local anesthetics- APEX Flashcards
which local anesthetic is not very potent so we have to give a large dose making its onset of action Rapid?
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
a higher degree of lipid solubility correlates with
longer duration of action
tell me about chloroprocaine and protein binding
it does not undergo protein binding
what is the pKa of benzocaine
3.5- acidic
what do we usually use benzocaine for
topical anesthesia - mucous membranes, for TEE, bronchoscopy,
how does hypercarbia increase the risk of CNS toxicity
by increasing cerebral blood flow it increases local anesthetics to the brain
how does hyperkalemia increase the risk of CNS toxicity
it raises the resting membrane potential making them more likely to depolarize
how does metabolic acidosis increase risk of CNS toxicity.
it decreases convulsion threshold and favors ion trapping inside the brain.
This drug hydrolyzes hyaluronic acid- allowing LA to improve diffusion through tissues
hyaluronidase
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
hyaluronidase
what is the benefit to adding sodium bicarbonate to local anesthetics
alkalization increases the number of lipid soluble molecules, which speeds up the onset of action
what is the concern with adding sodium bicarbonate to local anesthetics
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
how much 8.4% sodium bicarbonate can you add to 10ml of la
1ml
which la should not be mixed with opioids in the epidural space as it reduces the la effectiveness
chloroprocaine
how much clonidine can we add to local anesthetics
100mcg
why do we add clonodine to la
analgesia
what does dextran do when mixed with la
prolongs block by decreasing systemic uptake of la
how much can dexamethasone increase the duration of brachial plexus block when added to la
up to 50%
what receptor does dexamethasone work on to affect systemic uptake of la
steroid receptor
what does epi work best with
short, intermediate or long acting la
intermediate local anesthetics
does cocaine vasodilator or vasoconstrict
it vasoconstricts
what receptor does EPI work on?
alpha 1 agonist
what is the peripheral nerves order that local anesthetics inhibit greater-less
b fibers>c fibers > small diameter a fibers > large diameter a fibers
if the nerve is depolarized more frequently for the voltage gated sodium channel to open what does that mean for local anesthetics
there is more availability for local anesthetic binding to occur
can local anesthetics bind to sodium channels in their resting state
no
in the peripheral nerve what is the resting membrane potential set at
-70 to -90
what subunit does local anesthetics bind to
alpha subunit
local anesthetics bind to the alpha subunit inside or outside the sodium channel
inside the sodium channel
do local anesthetics affect resting membrane potential or threshold potential
NOOO
difficulty of cardiac resuscitation greater to least
bupivacaine> levobupivicaine > ropivacaine > lidocaine
liposuction- mortality from what
PE
hyper carbia and protein binding
decreases protein binding allowing more free fraction of the drug to enter the brain
hypokalemia
decreases resting membrane potential - more la is needed
hypocarbia
decreases drug delivered to the brain
