Which nerve fibers are blocked last (in vivo) by local anesthetic? Local anesthetics

A-alpha & A-beta lesson 1 flashcard

The voltage-gated sodium channel can exist in what 3 states? Local anesthetics

1. resting 2. active 3. inactive lesson 2 flashcard

Local Anesthetics (5.1) Flashcards by Kelly K

Match each type of peripheral nerve with its function.
1. A delta
2. A alpha
3. B
4. C
a. motor
b. fast pain
c. preganglionic SNS
d. slow pain

Local anesthetics

2a (A alpha motor)
1b (A delta fast pain)
3c (B preganglionic SNS)
4d (C slow pain)

pre-lesson Q1

How well did you know this?

Not at all

Perfectly

Local anesthetics can bind to the voltage-gated sodium channel when it is in the:
a. resting and active states
b. resting and inactive states
c. active and inactive states
d. active state only

Local anesthetics

c. active and inactive states

pre-lesson Q2

How well did you know this?

Not at all

Perfectly

Local anesthetics: (Select 2)
a. increase threshold potential
b. decrease resting membrane potential
c. have no effect on threshold potential
d. have no effect on resting membrane potential

Local anesthetics

c. have no effect on TP
d. have no effect on RMP

pre-lesson Q3

How well did you know this?

Not at all

Perfectly

Select the true statement regarding the primary mechanism of action of local anesthetics.
a. the conjugate acid binds to the extracellular portion of the sodium channel
b. the conjugate acid binds to the intracellular portion of the sodium channel
c. the uncharged base binds to the extracellular portion of the sodium channel
d. the uncharged base binds to the intracellular portion of the sodium channel

Local anesthetics

b. the conjugate acid binds to the intracellular portion of the sodium channel

pre-lesson Q4

How well did you know this?

Not at all

Perfectly

A patient states she experienced hypotension, tachycardia, and shortness of breath after receiving tetracaine during a previous surgery. Which drugs should be avoided in this patient? (Select 3)
a. benzocaine
b. chloroprocaine
c. EMLA cream
d. articaine
e. cocaine
f. mepivacaine

Local anesthetics

a. benzocaine
b. chloroprocaine
e. cocaine

all ester LAs

pre-lesson Q5

How well did you know this?

Not at all

Perfectly

Which characteristics correlate best with local anesthetic duration of action?
a. protein binding
b. lipid solubility
c. pKa
d. concentration

Local anesthetics

a. protein binding

pre-lesson Q6

How well did you know this?

Not at all

Perfectly

Match each local anesthetic with its pKa.
1. mepivacaine
2. ropivacaine
3. lidocaine
4. chloroprocaine
a. 7.9
b. 8.1
c. 7.6
d. 8.7

Local anesthetics

1c (Mepivacaine 7.6)
2b (Ropivacaine 8.1)
3a (Lidocaine 7.9)
4d (Chloroprocaine 8.7)

pre-lesson Q7

How well did you know this?

Not at all

Perfectly

Rank the speed of local anesthetic uptake after injection into each location. (1 is fastest, 4 is slowest)
a. sciatic
b. caudal
c. intercostal
d. brachial plexus

Local anesthetics

CBDA
1. intercostal
2. caudal
3. brachial plexus
4. sciatic

IV>tracheal>interpleural>intercostal>caudal>epidural > brachial

pre-lesson Q8

How well did you know this?

Not at all

Perfectly

Match each local anesthetic with its maximum allowable dose in the adult.
1. lidocaine
2. mepivacaine
3. bupivacaine
4. ropivacaine
a. 300 mg
b. 200 mg
c. 175 mg
d. 400 mg

Local anesthetics

1a (lidocaine 300 mg)
2d (mepivacaine 400 mg)
3c (bupivacaine 175 mg)
4b (ropivacaine 200 mg)

pre-lesson Q9

How well did you know this?

Not at all

Perfectly

At what plasma concentration would you expect lidocaine to produce seizures? (mcg/mL)

Local anesthetics

10-15 mcg/mL

pre-lesson Q10

How well did you know this?

Not at all

Perfectly

One minute following an interscalene block, a 62-kg patient has a seizure. How much 20% lipid emulsion should you administer? (mL)

Local anesthetics

93 mL

1.5 mL/kg

pre-lesson Q11

How well did you know this?

Not at all

Perfectly

What is the maximum recommended dose for lidocaine during tumescent anesthesia?
a. 5 mg/kg
b. 7 mg/kg
c. 55 mg/kg
d. 75 mg/kg

Local anesthetics

c. 55 mg/kg

pre-lesson Q12

How well did you know this?

Not at all

Perfectly

Which local anesthetics are most likely to produce methemoglobinemia? (Select 3)
a. benzocaine
b. cetacaine
c. mepivacaine
d. EMLA cream
e. ropivacaine
f. etidocaine

Local anesthetics

a. benzocaine
b. cetacaine
d. EMLA cream

pre-lesson Q13

How well did you know this?

Not at all

Perfectly

What is the maximum dose of EMLA cream for a 9-month-old infant who weights 8-kg? (g)

Local anesthetics

2 g

pre-lesson Q14

How well did you know this?

Not at all

Perfectly

Each additive prolongs the duration of local anesthetics except:
a. dexamethasone
b. dextran
c. epinephrine
d. hyaluronidase

Local anesthetics

d. hyaluronidase

pre-lesson Q15

How well did you know this?

Not at all

Perfectly

Which local anesthetic is the most likely to exhibit cross-sensitivity to another agent from the same class?
a. ropivacaine
b. bupivacaine
c. mepivacaine
d. benzocaine

Local anesthetics

d. benzocaine

ester-type LA d/t PABA

post lesson quiz

How well did you know this?

Not at all

Perfectly

What is the best agent to treat ventricular dysrhythmias in the patient who received an intravascular injection of ropivacaine?
a. amiodarone
b. vasopressin
c. lidocaine
d. epinephrine

Local anesthetics

a. amiodarone

avoid lidocaine & vasopressin; reduce epi dose

post lesson quiz

How well did you know this?

Not at all

Perfectly

In the setting of symptomatic methemoglobinemia, an exchange transfusion will most likely be required for a patient with a history of:
a. mitochondrial myopathy
b. glucose-6-phosphate reductase deficiency
c. kernicterus
d. Gaucher’s disease

Local anesthetics

b. glucose-6-phosphate reductase deficiency

they do not have methemoglobin reductase

post lesson quiz

How well did you know this?

Not at all

Perfectly

Administration of metoprolol to a patient exhibiting signs of cocaine intoxications is most likely to produce:
a. heart failure
b. hyperkalemia
c. hypoglycemia
d. acute kidney injury

Local anesthetics

a. heart failure

beta-blockade allows for unopposed alpha-1 stimulation

post lesson quiz

How well did you know this?

Not at all

Perfectly

Which factors have the most significant impact on the onset of action of local anesthetics? (Select 3)
a. concentration
b. pKa
c. dose
d. protein binding
e. intrinsic vasodilation effects
f. lipid solubility

Local anesthetics

a. concentration
b. pKa
c. dose

pKa most significant

post lesson quiz

How well did you know this?

Not at all

Perfectly

What is the mechanism of action of local anesthetics?
a. sodium channel blockade
b. nicotinic receptor inhibition
c. potassium channel activation
d. muscarinic receptor stimulation

Local anesthetics

a. sodium channel blockade

post lesson quiz

How well did you know this?

Not at all

Perfectly

Successful resuscitation of LAST is least likely following injection of which local anesthetic?
a. lidocaine
b. levobupivacaine
c. ropivacaine
d. bupivacaine

Local anesthetics

d. bupivacaine

difficulty of cardiac resuscitation: bupi>levobupi>ropiv>lido

post lesson quiz

How well did you know this?

Not at all

Perfectly

A local anesthetic with a pKa of 7.4 is exected to have a:
a. low degree of lipid solubility
b. high potency
c. fast onset
d. short duration of action

Local anesthetics

c. fast onset

pKa closer to blood pH = more uncharged

post lesson quiz

How well did you know this?

Not at all

Perfectly

What is the definitive treatment for a 70-kg patient who has received a toxic dose of intravenous lidocaine?
a. 20% lipid emulsion 100 mL
b. midazolam 2 mg
c. glucagon 1 mg
d. propofol 140 mg

Local anesthetics

a. 20% lipid emulsion 100 mL

post lesson quiz

How well did you know this?

Not at all

Perfectly

What compound is implicated in allergic reactions to ester-type local anesthetics? a. CYP3A1 metabolites b. pseudocholinesterase c. methylparaben d. para-aminobenzoic acid ## Footnote Local anesthetics

d. para-aminobenzoic acid ## Footnote post lesson quiz

Which nerve fibers are blocked first (in vivo) by local anesthetic? ## Footnote Local anesthetics

B ## Footnote lesson 1 flashcard

Which nerve fibers are blocked last (in vivo) by local anesthetic? ## Footnote Local anesthetics

A-alpha & A-beta ## Footnote lesson 1 flashcard

C fibers originating in the dorsal root transmit which types of signals? ## Footnote Local anesthetics

slow pain temperature touch ## Footnote lesson 1 flashcard

Which peripheral nerve fiber type is not myelinated? ## Footnote Local anesthetics

C fibers ## Footnote lesson 1 flashcard

What type of nerve fibers mediate skeletal muscle tone? ## Footnote Local anesthetics

A gamma ## Footnote lesson 1 flashcard

Which type of peripheral nerve fiber mediates fast pain? ## Footnote Local anesthetics

A delta ## Footnote lesson 1 flashcard

The voltage-gated sodium channel can exist in what 3 states? ## Footnote Local anesthetics

1. resting 2. active 3. inactive ## Footnote lesson 2 flashcard

When do the voltage-gated sodium channel assume the active state? ## Footnote Local anesthetics

When threshold potential is reached (during depolarization -70 to +35 mV) ## Footnote lesson 2 flashcard

When does the voltage-gated sodium channel assume the inactive state? ## Footnote Local anesthetics

repolarization (+35 to -70 mV) | the channel is closed during this time ## Footnote lesson 2 flashcard

Local anesthetics bind to which region of the sodium channel? ## Footnote Local anesthetics

The alpha-subunit on the inside of the sodium channel when its in the active or inactive state ## Footnote lesson 3 flashcard

Do local anesthetics affect resting membrane potential or threshold potential? ## Footnote Local anesthetics

neither-local anesthetics prevent the nerve from depolarizing, but they don't affect RMP or TP ## Footnote lesson 3 flashcard

How does hypocalcemia affect the threshold potential? ## Footnote Local anesthetics

It makes the TP more negative. Since it moves closer to the RP, the cell is easier to depolarize ## Footnote lesson 3 flashcard

Why can we predict >50% of lidocaine will exist in the ionized state when it enters the bloodstream? ## Footnote Local anesthetics

lidocaine is a weak base; it's pKa value is greater than physiologic pH so a greater fraction will exist in the ionized state ## Footnote lesson 4 flashcard

What 3 paths can a local anesthetic travel after it's injected near a peripheral nerve? ## Footnote Local anesthetics

1. It can diffuse into the nerve 2. It can diffuse into the surrounding tissue and bind to neighboring proteins 3. It can diffuse into the systemic circulation ## Footnote lesson 4 flashcard

Ester-Type LAs ## Footnote Local anesthetics

Benzocaine Chloroprocaine Tetracaine Cocaine allergy potential plasma esterase metabolism ## Footnote lesson 5 flashcard

Amide-Type LAs ## Footnote Local anesthetics

Dibucaine Lidocaine Mepivacaine Bupivacaine | metabolized by the liver; always has two "i" in the name ## Footnote lesson 5 flashcard

Match the variables to their affect. 1. Onset of Action 2. Potency 3. Duration of Action a. dose b. concentration c. pKa d. lipid solubility e. protein binding f. addition of vasoconstrictor ## Footnote Local anesthetics

1abc 2d 3ef ## Footnote lesson 6 flashcard

Which local anesthetic doesn't possess any intrinsic vasodilating activity? ## Footnote local anesthetics

cocaine | it inhibits NE reuptake and causes vasoconstriction ## Footnote lesson 6 flashcard

In an acidic solution, weak bases are: ## Footnote local anesthetics

more ionized and water-soluble ## Footnote lesson 7 flashcard

In a basic solution, weak bases are: ## Footnote local anesthetics

more non-ionized and lipid-soluble ## Footnote lesson 7 flashcard

In an acidic solution, weak acids are: ## Footnote local anesthetics

more non-ionized and lipid-soluble ## Footnote lesson 7 flashcard

In a basic solution, weak acids are: ## Footnote local anesthetics

more ionized and water-soluble ## Footnote lesson 7 flashcard

Which local anesthetic does not undergo protein binding? ## Footnote local anesthetics

chloroprocaine ## Footnote lesson 7 flashcard

What is the pKa of each LA? 1. bupivacaine 2. ropivacaine 3. lidocaine 4. mepivacaine 5. chlorprocaine 6. tetracaine ## Footnote local anesthetics

1. 8.1 2. 8.1 3. 7.9 4. 7.6 5. 8.7 6. 8.5 ## Footnote lesson 7 flashcard

Local anesthetics bind to what serum proteins? ## Footnote local anesthetics

alpha-1-acid glycoprotein (preferred) albumin ## Footnote lesson 8 flashcard

How is cocaine metabolized? ## Footnote local anesthetics

1. pseudocholinesterase (like ester LAs) 2. hepatic P450 enzymes (like amide LAs) ## Footnote lesson 8 flashcard

What is the maximum dose of Exparel? ## Footnote local anesthetics

266 mg (2 vials) ## Footnote lesson 8 flashcard

How soon must lidocaine be injected before Exparel is used? ## Footnote local anesthetics

at least 20 minutes ## Footnote lesson 8 flashcard

How soon can be bupivacaine be injected after Exparel is used? ## Footnote local anesthetics

at least 96 hours ## Footnote lesson 8 flashcard

What is the maximum dose of each amide LA? 1. bupivacaine 2. lidocaine 3. lidocaine w/epi 4. ropivacaine 5. levobupivacaine 6. mepivacaine ## Footnote local anesthetics

1. 2.5 mg/kg (175 mg) 2. 4.5 mg/kg (300 mg) 3. 7 mg/kg (500 mg) 4. 3 mg/kg (200 mg) 5. 2 mg/kg (150 mg) 6. 7 mg/kg (400 mg) ## Footnote lesson 9 flashcard

What is the maximum dose of each ester local anesthetic? 1. procaine 2. chloroprocaine 3. chloroprocaine w/epi ## Footnote local anesthetics

1. 7 mg/kg (350-600 mg) 2. 11 mg/kg (800 mg) 3. 14 mg/kg (1000 mg) ## Footnote lesson 9 flashcard

At what plasma concentration of lidocaine do these CNS effects occur? 1. tinnitus 2. coma 3. seizures 4. analgesia 5. loss of consciousness 6. perioral numbness ## Footnote local anesthetics

1. 5-10 mcg/mL 2. 15-25 mcg/mL 3. 10-15 mcg/mL 4. 1-5 mcg/mL 5. 10-15 mcg/mL 6. 5-10 mcg/mL ## Footnote lesson 10 flashcard

At what plasma concentration of lidocaine do these cardiopulmonary effects occur? 1. hypotension 2. respiratory arrest 3. CV collapse 4. myocardial depression ## Footnote local anesthetics

1. 5-10 mcg/mL 2. 15-25 mcg/mL 3. >25 mcg/mL 4. 5-10 mcg/mL ## Footnote lesson 10 flashcard

What ACLS drugs should be avoided in the patient with LAST? ## Footnote local anesthetics

1. vasopressin 2. lidocaine 3. procainamide 4. epinephrine (limit doses <1 mcg/kg) ## Footnote lesson 11 flashcard

What is the treatment of choice for seizures in the patient with LAST? ## Footnote local anesthetics

benzodiazepines ## Footnote lesson 11 flashcard

What is the initial loading dose and infusion dose for 20% lipid emulsion therapy in a patient over 70 kg? ## Footnote local anesthetics

loading dose = 100 mL over 2-3 min infusion = 250 mL over 15-20 min ## Footnote lesson 11 flashcard

Can you repeat the bolus dose of 20% lipid emulsion therapy? ## Footnote local anesthetics

yes up to 2 times ## Footnote lesson 11 flashcard

Can you increase the infusion dose of 20% lipid emulsion therapy? ## Footnote local anesthetics

yes you can double it ## Footnote lesson 11 flashcard

What is the recommended maximum dose of lipid emulsion therapy? ## Footnote local anesthetics

~12 mL/kg ## Footnote lesson 11 flashcard

What is the most common cause of death in patients undergoing liposuction? ## Footnote local anesthetics

pulmonary embolism ## Footnote lesson 12 flashcard

When is general anesthesia recommended for patients undergoing liposuction? ## Footnote local anesthetics

GA is recommended if >2-3 L of tumescent is injected (due to the risk of fluid shifts) ## Footnote lesson 12 flashcard

Meds associated with Methemoglobin ## Footnote local anesthetics

Cetacaine Benzocaine Prilocaine EMLA Sulfonamides Phenytoin Nitroprusside Nitroglycerine ## Footnote lesson 13 flashcard

Name 7 signs of methemoglobinemia. ## Footnote local anesthetics

1. hypoxia 2. cyanosis 3. chocolate-colored blood 4. tachycardia 5. tachypnea 6. decrease LOC 7. death ## Footnote lesson 13 flashcard

What 2 patient populations have the highest risk for methemoglobin toxicity? ## Footnote local anesthetics

1. neonates (HgbF is relatively deficient in methemoglobin reductase) 2. glucose-6-phosphate reductase deficiency (don't have methemoglobin reductase) ## Footnote lesson 13 flashcard

What is the primary treatment for methemoglobinemia? ## Footnote local anesthetics

Methylene blue 1-2 mg/kg IV over 5 minutes with a maximum doses of 7-8 mg/kg ## Footnote lesson 13 flashcard

What are the optical characteristics of methemoglobin? ## Footnote local anesthetics

HgbMet absorbs 660 nm and 940 nm wavelengths equally. This explains why a pulse oximeter can't measure it correctly. ## Footnote lesson 13 flashcard

What is the maximum dose of EMLA cream for each age group? a. 0-3 months b. 3-12 months c. 1-6 years d. 7-12 years ## Footnote local anesthetics

a. 1 g b. 2 g c. 10 g d. 20 g ## Footnote lesson 14 flashcard

What are the 2 major components of EMLA cream? ## Footnote local anesthetics

2.5% lidocaine 2.5% prilocaine ## Footnote lesson 14 flashcard

What drug can be added to EMLA cream to hasten its onset? ## Footnote local anesthetics

nitroglycerin ## Footnote lesson 14 flashcard

Are there skin conditions that preclude the application of EMLA? ## Footnote local anesthetics

eczema, psoriasis, and skin wounds (don't apply over affected areas, increased risk of toxicity) ## Footnote lesson 14 flashcard

LA adjuncts that prolong duration ## Footnote local anesthetics

epinephrine dexamethasone dextran ## Footnote lesson 15 flashcard

LA adjuncts that supplement analgesia ## Footnote local anesthetics

clonidine epinephrine opioids (neuraxial only) ## Footnote lesson 15 flashcard

LA adjuncts that shorten onset time. ## Footnote local anesthetics

sodium bicarbonate ## Footnote lesson 15 flashcard

LA adjuncts that improve diffusion through tissues. ## Footnote local anesthetics

hyaluronidase | common in opthalmic blocks ## Footnote lesson 15 flashcard

Which local anesthetic is unionized at physiologic pH? a. benzocaine b. ropivacaine c. cocaine d. dibucaine ## Footnote local anesthetics

a. benzocaine | pKa well below physiologic pH (3.5) ## Footnote review exam

Saltatory conduction occurs in all of the following nerve types except: a. A gamma fibers b. A delta fibers c. B fibers d. C fibers ## Footnote local anesthetics

C fibers | C fibers are not myelinated ## Footnote review exam

Select the best local anesthetic to use for a subarachnoid block in the patient who has a sensitivity to bupivacaine. a. tetracaine b. mepivacaine c. lidocaine d. etidocaine ## Footnote local anesthetics

tetracaine | other options are amides which can cross react with allergy ## Footnote review exam

Local anesthetic potency best correlates with: a. duration of action b. concentration c. lipid solubility d. pKa ## Footnote local anesthetics

lipid solubility ## Footnote review exam

One minute following an axillary block, a 36 kg patient has a seizure. How much 20% lipid emulsion should you administer? ## Footnote local anesthetics

54 mL | 1.5 mL/kg over 2-3 minutes ## Footnote review exam

The primary mechanism of action for local anesthetics blockade is: a. G-protein coupled sodium channels b. voltage-gated potassium channels c. metabotropic calcium channels d. voltage-gated sodium channels ## Footnote local anesthetics

d. voltage-gated sodium channel ## Footnote review exam

How many mL of a 0.5 percent bupivacaine solution can be safely injected into a child weighing 35 kg? ## Footnote local anesthetics

17.5 mL | max: 2.5 mg/kg 0.5% bupi = 5 mg/mL ## Footnote review exam

Rank the sensitivity of each nerve fiber type to the physiologic effects of local anesthetics in vivo. (1-most, 4-least) a. A delta fibers b. C fibers c. B fibers d. A alpha fibers

1c 2b 3a 4d B>C>Adelta>Agamma>Abeta>Aalpha | Beer Cheese AnD A Game better than ABbA ## Footnote review exam

Rank the local anesthetics according to their degrees of ionization at physiologic pH. (1-most, 4-least) a. bupivacaine b. chloroprocaine c. tetracaine d. lidocaine ## Footnote local anesthetics

1b 2c 3a 4d | chloro 8.7-9.1 (most ion) tetra 8.4 bupi 8.1 lido 7.8 (least ion) ## Footnote review exam

Which local anesthetic is the least protein bound in the plasma? ## Footnote local anesthetics

chloroprocaine | zero protein binding levobupi, bupi, and ropi >90% ## Footnote review exam

What metabolite of ester-type local anesthetics is most likely to cause a type I hypersensitivity reaction? a. O-toluidine b. methylparaben c. metabisulfite d. para-aminobenzoic acid ## Footnote local anesthetics

d. para-aminobenzoic acid ## Footnote review exam

Rank the speed of local anesthetic uptake after injection into the following sites. (1-fastest, 4-lowest) a. intrapleural b. epidural c. caudal d. intercostal ## Footnote local anesthetics

1a 2d 3c 4d | interpleural>intercostal>caudal>epidural>brach. plex>femoral>sciatic>SQ ## Footnote review exam

Choose the statements that most accurately describe EMLA cream. (Select 2) a. a dressing should be applied after EMLA is applied to the patient b. analgesia is achieved within 15 minutes c. procaine is metabolized to o-toluidine d. compared to adults, infants are more susceptible to methemoglobinemia ## Footnote local anesthetics

a. a dressing should be applied after EMLA is applied to the patient d. compare to adults, infants are more susceptible to methemoglobinemia | lido & prilo; analgesia in 1H ## Footnote review exam

Identify the factors that increase the risk of local anesthetic systemic toxicity. (Select 2) a. local anesthetic potency b. hypokalemia c. hypercarbia d. alkalosis ## Footnote local anesthetics

a. local anesthetic potency c. hypercarbia | acidosis=inc. brain blood flow; higher potency = higher risk CNS toxic ## Footnote review exam

What is the maximum dose of cocaine that can be used as a topical vasoconstrictor? ## Footnote local anesthetics

150 mg or 200 mg | 1.5-3.0 mg/kg avoid with MAOIs, TCAs, sympathomimetics no beta-blockers ## Footnote review exam