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Flashcards in Anesthetics II Deck (90):
1

What are the major disadvantages of local anesthesia?

Potential for systemic toxicity if use large enough amounts

Poor minute-minute control

2

Procaine = ?

Novocain

3

What is perineural infiltration of anesthetics?

Nonspecific injection of the agent at one or more sites around specific area

4

What is regional nerve blocks?

Inject around a specific nerve to block sensory and motor fibers distal to the block

5

What is the major advantage and major disadvantage to nerve blocks?

Advantage = less drug required

Disadvantage = Require more skill and anatomical knowledge

6

What is the MOA of a spinal block?

Injection of an agent into the lumbar subarachnoid space to read the roots of the spinal nerves that supply a specific region

7

True or false: once in the spinal canal, there are no barriers to keep a drug from reaching the brain

true

8

What are the two main advantages of spinal blocks?

More reliable; return of CSF indicates correct placement

Pt is conscious with minimal disruption of heart/lungs

9

What are the major disadvantages of spinal blocks?

Not reversible
No titration

10

Why can spinal blocks lead to hypotension?

Blockage of sympathetic innervation to the distal regions of the block

11

What is an epidural block?

Inject into the extradural space and block the root as it passes through the space

12

What is the major advantage to epidurals?

Not time limited
Can be titrated

13

What is the major disadvantage to an epidural?

Less reliable than spinal block

14

What is the way to inject IV anesthesia locally?

Inject with tourniquet, but will eventually go through circulation, so not used often

15

For the ideal local anesthetic, do you want it to be short or long lasting?

Short

16

What is the MOA of brain signalling of pain? What signalling pathway is utilized? Where does this cross?

Local release of bradykinin, substance P causes activation of local spinothalamic fibers, which crosses at and above the level, and ascends to the sensory cortex

17

What is the MOA of local anesthetics?

Block the transient increase in Na channel permeability, thereby raising the threshold for excitability

18

Is the resting permeability of K affected by local anesthetics?

Yes

19

What happens to local anesthetics when they enter the body? How do they get into a cell?

Deprotonated, which allows them to cross the lipid bilayer

20

Which side of the Na channels do local anesthetics work on: intracellular or extracellular side?

Intracellular

21

What are the local anesthetics that bind to the outside of the Na channel?

Biotoxins

22

What is the MOA of lidocaine?

Binds to the intracellular side of the Na channel, preventing its opening

23

What is the MOA of benzocaine?

Gets into the lipid bilayer, and changes the conformation of the Na channel (membrane expansion theory)

24

What is the MOA of most locally used anesthetics?

Binds to the intracellular Na channel binding site

Interrupts the geometry of lipid bilayer

25

What is the MOA of tetrodotoxin? Where does this come from?

Pufferfish toxin that binds to the outside of the local Na channels, and prevents opening of the channel

26

What are the two chemical structural parts of all local anesthetics? Why is each important?

Aromatic ring for lipophilicity to pass through membrane

Tertiary amine (polar) for binding

27

What are the two general classification of local anesthetics (based on chemical structure)? What differentiates each agent within each of these groups?

Amides
Esters

The intermediate chain (between the amide/ester and the tertiary amine group)

28

What is the suffix associated with local anesthetics?

"-caine"

29

What is the rule for differentiating amides from esters?

Generally, amides have two "i"s in their name, while esters have one

30

Amide or ester: lidocaine

Amide

31

Amide or ester: cocain

Ester

32

Amide or ester: articaine

Amide

33

Amide or ester: mepivacaine

Amide

34

Amide or ester: procaine

Ester

35

Amide or ester: etidocaine

Amide

36

Amide or ester: benzocaine

Ester

37

Amide or ester: tetracaine

Ester

38

Amide or ester: Prilocaine

Amide

39

Amide or ester: Bupivacaine

Amide

40

Amide or ester: chloroprocaine

Ester

41

Amide or ester: ropivacaine

Amide

42

Amide or ester: levobupivacaine

Amide

43

What type of chemical are all local anesthetics: weak bases, weak acids, strong bases, or strong acids?

Weak bases

44

What is the uncharged form of local anesthetics important for?

Lipid penetration of membranes

45

What is the charged forms of local anesthetics useful for?

Active form at Na receptor

46

How are amides metabolized? Esters? Which, therefore, is impaired with hepatic problems

Amides = p450s **hepatic
Esters = butyryl cholinesterases

47

What is the relative half life of amides? Esters?

Amides = Long
Esters = short (

48

What is the minimum anesthetic concentration (Cm)?

Minimum concentration of drug for standard block (relative standard of potency)

49

How does the size of the neuronal fiber that is being blocked relate to the Cm needed to block it?

increased fiber size = increase Cm needed

50

What is order of fibers that are blocked, from first to last? (hint: same order as smallest to largest)

B fibers
C fibers
A-delta
A-gamma
A-beta
A-alpha

51

Are C fibers myelinated? What information do they carry?

No
Slow pain and temp

52

What are A-alpha fibers used for?

motor/proprioception

53

What are A-beta fibers used for?

Discriminative touch

54

What are A-delta fibers used for?

Fast pain, temp, crude touch

55

What are B fibers used for?

Preganglionic fibers

56

What is the standard of potency for local anesthetics?

Cm

57

Which are affected first: myelinated or unmyelinated fibers?

Myelinated

58

What is the relationship between pH and local anesthetic Cm?

Increased pH means lower Cm needed

59

What is the relationship between [Ca] and Cm?

Increased [Ca] = Increased Cm

60

What is the relationship between nerve stimulation rate and Cm?

Higher frequency nerves are most sensitive to LA

61

Why are vasoconstrictors added to LA preparations?

Stays local longer
Increases duration of action

62

What is the vasoconstrictor commonly used with LAs?

Epi

63

What are the areas that should never be injected with LA that have epi? (5) Why?

Digits
Toes
ear Lobes
Nose
Penis

All have arterioles, and have the potential to develop sloughing off of tissue

64

What are the four factors that affect reversal of LAs?

1. Dilution by ECF
2. Absorption into circulation
3. Redistribution to other areas
4. use of vasoconstrictors

65

What is the most important factor that affects the reversal of LAs?

Absorption into circulation

66

What are the two factors that are involved in redistribution of LAs?

Organ blood flow and plasma protein binding

67

Where are amides/esters metabolized

Amide = liver
Esters = plasma by BChE

68

What is the metabolite that is produced by metabolism of esters? Why is this concerning?

Para-Aminobenzoic acid (PABA)

May cause allergic reaction

69

True or false: there is cross reactivity between esters and amides. Thus if a pt is allergic to one group, they are likely allergic to the other

False

70

Why are esters less likely to have systemic toxic effects?

Rapid metabolism in the blood

71

Most of the allergic reaction in LA are actually due to what preservative?

Methylparaben

72

Systemic toxicity of what LA can cause Cardiac collapse and death d/t its selectivity

Bupivacaine

73

What is the treatment for local anesthetic systemic toxicity (LAST)? MOA?

IV lipid emulsion (intralipid)

Forms a sink for the LA

74

What is the reference standard for amide LAs?

Lidocaine

75

What is the LAs that can be used both topically and via injection?

Lidocaine

76

If attempting to give an epidural for a c-section, what LA would you use?

Lidocaine

77

What is the toxic effect of lidocaine?

Transient neurologic symptoms (with spinal administration

78

What is the clinical use of bupivacaine?

Agent of choice for epidural infusion for labor analgesia and post-op pain

79

True or false: bupivacaine is an excellent spinal anesthetic?

True

80

What are the toxic effects of bupivacaine?

CNS excitation and cardiac collapse

81

What is the less toxic form of bupivacaine?

Levobupivacaine

82

What is the clinical use of articaine?

Dental anesthetic

83

What is the clinical use of cocaine?

Topical anesthetic for HENT procedures

84

What is the clinical uses for benzocaine?

Topical only anesthetic,

85

What is the clinical use of chloroprocaine

epidural agent for labor

86

What is exparel-liposome?

Encased bupivacaine in a liposome, that is given post op for pain

87

What is EMLA? Clinical use?

Eutectic mixture of Local Anesthetics (lidocaine + prilocaine)

Topical anesthetic

88

What is TAC? Clinical use?

Tetracaine
Adrenalin
Cocaine

Topical used in pediatric emergencies

89

What are neurolytics?

Agents that are not reversible, and achieve a permanent local anesthesia

90

What are the two prototypical neurolytics?

Ethyl alcohol
Phenol