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SPR25: Anesthetic Pharm > SS25 Local Anesthetics II (Exam 4) > Flashcards

SS25 Local Anesthetics II (Exam 4) Flashcards

1
Q

What are the pharmacokinetic categories of LAs?

A
  • Alkalinization of LA Solutions
  • Adjuvant Mixed with LAs
  • Combining LAs
  • Vasoconstrictor Use
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2
Q

General LA uses

A
  • Topical
  • Local infiltration
  • Peripheral Nerve Block (PNB)
  • IV
  • Epidural
  • Spinal
  • Tumescent Lipsuction
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3
Q

What is the average pKa of LA?

A

8

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4
Q
  • What is the function of the Alkalinization of LA Solutions?
  • What are the benefits of alkalinization?
A

Function: Alkalinization increases the percentage of lipid-soluble or non-ionized form
- Sodium bicarb main buffer (except: not used in spinals)
Benefits:
* Faster onset of action (onset of peripheral and epidural blocks speed up by 3 to 5 mins)
* Enhances the depth
* Increase the spread (i.e., epidural)

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5
Q

Cheat sheet for weak bases introduced into soln with normal pH (7.4) to find more ionized form

A
  • The higher the pKa = the more non-ionized/unionized it is
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6
Q

Regarding weak bases, the pKa is ________ pH.

A
  • before
  • Ex. pKa 9, pH 7 → 9 - 7 = +2
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7
Q

Regarding weak acids, the pKa is ________ pH.

A
  • after
  • Ex. pKa 9, pH 7 → 7 - 9 = -2
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8
Q

Nicely negative numbers are _________.

A

non-ionized

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9
Q

If Drug V (weak base) has a pKa of 9.1, will the drug be more ionized or nonionized at physiological pH?

A

pKa - pH
9.1 - 7.4 = +1.7

Drug V will be more ionized at physiological pH.

Weak Bases, pKa before pH
Weak Acids, pKa afterpH

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10
Q

If the pKa of LA (a weak base) is at 4.5, will the drug be more ionized or nonionized at physiological pH?

A

pKa - pH
4.5 - 7.4 = -2.9

LA will be more non-ionized at physiological pH.

Weak Bases, pKa before pH
Weak Acids, pKa afterpH

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11
Q

LA1’s pKa is 9.2, and LA2’s pKa is 7.5. Which of the following are correct when placed in physiological pH? Select 2 answers.

A. LA2 has more non-ionized components
B. LA1 has more ionized components
C. LA2 has more ionized components
D. LA1 has more non-ionized components

A

B and C

LA1
9.2 - 7.4 = +1.8 (ionized)

LA2
7.5 - 7.4 = +0.1 (ionized)

Weak Bases, pKa before pH
Weak Acids, pKa afterpH

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12
Q

What Adjuvant Mixed medications prolong the duration of LAs?

A
  • IV Dexmedetomidine: Increased duration of both motor & sensory blocks; first analgesic request after subarachnoid block (SAB: type of spinal)
  • Magnesium: Increased duration with SAB w/ or w/o opioids
  • Clonidine & Ketamine: Increased duration in peds and regional
  • Dexamethasone: Increased duration either IV or mixed with LA

DM - CKD

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13
Q

What will be the results of combining LA Chloroprocaine & Bupivacaine?

A
  • Produce a rapid onset
  • Tachyphylaxis (Bupivacaine)
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14
Q

What is added to 30 mL of combo LA to alkalinize the drug?
- How much do you add?

A
  • 1 mL of 8.4% Sodium Bicarbonate
  • This will increase the non-ionized form of LA
  • Make sure the mixture does not contain any precipitate
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15
Q

T/F: Combining LAs and getting toxic effects is a synergistic process.

A
  • False
  • Additive
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16
Q

Compare the onset of action between chloroprocaine and bupivacaine.

A

Chloroprocaine: Rapid
Bupivacaine: Slow

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17
Q

What vasoconstrictors can be utilized with LA?

A
  • Epinephrine
  • Phenylephrine
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18
Q

Why is it important to use vasoconstrictors with LA?

A
  • The duration of action of a LA is proportional to the time the drug is in contact with nerve fibers
  • Adding a vasoconstrictor to LA solution, limits systemic absorption and maintains the drug concentration in the vicinity of the nerve fibers to be anesthetized
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19
Q

What are the results of using vasoconstrictors with LA?

A
  • Produce vasoconstriction
  • Increased neuronal uptake of LA
  • α-adrenergic effects may have some degree of analgesia
  • No effect on the onset rate of LA
  • Enhanced cardiac irritability with inhaled anesthetics
  • Systemic absorption → HTN (tachycardia?)
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20
Q

Explain effects of LA when Epinephrine is added to LA solution.

A
  • Will have a decrease in plasma levels of LA because Epinephrine prolongs duration of LA at the actual primary site
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21
Q

What is epinephrine 1:200,000 mean?
- Convert that to mcg/mL

A
  • 1:200,000 means 1 gram of epinephrine is dissolved in 200,000 mL of solvent
  • Shortcut: 1,000,000 / 200,000 = 5 mcg / mL
    OR
  • 1g/200,000 mL
  • 1000mg/200,000 mL
  • 1 mg/200 mL
  • 1000 mcg/200 mL
  • 10 mcg/2 mL
  • 5 mcg/mL
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22
Q

Compute 1:500,000 to mcg/mL

A
  • 1:500,000 means 1 gram of compound is dissolved in 200,000 mL of solvent
  • Short cut: 1,000,000 / 500,000 = 2 mcg / mL
    OR
  • 1 g/500,000 mL
  • 1000 mg/500,000 mL
  • 1 mg /500 mL
  • 1000 mcg/500 mL
  • 10 mcg/5 mL
  • 2 mcg/mL
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23
Q

How much epinephrine or phenylephrine is given with bupivacaine or lidocaine for a subarachnoid block (SAB)?

A
  • 0.2 mg Epi
  • 2 mg Phenylephrine
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24
Q

Compute 1:500,000 Epi to mcg/mL

A

1,000,000/ 500,000 = 2

2 mcg/mL

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25
Q

Compute 1:10,000 Epi to mcg/mL

A

1,000,000/ 10,000 = 100

100 mcg/mL

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26
Q

Compute 1:1000 Epi to mcg/mL

A

1,000,000/ 1000 = 1000

1000 mcg/mL or 1 mg/mL

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27
Q

LA strength of 0.25% equates to how many mg per mL ?

A

2.5 mg/mL

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28
Q

LA strength of 0.5% equates to how many mg per mL?

A

5 mg/mL

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29
Q

1% equates to how many mg per mL ?

A

10 mg/mL

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30
Q

2% equates to how many mg per mL ?

A

20 mg/mL
- 2% lidocaine is the most common concentration used in the OR

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31
Q

4% equates to how many mg per mL ?

A

40 mg/mL

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32
Q

Your surgeon injected 20 mLs of Bupivacaine 0.25% with 1:200,000 of Epi.

What are the total mgs for Bupivacaine and the total mcgs for Epinephrine?

A

Bupivacaine:
0.25% = 2.5 mgs/mL
2.5 mgs x 20 mLs = 50 mgs total

Epinephrine:
1:200,000 = 5 mcg/mL
5 mcg x 20 mLs = 100 mcg total

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33
Q

Lidocaine max single PLAIN dose & onset:
- Topical
- Infiltration
- IVRA
- PNB
- Epidural

A
  • Plain 300 mg
  • Fast
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34
Q

Lidocaine max single PLAIN for Spinal & onset:

A
  • 100 mg
  • Fast
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35
Q

Which clinical uses can you use Epi with?

A
  • Infiltration
  • Epidural
  • PNB
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36
Q

Lidocaine max single dose w/ Epinephrine:
- Infiltration
- PNB
- Epidural

A
  • 300 or 500 mg
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37
Q

Mepivacaine max single dose with or w/o Epi & onset:
- Infiltration
- PNB
- Epidural

A
  • 400 mg Plain & 500 mg w/ Epi
  • Fast
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38
Q

Mepivacaine max single dose for spinal & onset?

A
  • 100 mg
  • Fast
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39
Q

Prilocaine:
- Max Single Dose?
- Clinical uses?
- Do we use Epi?
- Onset?

A
  • 600 mg
  • Clincal uses: Infiltration; IVRA; PNB; Epidural
  • No Epi
  • Fast
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40
Q

Bupivacaine max single dose with or w/o Epi and onset:
- Infiltration
- PNB
- Epidural

A
  • 175 mg or 225 w/ Epi
  • Infiltration: Fast
  • PNB: Slow
  • Epidural: Moderate
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41
Q

Bupivacaine max single spinal dose & onset:

A
  • Spinal (plain only): 20 mg
  • Onset: Fast
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42
Q

112.5 mg of Bupivacaine with Epi and 250 mg of Lidocaine with Epi were given during surgery.

What are the percentages of each LA based on the recommended max single dose?

A

Max single dose of Bupivacaine with Epi: 225 mg
112.5/225 = 50%

Max single dose of Lidocaine with Epi: 500 mg
250/500 = 50%

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43
Q

Where are topical anesthetics applicable?

A
  • Applicable on the mucous membranes of the nose, mouth, tracheobronchial tree, esophagus, or GU tract
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44
Q
  • Which LA are used topically?
A
  • Cocaine 4 - 10% (most effective)
  • Tetracaine 1 - 2%
  • Lidocaine 2 - 4 %
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45
Q

Which anesthetic has localized vasoconstriction that will decrease blood loss and improve surgical visualization?
- Include LA concentration

A

Cocaine (4% - 10%)

46
Q

Which anesthetic is great with surface anesthesia?
- Include LA concentration

A

Lidocaine (2 - 4%)

47
Q

Lidocaine inhalation does not alter airway resistance, but does cause ______.

A

Vasodilation

48
Q

Which local anesthetics are not effective for topical anesthesia?

A

Procaine and Chloroprocaine

49
Q

What is does LTA stand for?

A
  • Lidocaine tracheal anesthesia
50
Q

What does black mark indicate?

A

-Vocal cord level

51
Q

Bonus: What is the total amount in mgs of a pre-filled syringe with 4 mL of 4% Lidocaine?

A
  • 40 mg/mL w/ 4 mL in tube (total 160 mg total of Lidocaine)
52
Q

Eutectic Mixture of LA (EMLA) contains what two local anesthetics?
- Dose:
- Onset (when will it be ready for surgery):

A
  • Lidocaine 2.5% + Prilocaine 2.5% = 5% LA
  • Dose: 1 to 2 g/ 10 cm2 area
  • Readiness: 45 mins
53
Q

EMLA has to be applied for ____ hours before skin graft.

54
Q

EMLA can be applied for 10 minutes before any of these procedures:

A
  • Cautery of genital warts
  • Venipuncture, lumbar puncture
  • Arterial cannulation (also can use NTG?)
  • Myringotomy - recurrent ear infxns
55
Q

What is the main adverse effect of EMLA?
- Why?

A
  • Methemoglobinemia
  • Contains Prilocaine
56
Q

Contraindications for EMLA?

A
  • No open skin wounds/infxns
  • No amide allergy patients
57
Q

Other Topical Anesthesia Preparations besides EMLA

A
  • Amethocaine (EMLA-like)
  • Tetracaine 4% Gel
  • Lidocaine 7%
  • Tetracaine 7%
58
Q

What is considered local infiltration with LA?

A
  • Extravascular placement of LA (Subcutaneous injection)
  • IV starts, hiatel hernia site, lap chole closures
59
Q

For Infiltration use, what LAs are used on Inguinal operative sites?
- duration of action?

A
  • Lidocaine 1% or 2%
  • Ropivacaine 0.25%
  • Bupivacaine 0.25%
  • Duration: doubled by adding Epi 1:200,000
60
Q

Why is Epinephrine contraindicated in LA infiltrations at end arteries?
- What is considered end artery tissues?

A
  • Not intracutaneously or into tissues at end arteries
  • Includes fingers, toes, ears, nose, & penis
  • Vasonstriction → ischemia → necrosis
61
Q

How is Peripheral Nerve Block achieved?
- MOA?

A
  • LA injection into tissues surrounding individual peripheral nerves or nerve plexuses
  • MOA: Diffusion from outer mantle to central core of nerve along a concentration gradient.
62
Q

Smallest ________ and _______ fibers first, then _____ motor and proprioceptive axons.
So the patient with feel ______ prior to _________.

A
  • Blank 1: sensory
  • Blank 2: ANS (or sympathetic nervous system)
  • Blank 3: Large
  • Blank 4: numb
  • Blank 5: paralysis (or no movement)
63
Q

What area (proximal or distal) is affected first with local anesthetic administration?

A
  • Proximal area (site of LA administration) is affected first and then distal
  • proximal → distal
64
Q

When the peripheral nerve block is wearing off, what comes back first (proximal or distal) ?

A
  • Proximal comes back first & then distal
  • proximal → distal
65
Q

Peripheral Nerve Block onset of action is dependent on the local anesthetic’s _________.

A

pK
- lower pk = faster onset
- Example: Lidocaine 7.9 (3 mins) v Bupivacaine 8.1 = 15 mins

66
Q

The duration of a peripheral nerve block depends on the _____ of the local anesthetic.

A

dose
- Ex: Bupivacaine w/ Epi + Fent & Clondine will last 12- 18hrs

67
Q

What are the benefits of a continuous infusion block?

A
  • Improved pain control
  • Less nausea
  • Greater satisfaction
  • Additives are used with continuous infusion blocks (Exparel ER common with additives)
68
Q

Examples of PNBs?

A
  • Interscalene
  • Axillary
  • Femoral
  • Sciatic

-Nerve stimulator (mA 0.1 - 1); pinpoint needles

  • US guided (in-plane v out-of-place)
69
Q

What is a Regional (August) Bier Block?

A
  • IV Regional Anesthesia
  • IV injection of LA into an extremity isolated from the rest of the systemic circulation with a tourniquet.
70
Q

Bier Block: Sensation and muscle tone are dependent on ________ release

A

tourniquet

71
Q

What LA is commonly used in Bier Block?
- Why?

A

Lidocaine
- Vasodilates = more comfort

72
Q

Which LA is the drug of choice for Bier Block?
-why?

A

Mepivacaine
- Vasoconstrictive properties

73
Q

T/F: You can only use Amides LA for Bier Blocks.

A

False
- Esters can be used as well

74
Q

What are the steps to performing a Bier Block?

A
  1. IV start
  2. Exsanguination
  3. Double cuff (deflate proximal cuff 1st then distal cuff)
  4. LA injection
  5. IV D/C
75
Q

What is the sequence of blockades for a segmental block in Neuraxial Anesthesia?

A
  1. SNS (Myelinated preganglionic B fibers) = ↓ BP & ↑ HR
  2. Sensory, (Myelinated A & B fibers, Unmyelinated C fibers) = loss of sensory
  3. Motor (Myelinated A-δ and Unmyelinated C fibers) = loss of motor
76
Q

Which of the following will be the last sign associated with injection of an anesthetic for neuraxial blockade?

A. NIBP
B. Heart Rate
C. Cold Alcohol Pad
D. Leg Movement

A

D. Leg Movement

77
Q

How is a Spinal Anesthesia Block (SAB) produced?

A
  • By direct injection of LA into Subarachnoid
78
Q

What is used for confirmation of a Spinal Anesthesia Block (SAB)?

79
Q

What is the principal site of action for subarachnoid block?

A

Preganglionic fibers

80
Q

For SAB, the _______ effect is on the same level of denervation.

81
Q

For SAB, the _______ effect is 2 spinal segments _______ of the sensory block.

For SAB, the _____ effect is 2 spinal segments below the sensory block.

A
  • SNS, cephalad (up towards head)
  • Motor
82
Q

If the sensory block is at T5, where is the SNS block?
- What will be triggered?

A
  • T3
  • SNS effect goes 2 levels cephalad (up towarda head)
  • This SNS block will trigger an asystole event by blocking cardiac accelerators
83
Q

What dermatomes correspond with our cardiac accelerator?

84
Q

What dermatomes correspond to the following:
- Nipple line
- Edge of Xiphoid process
- Lowest rib cage anteriorly
- Umbilical

A
  • Nipple line T4
  • Edge of Xiphoid process T6
  • Lowest rib cage anteriorly T8
  • Umbilical T10

Factor by 2 in anatomical order

85
Q

If the assessed sensory level after SAB is T6 (Top of Xiphoid Process), what are the blocked SNS and motor levels?

A
  • Sensory level T6
  • SNS Block: T4
  • Motor Block: T8
  • 6 - 2 = 4 & 6 + 2 = 8
86
Q

What are the most common local anesthetics used in SABs ?

A

Most common: Tetracaine, Lidocaine, Bupivacaine, Ropivacaine, and Levobupivacaine

87
Q

What factors affect SAB dosage?

A
  • Height of patient
  • Segmental level of anesthesia desired
  • Duration of anesthesia desired
88
Q

What does the height of the patient associated with in terms of SAB dosing:

A
  • volume of subarachnoid space
89
Q

For SAB, _____ is more important than _______ of drug or the volume of the solution injection.

A

Dose; Concentration

90
Q

What is the dose of bupivacaine for the scenario below?

  • 5 ft tall patient = _____mL of 0.75% Bupivacaine
    • ______ mL for every inch above…. 2 cc total ( 1½ hours to 2 hours)
  • What would be the dose for a 5’5” patient?
A
  • 1 mL
  • 0.1 mL
  • Give 1.5 mL of 0.75% Bupivacaine for a SAB*
    [ 1 mL + (0.1 mL * 5 in) ] =1.5
91
Q

What is the max Bupivacaine dose for Neuraxial Spinal/SAB?
- duration of action?

A
  • 2 mL for 1.5 - 2 hrs

6’ or more will get 2 mL + probabky additives

92
Q

For SAB, the _________ of LA is important in determining the spread of the drug.

A

specific gravity

93
Q

What can be added to LA so that its specific gravity can increase?

What can be added to LA so that its specific gravity can decrease?

A

Glucose added → Hyperbaric solution (LA S.G > CSF)

Distilled water added → Hypobaric solution

94
Q

Review: Which side will you want to position a right-hip arthroplasty patient on if they receive a hyperbaric LA solution?

A

Right side lying, the hyperbaric solution will “sink.”

95
Q

Review: Which side will you want to position a right-hip arthroplasty patient on if they receive a hypobaric LA solution?

A

Left side lying, the hypobaric solution will “float”.

96
Q

The most common LA used in Epidural Anesthesia.

A

Lidocaine
- Good diffusion through tissue and safer
- Great with loading dose & intermittent/ boluses

97
Q

Order of efficacy for following :
- Bupivacaine
- Ropivacaine
- Lidocaine
- Levobupivacaine

A
  • Lidocaine >
  • Bupivacaine > Levobupivacaine & Ropivacaine: highly protein binding →cardiac & CNS toxicity risk → need cardiac bypass
98
Q

What is the onset of epidural anesthesia?

A
  • Onset: 15 to 30 minutes (slow diffusion)
99
Q

Epi 1:200,000 with ___________ offers no advantage in an epidural block.

A
  • Bupivacaine
    (people still use it)
100
Q

Can epidural anesthesia cross the placental-blood barrier (PBB) with OB and C-section patients?
- How long?

A
  • Yes; Imaginary space has veins so can go intravascularly & cross PBB
  • can effect fetus up 24 - 48 hrs
101
Q

Does Bupivacaine or Lidocaine cross the placental barrier more?

A
  • Lidocaine d/t rapid onset
  • AE: Ion trapping
102
Q

What is the difference between spinals (SAB) and epidurals?
- What does the effect?

A
  • Epidurals have no differential zone of SNS, sensory, and motor blockade
  • Just one level
  • Effects dose requirement: Epidurals require larger doses
103
Q

What is considered an acceptable additive to both epidural and SAB to produce a synergistic effect?

104
Q

What is Tumescent Liposuction?

A
  • Subcutaneous infiltration of large volume (5L or more)
105
Q

What makes up the tumescent solution?

A
  • Diluted Lidocaine (0.05% to 0.1%)
  • Epinephrine 1:100,000
106
Q

What causes the tumescent effect?

A
  • The taunt stretching of overlying blanched skin d/t large volume & vasoconstriction→ Tumescent Effect

Indicates it’s safe to start liposuction

107
Q

Advantage of Tumescent Effect?

A
  • Fat can be aspirated without blood loss and provide prolonged post-op analgesia
108
Q

Where is tumescent usually administered?

A
  • Thigh
  • Abdomen
  • Hips
  • Buttocks

BBL mami

109
Q

When is the plasma peak for tumescent anesthesia?

A

12 to 14 hours s/p injection
- re-absorption of LA → risk for LA toxicity

110
Q

What is the normal dose for Regional Anesthesia Lidocaine with Epi?

111
Q

Highly diluted Lidocaine with Epi Tumescent dose.

A

35 to 55 mg/kg

112
Q

What is the theory of the Tissue Buffering System?

A
  • 1 gram of SQ tissue can absorb up to 1 mg of Lidocaine

SPR25: Anesthetic Pharm (10 decks)

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