Local Anesthetics Flashcards
Which anesthetics are esters? 1 i
Procaine
Tetracaine
Benzocaine
Cocaine
Which anesthetics are amides? 2 i’s
Lidocaine
Mepivacaine
Bupivacaine
Ropivacaine
Rank from most potent to least (ester anesthetic)
tetracaine >cocaine>procaine
long med short duration of action
Rank from most potent to least (amides anesthetic)
Ropivacaine or Bupivacaine >lidocaine>mepivacaine
long medium
What is MOA of local anesthetics?
blocks the Na channels of excitable membranes
blocks conduction of the AP
T/F Sodium bicarbonate may accelerate the action of local anesthetics
TRUE-sodium bicarbonate changes the pH and allows anesthetic to bind
T/F Non charged form passes through the lipohilic membrane
true
T/F The slightly acidic pH within the extra vascular space causes the non charged weakly basic anesthetic to become protanated (charged) and active
TRUE
T/F Addition of epineprhrine to short acting anesthetics prolongs duration
TRUE
How are ester anesthetics metabolized?
plasma cholinesterase-very rapid
Procaine>cocaine>tetracaine (slowest)
How are amide anesthetics metabolized?
liver
lidocaine> bupivacaine>ropivacaine (slowest)
T/F Small fibers are blocked more easily than larger fibers
TRUE
T/F myelinated fibers are blocked more easily than unmyelinated fibers
TRUE
Explain signaling info to CNS for each fiber? A-D A-B A-A C-fibers
A-D: temp and pain
A-B: touch
A-A: propioception
C fibers: pain, temp, itch
Which fibers are more sensitized by anesthetics?
In order of most sensitized to least:
Type B-preganglionic autonomic fibers -light myelination
Type C: post ganglionic or pain-no myelination
Type A delta most sensitive in A group-heavy myleination
T/F Local anesthetics are capable of blocking all nerves?
TRUE
What complications can result from epidural or spinal blockade?
respiratory depression
-hypotension
MOTOR paralysis is not desirable in OB/GYN because it can inhibit the patient from “bearing down”
TRUE
What is blockade sequence?
- sympathetic transmission
- Temperature
- Pain
- light touch
- motor block
T/F liposomal bupivicaine has longer duration of action
TRUE
Which anesthetic is banned by FDA because of its cardiotoxictity in OB/GYN pts? what antidote?
- 75% bupivicaine
antidote: lipid resuscitation
Which anatomic site has high systemic absorption of anestheic?
intercostal
refer to slide 26 in PP
What are clinical application of amides?
perineural, epidural, subarachnoid
What is clinical application of esters?
analgesia
topical only for cocaine and benzocaine
