local anesthetics- APEX

Question 1

which local anesthetic is not very potent so we have to give a large dose making its onset of action Rapid?

Answer 1

chloroprocaine

has a high pKa- which suggests a slow onset, yet since we give it in a high dose due to its low potency it has a rapid onset of action

Question 2

a higher degree of lipid solubility correlates with

Answer 2

longer duration of action

Question 3

tell me about chloroprocaine and protein binding

Answer 3

it does not undergo protein binding

Question 4

what is the pKa of benzocaine

Answer 4

3.5- acidic

Question 5

what do we usually use benzocaine for

Answer 5

topical anesthesia - mucous membranes, for TEE, bronchoscopy,

Question 6

how does hypercarbia increase the risk of CNS toxicity

Answer 6

by increasing cerebral blood flow it increases local anesthetics to the brain

Question 7

how does hyperkalemia increase the risk of CNS toxicity

Answer 7

it raises the resting membrane potential making them more likely to depolarize

Question 8

how does metabolic acidosis increase risk of CNS toxicity.

Answer 8

it decreases convulsion threshold and favors ion trapping inside the brain.

Question 9

This drug hydrolyzes hyaluronic acid- allowing LA to improve diffusion through tissues

Answer 9

hyaluronidase

Question 10

this drug is commonly used in ophthalmic blocks to increase the speed of onset, enhance the block quality and mitigate any rise in intraocular pressure

Answer 10

hyaluronidase

Question 11

what is the benefit to adding sodium bicarbonate to local anesthetics

Answer 11

alkalization increases the number of lipid soluble molecules, which speeds up the onset of action

Question 12

what is the concern with adding sodium bicarbonate to local anesthetics

Answer 12

there is a limit to how much a local anesthetic solution can be alkalized before it precipitates so this technique only produces a modest benefit

Question 13

how much 8.4% sodium bicarbonate can you add to 10ml of la

Answer 13

1ml

Question 14

which la should not be mixed with opioids in the epidural space as it reduces the la effectiveness

Answer 14

chloroprocaine

Question 15

how much clonidine can we add to local anesthetics

Answer 15

100mcg

Question 16

why do we add clonodine to la

Answer 16

analgesia

Question 17

what does dextran do when mixed with la

Answer 17

prolongs block by decreasing systemic uptake of la

Question 18

how much can dexamethasone increase the duration of brachial plexus block when added to la

Answer 18

up to 50%

Question 19

what receptor does dexamethasone work on to affect systemic uptake of la

Answer 19

steroid receptor

Question 20

what does epi work best with

short, intermediate or long acting la

Answer 20

intermediate local anesthetics

Question 21

does cocaine vasodilator or vasoconstrict

Answer 21

it vasoconstricts

Question 22

what receptor does EPI work on?

Answer 22

alpha 1 agonist

Question 23

what is the peripheral nerves order that local anesthetics inhibit greater-less

Answer 23

b fibers>c fibers > small diameter a fibers > large diameter a fibers

Question 24

if the nerve is depolarized more frequently for the voltage gated sodium channel to open what does that mean for local anesthetics

Answer 24

there is more availability for local anesthetic binding to occur

Question 25

can local anesthetics bind to sodium channels in their resting state

Answer 25

no

Question 26

in the peripheral nerve what is the resting membrane potential set at

Answer 26

-70 to -90

Question 27

what subunit does local anesthetics bind to

Answer 27

alpha subunit

Question 28

local anesthetics bind to the alpha subunit inside or outside the sodium channel

Answer 28

inside the sodium channel

Question 29

do local anesthetics affect resting membrane potential or threshold potential

Answer 29

NOOO

Question 30

difficulty of cardiac resuscitation greater to least

Answer 30

bupivacaine> levobupivicaine > ropivacaine > lidocaine

Question 31

liposuction- mortality from what

Answer 31

PE

Question 32

hyper carbia and protein binding

Answer 32

decreases protein binding allowing more free fraction of the drug to enter the brain

Question 33

hypokalemia

Answer 33

decreases resting membrane potential - more la is needed

Question 34

hypocarbia

Answer 34

decreases drug delivered to the brain