regional Flashcards
what nerve layer encapsulates individual neurons
endoneurium
what nerve layer is tough and contains several neruons
perineum
what nerve layer is the toughest for local anesthetics to cross
perineurim
what is the nerve layer that is outermost and protects several groups of perineurium, essentially the sheath
epineurium
T/F a nerve will heal if you cut through it
F
are smaller or larger nerves blocked first
smaller
are myelinated or unmyelinated nerves blocked first
myelinated
why are C fibers resistant to LA
they are unmyelinated
where does LA pool
near axonal membrane/ nodes of ranvier
what nerve types are the aim for blocks
A delta- pain
A beta-muscle
what is the order of nerve block onset
B,
A delta,
A gamma,
A beta,
A alpha,
C
what is the order of nerve recovery
C,
A delta,
A gamma,
A beta,
A alpha,
what do A-alpha nerves transmit
muscle length, force, propioception
what do A-beta nerves transmit
proprioception, touch, pressure
what do A-gamma nerves transmit
skeletal muscle tone
what do A-delta nerves transmit
pain, temp, touch
what do B nerves transmit
autonomic fxn
what do sC nerves transmit
autonomic fxn
what do dC nerves transmit
pain, temp, temp, touch, autonomic fxn
what is the action of local anesthetics
impair propagation of the AP along nerve axon
direct action on voltage-gated sodium channels to prevent sodium influx
the __________ form of the LA penetrates the libip bilayer of the nerve
non-ionized
the ________ form of the LA locks the sodium channel
ionized
what can you add to LA to increase onset
HCO3, makes in more non-ionized
what happens to the non-ionized LA that crosses over into the nerve
becomes ionized
what does pKa correlate with
onset
the ____________ the pKa the more non-ionized and the ________ the onset
lower (pH)
faster
local anesthetics are weak (acids/bases_
bases
pKa chart
tetracaine Pka onset and %nonionized @ ph 7.4
pka 8.6
% non ionized 14
slow onset
bupivicaine Pka onset and %nonionized @ ph 7.4
pka 8.1
non ionized 17
moderate onset
ropivicaine Pka onset and %nonionized @ ph 7.4
pka 8.1
% nonionized 17
moderate onset
chloroprocaine Pka onset and %nonionized @ ph 7.4
pka 9.1
% nonionized 2
fast onset
lidocaine Pka onset and %nonionized @ ph 7.4
pka 7.7
% nonionized 24
fast onset
etidocaine Pka onset and %nonionized @ ph 7.4
pka 7.7
% nonionized 33
fast onset
mepivicaine Pka onset and %nonionized @ ph 7.4
pka 7.6
%non ionized 99
fast onset
lipid solubility is correlated with
potency
the more lipid soluble the _________ the potency
greater
non lipid soluble LA require a _________ concentration
higher
protein binding is related to
duration of action
what protein does LA bind to first
AAG (alpha1-acid glycoprotein)
what protein does LA bind to second
albumin
a decreased pH results in (higher/lower) protein binding
lower
how does systemic acidosis affect local anesthetic
increased free local anesthetic, increased risk of toxicity
the higher the protein binding the ________ the DOA
longer
3% 2-chlorprocain (HCO3 +EPI) onset, anesthesia hrs, analgesia hours
onset 10-15 min
anesthesia hrs 1.5-2hrs
analgesia hrs 2-3 hrs
1.5% mepivacaine (HCO3 + EPI) onset, anesthesia hrs, analgesia hrs
onset 10-20 min R: 5 min
anesthesia hrs 2-5 hrs
analgesia 3-5 hrs
2% lidocaine (HCO3 + EPI) onset, anesthesia hrs, analgesia hrs
onset 10-20 min
anesthesia hrs 2-5 hrs
analgesia hrs 3-8 hrs
ropivicaine 0.5% onset, anesthesia hrs, analgesia hrs
onset 15-30 min
anesthesia hrs 4-8 hrs
analgesia 5-12 hrs
0.5% bupivicaine +EPI onset, anesthesia hrs, analgesia hrs
onset 15-30 min
anesthesia hrs 5-15
analgesia hrs 6-30 hrs
for a motor block use a LA of (higher/lower) concentration
higher
for a sensory block use a LA of (higher/lower) concentration
lower
T/F local anesthetics are neurotoxic
true
what happens if you inject LA directly into nerve
nerve injury
what happens if you inject into peritoneum
increased hydrostatic pressure
ischemia
T/F 99% of nerve injuries resolve in 6 months
TRUE
when advancing needle under ultrasound, always keep __________ inview
the tip
if injecting multipile nerves, inject the (most shallow, deepest) first
deepest
what order to you inject a nerve in
underneath
side
top
when you inset nerve stimulator what is the output setting
0.4 mA
when you get a twitch with 0.4 mA what do you do next
dial back to 0.2 mA
what is the goal of nerve stimulation
no twitch at 0.2 mA and twitch at 0.3 mA
if you have a strong twitch at 0.2 mA where is the needle
intraneural
what block do you do for anterior aspect of the knee
femoral nerve
what block do you do for posterior part of the knee
sciatic
what do you block for erector spinae
T6-T10
what do you block for medial ankle
saphenous
what do you block for lateral ankle
sural
what volume do you use for a specific nerve
2-3cc
what volume do you use for a large area
30-50 cc
what is the max dosage of marcaine
2.5 mg/kg
what is the max dose of lidocaine
4 mg/kg
what is the max dose of lidocaine with epi
7 mg/kg
brachial plexus
what does the interscalene block block
C5 C6 C7 roots
what do we use supraclavicular block for
anesthesia for upper arm below shoulder
T/F in supraclavicular block the medial aspect of skin is no anesthetized
F, not blocked by any brachial plexus block (T2)
what position do we do supraclavicular block for
supine or semi-sitting position
how do you place transducer in SCB
transverse on neck, superior to clavicle at midpoint
what does the supraclavicular block block
superior, middle, inferior trunks
what is Cm
the unit of measure that quantifies the concentration of LA that is required to block conduction
