24 Local Anesthesia Flashcards Preview

2 Pharm Unit > 24 Local Anesthesia > Flashcards

Flashcards in 24 Local Anesthesia Deck (42):
1

What are the key differences of local anesthetics from general anesthesia?

nerve blockade to eliminate SENSORY and MOTOR response to a surgical stimulus

2

What are the 2 classifications of local anesthetics?

Amide and ester

3

Where are the amides metabolized?

liver

4

Where are the esters metabolized or by what?

plasma esterases

5

Cocaine and benzocaine are used as what in local anesthesia?

topical esters

6

Amides have what in their name to help give you a clue?

an I before the caine

7

T-F--local anesthetics are more potent when they are lipid soluble?

true

8

Is procaine high potency?

No, low

9

Is mepivacaine and lidocaine intermediate potency?

Yes

10

Is tetracaine and bupivicaine low potency?

No, high

11

T-F--local anesthetics are protonated as a weak acid?

False--protonated but are weak bases

12

Where doe the protonated local anesthetic act?

Binds to the voltage gated Na channel from the intracellular space

13

Na influx is important for what in the nerve?

Initiation of action potential,

14

Small doses of lidocaine can give a good block?

False, need huge doses

15

A lot of locations for lidocaine on a nerve causes what?

scrambles the conduction

16

T-F--Esters pKa are lower that amides?

False

17

As tissue pH decreases the amount of local anesthetic in the nonionized form _________?

decreases

18

T-F--local anesthetics differ in duration of action>

True

19

How well do local anesthetics work in acidotic tissue? Outcome?

not very well

Drug cannot enter intracellular space and this is when toxicity can be a major concern

20

What is the henderson hasselbach equation as it relates to local anesthetics?

pH=pKa+log LA/LA+

[LA+=local anesthetic protonated]

21

What is the fraction of neutral local anesthetic to local anesthetic protonated of a drug at pH6.4 and a pka of 7.4?
What about a pH of 8.4?

LA/LA+ = 1/10

LA/LA+=10

22

T-F--local anesthetic drugs bind the extracellular Na channel portion blocking the depolarization and sensory/motor signals.?

False-intracellular

23

Which subclass [2] of nerve fibers are less sensitive (1/2 sensitive) to local anesthetics? What do they do?

Csymp-->autonomic functions

Csens-->pain, temp, touch

24

Nerve subclasses below have what functions?
Aalpha=?
Abeta?
Agamma?
Asigma?
B?

alpha=motor/proprioception
beta=motor/proprio/touch
gamma=muscle tone
sigma=pain/temp/touch
B=autonomic functions

25

Is B or C symp nerve subclass preganglionic sympathetics?

B is. C is postganglionic sympathetics

26

With increasing plasma concentrations, what are the signs and symptoms of local anesthetic toxicity? [There are several, try climbing the latter]

Numb Tongue
Lighthead
vis/aud disturb
Unconsciousness
Convulsions
Coma
Respiratory Arrest
Cardiac Toxicity

27

Does cardiac toxicity come before or after coma in regards to local anesthetic toxicity?

After

28

What type of administration technique of local anesthetic creates the highest plasma concentration levels and subsequently leads to greatest risk of toxicity?

Intercostal
[Then epidural and then subcutaneous]

29

What is used in conduction with local anesthetics to lower the systemic plasma concentration of the drug?

Epinephrine because of its vasoconstrictive actions

30

For local anesthetic toxicity what drugs do we give? [2]

Intralipid-intravenously
Also, barbiturates or benzodiazepines for seizures

31

Are esters or amides local anesthetics more likely to give an allergic reaction to ? [what are the major or more common culprits though?]

Esters

[Others are the EPI/preservatives and other drugs used]

32

Ester local anesthetics such as benzocaine for baby teeth have shown what dangerous side effect in children?

methemoglobinemia

33

What local anesthetic is most used for starting IV and minor surgeries?

1% lidocaine intra or subQ

34

What is the Bier Block?

Intravenous injection of anesthetic into extremity that has a tourniquet more proximal to injection
[surgeries up to 2 hours, may be useful for chronic pain]

35

How do we find the nerve for a femoral nerve blockade?

electrical stimulator

36

What are the 2 major peripheral nerve blockade for leg surgery?

Femoral and sciatic

37

What is the major toxicity/side effect we must always be concerned about with cocaine?

vasoconstrict--->MI

38

Is ropivacaine the s-isomer or r-isomer of a racemic mixture?

S

39

What is a common additive to increase basicity or create heaviness?

8.5% Dextrose

40

If epinephrine has a 1 to 200,000 ratio, what does this mean?

1 gram to 200,000ml

41

If I wanted to convert an epinephrine 1:200,000 to mcg/ml what would it be?

5mcg/ml

[1g/200,000ml--->1,000,000mcg/200,000ml--->5mcg/ml]

42

1% solution of lidocaine contains what g/ml? mg/ml?

1g/100ml

10mg/ml