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2 Pharm Unit > 24 Local Anesthesia > Flashcards

24 Local Anesthesia Flashcards

1
Q

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

A

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

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2
Q

What are the 2 classifications of local anesthetics?

A

Amide and ester

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3
Q

Where are the amides metabolized?

A

liver

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4
Q

Where are the esters metabolized or by what?

A

plasma esterases

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5
Q

Cocaine and benzocaine are used as what in local anesthesia?

A

topical esters

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6
Q

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

A

an I before the caine

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7
Q

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

A

true

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8
Q

Is procaine high potency?

A

No, low

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9
Q

Is mepivacaine and lidocaine intermediate potency?

A

Yes

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10
Q

Is tetracaine and bupivicaine low potency?

A

No, high

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11
Q

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

A

False–protonated but are weak bases

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12
Q

Where doe the protonated local anesthetic act?

A

Binds to the voltage gated Na channel from the intracellular space

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13
Q

Na influx is important for what in the nerve?

A

Initiation of action potential,

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14
Q

Small doses of lidocaine can give a good block?

A

False, need huge doses

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15
Q

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

A

scrambles the conduction

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16
Q

T-F–Esters pKa are lower that amides?

A

False

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17
Q

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

A

decreases

18
Q

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

A

True

19
Q

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

A

not very well

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

20
Q

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

A

pH=pKa+log LA/LA+

[LA+=local anesthetic protonated]

21
Q

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?

A

LA/LA+ = 1/10

LA/LA+=10

22
Q

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

A

False-intracellular

23
Q

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

A

Csymp–>autonomic functions

Csens–>pain, temp, touch

24
Q 
Nerve subclasses below have what functions?
Aalpha=?
Abeta?
Agamma?
Asigma?
B?
A 
alpha=motor/proprioception
beta=motor/proprio/touch
gamma=muscle tone
sigma=pain/temp/touch
B=autonomic functions
25
Q

Is B or C symp nerve subclass preganglionic sympathetics?

A

B is. C is postganglionic sympathetics

26
Q

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

A 
Numb Tongue
Lighthead
vis/aud disturb
Unconsciousness
Convulsions
Coma
Respiratory Arrest
Cardiac Toxicity
27
Q

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

A

After

28
Q

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

A

Intercostal

[Then epidural and then subcutaneous]

29
Q

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

A

Epinephrine because of its vasoconstrictive actions

30
Q

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

A

Intralipid-intravenously

Also, barbiturates or benzodiazepines for seizures

31
Q

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

A

Esters

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

32
Q

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

A

methemoglobinemia

33
Q

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

A

1% lidocaine intra or subQ

34
Q

What is the Bier Block?

A

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
Q

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

A

electrical stimulator

36
Q

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

A

Femoral and sciatic

37
Q

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

A

vasoconstrict—>MI

38
Q

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

A

S

39
Q

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

A

8.5% Dextrose

40
Q

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

A

1 gram to 200,000ml

41
Q

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

A

5mcg/ml

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

42
Q

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

A

1g/100ml

10mg/ml

2 Pharm Unit (17 decks)

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