Lecture2

Question 1

What are the three primary effects of Localized anesthetics?

Answer 1

Decreases rate of depolarization
Depolarization is not sufficient enough to reach threshold
Impulse is not propagated, never reaching CNS

Question 2

What ratio of positive charge to neutral charge do we want in LAs?

Answer 2

75:25

Question 3

What is the normal pH of tissues? and what direction does it go with inflammation?

Answer 3

7.4 and it decreases (acidic)

Question 4

What does sodium metabisulfite do to the LA’s and why is it added?

Answer 4

It acidifies to prevent oxidation of the vasoconstrictor

Question 5

What is the mode of action of LAs?

Answer 5

Decrease the permeability of sodium ions and conduction blockade.

Question 6

What tissue has the highest perfusion rate and potential of toxicity?

Answer 6

Skeletal muscles (largest mass in the body)

Question 7

Can LA cross BBB or the placental barrier?

Answer 7

Yes both

Question 8

The longer it takes to hydrolyze esters, the higher or lower the toxicity?

Answer 8

higher toxicity

Question 9

Where are amides metabolized? and which one is partially in the lungs?

Answer 9

In the liver, prilocaine

Question 10

What is the metabolic byproduct of prilocaine?

Answer 10

O-toluidine leading to methemoglobinemia

Question 11

Amide and ester half lives?

Answer 11

Amides: 90-160 minutes
Esters: .1-.7 hrs

*Increased half life is increased toxicity

Question 12

Amino esters are metabolized by what?

Answer 12

Plasma pseudocholinesterases

*Benzocaine (topical anesthetic), cocaine (both vasoconstrict and dilate, procaine (used for vastdilation)

Question 13

What are the amino amides?

Answer 13

articaine, bupivicaine, lidocaine, mepivocaine, prilocaine

Question 14

Why are LA vasoconstrictors?

Answer 14

decreased perfusion (localized response), lower plasma levels, more LA into the nerve, less bleeding at site

Question 15

what are the three catecholamines that are vasoconstrictors and what do they bind to?

Answer 15

Epinephrine, norepinephrine, and levonodefrin.

They activate alpha receptors

Question 16

1:1,000 dilution is what in mg/mL? 1:10,000?

Answer 16

1 mg/mL, 0.1mg/mL

Question 17

How much LA is in a 2% carpel?

Answer 17

20 mg/mL * 1.8 mL = 36 mg of LA

Question 18

What are five factors that determine the duration of LA?

Answer 18

Individual
accuracy of delivering
status of tissues in the area
anatomic variation
type of block

Question 19

What are the big five LAs?

Answer 19

2% lidocaine, 3% mepivocaine, 4% articaine, 4% prilocaine, 0.5% bupivocaine.

Question 20

Stats of lidocaine? onset, duration, max dose, etc

Answer 20

onset: 5 min
duration: 90-120
max: 300 mg per appt
pregnancy risk B

Question 21

What is the maximum dose of epi a pt can have?

Answer 21

0.2 mg in healthy pt and 0.04 in a CV pt

Question 22

Stats of mepivocaine? onset, duration, max dose, etc

Answer 22

onset, upper:30-120 seconds, lower:1-4 min
duration: U 20 min L40 min
max: 300 mg per appt
pregnancy risk C

Question 23

Stats of articaine? onset, duration, max dose, etc

Answer 23

onset: 1-6 minutes
duration: under an hour
Max: 400 mg per appt
Pregnancy risk C

Question 24

Stats of prilocaine? onset, duration, max dose, etc.

Answer 24

onset: 2-3 minutes
duration: 20 min complete, 1.5 hr IA
Max: 400 mg per appt
Pregnancy risk B
liver and lung toxicity: 0-toluidine =methemoglobinemia

Question 25

Stats of bupivicaine? onset, duration, max dose, etc.

Answer 25

onset: 1-17 minutes
duration: 2-9 hrs
max: 90mg per appt
Pregnancy risk C

Question 26

What is the safest LA to use on children and pregnant people?

Answer 26

lidocaine

Question 27

What LA do you use on pts who can’t have epinephrine?

Answer 27

mepivocaine (short duration though)

Prilocaine (liver and lung toxicity)

Question 28

What is this methemoglobinemia?

Answer 28

oxidation of Hb to methemoglobin so then there is less oxygen to the tissues = hypoxia.and it is treated with methylene blue and o2 solution.

Question 29

What LA do you use when lidocaine doesn’t get the pt numb?

Answer 29

Articaine - penetrates bone!
caution with regional blocks
be so careful with kids and articaine

Question 30

What LA is extremely cardiotoxic and how?

Answer 30

bupivicaine - binds strongly to the sodium channels and causesCV collapse and resistant resuscitation. (never use in kids or preggers)

Question 31

What goes in the chart for LA?

Answer 31

What type and concentration, # of carpels, and method of administration.