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Anesthesia Pharmacology > Lecture 17 (Exam 4) - Local Anesthetics Pt. 2 > Flashcards

Lecture 17 (Exam 4) - Local Anesthetics Pt. 2 Flashcards

1
Q

Although Chloroprocaine and Bupivacaine have similar potency values… which has a faster onset and why?

A

Chloroprocaine has a faster onset because it has a more lipid soluble component
Slide 10

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2
Q

Which drug has an additive effect with Bupivacaine, increasing the onset of action when given in conjunction?

A

Chloroprocaine
Slide 10

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3
Q

What are the two most common vasoconstrictors used in conjunction with local anesthetics?

A

Neo and Epi
Slide 11

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4
Q

The duration of action of a local anesthetic is proportional to what?

A

The time the drug is in contact with nerve fibers
Slide 11

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5
Q

What are some reasons we use vasoconstrictors with local anesthetics?

A
  • Produce vasoconstriction
  • Increased neuronal uptake of LA
  • Alpha-adrenergic effects may have some degree of analgesia
  • No effect on the onset rate of LA
  • Enhanced cardiac irritability with inhaled anesthetics

Slide 11

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6
Q

Alpha-adrenergic effects have some degree of ___________ by blocking nerve transmission.

A

Analgesia

Slide 11

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7
Q

Patient A receives plain Lidocaine while Patient B receives Lidocaine with Epi, which patient has a faster rate of plasma absorption?

A

Patient A

Slide 12

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8
Q

No question… Just a graph

A

Local anesthetics given with Epi have a slower rate of plasma absorption due to vasoconstriction and the drug staying at the site of action for longer durations.

Slide 12

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9
Q

Local Anesthetic Strengths:
0.25%
0.5%
1%
2%
4%

A

0.25% = 2.5 mg/mL
0.5% = 5 mg/mL
1% = 10 mg/mL
2% = 20 mg/mL
4% = 40 mg/mL

Slide 14 (Pack this in your brain)

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10
Q

What is the concentration of 1:200,000 Epi?

A

5 mcg/mL (1,000,000/200,000)

Slide 14

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11
Q

What is the concentration of 1:500,000 Epi?

A

2 mcg/mL
(1 million/500 thousand)

Slide 14

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12
Q

What is the concentration of 1:10,000 Epi?

A

100 mcg/mL (1 million/10 thousand)

Slide 14

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13
Q

What is the concentration of 1:1,000 Epi?

A

1,000 mcg/mL (1 million/1 thousand)
This also equals 1 mg/mL

Slide 14

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14
Q

Spinal (Subarachnoid) anesthesia results in blockade in segments, referred to as “segmental block.”

What is the 1st segment that is affected when we do a spinal/epidural block?
2nd?
3rd?

A
  1. SNS
  2. Sensory
  3. Motor

Slide 35

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15
Q

Which fibers are affected in the 1st segment in a segmental blockade?

Which fibers are affected in the 2nd segment in a segmental blockade?

Which fibers are affected in the 3rd segment in a segmental blockade

A

PREganglionic B (myelinated, fastest) fibers are blocked 1st!!! (THESE ARE NOT BETA!) –> these affect the SNS!

Followed by the sensory fibers (pain, temp) - myelinated A , myelinated B, then unmyelinated, small, C…

Followed by proprioception/motor fibers - myelinated A-delta and unmyelinated C

Recap: (SNS) Preganglionic B > (pain/temp) A, B, C > (motor) A-delta, C

Slide 35

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16
Q

With LA in a spinal, what is the 1st sign you will see? and why?

A

Hypotension from vasodilation 2/2 blocking B fibers (SNS) & tachycardia

Can also be called a “sympathectomy”

Slide 35

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17
Q

You are doing an Interscalene Block on one of your patients. You lay them down and scan their neck, and get the image below. Where would you inject the LA?

A

You would inject the LA into the shaded blue area and let the nerves (Yellow) absorb the LA.

(Slide 30)

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18
Q

Lets practice!
Below is an image of a few nerves you want to numb!
Identify which area you would inject the LA into!

A

You would inject the LA into the blue shaded area and then let the nerve absorb the medication.

(Slide 32)

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19
Q

Tell me about IV Regional Anesthesia.
AKA (August) Bier Block.

A

IV injection of LA into an extremity isolated from the rest of the systemic circulation with a tourniquet
Sensation and muscle tone are dependent on tourniquet!

Ester or amide LA can be used
Mepivacaine > Lidocaine, but …
Most commonly used: Lidocaine because of less side effects.

(Slide 33)

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20
Q

What are the steps for a Bier Block?

A
  1. IV start
  2. Exsanguination
    ➤ Exsanguinate with a rubber (Esmarch) tourniquet, you are trying to wring out as much blood out of the extremity so that there is little amount of blood.
  3. Double cuff
    ➤ Apply double cuffs on top of tourniquet. One cuff proximal and one distal.
  4. Give LA injection
    ➤ Surgeon does his thing.
  5. IV D/C
    ➤Release tourniquets one by one so that the anesthetic goes systemic slowly not fast.

(Slide 34 and Castillo)

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21
Q
  1. For a Bier Block, how long do you have to stop circulation before giving LA?
  2. If you are doing ankle surgery, how long can you keep the tourniquet on that leg?
  3. How will you know how much pressure to apply to your tourniquet when doing a Bier Block?
A
  1. Circulation is stopped 30 min to an hour before injection of LA.
  2. For a leg procedure using the Bier Block, you can keep the tourniquet for up to 2 hours on that leg,
  3. To perform the block will have to be on 100 points higher than the systolic BP of the leg.
    If the blood pressure on the leg Is 150/80 mmHg, the tourniquet must be applied with a pressure of 250 mmHg.
    ➤The leg is not at risk for amputation being at this pressure for 2 hours. The artery is still supplying the leg with blood. It is the vein that is mainly blocked.

(Slide 33)

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22
Q

How do we know we are in the spinal (subarachnoid) area?

A

Aspiration of CSF

Slide 36

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23
Q

What is the principle site of action in SAB (spinal anesthesia block)?

A

Preganglionic fibers

Slide 36

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24
Q

Not only do we have time segments, we also have ______ segments with LA’s.

These will have effects below and above the denervation site.

A

layer/anatomic

Slide 36

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25
Q

If you block at T10 (umbilicus), where will you see sensory blockade?

A

T10

Slide 36-37

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26
Q

If you block at T10 (umbilicus), where will you see SNS blockade?

A

up to T8 (2 levels cephalad of denervation)

Slide 36-37

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27
Q

If you block at T10 (umbilicus), where will you see motor blockade?

What sx is this block useful for?

A

down to T12 (2 levels below denervation)

This block can be useful for an appendectomy. (not for C section)

Slide 36-37

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28
Q

What dermatomes correlate with our cardiac accelerators?

If you block here, what will happen?

A

T1- T4 ❤️

Can cause bradycardia/asystole 😅

Slide 37

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29
Q

What are the 5 most common LA for a SAB (subarachnoid block)?
HINT: TLBRB

A

Slide 38

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30
Q

The dosage of SAB LA’s is based on what 3 things?

A

Slide 38

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31
Q

_______ is more important than concentration of the drug (%) or the volume (mL) of the solution injection when it comes to SAB’s.

For 0.75% bupivacaine, you give 1mL if the patient is 5ft.
You add _____ ml for every _____ above.
So if your patient is 5’5”, you will give how many ml’s?

A

Dose
(This is bc the drug is the same mg / %…0.75% bupivacaine…)

You add 0.1mls for every inch above 5ft…
1.5mls

**not really sure where he got the 2cc’s total on the slide…

Slide 39

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32
Q

What is important in determining the spread of the drug?

A

Its specific gravity!

Slide 39

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33
Q

If you add glucose to the LA, it will _____. This can also be called _______.
If you add distilled water to the LA, it will ____. This can also be called ______.

If you are using a hypobaric spinal LA, which side will you want your pt lying on if you are operating on the R hip?

A

Glucose = sinks; hyperbaric (LA sp. gravity > CSF)
Distilled water = Float; hypobaric

You will want the pt LEFT side-lying bc the drug will float and affect the upper (right) hip.

Slide 39

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34
Q

112.5 mgs of Bupivacaine with Epi and 250 mgs of Lidocaine with Epi were both given during a plastic surgery case.
What are the percentages of each local anesthetic based on the recommended maximum single dose in mgs?

A

Max dose of Bupivacaine is 225mg with Epi, so 112.5mg is 50% of the max dose of Bupivacaine.
Max dose of Lidocaine is 500mg with Epi, so 50% of max dose for lidocaine.
So, 50% of lidocaine and 50% of Bupivacaine totals to 100% of LA. You cannot give LA anymore as you have already given max of 100% LA and they have additive effect.
Slide after 21clinical scenario.
(use other adjunct like, ketamine, magnesium, propofol etc)

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35
Q

What are single Max recommended maximum dose for lidocaine with Topical, Infiltration, IVRA, PNB, Epidural, and spinal usages?

A

Topical 300mg
IVRA 300mg
Infiltration, PNB, and Epidural 300 or 500mg with Epi
Spinal 100mg
Slide 21

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36
Q

What are single max recommended maximum dose for Mepivacaine with clinical usage of infiltration, PNB, Epidural, Spinal?

A

Infiltration, PNB, and Epidural 400 or 500mg with epi
Spinal 100mg
Slide 21

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37
Q

What are the single max recommended dosages for Prilocaine with clinical usages of infiltration, IVRA, PNB, Epidural?

A

Infiltration, IVRA, PNB, and Epidural → 600mg
Slide 21

38
Q

What are the single max recommended dosages for Bupivacaine with clinical usages of infiltration, PNB, Epidural, and spinal?

A

Infiltration, PNB, and Epidural → 175 or 225mg with epi.
Spinal 20mg
Slide 21

39
Q

Topical Anesthesia is applicable on _____.

A

Mucous membranes of the nose, mouth, tracheobronchial tree, esophagus, or GU tract.
Slide 22

40
Q

What are the most common LA seen in clinical practice?

A

Tetracaine (1% to 2%)
Lidocaine (2% to 4%)
Cocaine (4% to 10%)
Slide 22

41
Q

What are two LA that are not effective as Topical anesthesia?

A

Procaine and Chloroprocaine
(They do not penetrate mucous membranes as much as cocaine, tetracaine, and lidocaine)
Slide 22

42
Q

Cocaine produces localized ___________, hence it ______blood loss and ______surgical visualization.

A

Cocaine produces localized VASOCONSTRICTION, hence it DECREASES blood loss and IMPROVES surgical visualization.
Slide 22
(A lot of ENT surgeons especially sinus procedures use cocaine by applying on Qtips.)

43
Q

T/F. Lidocaine is great with surface anesthesia.

A

True
Slide 22

44
Q

T/F. Inhalation of lidocaine alter airway resistance.

A

False, It does not alter airway resistance but it causes vasodilation.
Slide. 22

45
Q

Would you use lidocaine gel in oral airway or nasal airway and why?

A

Nasal airway as you are just suppressing the sneezing reflex of the upper airway.
You do not want to use in the oral airway because you want to keep your lower respiratory reflexes intact, like Pharyngeal, and laryngeal (swallowing, gaging, and coughing).
Slide 22

46
Q

What are the two ways you can give topical lidocaine to the patient?

A

Inhalation and topical lidocaine gel.
Slide 23

47
Q

When do you use lidocaine inhalation?

A

4% lidocaine is used before bronchoscopy and EGD to prevent airway reflexes when pt is not intubated.
Slide 23

48
Q

LTA (Lidocaine tracheal anesthesia or Localized tracheal anesthesia) is used for _____.

A

Especially used in patients with reactive airway diseases (asthma and COPD) and smokers (marijuana, Vape and cigarettes)
Slide 23

49
Q

What LA does EMLA (Eutectic Mixture of LA) contains?

A

Lidocaine 2.5% and Prilocaine 2.5% = 5% LA in cream
Slide 24

50
Q

What is the dosage EMLA and the onset of action?

A

1 to 2 gms/10cm square area
Onset of action: 45 minutes but can be used in 10 minutes for
Cautery of genital warts
venipuncture, lumbar puncture
Arterial cannulation (nitroglycerine)
Myringotomy (ear tube placement)

With skin grafting, you need to wait at least 2 hours for onset of action.
Slide 24

51
Q

What is the average pKa of LA?
Are they weak acids of bases?

A

8
Alkalotic- weak bases

(slide 5)

52
Q

What is the function of Alkalinization of LA?

A

alkalinization increases the % of lipid-soluble or non-ionized form

(slide 5)

53
Q

What is the benefits of Alkalinization of LAs?

A

Faster onset of action
- Peripheral and epidural blocks by 3 to 5 mins.
Enhances the depth
Increase the spread (i.e., epidural)

54
Q

How can we find the ionization vs non-ionization? (Dr. Kane’s way)

A
55
Q

If the weak base drug V has a pKa of 9.1, is the drug more ionized or nonionized in the blood with a pH of 7.4?

A

ionized (+)
9.1-7.4= +1.7

(slide 6)

56
Q

If the weak base drug W has a pKa of 4.5, is the drug more ionized or nonionized in the blood with a pH of 7.4?

A

nonionized (-)
4.5 - 7.4= -2.9

(slide 6)

57
Q
A

2 correct answers. Both LAs will have a more ionized components

58
Q

what 5 drugs discussed in class are given as adjuvant therapies with LA to either increase/prolongs DOA of LAs?
(And which drugs do what?)

A

Dexmedetomidine IV- Increases duration
Magnesium- increases duration
Clonidine- prolongs
Ketamine- prolongs
Dexamethasone- increases

(slide 8)

59
Q

If you are in the OR mixing your concoction of LA drugs to give to your patient and you notice the medications produce precipitate, what do you do?

A

Do not give!! Yeet it to the waste bend

(slide 9)

60
Q

For combinations of LA, which 2 drugs added together can produce a rapid onset BUT can also cause tachyphylaxis?

A

Chloroprocaine & Bupivacaine

(sldie 9)

61
Q

For combinations of LA, what drug can be added in a very small amount? what is that amount?
And what other combination of LA can this also be added to?

A

8.4% Sodium Bicarbonate (1mL added to 30mL of LA)
Chloroprocaine & Bupivacaine combo

(slide 9)

62
Q

What’s the most commonly used drug for epidural anesthesia with our local anesthetics?

A

Lidocaine! It has good diffusion and is safest. (Slide 41)

63
Q

Which is safer for use in the epidural space, bupivacaine, ropivacaine, or levobupivicaine? (pick 2)

A

Levobupivicaine and ropivacaine
- less toxic cardiac and CNS effects. (Slide 41)

64
Q

Epidural anesthesia onset is usually?

A

15 - 30 min. This slower onset is due to the drug having to diffuse across the epidural space before reaching the nerve fibers. (slide 41)

65
Q

In the epidural space, will mixing epi with bupivicaine increase the duration of the local anesthetic?

A

NO! Not in this instance. (Slide 41)

66
Q

Epidural doses are generally larger or smaller than spinal doses?

A

Larger! (Slide 42)

67
Q

What can be added to an epidural anesthetic dose to cause a synergistic effect for pain control?

A

Opioids! (Slide 42)

68
Q

Local anesthetics in the epidural space can have an effect on the fetus at this time frame:

A

Between 24 - 48 hrs. (Slide 42)

69
Q

Is there a segmental blockade in epidural anesthesia like with spinal anesthesia?

A

No! There is no differential zone of SNS, sensory, or motor like with spinal anesthesia. (Slide 42)

70
Q

Between lidocaine and bupivicaine, which is least likely to cross placenta?

A

The answer depends on the clinical practitioner!

  • Lidocaine has less protein binding —> washed out of system sooner and less likely to lead to toxic effects in baby and mom.

-Bupivicaine has more protein binding, so less likely to cross placenta and affect baby. (No slide, this is based off a question near end of lecture)

71
Q

Tumescent liposuction involves giving how much local anesthetic?

A

SQ infiltration of a LARGE amount of local anesthetics! 5L or more! (Slide 43)

72
Q

What is the concentration of local anesthetics that is used for tumescent liposuction?

What is the concentration of typical vasoconstrictor additive?

A

Diluted lidocaine of 0.05% to 0.10%.

Epinephrine 1: 100,000

(Slide 43)

73
Q

Where is tumescent local anesthetic given?

A

Typically the thigh, abdomen, hips, booty. (Slide 44)

74
Q

The local anesthetic used in tumescent liposuction peaks around what time frame?

A

12 - 14 hrs later!
Make sure pt has someone watching them at home!
(Slide 44)

75
Q

What is the recommended dosing for local anesthetics with tumescent liposuction?

A

Regional anesthesia lido with epi: 7mg/kg
Highly diluted lido with epi tumescent: 35 - 55 mg/kg

Theory: 1g of SQ can absorb up to 1 mg of lido
(Slide 44)

76
Q

Is EMLA cream recommended for skin wounds?

What caution should a provider be cognizant of when dealing with EMLA cream?

What allergies are contraindicated with EMLA?

A

No - do not place on skin wounds

Caution with methemoglobinemia when absorbed systemically

EMLA C/I w/ Amide allergies

(slide 25)

77
Q

Name some other preparations of EMLA. (4)

A

Amethocaine (EMLA-like)
Tetracaine 4% gel
Lidocaine 7%
Tetracaine 7%

(slide 25)

78
Q
A

(slide 15 and 16)

79
Q

Local Infiltration (extravascular placement) of an LA is ____ (SQ or IM)?

What would the addition of Epi 1:200,000 do to the duration of action of the LA?

What anatomical sites would Epi be C/I in?

What would happen if you were to inject Epi into one of these sites?

A

SQ

the addition of Epi 1:200,000 would DOUBLE the duration of action of the LA

Anatomical sites to avoid injecting with Epi: intracutaneously or into tissues with end-arteries;
i.e. Fingers, toes, ears, nose, and penis (ouch)

vasoconstriction –> ischemia –> necrosis

(slide 26)

80
Q

Give an example per lecture of common operative sites where Local Infiltration is used?

What med and what strength? (3)

A

Inguinal operative sites:

  • Lidocaine 1-2%
  • Ropivacaine 0.25%
  • Bupivacaine 0.25%

(slide 26)

81
Q

How is a Peripheral Nerve Block achieved?

MOA of a peripheral nerve block: _________ from outer mantle to central core of _____ along a concentration ________.

A

Achieved by LA injection into tissues surrounding individual peripheral nerves or nerve plexuses

diffusion from outer mantle to central core of nerve along a concentration gradient

(slide 27)

82
Q

Peripheral nerve block was just administered to your patient. You tell them to expect ________ to be affected first and then ______.

A period of time passes and now the block should be wearing off. You tell the patient to expect ________ to return first followed by ______.

A

proximal; distal

proximal; distal

(slide 27)

83
Q

Which nerve fiber types would be affected first by a peripheral nerve block?

What nerve fibers are affected following those?

A

smallest sensory and ANS fibers first, followed by larger motor and proprioceptive axons

(slide 27)

84
Q

OOA of Peripheral Nerve Block is dependent on what?

OOA for Lidocaine?

OOA for Buvicaine?

A

dependent on the pK of the LA

3 mins (faster)

15 mins (slower)

(slide 28)

85
Q

Continuous Infusion blocks yield ________ pain control, _____ nausea, and _______ satisfaction.

Besides pK of a chosen LA, what other factors would affect its DOA? (2 more)

A

Improved pain control, less nausea, and greater satisfaction.

Dose and additives will change the DOA for a LA

(slide 28)

86
Q

What are the 7 uses of LA’s discussed in lecture?

A

Topical
Local infiltration
Peripheral nerve block
IV
Epidural
Spinal
Tumescent Liposuction

87
Q

What additives might be good for a LA in a pt who is due to be discharged home immediately following surgery?

A

Ketorolac/Toradol (good choice in pain management and will not cause sedation)

Decadron/Dexamethasone

(clinical pearl)

88
Q

Give 4 examples of types of Peripheral Nerve Blocks.

A

Interscalene
Axillary
Femoral
Sciatic

(slide 29)

89
Q

what two types of block injection verification techniques do we have at our disposal?

Which one is preferred and why?

A

Ultrasound-guided and Nerve stimulator (never seen this before)

US-guided is preferred as it is less noxious to the patient

(slide 29)

90
Q

State any 1-2 details about Nerve Stimulator guided blocks.

State any 1-2 details about US-guided blocked.

A

Nerve stimulator:
- mA 0.1-1
- pinpoint needles

US-guided:
- in-plane
- out-of-plane

(slide 29)

Anesthesia Pharmacology (20 decks)

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