory relay nuclei and the deep layer of the cortex to which these nuclei project

Question 11

what are inhalant anesthetics?

Answer 11

volatile anesthetics: gas

Question 12

what is the mechanism of action for inhalant anesthetics?

Answer 12

general disruption of neurotransmission

Question 13

what do the main differences in agents of inhalant anesthetics relate to?

Answer 13

pharmacokinetics and adverse effects

Question 14

what does it mean for something to be a volatile anesthetic?

Answer 14

liquid at room temperature
gas as pressure drops

Question 15

what are some gas anesthetics?

Answer 15

isoflurane
sevoflurane

Question 16

how do inhalant anesthetics work?

Answer 16

augment inhibitory activity (GABA receptors) and depress neurotransmission pathways (glutamate/NMDA and other pathways)

Question 17

how is the potency of inhaled anesthetics defined quantitatively?

Answer 17

minimum alveolar concentration (MAC)

Question 18

what is the minimum alveolar concentration (MAC)?

Answer 18

concentration of anesthetic gas needed to eliminate movement in 50% of patients with a standardized skin incision

Question 19

what is the blood:gas partition coefficient?

Answer 19

how much gas dissolves in blood

Question 20

what is the tissue:gas partition coefficient?

Answer 20

how much gas dissolves in tissues

Question 21

the _____________ of an individual gas is proportional to its concentration

Answer 21

tension

Question 22

what determines the flow of an anesthetic gas?

Answer 22

difference in tension between two sites, or the pressure gradient

Question 23

where are gas anesthetics absorbed and eliminated?

Answer 23

lungs are only quantitatively important route

Question 24

true/false: anesthetics cross blood-brain barrier quickly, so brain tension follows blood tension

Answer 24

true

Question 25

what determines distribution of an anesthetic?

Answer 25

blood flow to tissue capacity of tissue to absorb anesthetic

Question 26

what is the main factor in determining rate of induction and recovery?

Answer 26

blood:gas partition coefficient

Question 27

does a lower blood:gas partition coefficient take longer or shorter to induce a response?

Answer 27

shorter drops alveolar gas concentration if higher

Question 28

agents with _____ blood and tissue solubility have more rapid elimination

Answer 28

low

Question 29

why do high tissue solubility anesthetics take longer to recover from?

Answer 29

95% of total amount in body is in fat after a long anesthetic, must come out and does so slowly

Question 30

what are the physiological factors that influence kinetic behavior of inhaled anesthetics?

Answer 30

alveolar ventilation rate cardiac output distribution of anesthetic in body

Question 31

what is the most commonly used inhalant anesthetic now?

Answer 31

isoflurane

Question 32

how soluble is isoflurane?

Answer 32

relatively insoluble: relatively rapid induction and recovery

Question 33

does isoflurane put stress on the liver and kidneys?

Answer 33

not really

Question 34

does isoflurane impact the cardiovascular system?

Answer 34

dose-dependent cardiovascular depression generally minimal at doses used for surgery minimal sensitization of heart to catecholamines

Question 35

what is a positive of sevoflurane?

Answer 35

very rapid induction and recovery

Question 36

what are the respiratory and cardiovascular impacts of sevoflurane?

Answer 36

similar to isoflurane dose-dependent cardiovascular depression respiratory depressant

Question 37

what is special about sevoflurane pertaining to toxicity?

Answer 37

reacts with carbon dioxide to make compound A, which is potentially nephrotoxic

Question 38

what are the advantages of injectable anesthetics?

Answer 38

act more rapidly than inhaled less menacing than having face mask rapid induction avoids excitement phase of inhaled

Question 39

what are the disadvantages of injectable anesthetics?

Answer 39

more difficult to quickly alter dose delivered elimination slower than inhaled anesthetics, particularly if body tissues become saturated

Question 40

what are some nonbartituate sedative injectable anesthetic agents?

Answer 40

propofol etomidate alfaxalone

Question 41

what are some dissociative agent injectable anesthetics?

Answer 41

ketamine tiletamine

Question 42

what receptors do injectable anesthetics act on?

Answer 42

GABAa glutamate-NMDA glycine AMPA (glutamate) receptors

Question 43

what drugs act on the GABAa receptor?

Answer 43

barbituates propofol etomidate alfaxalone

Question 44

what do the injectable anesthetics that act on GABAa receptor do?

Answer 44

enhance inhibitory GABAergic effects do not bind to GABA binding site

Question 45

what do barbituates generally do?

Answer 45

depress the CNS potentiate GABAa-induced increases in chloride conductance (inhibitory receptors) bind to specific barbituate receptor sites on GABA-sensitive ion channels

Question 46

are barbituates acidic or basic?

Answer 46

weak acids

Question 47

do barbituates have a low or high therapeutic index?

Answer 47

low

Question 48

what can underdosing of barbituates lead to?

Answer 48

stage 2 excitement

Question 49

is methohexital short acting?

Answer 49

ultrashort acting, rapid recovery

Question 50

what are the adverse effects of barbituates?

Answer 50

dose dependent depression of all organ systems respiratory depression cardiovascular depression

Question 51

how does propofol act?

Answer 51

primarily through potentiation of GABA pathways

Question 52

is propofol related to other anesthetics?

Answer 52

no alkoxyphenol derivative

Question 53

true/false: propofol accumulates in the body

Answer 53

false: rapidly metabolized so does not

Question 54

does propofol have analgesic effects?

Answer 54

no

Question 55

how does propofol affect respiration?

Answer 55

significant respiratory depression can cause period of apnea on induction

Question 56

does proopofol have a rapid recovery after prolonged infusion?

Answer 56

yes

Question 57

what animals can you use propofol in?

Answer 57

dogs and cats

Question 58

how is propofol metabolized?

Answer 58

glucuronidation

Question 59

what can repeated use of propofol cause in cats?

Answer 59

heinz body formation lethargy malaise diarrhea

Question 60

where does alfaxalone (neurosteroid) bind?

Answer 60

GABAa receptor

Question 61

what is alfaxalone?

Answer 61

ultra-short acting anesthetic

Question 62

does accumulation of alfaxalone occur?

Answer 62

no

Question 63

what are the adverse effects of alfaxalone?

Answer 63

respiratory and CV depression

Question 64

is the NMDA glutamate receptor excitatory or inhibitory?

Answer 64

excitatory (depolarization)

Question 65

what are the NMDA glutamate receptor antagonists?

Answer 65

ketamine tiletamine dissociative anesthetics

Question 66

what do NMDA glutamate receptor antagonists cause?

Answer 66

stage I and II anesthesia, no stage III amnesia and paralysis of movement, but do not cause a true and complete loss of consciousness significant analgesic

Question 67

what are some body effects of ketamine?

Answer 67

minimal cardiopulmonary depressant effects apneustic breathing high muscle tone

Question 68

how do you recover from ketamine IV?

Answer 68

redistribution

Question 69

what are the practical considerations of ketamine?

Answer 69

excellent somatic analgesia some visceral analgesia poor muscle relaxation

Question 70

what are some adverse effects of ketamine?

Answer 70

increase CSF pressure +/- increased seizures should not be used in combination with xylazine in dogs: severe cardiopulmonary depression cat eyes remain open painful on IM injection