Local Anesthestics

Question 1

List the most common local anesthetics in order of decreasing lipid solubility

Answer 1

Tetracaine>bupivacaine >lidocaine>mepivacaine

TBLM tetracaine best lipid, mate

Question 2

What quality of local anesthetics affects their potency?

Answer 2

Lipid solubility

Question 3

What quality of local anesthetics affects their onset?

Answer 3

pKa

Having a lower pKa for phys pH gives faster onset

Question 4

List the following in decreasing order of pKa:
Chlorprocaine 
Bupivacaine 
Lidocaine
Mepivicaine

Answer 4

pKa CBLM

Chlor 8.7, bupiv 8.1, lido 7.9, mepiv 7.6

Question 5

What is the MOA for local anesthetics?

Answer 5

Voltage gated sodium channels.

Question 6

A local anesthetic with a high pKa will have a fast or slow onset?

Answer 6

Slow

Question 7

Which isomer has a propensity for cardiac and neural side effects?

Answer 7

R isomers

Question 8

Which anesthetics cause more allergy?

Answer 8

Esters because they metabolize to PABA

Also look out for preservative allergy: methylparaben and metabisulfite

Question 9

Which type of local causes more systemic toxicity

Answer 9

Amides because they are metabolized by the liver.

Esters are broken down by plasma esterases

Question 10

Which blocks cause the highest amounts of toxicity?

Answer 10

IV, tracheal, and intercostal

Question 11

CNS side effects

Answer 11

Tinnitus, circumoral numbness, excitation at first

Seizures

Coma

Reps arrest

Question 12

Toxicity is worth with:

Answer 12

Hypoxia, acidosis, hyper car is, pregnancy

Treat the abcs, then suppress seizures with benzos

Question 13

What’s unique about cocaine toxicity?

Answer 13

Cocaine blocks NE reuptake, causing HTN, tachycardia, ventricular ectopy

Treat with with NTG not bb

Question 14

Epi in peds caudal side effects

Answer 14

Peaked T waves, tachycardia, hypotension

The injection was either intraosseous or IV

Question 15

What symptoms happen with TNS after subarachnoid block? 
How long do they last?
Most common drug that causes it?
Highest incidence?
Treatment

Answer 15

Irritation, pain in the low back, buttocks, and thighs
Start within 24 hrs, last 7 days
Hyperbaric lidocaine 
Outpatient obesity, lithotomy
R/o hematoma or abscess, give nsaids

Question 16

How long would lidocaine toxicity take to appear after liposuction?
What symptoms?

Answer 16

12-14 hrs

Similar to local anesthetics toxicity

Question 17

Which local is safest to use during fetal distress and why?

Answer 17

Chlorprocaine because is is the most rapidly metabolized via ester hydrolysis in the plasma

Question 18

Bupivicaine toxicity requires a prolonged resuscitation of LAST.
Which med should you give for resistant vfib?

Answer 18

Amio
Avoid CCBs and beta blockers due to reduced contractility
Avoid vasopressin
definitely avoid lido