Local Anesthetics - 8/25/15 (Byram)

Question 1

Local anesthetics bind to

Answer 1

Na channels to block nerve transmission

Question 2

smaller vs. larger fibers - which are easier to block?

Answer 2

smaller fibers (A-delta fibers smallest)

Question 3

Largest A-type fibers?

Answer 3

A-alpha

Question 4

No matter what type of nerve block,

Answer 4

B fibers suppression - sympathetic blockade

Question 5

sympathectomy > sensory > motor

Answer 5

?

Question 6

Where is the R-site?

Answer 6

inside of cell

Question 7

frequency dependent blockade due to

Answer 7

steric hindrance of R-site by H-gate

Question 8

Primary determinants of onset time

Answer 8

pH and pKa

Question 9

Primary determinant of potency

Answer 9

Lipid solubility

Question 10

Primary determinant of duration

Answer 10

protein binding

Question 11

Where does spinal cord end in adults?

Answer 11

L1

Question 12

Where does spinal cord end in infants?

Answer 12

L3 (lower)

Question 13

Spinal vs. epidural

Answer 13

?

Question 14

which fibers are the first to block?

Answer 14

B-type sympathetic fibers; small myelinated

Question 15

Vascularity ranking

Answer 15

ICNB>caudal>epidural>brachial plexus>sciatic

Question 16

bupibicain

Answer 16

3mg/kg

Question 17

lidocaine

Answer 17

5mg/kg

Question 18

adding vasoconstrictor changes

Answer 18

highly protein bound drugs….?

Question 19

neurotoxicity comes before

Answer 19

cardiotoxicity

Question 20

why is epinephrine added?

Answer 20

if see HR increase, reposition needle

Question 21

Local anesthetic mediated cardiotoxicity - antidote?

Answer 21

intralipid

Question 22

allergic reaction - what type of hypersensitivity

Answer 22

I or IV

Question 23

In what two states of the Vg Na channel, can local anesthetics bind?

Answer 23

Inactivated state
open state

explains frequency dependent blockade

Question 24

common complication of neuraxial anesthesia

Answer 24

PDPH (post-dural puncture headache)

Question 25

17 yo female outpatient hand surgery. Block. EKG went cray

Answer 25

intralipid

Question 26

43 yo patient. surgeon wants to cut NOW. how do u speed up the block?

Answer 26

1. use drug w low pKa such as
   mapivicaine (7.6 pka, close to physiological pH)
2. Add bicarb (increase proportion of uncharged molecules to speed onset)