24 general and local anesthetics

Question 1

what is MAC?

Answer 1

For inhaled anesthetics, defined as minimal alveolar concentration (MAC) that prevents movement in response to pain 50% of subjects

Question 2

what do most anesthetics do to GABA?

what do they do to NDMA?

Answer 2

GABAa receptors are enhanced

they inhibit NDMA

Question 3

what drug is useful for inducing a pt, but has side effects of hypotension and and hangover?

Answer 3

sodium thiopental

Question 4

what IV is used for induction and maintenance but can cause hypotension and respiratory depression?

Answer 4

propofol

Question 5

what IV is used for pt with hypotension? induction?

what is one bad side effect of this?

Answer 5

etomidate

causes adrenal supression

Question 6

what IV causes a coma with the eyes open? it is for use in people with bronchospams,
what is a side effect?

Answer 6

ketamine

it causes a increase in intracranial pressure.

Question 7

what IV causes conscious sedation?

what are soem concerns with it?

Answer 7

midazolam

there is slow induction and respiratory depression.

Question 8

If the anesthetic has a low blood:gas partition coefficient:
induction is ?
need a lot or a little?
recovery is ?

Answer 8

– need high amounts in inspired air
– Induc0on is quick (because equilibrium is reached quickly)
– Recovery will be quick (drug will move out of blood into gas readily)

Question 9

If the anesthetic has a high blood:gas partition coefficient:
induction is ?
need a lot or a little?
recovery is ?

Answer 9

– Need less in inspired air

– Induc0on and recovery are slow (equilibria are reached slowly)

Question 10

if anesthetic has a high fat:blood PC?

Answer 10

– Half-life will be long (hang over) due to slow release into the blood; enough gets into the brain to make the pa0ent feel sleepy.

Question 11

Increased blood flow ______ the rate of rise of arterial par0al pressure (shorter 0me for equilibra0on)

Answer 11

Increased blood flow slows the rate of rise of arterial par0al pressure (shorter 0me for equilibra0on)

Question 12

• Anesthesia is achieved when the brain par0al pressure is ______ to MAC

Answer 12

• Anesthesia is achieved when the brain par0al pressure is equal to MAC

Question 13

• Rate of elimina0on is dependent upon the blood:gas par00on coefficient

what is eleimnated the fastest?

Answer 13

– Lowest will be eliminated the fastest

Question 14

• Agents with _____ solubility in blood and fat, have slower recovery AND the dura0on of the recovery will depend upon the length of 0me that the anesthe0c was administered

Answer 14

• Agents with high solubility in blood and fat, have slower recovery AND the dura0on of the recovery will depend upon the length of 0me that the anesthe0c was administered

Question 15

what gas has Moderate blood:gas PC
is slow and is a slight airway irritatn?
has cardivascular side effects of increased intercranial pressure vasodialation of cerebral vessels and decrease in BP

Answer 15

Isoflurane

Question 16

what gas has very low soluablity in blood? causing rapid induction and recovery?

– Respiratory- Worse as an irritant; can produce bronchospasm

Answer 16

desflurane
not used to induce because of respiratory irritation

Side effects: rela0ve to isoflurane
– Cardiovascular-similar
– Respiratory- Worse as an irritant; can produce bronchospasm

Question 17

what gas causes renal toxciticy? how does this happen?

what is good about this one?

Answer 17

SERVOFLURANE

no respitory irritation very popular.

About 5% of the administered dose is metabolized to fluoride ion in the liver. can cause renal damage.
Is degraded to “compound A” by absorbants in the anesthesia administra0on apparatus

Question 18

what gas is not a volitile liquid? and used as an adjunct to enhance induction.

cant be used as an anesthetics.

Answer 18

nitrous oxide

it dilutes oxygen.

– Weak anesthe0c, cannot get enough into the air to produce MAC
– Good for seda0on and analgesia at 50% concentra0on in inspired air

Question 19

how do local anesthetics produce an effect?

Answer 19

Bind reversibly to a site within the pore of votage gated Na+ channels; blocking sodium entry when the channel is openned

Question 20

what is the mechanism of action of local anesthetics?

Answer 20

binds on the intracellular side insde the pore as a cation.

has to cross in the unionized form.
they are all weak bases.

Question 21

resting nerves are less sensative to local anesthetics.

Answer 21

b/c they are not openning alot for the drug to get in.

Question 22

how does pH releate to the mechanism of action of the local anesthetics.

Answer 22

Efficacy decreased when 0ssue pH is decreased such as during infec0on or inflamma0on. Too liZle drug can get to site of ac0on.

Question 23

what does coadministering local anesthetics with epinepherine do?

Answer 23

Decrease the rate of absorp0on into the circula0on thereby increasing depth and dura0on of anesthesia
 Due to decreased rate of absorp0on, less poten0al for systemic toxicity and can increase the maximal dose that can be given

Question 24

what nerve fiber is more sensative?

Answer 24

the smaller diameter.

so pain and cold goes first

Question 25

what local is a vasoconstricteor?

Answer 25

cocaine

used for some upper respiratory surgeries.

Question 26

what local is short acting and low potency and slow onset and short duration of action?

Answer 26

procaine

Question 27

what local is only used for spinal that is long acting; not for peripheral nerves.

Answer 27

tetracaine

Question 28

what is local for only surface wounds?

Answer 28

benzocaine

Question 29

where are the local esters metabolized?

Answer 29

plasma cholinesterase there are rare allergic reactions.

Question 30

where are the local amides metabolized?

Answer 30

in the liver and there is no chance of allergic.

Question 31

what local?
 Intermediate duration of action
 Produces faster, more intense, longer las-ng, and more extensive anesthesia
compared to procaine

Answer 31

lidocaine

Question 32

Long ac0ng amide local anesthe0c?
provides more sensory than motor blcok?
and has cardiotoxic sideeffects?

Answer 32

bupivicaine

Question 33

what local is the most sensory block and is less toxic?

Answer 33

ropivacaine