Local Anesthetics - 8/25/15 (Byram) Flashcards
(26 cards)
Local anesthetics bind to
Na channels to block nerve transmission
smaller vs. larger fibers - which are easier to block?
smaller fibers (A-delta fibers smallest)
Largest A-type fibers?
A-alpha
No matter what type of nerve block,
B fibers suppression - sympathetic blockade
sympathectomy > sensory > motor
?
Where is the R-site?
inside of cell
frequency dependent blockade due to
steric hindrance of R-site by H-gate
Primary determinants of onset time
pH and pKa
Primary determinant of potency
Lipid solubility
Primary determinant of duration
protein binding
Where does spinal cord end in adults?
L1
Where does spinal cord end in infants?
L3 (lower)
Spinal vs. epidural
?
which fibers are the first to block?
B-type sympathetic fibers; small myelinated
Vascularity ranking
ICNB>caudal>epidural>brachial plexus>sciatic
bupibicain
3mg/kg
lidocaine
5mg/kg
adding vasoconstrictor changes
highly protein bound drugs….?
neurotoxicity comes before
cardiotoxicity
why is epinephrine added?
if see HR increase, reposition needle
Local anesthetic mediated cardiotoxicity - antidote?
intralipid
allergic reaction - what type of hypersensitivity
I or IV
In what two states of the Vg Na channel, can local anesthetics bind?
Inactivated state
open state
explains frequency dependent blockade
common complication of neuraxial anesthesia
PDPH (post-dural puncture headache)
