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Levi's Class 2014 > Week 6 Review of Local Anesthetics > Flashcards

Week 6 Review of Local Anesthetics Flashcards

1
Q

T/F: Local anesthetics can produce a reversible conduction blockade of impulses along the central and peripheral nerve pathways.

A

True

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2
Q

When and what was the 1st local anesthetic?

A
  • Cocaine

- 1884

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3
Q

When and what was the 1st synthetic local ester?

A
  • Procaine

- 1905

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4
Q

When and what was the 1st local amide?

A

-lidocaince

1943

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5
Q

What separates the lipophilic and hydrophilic portion of the chemical structure?

A

-hydrocarbon

which makes it a amide or ester

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6
Q

What part of the chemical structure makes the drug lipophilic active?

A

-Benzene Ring

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7
Q

What is the chemical chain for a ester?

A

-CO

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8
Q

What is the chemical chain for a amide?

A

-NHC

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9
Q

T/F: The quaternary amine is hydrophilic.

A

TRUE

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10
Q

What is the pH extracellular (usually)?

A

7.4

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11
Q

What is the pH intracellular (usually)?

A

7.0

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12
Q

What type of enantiomers does racemic use?

A

-s enantiomers and r enantiomers

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13
Q

T/F: A pure isomers uses both enantiomers s and r.

A

FALSE

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14
Q

What two drugs are pure isomers and what enantiomer do they use?

A
  • Ropivacaine
  • Levobupivacaine
  • Enantiomers s
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15
Q

What is the benefit of a S enantiomer?

A
  • Less nuero toxic

- Less cardio toxic

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16
Q

What is the mechanism of action for a local anesthetic?

A

-INHIBITS Na IONS PASSAGE THROUGH ION-SELECTIVE Na CHANNELS

  • Slows rate of depolarization
  • Threshold potential not reached
  • No action potential propogated
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17
Q

What does a local anesthetic NOT alter?

A
  • Resting membrane potential

- Threshold potential

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18
Q

What does the alpha Na+ channel subunit do?

A

Allows ion conduction and binds local

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19
Q

T/F: Local anesthetic bind to receptors in inactivated or open states.

A

True

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20
Q

What occurs if local is not permeable to the Na+?

A

The threshold and action potential cannot be obtained.

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21
Q

Is local anesthetic a strong or weak bond?

A

Weak

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22
Q

The local anesthetic binds both to the internal and external Na+ channel: which is the to be more important?

A

Internal channel

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23
Q

How does frequency dependent blockade work for local anesthetics?

A
  • Access only obtained when receptor is in activated open state
  • Nerves with more activity means faster blockade
  • More frequent firing means more opportunity for access
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24
Q

What is minimum concentration?

A

minimum concentration to produce conduction blockade

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25
Q

What factors influence minimum concentration?

A

INCREASES
-Nerve diameter

DECREASES

  • Higher frequency
  • Higher pH
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26
Q

About how much more blockade is required for a motor blockade then a sensory blockade?

A

2 times as much

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27
Q

How many nodes of Ranvier must a local anesthetic block to obtain local anesthetic?

A

2 to 3

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28
Q

Which nerve fibers are preganglionic sympathetic efferent?

A

B fiber

29
Q

Which nerve fibers are responsible for pain, temperature, and touch?

A
  • C fibers

- A fibers

30
Q

List the blockade order in which sensation will be last first?

A

ATP - TP - MVP

A - utonomic
T - Temperature
P - Pain

T - touch
P - Pressure

M - otor
V - ibration
P - Proprioception

31
Q

A differential blockade will NOT B fibers, C fiber, and small medium A fibers.

A

FALSE

32
Q

What nerve fiber will most likely not be blocked?

A

Large A Fibers

33
Q

What will a differential blockade achieve?

A
  • sympathectomy
  • Loss of sensation for pain and temp
  • May still have proprioception and moter.
34
Q

What is the pH on a weak base local anesthetic?

A

7.6 to 8.9

35
Q

Which form (ionized/unionized) crosses the lipid bylayer?

A

-unionized

36
Q

What local will have a faster onsent?

A

-locals with pH nearest physiologic pH

37
Q

Adding bicarb to a local will cause what to happen with the onset?

A

Faster onset by 3 to 5 minutes

38
Q

T/F: The lower the pH of a local anesthetic the less it will sting.

A

FALSE

39
Q

List the area of the body where 1st, 2nd, and 3rd distribution occur.

A

1st - Lungs

2nd - Heart, brain, kidney (high perfused tissue)

3rd - Muscle and fat (Low distrubution)

40
Q

Which class of local is more widely distributed?

A

-AMIDES

41
Q

Why do we worry about which vasopressor can cause fetal acidosis>

A

-Once the unionized local crosses the placental it become ionized do to the baby’s lower pH and can not transport.

42
Q

What does lipid solubility mean?

A

The more lipid soluble means easier to cross lipid bylayer (POTENCY)

43
Q

Amides are metabolized where mainly.

A
  • mainly in the hepatic system

- Minimal renal exretion

44
Q

Name to local amides from fastest to slow onset?

A
  • prilocaine (FASTEST)
  • Lidocaine and mepivicaine (Intermediate)

Etidocaine, Bupicaine, Popivacan (SLOW)

45
Q

Where are ester metabolized and how?

A
  • Plasma

- Cholinesterases found in the plasma through rapid hydrolysis

46
Q

What one esters is not metabolized by cholinesterases?

A

Cocaine

47
Q

What metabolite do ester make that are the main concern?

A

-Paraaminobenzoi acid (PABA)

48
Q

What common local infection site contains little to no cholinesterase enzyme?

A

CSF

49
Q

What factors will inhibit plasma cholinesterase?

A
  • Deficiency
  • Liver disease
  • Increase BUN
  • Parturients
  • Chemotherapy
50
Q

Which vasoconstrictor not an ester or amine can be added to a local?

A
  • Epinephrine
  • phenylephrine
  • norepinephrine
51
Q

Calculate the the mcg/mL if Epinephrine were labeled 1:200000.

A

5 mcg/cc

52
Q

By how much can a vasoconstrictor prolong an effect?

A

1/3 time longer

53
Q

Which two local anesthetic contain no vasodilator activity?

A
  • Cocaine

- Ropiviaine

54
Q

How much can clonidine prolong the effects of an epidural or a spinal?

A

Epidural from 1.8 hour to 5.3 hours

Spinal from 170 minutes to 215

55
Q

What does epi do to lidocaines pH when mixed?

A

Causes the pH to go down to 4.5

56
Q

T/F: Mixing locals together has a synergistic effect.

A

FALSE (Additive)

57
Q

Which local may cause more of an allergic reaction

A

Esters.

58
Q

If a local is injected intravascularly what are the symptoms?

A
  • Hypotension
  • syncope
  • tachycardia
59
Q

List Hadzic’s Progression from least to greatest.

A
  • vertigo
  • Tinnitus
  • Ominous feelings
  • Circumoral numbeness
  • Garrulousness
  • Tremors
  • myoclonic jerks
  • Convulsions
  • Coma
  • Cardiovascular collaspe
60
Q

List the systemic levels related to blood flow of tissue from fastest to slowest for a local?

A
  • IV
  • Tracheal
  • Intercostal
  • Caudal
  • Paracervical
  • Epidural
  • Brachial Plexus
  • Subarachnoid
  • Subcutaneous

Acronym: In Time I can Please Everyone But Suzi and Sally.

61
Q

List important information about Transient Neurologic Symptoms (TNS)?

A

-Moderate to severe pain
Lower back, buttocks, and posterior thighs
-Unknown etiology
-Highest risk after intrathecal lidocaine

62
Q

List important information about Cauda Equina Syndrome?

A

-Diffuse injury across lumbosacral plexus
Various degrees of sensory anesthesia
Bowel and bladder sphincter dysfunction
Paraplegia
-Related to Lidocaine

63
Q

List important information about Anterior Spinal Artery Syndrome?

A

-Lower extremity paresis and variable sensory defecit.

64
Q

What must the Bupivacaine levels be to see cardiotoxicity?

A
  • 8 to 10 mcg/mL
65
Q

How would you treat local anesthetic toxicity?

A
  • Airway management
  • Seizure suppression
  • Management of arrhythmias
  • Lipid emulsion (20%)
66
Q

What drugs would be avoided for local toxicity especially if you had arrythmias.

A
  • vasopressin
  • calcium channel blocker
  • Betablockers
  • local anesthetic
67
Q

Methemoglobinemia is related to local, but how would it be treated?

A

-methylene blue 1 to 2 mg/kg over 5 minutes

68
Q

What is the correct dosage for a lipid emulsion (20%) therapy?

A
  • 1.5 mL/kg (LEAN BODY MASS)

- 0.25 ml/kg

69
Q

How long after would you continue to treat for a local cardiogenic toxicity?

A

10 minutes

Levi's Class 2014 (16 decks)

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