Pharm: Exam 4- Local Anesthetics

Question 1

Which of the following local anesthetics is recognized as the standard to which all other local anesthetics are compared?
A. Cocaine
B. Procaine
C. Lidocaine
D. Bupivacaine

Answer 1

Correct Answer:
C. Lidocaine

Rationale:
Lidocaine, the first synthetic amide local anesthetic introduced in 1943, is considered the standard to which all other local anesthetics are compared due to its efficacy and safety profile.

Question 2

Cocaine was the first local anesthetic used in which field of medicine?
A. Dentistry
B. Ophthalmology
C. Cardiology
D. Dermatology

Answer 2

Correct Answer:
B. Ophthalmology

Rationale:
According to the slide, cocaine, which is known for its cerebral stimulating qualities and ability to cause localized vasoconstriction, was first used as a local anesthetic in ophthalmology in 1884.

Question 3

What was the first synthetic ester local anesthetic?
A. Benzocaine
B. Procaine
C. Tetracaine
D. Lidocaine

Answer 3

Correct Answer:
B. Procaine

Rationale:
Procaine, introduced in 1905, was the first synthetic ester local anesthetic developed as a less toxic alternative to cocaine.

Question 4

Which class of antiarrhythmic drugs shares the mechanism of action with local anesthetics?
A. Class I - Sodium-channel blockers
B. Class II - Beta-blockers
C. Class III - Potassium-channel blockers
D. Class IV - Calcium-channel blockers

Answer 4

Correct Answer:
A. Class I - Sodium-channel blockers

Rationale:
Local anesthetics act as sodium-channel blockers, which is the mechanism of action for Class I antiarrhythmic drugs. They stabilize the cardiac cell membrane by inhibiting the influx of sodium ions during action potentials, which helps to treat dysrhythmias.

Question 5

For a patient with obstructive sleep apnea (OSA), which medication is recommended to be given intraoperatively?
A. Acetaminophen
B. Ondansetron
C. Ofirmev
D. Lidocaine

Answer 5

Correct Answer:
C. Ofirmev

Rationale:
The chart indicates that for patients with OSA, Ofirmev (intravenous acetaminophen) at a dose of 1 gram is recommended intraoperatively. This is likely due to its analgesic properties and favorable safety profile, particularly for patients with OSA.

Question 6

Which medication is administered preoperatively and continued postoperatively for pain management?
A. Gabapentin
B. Ketorolac
C. Magnesium
D. Celebrex or Advil

Answer 6

Correct Answer:
A. Gabapentin

Rationale:
Gabapentin is listed as being administered preoperatively at a dose of 300 mg PO and is also continued postoperatively at the same dosage of 300 mg taken three times a day (TID).

Question 7

What is the maximum daily dose of ibuprofen & recommended dose intraoperatively?
A. 3200 mg/day
B. 300 - 750mg IV Q6
C. 2500 mg/day
D. 200- 800mg IV Q6

Answer 7

A & D

Question 8

In the postoperative period, which form of magnesium is recommended if the patient was not receiving magnesium intraoperatively?
A. Magnesium sulfate
B. Super Mag
C. Magnesium aspartate
D. Magnesium oxide
E. Doesn’t matter

Answer 8

E. Doesn’t matter

Rationale:
Postoperatively, the chart indicates the use of either Super Mag 400 mg twice a day (BID), magnesium aspartate 615 mg three times a day (TID), or magnesium oxide 500 mg twice a day (BID), if the patient requires

Intra-op use 30-60mg/kg mag with MAX of 6g infused over 1 hour.

Question 9

Which of the following plasma lidocaine concentrations is typically associated with therapeutic analgesic effects?
A. 0.5-1 mcg/ml
B. 1-5 mcg/ml
C. 5-10 mcg/ml
D. 10-15 mcg/ml

Answer 9

Correct Answer:
B. 1-5 mcg/ml

Rationale:
Therapeutic analgesia with lidocaine is achieved with plasma concentrations ranging from 1-5 mcg/ml. Concentrations below 1 mcg/ml may not provide adequate analgesia, and levels above 5 mcg/ml can start to produce side effects such as circum-oral numbness and tinnitus.

Question 10

During the administration of lidocaine, what is the initial IV bolus dose recommended for an adult patient?
A. 0.5 mg/kg
B. 1 to 2 mg/kg
C. 2 to 4 mg/kg
D. Over 4 mg/kg

Answer 10

Correct Answer:
B. 1 to 2 mg/kg

Rationale:
For intravenous administration, lidocaine is typically started with an initial bolus of 1 to 2 mg/kg, administered over 2 to 4 minutes. This is to achieve a rapid therapeutic plasma concentration while minimizing the risk of adverse effects.

Question 11

A patient with a plasma lidocaine concentration of 7 mcg/ml is likely to experience which of the following symptoms?
A. Adequate analgesia without side effects
B. Circum-oral numbness and tinnitus
C. Seizures
D. Cardiovascular depression

Answer 11

B. Circum-oral numbness and tinnitus

Rationale:
A plasma lidocaine concentration of 5-10 mcg/ml can cause symptoms such as circum-oral numbness, tinnitus, muscle twitching, systemic hypotension, and myocardial depression. Seizures and cardiovascular depression are associated with higher plasma concentrations.

Question 12

What is the maximum recommended duration for an infusion of lidocaine?
A. Up to 12 hours
B. Up to 24 hours
C. Up to 72 hours
D. There is no maximum as long as plasma levels are therapeutic

Answer 12

Correct Answer:
C. Up to 72 hours

Rationale:
According to the information provided, lidocaine infusion should be terminated between 12 to 72 hours based on clinical judgment and patient response. Prolonged infusion beyond 72 hours increases the risk of accumulation and adverse effects, especially in patients with existing

Question 13

What structural feature determines whether a local anesthetic is classified as an ester or an amide?
A. The presence of a benzene ring
B. The bond between the lipophilic portion and the hydrocarbon chain
C. The bond between the hydrocarbon chain and the hydrophilic portion
D. The length of the hydrocarbon chain
E. The bond between the lipophilic portion and the hydrophilic portion

Answer 13

B. The bond between the lipophilic portion (aromatic part) and the hydrocarbon chain.

The hydrocarbon chain (intermediate chain) determines ester/amide

Question 14

Local anesthetics are typically weak bases. How are they commonly administered in clinical settings to enhance their stability and solubility?
A. As freebase compounds
B. As neutral solutions
C. As hydrochloride (HCl) salts
D. As pure acid forms

Answer 14

Correct Answer:
C. As hydrochloride (HCl) salts

Rationale:
Local anesthetics, being weak bases, are usually formulated as hydrochloride (HCl) salts to enhance their stability and solubility when administered clinically.

Question 15

What is the primary lipophilic component of a local anesthetic molecule?
A. Amino group
B. Intermediate chain
C. Aromatic part, typically a benzene ring
D. Hydrocarbon chain

Answer 15

C. Aromatic part, typically a benzene ring

Rationale:
The lipophilic portion of a local anesthetic molecule is the aromatic part, which is often a benzene ring. This structure facilitates the anesthetic’s ability to penetrate the lipid-rich cellular membranes.

Question 16

Epinephrine is sometimes added to local anesthetic solutions. What is the purpose of this addition?
A. To decrease the pH of the solution
B. To increase the duration of action of the anesthetic
C. To provide anti-inflammatory effects
D. To act as an alternative pain reliever

Answer 16

Correct Answer:
B. To increase the duration of action of the anesthetic

Rationale:
Epinephrine is added to local anesthetic solutions to cause vasoconstriction at the site of administration. This reduces blood flow, which decreases the rate of absorption of the anesthetic into the bloodstream, prolonging its duration of action, and provides a more localized effect.

Question 17

Which local anesthetic has the highest potency?
A. Procaine
B. Tetracaine
C. Lidocaine
D. Chloroprocaine

Answer 17

Correct Answer:
B. Tetracaine

Rationale:
The table lists tetracaine with a potency of 16, making it the highest compared to the other local anesthetics listed, such as procaine (1), chloroprocaine (4), and lidocaine (1).

Question 18

What is the maximum single dose for infiltration anesthesia with bupivacaine?
A. 300 mg
B. 175 mg
C. 500 mg
D. 200 mg

Answer 18

Correct Answer:
B. 175 mg

Rationale:
The table specifies a maximum single dose of 175 mg for infiltration anesthesia with bupivacaine, indicating its safe upper limit for a single administration.

Question 19

Which local anesthetic has the quickest onset of action?
A. Lidocaine
B. Chloroprocaine
C. Prilocaine
D. Bupivacaine

Answer 19

Correct Answer:
B. Chloroprocaine

Rationale:
Chloroprocaine is listed as having a rapid onset, which suggests it acts faster than the other local anesthetics presented in the table, including lidocaine (rapid), prilocaine (slow), and bupivacaine (slow).

Question 20

which local anesthetic has the lowest protein binding percentage?
A. Procaine
B. Tetracaine
C. Mepivacaine
D. Ropivacaine

Answer 20

Correct Answer:
A. Procaine

Rationale:
Procaine has the lowest protein binding at 6%, which can affect its duration of action and toxicity profile, as local anesthetics with lower protein binding typically have a shorter duration and a higher free fraction in the plasma

Question 21

Local anesthetics have different durations of action after infiltration. Which anesthetic would you choose for a procedure requiring a long duration of anesthesia?
A. Procaine
B. Lidocaine
C. Bupivacaine
D. Prilocaine

Answer 21

Correct Answer:
C. Bupivacaine

Rationale:
Bupivacaine is listed with a duration of action after infiltration of 240-480 minutes, making it suitable for longer procedures. In comparison, procaine (45-60 min), lidocaine (60-120 min), and prilocaine (60-120 min) have shorter durations of action.

Question 22

Which local anesthetic is known for its high lipid solubility and is, therefore, very potent?
A. Procaine
B. Lidocaine
C. Tetracaine
D. Ropivacaine

Answer 22

Correct Answer:
C. Tetracaine

Rationale:
The table lists tetracaine as having a potency of 16, which is the highest among the presented anesthetics, suggesting high lipid solubility and consequent high potenc

Question 23

Which of the following local anesthetics has both high lipid solubility and high protein binding, contributing to a long duration of action and a slower onset?
A. Mepivacaine
B. Bupivacaine
C. Procaine
D. Prilocaine

Answer 23

Correct Answer:
B. Bupivacaine

Rationale:
Bupivacaine is known for its high lipid solubility 28 and high protein binding (greater than 95%), which contributes to its longer duration of action and potential for a slower onset when compared to drugs with lower protein binding. The highest lipid solubility is Tetracaine at 80 and the lowest is Prilocaine at 0.9

Question 24

What can prolong the duration of action of local anesthetics?
A. Combining with antihistamines
B. Addition of dexamethasone
C. Decreasing the lipid solubility
D. Administering the drug in an acidic pH

Answer 24

Correct Answer:
B. Addition of dexamethasone

Rationale:
Adding dexamethasone or epinephrine to local anesthetics can prolong their duration of action. Epinephrine induces vasoconstriction, slowing absorption into the bloodstream and prolonging the local effect. Dexamethasone has been shown to extend the duration of action when used as an adjunct.

Question 25

Why is it essential to memorize the “maximum single dose for infiltration” for local anesthetics?
A. To avoid systemic toxicity
B. To ensure rapid onset of action
C. To prevent allergic reactions
D. To prolong the duration of anesthesia

Answer 25

Correct Answer:
A. To avoid systemic toxicity

Rationale:
Knowing the maximum single dose for infiltration of local anesthetics is critical to prevent systemic toxicity. Exceeding these limits can result in toxic plasma concentrations, leading to adverse effects ranging from mild systemic symptoms to severe complications like seizures or cardiovascular depression.

Question 26

What is the advantage of using a liposome delivery system for local anesthetics?
A. Increases the potency of the local anesthetic
B. Provides a timed release for prolonged duration of action
C. Completely eliminates the toxicity of the local anesthetic
D. Allows for immediate onset of action

Answer 26

Correct Answer:
B. Provides a timed release for prolonged duration of action

Rationale:
Liposome delivery systems can encapsulate a higher amount of local anesthetic and provide a consistent release of the drug in the tissues, thereby prolonging the duration of action and potentially decreasing toxicity.

Question 27

How do local anesthetics prevent the propagation of action potentials?
A. By binding to voltage-gated potassium channels
B. By increasing the permeability of the cell membrane to sodium ions
C. By binding to voltage-gated sodium channels and inhibiting sodium passage
D. By activating the H gate from the outside of the cell membrane

Answer 27

Correct Answer:
C. By binding to voltage-gated sodium channels and inhibiting sodium passage

Rationale:
Local anesthetics bind to the intracellular portion of voltage-gated sodium channels, inhibiting sodium ion passage through nerve membranes and thus preventing the nerve from reaching the threshold potential necessary for action potential propagation.

Question 28

Which factor can increase the sensitivity of nerve endings to local anesthetics?
A. Alkaline tissue pH
B. Infrequent nerve stimulation
C. Large diameter of nerve fibers
D. Repetitively stimulated nerves

Answer 28

Correct Answer:
D. Repetitively stimulated nerves

Rationale:
Repetitive stimulation of nerves increases their sensitivity to local anesthetics, meaning less drug is needed to achieve the desired anesthetic effect.

Question 29

In an acidotic patient, what effect does the condition have on the action of local anesthetics?
A. Enhances the action of local anesthetics
B. Converts more local anesthetic to its ionized form, reducing effectiveness
C. Increases the lipid solubility of local anesthetics
D. Does not affect the action of local anesthetics

Answer 29

Correct Answer:
B. Converts more local anesthetic to its ionized form, reducing effectiveness

Rationale:
If a patient is acidotic, the acidic environment will convert more of the local anesthetic to its ionized form, which is less lipid-soluble and less able to penetrate nerve cell membranes to exert its effect.

Question 30

Which fibers are most rapidly affected by local anesthetics?
A. Unmyelinated C fibers
B. Myelinated B fibers
C. Myelinated A-delta fibers
D. Preganglionic B fibers

Answer 30

Correct Answer:
D. Preganglionic B fibers

Rationale:
Preganglionic B fibers are the fastest blocked by local anesthetics, affecting the sympathetic nervous system responses such as blood pressure and heart rate.

Question 31

What is the Minimum Effective Concentration (MEC) for local anesthetics analogous to in volatile anesthetics?
A. The minimum inhibitory concentration (MIC)
B. The maximum allowable concentration (MAC)
C. The median effective concentration (EC50)
D. The blood concentration for induction (BCI)

Answer 31

Correct Answer:
B. The minimum aleveolar concentration (MAC)

Rationale:
MEC or Cm for local anesthetics is similar to MAC for volatile anesthetics. It represents the concentration needed to achieve a clinical effect without causing systemic toxicity

Question 32

What effect does a local anesthetic’s pKa value have on its onset of action?
A. pKa has no influence on the onset of action.
B. A higher pKa significantly speeds up the onset of action.
C. A pKa value closer to physiologic pH correlates with a slower onset of action.
D. A pKa value closer to physiologic pH is associated with the most rapid onset of action.

Answer 32

Correct Answer:
D. A pKa value closer to physiologic pH is associated with the most rapid onset of action.

Rationale:
Local anesthetics with pKa values close to the physiological pH will have a greater proportion of the drug in the non-ionized form at physiological pH, which more readily penetrates nerve membranes, leading to a more rapid onset of action.

Question 33

What is the consequence of lidocaine’s intrinsic vasodilator activity?
A. Decreased systemic absorption
B. Increased potency and shorter duration of action (DOA)
C. Decreased potency and longer duration of action
D. Greater systemic absorption

Answer 33

Correct Answer:
D. Greater systemic absorption

Rationale:
Intrinsic vasodilator activity of local anesthetics like lidocaine increases local blood flow, which can lead to greater systemic absorption of the drug. With a decrease in potency and shorter duration of action.

Question 34

During pregnancy, why might local anesthetic dosing need to be adjusted?
A. Pregnancy decreases the sensitivity to local anesthetics.
B. Pregnancy does not affect the pharmacodynamics of local anesthetics.
C. Increased sensitivity in pregnancy may require higher doses.
D. Pregnancy is associated with increased sensitivity, requiring careful dosing.

Answer 34

Correct Answer:
D. Pregnancy is associated with increased sensitivity, requiring careful dosing.

Rationale:
Pregnant patients often exhibit increased sensitivity to local anesthetics, potentially due to physiological changes that affect the drug’s pharmacokinetics and pharmacodynamics, necessitating careful dosing to avoid toxicity.

Question 35

How does the site of injection influence the duration of action of local anesthetics?
A. More vascular sites result in a shorter duration of action due to rapid absorption.
B. Less vascular sites lead to a prolonged duration of action due to slower absorption.
C. The site of injection has no impact on the duration of action.
D. A and B are correct.

Answer 35

Correct Answer:
D. A and B are correct.

Rationale:
The site of injection significantly impacts the duration of action for local anesthetics. More vascular sites will have shorter durations due to faster systemic absorption, whereas less vascular sites like subcutaneous tissue will have a longer duration of action.

Question 36

Which site of injection is associated with the highest blood concentration of local anesthetics?
A. Subcutaneous
B. Intravenous
C. Caudal
D. Sciatic

Answer 36

Correct Answer:
B. Intravenous

Rationale:
According to the hierarchy presented, intravenous injections result in the highest blood concentrations of local anesthetics, due to direct entry into the vascular system.

Question 37

For procedures like circumcisions and hernia repairs in children, which regional anesthesia technique is commonly used?
A. Brachial plexus block
B. Caudal block
C. Sciatic nerve block
D. Tracheal instillation

Answer 37

B. Caudal block

Question 38

Rank the following regional anesthesia techniques in order of increasing systemic absorption of local anesthetics:

A. Caudal
B. Intravenous
C. Subcutaneous
D. Epidural

Answer 38

Correct Answer Order:

1.Subcutaneous (Lowest systemic absorption)
2. Epidural
3. Caudal
4.Intravenous (Highest systemic absorption)

Question 39

How does lipid solubility affect the potency of local anesthetics?
A. Greater lipid solubility decreases the potency of the anesthetic.
B. Lipid solubility has no impact on the potency of the anesthetic.
C. Lesser lipid solubility leads to increased potency of the anesthetic.
D. Increased lipid solubility is directly related to greater potency of the anesthetic.

Answer 39

Correct Answer:
D. Increased lipid solubility is directly related to greater potency of the anesthetic.

Rationale:
The potency of local anesthetics is directly related to their lipid solubility, as this property enables the drug to penetrate the lipid-rich neuronal membranes more effectively.

Question 40

Which of the following factors can influence the rate of clearance for local anesthetics?
A. Patient age and body temperature
B. Cardiac output and protein binding
C. Dosage and duration of action
D. Site of injection and rate of tissue distribution

Answer 40

Correct Answer:
B. Cardiac output and protein binding

Rationale:
The rate at which a local anesthetic is cleared from the body depends on the cardiac output and the extent to which the drug binds to proteins. An increased cardiac output leads to increased metabolism of the drug, and the percentage bound is inversely related to the percentage available in plasma.

Question 41

Which class of local anesthetics is most rapidly metabolized, and why?
A. Amides, because they are less protein-bound and more available in plasma.
B. Esters, because they undergo rapid hydrolysis by cholinesterase enzymes in the plasma.
C. Amides, because they have the highest lipid solubility and protein binding.
D. Esters, because they are metabolized in the liver by CYP450 enzymes.

Answer 41

Correct Answer:
B. Esters, because they undergo rapid hydrolysis by cholinesterase enzymes in the plasma.

Rationale:
Esters are generally metabolized more rapidly than amides because they are hydrolyzed by cholinesterase enzymes present in plasma, which occurs faster than the metabolism of amides by liver enzymes.

Question 42

Why are amides less likely to cause allergic reactions compared to esters?
A. Amides are not metabolized into para-aminobenzoic acid (PABA), a known allergen.
B. Amides have higher protein binding, which reduces the immune response.
C. Amides are more rapidly cleared from the body, reducing the chance of an allergic reaction.
D. Amides have lower lipid solubility, which makes them less allergenic.

Answer 42

Correct Answer:
A. Amides are not metabolized into para-aminobenzoic acid (PABA), a known allergen.

Rationale:
Esters can be metabolized into PABA, which is associated with allergic reactions. Amides, on the other hand, do not have this metabolic pathway and thus are less likely to cause allergic reactions.

Question 43

In the elderly, the dose of local anesthetics is often reduced. What is the primary reason for this adjustment?
A. Increased body fat percentage in the elderly leading to higher drug storage.
B. Decreased rate of clearance due to reduced cardiac output and protein plasma levels.
C. Higher baseline cardiac output in the elderly leading to rapid drug clearance.
D. Enhanced sensitivity of the elderly to the pharmacologic effects of local anesthetics.

Answer 43

Correct Answer:
B. Decreased rate of clearance due to reduced cardiac output and protein plasma levels.

Rationale:
As individuals age, they typically experience a decrease in cardiac output and a reduction in protein plasma levels, which can lead to a slower rate of clearance for local anesthetics, necessitating a lower dose to avoid toxicity.

Question 44

Which local anesthetic has a protein binding percentage of 55% and a single dose for infiltration of 600mg depending on what ?

Options:
A. Lidocaine
B. Prilocaine
C. Bupivacaine
D. Ropivacaine

Answer 44

Correct Answer:
B. Prilocaine

Rationale:
According to the slide, Prilocaine, classified under amides, has a protein binding of 55% and a maximum single dose for infiltration of 400 mg on chart but slide 32 says 600mg so who fucking knows.

Question 45

What is the maximum single dose for infiltration and protein binding percentage of Lidocaine?

Options:
A. 300 mg, 70%
B. 175 mg, >97%
C. 500 mg, 6%
D. 400 mg, 55%

Answer 45

Correct Answer:
A. 300 mg, 70%

Rationale:
Lidocaine, which is an amide local anesthetic, has a maximum single dose for infiltration of 300 mg and a protein binding percentage of 70%.

Question 46

Which local anesthetic undergoes metabolism by microsomal enzymes in the liver at the most rapid rate?

Options:
A. Lidocaine
B. Bupivacaine
C. Prilocaine
D. Ropivacaine

Answer 46

Correct Answer:
C. Prilocaine

Rationale:
The slide indicates that among the listed amides, Prilocaine is metabolized at the most rapid rate by liver microsomal enzymes.

Question 47

Which type of local anesthetic is primarily metabolized by cholinesterase enzyme in plasma rather than in the liver?

Options:
A. Amides
B. Esters
C. Both A and B
D. Neither A nor B

Answer 47

Correct Answer:
B. Esters

Rationale:
Esters are primarily metabolized by hydrolysis through cholinesterase enzymes in the plasma, as mentioned in the slide. An exception is cocaine, which is metabolized in the liver.

Question 48

What percentage of cocaine is excreted unchanged in the urine?

Options:
A. Less than 5%
B. Approximately 10-12%
C. Over 95%
D. None of the above, cocaine is fully metabolized

Answer 48

Correct Answer:
B. Approximately 10-12%

Rationale:
Unlike most local anesthetics that are metabolized before renal excretion, cocaine has a unique characteristic where 10-12% can be excreted unchanged in the urine.

Question 49

Which 2 of the following local anesthetics has an intermediate rate of metabolism by liver enzymes?

Options:
A. Etidocaine
B. Ropivacaine
C. Lidocaine
D. Mepivacaine

Answer 49

Correct Answer:
C. Lidocaine D. Mepivacaine

Rationale:
Lidocaine has an intermediate rate of metabolism when processed by liver microsomal enzymes, alongside Mepivacaine.

Question 50

The majority of local anesthetics have a low percentage of unchanged drug excreted in the urine. What is the primary reason for this characteristic?

Options:
A. High rate of protein binding
B. High rate of metabolism by liver enzymes
C. Poor water solubility of the drugs
D. Active transport mechanisms in the renal tubules

Answer 50

Correct Answer:
C. Poor water solubility of the drugs

Rationale:
Local anesthetics are typically weak bases with poor water solubility, which means that a relatively small amount of the unchanged drug can be excreted through the kidneys. As the slides indicate, less than 5% of the unchanged drug is usually found in the urine, primarily due to their poor solubility in water. This means that most of the drug is metabolized before it is excreted.

Question 51

Lower levels of plasma cholinesterases during pregnancy can influence the metabolism of which type of local anesthetics?
A. Amides
B. Esters
C. Both amides and esters
D. Neither amides nor esters

Answer 51

Answer: B. Esters
Rationale: Esters are rapidly hydrolyzed by plasma cholinesterases, and lower levels of these enzymes during pregnancy would affect the metabolism of ester local anesthetics.

Question 52

Why might amides be more concerning for fetal exposure during pregnancy compared to esters?
A. They have a lower rate of placental transfer.
B. They are rapidly metabolized by the fetus.
C. They have higher protein binding, potentially leading to greater fetal accumulation.
D. They are less potent than esters.

Answer 52

Answer: C. They have higher protein binding, potentially leading to greater fetal accumulation.
Rationale: Higher protein binding in the fetus can result in more of the drug being retained, and the significant transplacental transfer of amides compounds this effect.

Question 53

What is the phenomenon of ‘ion trapping’ in the context of fetal acidosis and local anesthetics?
A. Nonionized local anesthetics are unable to cross the placental barrier.
B. Ionized local anesthetics can more easily cross back into the maternal circulation.
C. Fetal acidosis can lead to nonionized local anesthetics becoming ionized within the fetus, leading to accumulation.
D. Local anesthetics do not become ionized in the fetus regardless of pH levels.

Answer 53

Answer: C. Fetal acidosis can lead to nonionized local anesthetics becoming ionized within the fetus, leading to accumulation.
Rationale: Nonionized forms of local anesthetics cross the placental barrier but may become ionized in the acidic environment of the fetal bloodstream, leading to accumulation since the ionized form cannot easily cross back into the maternal circulation.

Question 54

Which intervention can be used to manage increased local anesthetic concentrations in the fetus due to acidosis?
A. Administering bicarbonate to the mother
B. Increasing fetal plasma cholinesterase levels
C. Decreasing the maternal dose of local anesthetics
D. Administering calcium gluconate to the mother

Answer 54

Answer: A. Administering bicarbonate to the mother
Rationale: Administering bicarbonate to the mother can help correct fetal acidosis, potentially reducing the ion trapping of local anesthetics in the fetus.

Question 55

Which of the following statements about the pharmacokinetics of Lidocaine is correct?

A. Lidocaine is primarily metabolized in the kidneys, with the main metabolite being Xylidide.
B. Hepatic disease has no significant impact on the metabolism and elimination of Lidocaine.
C. Lidocaine’s maximum recommended infiltration dose is 300 mg when used without epinephrine and 500 mg when combined with epinephrine.
D. Lidocaine does not have anti-dysrhythmic properties and is used exclusively for local anesthesia

Answer 55

Answer and Rationale:
C. Lidocaine’s maximum recommended infiltration dose is 300 mg when used without epinephrine and 500 mg when combined with epinephrine.

Rationale: The correct answer is C. The slide indicates that Lidocaine undergoes oxidative dealkylation in the liver, not the kidneys, making A incorrect. Hepatic disease does indeed affect the metabolism and elimination of Lidocaine, which rules out B. D is incorrect as the slide specifies that Lidocaine has anti-dysrhythmic properties. Therefore, the correct statement is C, as it accurately reflects the information given on the maximum doses of Lidocaine with and without epinephrine.

Question 56

A 70 kg patient is being treated for methemoglobinemia after receiving Prilocaine. What is the maximum recommended dose of Methylene Blue for this patient?

A. 60 mg IV over 5 minutes
B. 140 mg IV over 5 minutes
C. 560 mg IV over 5 minutes
D. None of the above

Answer 56

Answer and Rationale:
B. 140 mg IV over 5 minutes

Rationale: Methemoglobinemia can occur when Prilocaine is metabolized to its metabolite, orthotoluidine, which then converts hemoglobin to methemoglobin, reducing the oxygen-carrying capacity of the blood and leading to symptoms like cyanosis. The treatment for methemoglobinemia is Methylene Blue, administered at 1-2 mg/kg IV. Given the patient’s weight of 70 kg, and not exceeding the total dose limit of 7 to 8 mg/kg as stated on the slide, the maximum recommended dose would be 70 kg x 2 mg/kg = 140 mg given over 5 minutes, which corresponds to answer B. A is underdosed

Question 57

Which of the following is a characteristic that differentiates Mepivacaine from Lidocaine?

A. Shorter duration of action
B. Greater Vasodilatory activity
C. Prolonged elimination in fetus and newborn
D. Metabolized by N-dealkylation

Answer 57

Answer and Rationale:
C. Prolonged elimination in fetus and newborn.

Rationale: Mepivacaine is similar to Lidocaine in many respects; however, it lacks vasodilatory activity, which confers a longer duration of action. Another distinguishing factor is that Mepivacaine has prolonged elimination in the fetus and newborn, and hence, it is not typically used for obstetrical anesthesia (OB). This characteristic is highlighted in the slide as a key difference, making option C the correct answer. Options A and B are incorrect as they describe properties that are not associated with Mepivacaine when compared to Lidocaine. Option D is incorrect as the slide does not discuss the metabolism of Mepivacaine via N-dealkylation; this is mentioned in relation to Bupivacaine.

Question 58

Which local anesthetic has a maximum single infiltration dose of 300mg when used plain and 500mg when combined with epinephrine?

A. Mepivacaine
B. Bupivacaine
C. Lidocaine
D. Ropivacaine

Answer 58

Answer: C. Lidocaine

Rationale: Lidocaine’s maximum recommended doses are 300mg for plain and 500mg when combined with epinephrine, to slow absorption and prolong the effect.

Question 59

Which local anesthetic, when metabolized, can lead to methemoglobinemia if the dose exceeds 600mg?

A. Tetracaine
B. Lidocaine
C. Prilocaine
D. Bupivacaine

Answer 59

Answer: C. Prilocaine

Rationale: Prilocaine’s metabolite orthotoluidine can convert hemoglobin to methemoglobin, leading to methemoglobinemia at high doses.

Question 60

Which statement accurately reflects the transplacental transfer characteristics of local anesthetics?

A. Esters and amides both have significant transplacental transfer.
B. Amides, not esters, have significant transplacental transfer
C. Esters have a higher transplacental transfer than amides.
D. Protein binding has no impact on the transplacental transfer of local anesthetics.

Answer 60

Answer: B. Amides, not esters, have significant transplacental transfer

Rationale: Esters are rapidly hydrolyzed by plasma cholinesterases, reducing their transplacental transfer compared to amides. Protein binding also affects the rate and degree of diffusion across the placental barrier.

Question 61

For which local anesthetic is the protein binding site specifically α1-Acid glycoprotein- select 2?

A. Mepivacaine
B. Prilocaine
C. Ropivacaine
D. Bupivacaine

Answer 61

Answer: D. Bupivacaine and C. Ropivacaine

Rationale: Bupivacaine has a high protein binding capacity, particularly to α1-acid glycoprotein, influencing its duration of action and metabolism.

Question 61

Which local anesthetic is known to have less systemic toxicity compared to Bupivacaine due to its higher amount of α1-acid glycoprotein binding?

A. Lidocaine
B. Mepivacaine
C. Ropivacaine
D. Dibucaine

Answer 61

Answer: C. Ropivacaine

Question 62

The Dibucaine number is used to diagnose what condition?

A. Uremia
B. Liver dysfunction
C. Atypical pseudocholinesterase
D. Methemoglobinemia

Answer 62

Answer: C. Atypical pseudocholinesterase

Rationale: The Dibucaine number is a measure of the inhibition of plasma cholinesterase activity by Dibucaine and is used to diagnose atypical forms of the enzyme that are associated with prolonged paralysis after the administration of Succinylcholine.

Question 63

In patients with renal failure, which local anesthetic’s metabolites are likely to accumulate, potentially leading to systemic toxicity?

A. Lidocaine
B. Ropivacaine
C. Mepivacaine
D. Bupivacaine

Answer 63

Answer: B. Ropivacaine

Rationale: Ropivacaine’s metabolites can accumulate in uremic patients, which is a concern due to the potential for systemic toxicity. However, Ropivacaine has lesser systemic toxicity overall compared to Bupivacaine.

Question 64

Which ester local anesthetic is hydrolyzed the fastest by plasma cholinesterase?

A. Procaine
B. Chloroprocaine
C. Tetracaine
D. Bupivacaine

Answer 64

Answer: B. Chloroprocaine

Rationale: Chloroprocaine is hydrolyzed 3.5 times faster than procaine by plasma cholinesterase, making it the ester local anesthetic with the fastest hydrolysis rate.

Question 65

The primary metabolite of ester local anesthetics that is excreted unchanged in the urine is:

A. Xylidide
B. Orthotoluidine
C. Para-aminobenzoic acid (PABA)
D. Glycine

Answer 65

Answer: C. Para-aminobenzoic acid (PABA)

Rationale: The metabolism of ester local anesthetics such as procaine, chloroprocaine, and tetracaine results in the production of PABA, which is excreted unchanged in the urine.

Question 66

What is the effect of pregnancy on plasma cholinesterase activity?

A. Increases activity by 40%
B. Decreases activity by 40%
C. No change in activity
D. Completely inhibits the enzyme

Answer 66

Answer: B. Decreases activity by 40%

Rationale: Pregnancy is associated with a 40% decrease in plasma cholinesterase activity, which could affect the metabolism of local anesthetics that are hydrolyzed by this enzyme.

Question 67

What is the unique property of Benzocaine as a local anesthetic and one of the potential complications associated with its use?

A. It is a weak base and can cause Methemoglobinemia if overdosed.
B. It is a strong acid with rapid metabolism and no significant side effects.
C. It is a weak acid which makes it predominantly nonionized at physiological pH, potentially causing Methemoglobinemia if overdosed.
D. It is a neutral compound that can cause Tachyphylaxis on repeated use.

Answer 67

Answer:
C. It is a weak acid which makes it predominantly nonionized at physiological pH, potentially causing Methemoglobinemia if overdosed.

Rationale:
Benzocaine is unique because it is a weak acid with a pKa of 3.5, making it predominantly nonionized at the physiological pH of 7.4. This is in contrast to most local anesthetics, which are weak bases. A potential complication of Benzocaine is Methemoglobinemia, which can occur with doses exceeding 200-300mg. Methemoglobinemia is a condition where hemoglobin is modified into methemoglobin, which cannot effectively release oxygen to tissues, leading to hypoxia.

Question 68

Which patient population is known to have decreased plasma cholinesterase activity, affecting the metabolism of Cocaine?
A) Adolescents
B) Parturients
C) Middle-aged adults
D) Teenagers

Answer 68

Answer: B) Parturients
Rationale: Cocaine is metabolized by plasma and liver cholinesterases. Plasma cholinesterase activity is decreased in parturients (those about to give birth), neonates, the elderly, and those with severe hepatic disease. This affects the metabolism and clearance of cocaine in these populations.

Question 69

How long after the peak effect should one expect the duration of Cocaine’s action to last?
A) 15 minutes
B) 30 minutes
C) 60 minutes
D) 120 minutes

Answer 69

Answer: C) 60 minutes
Rationale: The peak effect of Cocaine occurs between 30 to 45 minutes after administration, and the duration of action lasts for about 60 minutes post-peak.

Question 70

Cocaine elimination through urine is detected for how long after administration?
A) 6 to 12 hours
B) 12 to 24 hours
C) 24 to 36 hours
D) 48 to 72 hour

Answer 70

Answer: C) 24 to 36 hours
Rationale: After its effect peaks, Cocaine is eliminated in the urine within 24 to 36 hours.

Question 71

Which of the following is a caution when administering Cocaine due to its pharmacological effects?
A) Hypoglycemia
B) Coronary vasospasm
C) Hypothyroidism
D) Anemia

Answer 71

Answer: B) Coronary vasospasm
Rationale: Cocaine can cause significant cardiovascular effects such as coronary vasospasm, ventricular dysrhythmias, hypertension (HTN), tachycardia, and can aggravate coronary artery disease (CAD). These risks warrant caution during its use.

Question 72

What is the function of alkalization in local anesthetic (LA) solutions?
A) It decreases the potency of LAs.
B) It reduces the percentage of the lipid-soluble or non-ionized form of LAs.
C) It increases the percentage of the lipid-soluble or non-ionized form of LAs.
D) It prolongs the onset of action of LAs.

Answer 72

Answer: C) It increases the percentage of the lipid-soluble or non-ionized form of LAs.
Rationale: Alkalization of LA solutions is used to increase the percentage of the drug that is in a lipid-soluble or non-ionized form, which can more easily diffuse across nerve membranes.

Question 73

What is the benefit of increasing the lipid-soluble or non-ionized form of local anesthetics?
A) Slower onset of action
B) Faster onset of action
C) Decreased effectiveness of the anesthetic
D) Decreased depth of anesthesia

Answer 73

Answer: B) Faster onset of action
Rationale: By increasing the lipid-soluble or non-ionized form of LAs through alkalization, the onset of the anesthetic action is faster. This also enhances the depth and increases the spread of epidural blockage.

Question 74

How does alkalization affect the onset time for peripheral and epidural blocks?
A) Delays onset by 3 to 5 minutes
B) Has no effect on onset time
C) Speeds onset by 3 to 5 minutes
D) Speeds onset by 10 to 15 minutes

Answer 74

Answer: C) Speeds onset by 3 to 5 minutes
Rationale: Alkalizing local anesthetic solutions can reduce the time it takes for peripheral and epidural blocks to take effect, typically speeding the onset by 3 to 5 minutes.

Question 75

A weak acid drug (Drug X) with a pKa of 3.5 is administered to a patient. At a physiological pH of 7.4, this drug will primarily be in which form?
A) More ionized
B) More nonionized
C) Equally ionized and nonionized
D) Cannot be determined

Answer 75

Answer: A) More Ionized
Rationale: Weak acids are more ionized when the environmental pH is higher than their pKa, as they will have donated their protons. A weak acid has a charge when it donates a proton

Question 76

For a weak base drug (Drug W) with a pKa of 4.5, at a pH of 7.4, the drug will be:
A) Mostly nonionized
B) Mostly ionized
C) Neither ionized nor nonionized
D) Completely ionized

Answer 76

Answer: A) Mostly nonionized
Rationale: Weak bases are predominantly nonionized at pH levels above their pKa because they will have donated protons and weak bases have no charge when they are unprotonated

Question 77

If Drug Y is a weak acid with a pKa of 9.5, at the physiological pH of 7.4, it will be:
A) Mostly ionized
B) Mostly nonionized
C) In a 50:50 ratio of ionized to nonionized
D) Completely nonionized

Answer 77

Answer: B) Mostly non-ionized
Rationale: Weak acids with a pKa significantly higher than the physiological pH will not donate protons bc the environment is more acidic, and an acid with its proton is not charged and therefor unionized .

Question 78

Thiopental, a weak acid used in anesthesia, has a pKa of approximately 7.6. At physiological pH, thiopental will be:
A) Mostly ionized
B) Mostly nonionized
C) Equally ionized and nonionized
D) Completely ionized

Answer 78

Answer: b) Mostly non-ionized
Rationale: Since thiopental’s pKa is close to but slightly higher than physiological pH, it will tend to be more keep its protons and thus make it non-ionized. Note if this was a base, a base that accepts protons is charged and ionized, that is why LA’s are in effective in acidic tissue

Question 79

Consider a drug (Drug V) that is a weak base with a pKa of 9.1. When given to a patient, the majority of this drug at pH 7.4 will be:
A) In the ionized form
B) In the nonionized form
C) Equally ionized and nonionized
D) Cannot be determined without more information

Answer 79

Answer: A) In the ionized form
Rationale: Weak bases are more likely to be ionized in environments where the pH is lower than their pKa. At pH 7.4, Drug V with a pKa of 9.1 will be more in the ionized form, meaning it has accepted protons.

Question 80

When considering adjuvants to local anesthetics for prolonging the effects of nerve blocks, which of the following agents is known to increase the duration of both motor and sensory blocks when administered intravenously?

A) Magnesium
B) Clonidine
C) Dexamethasone
D) Dexmedetomidine

Answer 80

Answer:
D) Dexmedetomidine

Rationale:
Dexmedetomidine is a selective α2-adrenergic agonist that, when used intravenously, has been shown to prolong the duration of motor and sensory blocks. It can also delay the first analgesic request after spinal anesthesia, which makes it a valuable adjuvant in enhancing the efficacy of local anesthetics during various procedures.

Other options listed such as magnesium, clonidine, ketamine, and dexamethasone also serve as adjuvants to local anesthetics, each with its unique properties and benefits. Magnesium is often used to prolong the duration of spinal anesthesia with or without opioids. Clonidine and ketamine can be useful in pediatric regional anesthesia for their sedative properties and pain modulation effects, respectively. Dexamethasone has been found to prolong block duration when administered intravenously or mixed with local anesthetics.

Question 81

For pediatric regional anesthesia, which adjuvant mixed with local anesthetics can prolong the duration of the block?

A) Magnesium
B) Dexmedetomidine
C) Clonidine and Ketamine
D) Dexamethasone

Answer 81

Answer:
C) Clonidine and Ketamine

Question 82

Which adjuvant, when used with subarachnoid block (SAB), can increase the duration of the block in the presence of opioids?

A) Clonidine
B) Dexamethasone
C) Magnesium
D) Dexmedetomidine

Answer 82

Answer:
C) Magnesium

Question 83

Which of the following adjuvants is the first analgesic request after spinal anesthesia?

A) Ketamine
B) Dexamethasone
C) Magnesium
D) Dexmedetomidine

Answer 83

D) Dexmedetomidine

Question 84

Which of the following is a potential benefit of combining Chloroprocaine and Bupivacaine in local anesthesia?

A) Delayed onset of action
B) Minimization of tachyphylaxis
C) Reduction of toxic effects
D) Production of a rapid onset

Answer 84

D) Production of a rapid onset
Rationale: Combining Chloroprocaine, a fast-acting anesthetic, with Bupivacaine, which has a longer duration, can produce a rapid onset while maintaining prolonged anesthesia.

Question 85

Why is a small amount (1 mL) of 8.4% Sodium Bicarbonate typically added to a 30 mL solution of local anesthetics?

A) To increase pH and improve solubility
B) To decrease the onset time of the anesthetic
C) To prolong the duration of the anesthetic
D) Both A and B are correct

Answer 85

Answer:
D) Both A and B are correct
Rationale: Alkalinization with sodium bicarbonate increases the proportion of the non-ionized form of the anesthetic, enhancing its ability to penetrate nerve membranes, thus speeding up the onset.

Question 86

What must be carefully monitored when combining local anesthetics like Chloroprocaine and Bupivacaine?

A) The total volume of the solution
B) The temperature of the solution
C) The speed of the infusion
D) The toxic effects

Answer 86

Answer:
D) The toxic effects
Rationale: Toxic effects of local anesthetics are additive; hence, combining different local anesthetics requires careful dosing to prevent systemic toxicit

Question 87

What is the potential risk of adding too much sodium bicarbonate to a local anesthetic solution?

A) Reduced effectiveness of the anesthetic
B) Precipitation and instability of the solution
C) Enhanced risk of infection
D) Increased risk of allergic reactions

Answer 87

Answer:
B) Precipitation and instability of the solution
Rationale: Over-alkalinization can cause precipitation, which can compromise the efficacy and safety of the anesthetic solution.

Question 88

If a practitioner chooses to use a combination of Lidocaine and Bupivacaine for a procedure, and decides to administer 40% of the maximum dose of Lidocaine and 60% of the maximum dose of Bupivacaine, what would be the total administered dose?

A) 475 mg
B) 225 mg
C) 300 mg
D) 175 mg

Answer 88

Correct Answer: B) 225 mg

Rationale: 40% of the maximum dose of Lidocaine (300 mg) is 120 mg, and 60% of the maximum dose of Bupivacaine (175 mg) is 105 mg. Adding these together gives a total of 225 mg, which is below the maximum dose for each drug individually to prevent additive toxicity.

Question 89

To prevent systemic toxicity, a surgeon decides to use both Lidocaine and Bupivacaine for a sensitive surgical procedure. If the maximum safe dose of Lidocaine is 300 mg and Bupivacaine is 175 mg, which of the following combination dosages is safe to administer?

A) Lidocaine 200 mg and Bupivacaine 150 mg
B) Lidocaine 150 mg and Bupivacaine 100 mg
C) Lidocaine 120 mg and Bupivacaine 105 mg
D) Lidocaine 300 mg and Bupivacaine 175 mg

Answer 89

Correct Answer: C) Lidocaine 120 mg and Bupivacaine 105 mg

Rationale: Both A) and D) exceed the safety margin when drugs are combined, with D) being the maximum dose of each drug if used alone, which could lead to systemic toxicity. C) uses the 40% of Lidocaine’s maximum dose and 60% of Bupivacaine’s maximum dose, summing up to 225 mg, which is within the safe combined dosage limit.

Question 90

Which local anesthetic has a recommended maximum single dose of 175 mg when used alone, but this dose can be increased to 225 mg when combined with epinephrine?

A) Lidocaine
B) Mepivacaine
C) Prilocaine
D) Bupivacaine

Answer 90

Correct Answer: D) Bupivacaine

Rationale: The image indicates that for Bupivacaine, the recommended maximum single dose is 175 mg, but this can be increased to 225 mg when combined with epinephrine, which is used to prolong the anesthetic effect and reduce systemic absorption.

Question 91

What is the recommended maximum single dose of Lidocaine for infiltration without epinephrine?

A) 100 mg
B) 300 mg
C) 500 mg
D) 600 mg

Answer 91

Correct Answer: B) 300 mg

Rationale: According to the table, Lidocaine can be administered up to a maximum single dose of 300 mg for infiltration without the addition of epinephrine.

500mg w/ epi

Question 92

When using Mepiacaine for a peripheral nerve block (PNB), what is the recommended maximum single dose if epinephrine is added?

A) 400 mg
B) 500 mg
C) 600 mg
D) 700 mg

Answer 92

B) 500 mg

400 without

Question 93

What is the concentration of epinephrine in a 1:200,000 solution?

A) 5 mcg/mL
B) 10 mcg/mL
C) 50 mcg/mL
D) 100 mcg/mL

Answer 93

Correct Answer: A) 5 mcg/mL

Rationale: A 1:200,000 epinephrine solution means that there is 1 gram of epinephrine in 200,000 mL of solution. Converting 1 gram to 1,000,000 mcg and then dividing by 200,000 mL yields a concentration of 5 mcg/mL.

Question 94

Which local anesthetic strength corresponds to a concentration of 10 mg/mL?

A) 0.25%
B) 0.5%
C) 1%
D) 2%

Answer 94

Correct Answer: C) 1%

Rationale: Local anesthetic concentrations are often given in percentage form. A 1% solution means there is 1 gram of anesthetic in 100 mL of solution, which is equivalent to 10 mg/mL.

Question 95

If you have a 1:1,000 solution of epinephrine, how many micrograms of epinephrine are in 1 mL?

A) 1 mcg
B) 100 mcg
C) 1,000 mcg
D) 10,000 mcg

Answer 95

Correct Answer: C) 1,000 mcg

Rationale: A 1:1,000 ratio means 1 gram of epinephrine is diluted in 1,000 mL. Since 1 gram is equal to 1,000,000 mcg, dividing by 1,000 mL gives you 1,000 mcg/mL.

Question 96

If you want to achieve a more potent local anesthetic effect, which concentration should you increase?

A) 0.25%
B) 1%
C) 2%
D) 4%

Answer 96

Correct Answer: D) 4%

Rationale: The higher the percentage, the higher the concentration of the anesthetic agent. Therefore, a 4% solution has a higher concentration (40 mg/mL) compared to the others listed and would provide a more potent effect.

Question 97

When using a 4% lidocaine solution for localized tracheal anesthesia (LTA), what is the total dose of lidocaine in a pre-filled 4mL syringe?
A. 40 mg
B. 80 mg
C. 160 mg
D. 320 mg

Answer 97

Answer: C. 160 mg
Rationale: A 4% solution means 4 grams per 100mL, or 40mg per mL. Thus, in a 4mL syringe, the total dose is 40mg/mL x 4mL = 160mg.

Question 98

What is the contraindication for using epinephrine with local anesthetics?
A. When administered intramuscularly
B. When applied topically on mucous membranes
C. When injected into tissues supplied by end arteries
D. When used in conjunction with cocaine

Answer 98

Answer: C. When injected into tissues supplied by end arteries
Rationale: Epinephrine causes vasoconstriction, which can lead to ischemia and potential necrosis in areas with end-arterial blood supply, such as fingers, toes, ears, nose, and penis.

Question 99

Which topical anesthetic is known for causing localized vasoconstriction and reducing blood loss during surgical procedures?
A. Tetracaine
B. Lidocaine
C. Cocaine
D. Prilocaine

Answer 99

Answer: C. Cocaine
Rationale: Cocaine causes localized vasoconstriction, which can help to decrease blood loss and improve surgical visualization.

Question 100

For what reason is EMLA cream cautioned against in patients with methemoglobinemia?
A. It contains cocaine.
B. It is less effective in methemoglobinemia.
C. It contains prilocaine, which can exacerbate methemoglobinemia.
D. It is only effective with intact skin.

Answer 100

Answer: C. It contains prilocaine, which can exacerbate methemoglobinemia.
Rationale: Prilocaine, one of the components of EMLA, can lead to the formation of methemoglobin, a form of hemoglobin that is unable to carry oxygen efficiently.

Question 101

What is the total percentage of local anesthetics present in EMLA cream?
A. 2.5%
B. 5%
C. 7.5%
D. 10%

Answer 101

Answer: B. 5%
Rationale: EMLA cream contains a eutectic mixture of 2.5% lidocaine and 2.5% prilocaine, totaling 5% local anesthetic.

Question 102

What is the recommended onset of action time for EMLA cream when used for skin grafting procedures?
A. 45 minutes
B. 10 minutes
C. 2 hours
D. 30 minutes

Answer 102

Answer: C. 2 hours
Rationale: EMLA cream typically requires 2 hours to take effect for skin grafting procedures.

Question 103

Which of the following procedures would require the shortest readiness time after application of EMLA cream- select all?
A. Skin grafting
B. Venipuncture
C. Cautery of genital warts
D. Arterial cannulation

Answer 103

Answer: B,C,D

Rationale: EMLA cream requires the shortest onset time of 10 minutes for procedures like cautery of genital warts.

Question 103

EMLA cream should be dosed at 1 to 2 grams per what area size?
A. 5 cm²
B. 10 cm²
C. 20 cm²
D. 25 cm²

Answer 103

Answer: B. 10 cm²
Rationale: The recommended dose for EMLA cream is 1 to 2 grams per 10 cm² of skin area.

Question 104

EMLA cream contains which two local anesthetics?
A. Lidocaine and bupivacaine
B. Tetracaine and ropivacaine
C. Lidocaine and prilocaine
D. Benzocaine and tetracaine

Answer 104

Answer: C. Lidocaine and prilocaine
Rationale: EMLA is a eutectic mixture of lidocaine and prilocaine, both present at 2.5% concentration.

Question 105

Which of these is NOT recommended for use on skin wounds?
A. EMLA
B. Amethocaine
C. Lidocaine 7%
D. Tetracaine 7%

Answer 105

Answer: A. EMLA
Rationale: EMLA cream is not recommended for application on skin wounds.

Question 106

Which preparation is similar to EMLA in terms of compound type?
A. Tetracaine 4% Gel
B. Lidocaine 7%
C. Tetracaine 7%
D. Amethocaine

Answer 106

Answer: D. Amethocaine
Rationale: Amethocaine is described as EMLA-like, implying it’s a mixture similar to EMLA which is a eutectic mixture of lidocaine and prilocaine.

Question 107

For which of the following conditions should EMLA cream be used with caution?
A. Patients with allergies to ester-type local anesthetics
B. Patients with allergies to amide-type local anesthetics
C. Patients requiring prolonged anesthesia
D. Patients with a history of tachycardia

Answer 107

Answer: B. Patients with allergies to amide-type local anesthetics
Rationale: EMLA cream contains amide-type local anesthetics, so it is contraindicated in patients with allergies to these compounds. C/I in amide allergies

Question 108

What is the percentage concentration of Lidocaine in one of the alternative topical preparations listed?
A. 2%
B. 4%
C. 7%
D. 10%

Answer 108

Answer: C. 7%
Rationale: The slide lists Lidocaine 7% as one of the alternative preparations for topical anesthesia.

Question 109

What is the purpose of adding epinephrine 1:200,000 to a local anesthetic solution?
A. To decrease the duration of action
B. To increase the risk of necrosis
C. To double the duration of anesthesia
D. To enhance immediate pain relief

Answer 109

Answer: C. To double the duration of anesthesia
Rationale: Epinephrine is added to local anesthetics to prolong their action by causing vasoconstriction, which slows the systemic absorption of the drug.

Question 110

Which concentration of Ropivacaine is commonly used for local infiltration at an inguinal operative site?
A. 1%
B. 0.25%
C. 0.5%
D. 2%

Answer 110

Answer: B. 0.25%
Rationale: The slide indicates that Ropivacaine is used at a concentration of 0.25% for local infiltration at an inguinal operative site.

Question 111

Local infiltration anesthesia involves the placement of the anesthetic in which location?
A. Intravenous
B. Intramuscular
C. Subcutaneous
D. Epidural

Answer 111

Answer: C. Subcutaneous
Rationale: Local infiltration involves the extravascular placement of a local anesthetic, typically by subcutaneous injection.

Question 112

What is the method of action for a local anesthetic (LA) in a peripheral nerve block?
A. Inhibits calcium influx
B. Diffuses from outer mantle to central core of nerve
C. Activates the central nervous system
D. Increases permeability to sodium ions

Answer 112

Answer: B. Diffuses from outer mantle to central core of nerve
Rationale: The MOA of LAs in peripheral nerve blocks is based on diffusion from the outer layers of the nerve (mantle) to the inner layers (core), utilizing a concentration gradient to exert an anesthetic effect.

Question 113

In which order are fibers typically anesthetized during a peripheral nerve block?
A. Motor, sensory, autonomic
B. Sensory, autonomic, motor
C. Autonomic, sensory, motor
D. Motor, autonomic, sensory

Answer 113

Answer: C. Autonomic, sensory, motor
Rationale: Typically, the smallest sensory and autonomic nervous system (ANS) fibers are anesthetized first because they are more easily penetrated by the anesthetic due to their size and myelination status.

Question 114

During recovery from a peripheral nerve block, which area is likely to regain sensation first?
A. Distal
B. Proximal
C. Both at the same time
D. Neither, as recovery is not based on location

Answer 114

Answer: B. Proximal
Rationale: Sensation typically returns in the reverse order of the block; therefore, the area that was anesthetized last (distal) is usually the last to recover, making the proximal areas the first to regain sensation.

Question 115

A patient undergoes an interscalene block for shoulder surgery. Which area would you expect to be anesthetized last?
A. Shoulder
B. Elbow
C. Wrist
D. Fingers

Answer 115

Answer: D. Fingers
Rationale: In an interscalene block, anesthesia is applied to the brachial plexus, which affects the shoulder first and then spreads distally, with the fingers being the last to be numbed.

Question 116

The onset of action for a local anesthetic during a peripheral nerve block is dependent on:
A. The dose of the local anesthetic
B. The patient’s weight
C. The pKa of the local anesthetic
D. The type of nerve being blocked

Answer 116

Answer: C. The pKa of the local anesthetic
Rationale: The onset of action (OOA) for local anesthetics is dependent on the pKa of the drug, which determines the proportion present in the nonionized, lipid-soluble form that can diffuse across nerve membranes.

Question 117

Lidocaine has a faster onset of action compared to bupivacaine because:
A. It has a higher pKa
B. It has a lower pKa
C. It is administered at higher doses
D. It is a stronger base

Answer 117

Answer: B. It has a lower pKa
Rationale: Lidocaine has a faster onset of action because its pKa (7.9) is closer to the physiological pH, resulting in a higher proportion of the drug in the nonionized, lipid-soluble form. Bupivacaine is (8.1)

Question 118

The duration of a nerve block with bupivacaine can be extended by adding:
A. Epinephrine
B. Fentanyl
C. Clonidine
D. All of the above

Answer 118

Answer: D. All of the above
Rationale: The duration of a nerve block can be significantly extended by adding adjuncts such as epinephrine, fentanyl, or clonidine, which help prolong the anesthetic effect.

Question 118

Continuous infusion nerve blocks are preferred because they:
A. Provide shorter anesthesia duration
B. Require fewer additives
C. Improve pain control and patient satisfaction
D. Increase the risk of nausea

Answer 118

Answer: C. Improve pain control and patient satisfaction
Rationale: Continuous infusion blocks often use additives and are associated with improved pain control, less nausea, and greater patient satisfaction compared to single-injection blocks.

Question 119

Where is the local anesthetic ideally deposited in a sciatic nerve block?
A. Directly inside the nerve sheath
B. In the paraneural sheath surrounding the nerve

Answer 119

Answer: B
Rationale: The local anesthetic should be deposited in the paraneural sheath surrounding the nerve for effective diffusion and nerve block without damaging the nerve fibers directly.

Question 120

When performing a sciatic nerve block using ultrasound guidance, what is the importance of visualizing the paraneural sheath?
A. It helps identify the correct depth for injection.
B. It ensures the local anesthetic spreads effectively around the nerve.

Answer 120

Answer: B
Rationale: The paraneural sheath is the target for local anesthetic deposition. Visualizing it ensures that the local anesthetic will surround the nerve, leading to an effective block.

Question 121

For an effective sciatic nerve block, how should the local anesthetic appear on ultrasound after injection?
A. As a hypoechoic (darker) area surrounding the nerve
B. As a hyperechoic (brighter) area within the nerve

Answer 121

Answer: A
Rationale: Local anesthetics typically appear hypoechoic or darker on ultrasound, indicating appropriate distribution around the nerve when correctly injected.

Question 122

What is the purpose of exsanguination in a Bier Block procedure?
A. To remove air from the intravenous line.
B. To prevent systemic spread of the local anesthetic.
C. To minimize blood loss during the procedure.
D. To ensure that the local anesthetic remains confined to the extremity.

Answer 122

Answer: B. To prevent systemic spread of the local anesthetic.
Rationale: Exsanguination, which involves elevating the extremity and using a bandage or esmarch to expel blood, is used in a Bier Block to create a bloodless field and to help localize the effects of the local anesthetic to the extremity.

Question 123

Why is a double cuff used during a Bier Block?
A. To have a backup in case one cuff fails.
B. To distribute the pressure evenly on the limb.
C. To allow sequential inflation and deflation.
D. To increase the area affected by the anesthesia.

Answer 123

Answer: A. To have a backup in case one cuff fails.
Rationale: A double cuff is used to provide a safety margin in case one cuff deflates unintentionally, which could allow local anesthetic to enter systemic circulation and increase the risk of toxicity.

Question 124

What is the correct sequence of steps for a Bier Block?
A. LA injection, IV start, exsanguination, double cuff, IV D/C
B. IV start, double cuff, exsanguination, LA injection, IV D/C
C. IV start, exsanguination, double cuff ,LA injection, IV D/C
D. Exsanguination, IV start, LA injection, double cuff, IV D/C

Answer 124

C. IV start, exsanguination, double cuff ,LA injection, IV D/C

Question 125

Which fibers are affected first during a segmental block in neuraxial anesthesia?
A. Motor fibers
B. Sensory fibers
C. Sympathetic nervous system (SNS) fibers
D. Parasympathetic nervous system fibers

Answer 125

Answer: C. Sympathetic nervous system (SNS) fibers
Rationale: The sequence of blockade typically starts with the SNS fibers due to their myelination and smaller size, which makes them more susceptible to the effects of local anesthetics.

Question 126

During a segmental block, what is the usual order in which blockades occur?
A. Motor, Sensory, SNS
B. SNS, Sensory, Motor
C. Sensory, Motor, SNS
D. Motor, SNS, Sensory

Answer 126

Answer: B. SNS, Sensory, Motor
Rationale: The sequence of blockade typically follows the order of sympathetic (leading to hypotension, bradycardia), then sensory (affecting pain and temperature sensation), and finally motor blockade.

Question 127

In neuraxial blockade, which nerve fibers are the last to be affected?
A. Sympathetic nervous system fibers
B. Sensory fibers
C. Motor fibers
D. Parasympathetic nervous system fibers

Answer 127

Answer: C. Motor fibers
Rationale: Motor fibers are typically the last to be affected by local anesthetics during a neuraxial block due to their larger size and the myelination of the Aδ fibers which transmit proprioception and motor function.

Question 128

What is the typical delay in onset for epidural anesthesia due to the mode of action?
A. 1-5 minutes
B. 15-30 minutes
C. 45-60 minutes
D. 60-90 minutes

Answer 128

Answer: B. 15-30 minutes

Can speed it up to 3-5 min by adding bicarb and alkalizing it.
Rationale: Epidural anesthesia typically has a 15-30 minute delay in onset due to the slow diffusion of the local anesthetic through the dura to act on nerve roots and the spinal cord.

Question 129

Which local anesthetic is most commonly used for epidural anesthesia due to its good tissue diffusion?
A. Bupivacaine
B. Ropivacaine
C. Lidocaine
D. Levobupivacaine

Answer 129

Answer: C. Lidocaine
Rationale: Lidocaine is most commonly used for epidural anesthesia because it diffuses well through tissues and has a relatively rapid onset.

Question 130

How does the addition of epinephrine to bupivacaine affect the duration of action in epidural anesthesia?
A. It significantly increases the duration.
B. It has no advantage in terms of duration.
C. It decreases the duration.
D. It has variable effects on the duration.

Answer 130

Answer: B. It has no advantage in terms of duration.
Rationale: Adding epinephrine to bupivacaine in epidural anesthesia does not provide an advantage in extending the duration of action.

Question 131

After an epidural block, how do the effects on the fetus typically last?
A. 1-2 hours
B. 12-24 hours
C. 24-48 hours
D. 3-5 days

Answer 131

Answer: C. 24-48 hours
Rationale: The effects of an epidural block on the fetus can last for 24-48 hours due to the crossing of the local anesthetic through the placental barrier.

Question 132

In spinal anesthesia, where is the sensory effect relative to the sympathetic nervous system (SNS) and motor blockade?
A. SNS and motor effects are at the same spinal segments as the sensory blockade.
B. SNS blockade is 2 spinal segments cephalad, and motor blockade is 2 segments below the sensory level.
C. SNS and motor blockades are both 2 spinal segments below the sensory level.
D. SNS blockade is 2 spinal segments below, and motor blockade is at the same level as the sensory blockade.

Answer 132

Answer: B. SNS blockade is 2 spinal segments cephalad, and motor blockade is 2 segments below the sensory level.
Rationale: In spinal anesthesia, the blockade of the SNS usually occurs 2 segments above the level of sensory denervation, while motor blockade typically occurs 2 segments below.

Question 133

In comparison to spinal anesthesia, epidural anesthesia:
A. Requires smaller doses due to direct nerve root action.
B. Results in a differential zone of sympathetic nervous system blockade distinct from sensory levels.
C. Typically involves larger doses due to more systemic absorption.
D. Achieves motor blockade above the level of sensory blockade.

Answer 133

Answer: C. Typically involves larger doses due to more systemic absorption.
Rationale: Epidural anesthesia requires larger doses than spinal anesthesia because the local anesthetic must diffuse through the dura mater to reach the nerve roots, leading to more systemic absorption.

Question 134

If a patient is positioned on their right side after a hyperbaric local anesthetic is injected into the subarachnoid space, the primary area of the block will be:
A. More evenly distributed between both sides.
B. More pronounced on the left side.
C. More pronounced on the right side.
D. Unaffected by patient position.

Answer 134

Answer: C. More pronounced on the right side.
Rationale: Hyperbaric solutions are denser than CSF and will gravitate to the lowest point due to gravity. Therefore, positioning the patient on their right side will result in the local anesthetic settling more on that side, intensifying the block there.

Question 134

For a sensory block at the T10 dermatome level, the sympathetic nervous system blockade will typically occur at:
A. T12
B. T8
C. T10
D. L2

Answer 134

Answer: B. T8
Rationale: The sympathetic nervous system blockade occurs two segments above the sensory level. So, for a sensory block at T10, the SNS blockade would be at T8.

Question 135

The maximum dose of lidocaine for spinal anesthesia is:
A. 50 mg
B. 100 mg
C. 200 mg
D. 300 mg

Answer 135

Answer: B. 100 mg
Rationale: The maximum recommended dose of lidocaine for spinal anesthesia is 100 mg, considering the safety profile and potential for systemic toxicity.

Question 136

When determining the dosage for a subarachnoid block (SAB), which of the following is considered the most critical factor?
A. The concentration of the local anesthetic
B. The specific gravity of the local anesthetic
C. The total volume of the solution injected
D. The height of the patient

Answer 136

Answer: D. The height of the patient
Rationale: The dosage of local anesthetic for an SAB is tailored primarily according to the height of the patient because it correlates with the volume of the subarachnoid space, influencing the spread of the drug.

Question 137

For a patient who is 5 feet 5 inches tall, how much 0.75% bupivacaine is recommended for an SAB?
A. 1 mL
B. 1.5 mL
C. 2 mL
D. 2.5 mL

Answer 137

Answer: B. 1.5 mL
Rationale: The guideline suggests 1 mL of 0.75% bupivacaine for a 5-foot patient, with an additional 0.1 mL for every inch above 5 feet, which equals 1.5 mL for a person who is 5 feet 5 inches tall.

Question 138

What is the role of specific gravity in administering a subarachnoid block?
A. It is unrelated to the spread of the drug.
B. It is less important than the volume of the solution.
C. It determines the spread of the drug within the cerebrospinal fluid (CSF).
D. It is only relevant when using lidocaine.

Answer 138

Answer: C. It determines the spread of the drug within the cerebrospinal fluid (CSF).
Rationale: The specific gravity of the local anesthetic solution relative to CSF is a crucial factor in determining the cephalad or caudad spread of the drug within the subarachnoid space. Hyperbaric solutions will sink, and hypobaric solutions will rise.

Question 139

What is the maximum total volume of 0.75% bupivacaine suggested for a subarachnoid block in a patient over 5 feet tall?
A. 1 mL
B. 2 mL
C. 3 mL
D. 4 mL

Answer 139

Answer: B. 2 mL
Rationale: The text indicates a maximum of 2 mL total for a patient of any height over 5 feet, with 1 mL for the base height and 0.1 mL for each additional inch.

Question 140

During obstetric labor and C-sections, why is there concern regarding the type of local anesthetic used for epidural anesthesia?
A. All local anesthetics cross the placental barrier equally.
B. Bupivacaine has a reduced effect on the fetus due to protein binding.
C. Lidocaine does not cross the placental barrier.
D. Local anesthetics do not affect the fetus.

Answer 140

B. Bupivacaine has a reduced effect on the fetus due to protein binding.

Rationale: Bupivacaine has limited crossing of the placental barrier due to its lipid solubility and protein binding. This is an advantage in obstetric anesthesia as it reduces the potential effect on the fetus compared to less protein-bound local anesthetics like Lidocaine, which will cross more readily.

Question 141

How does epidural anesthesia differ from subarachnoid blocks (SABs) in terms of the zone of sympathetic nervous system (SNS) blockade?
A. Epidural anesthesia has a distinct differential zone of SNS blockade.
B. There is no differential zone of SNS blockade with epidurals.
C. SNS blockade occurs prior to sensory blockade in epidurals.
D. Motor blockade occurs before SNS blockade in epidurals.

Answer 141

Answer: B. There is no differential zone of SNS blockade with epidurals.
Rationale: Unlike subarachnoid blocks, where the SNS blockade is typically two spinal segments cephalad to the sensory level, epidural anesthesia does not create a differential zone of SNS blockade.

Question 142

What is the purpose of adding epinephrine to the solution used in tumescent liposuction?
A. To reduce the risk of infection
B. To produce vasoconstriction and minimize blood loss
C. To accelerate the metabolism of lidocaine
D. To decrease the duration of action of lidocaine

Answer 142

Answer: B. To produce vasoconstriction and minimize blood loss
Rationale: Epinephrine causes vasoconstriction when added to the dilute lidocaine solution in tumescent liposuction, which decreases bleeding and allows for clearer visibility during the procedure. It also contributes to prolonged postoperative analgesia due to the reduced systemic absorption of lidocaine.

Question 143

When is the peak plasma concentration of lidocaine typically observed after subcutaneous injection during tumescent liposuction?
A. Immediately after injection
B. 1 to 2 hours post-injection
C. 12 to 14 hours post-injection
D. 24 to 48 hours post-injection

Answer 143

Answer: C. 12 to 14 hours post-injection
Rationale: The peak plasma concentration of lidocaine occurs 12 to 14 hours after injection due to the slow and sustained release from the subcutaneous tissues, necessitating careful monitoring for signs of lidocaine toxicity.

Question 144

The “tumescent technique” in liposuction is characterized by which of the following?
A. Minimal use of local anesthetics
B. Quick onset and short duration of analgesia
C. Taut stretching of the skin due to large volume infiltration
D. Immediate removal of the injected solution

Answer 144

Answer: C. Taut stretching of the skin due to large volume infiltration
Rationale: The tumescent technique involves infiltrating large volumes of a dilute lidocaine and epinephrine solution into subcutaneous tissues, causing taut stretching of the overlying skin, vasoconstriction, and subsequent bloodless aspirates, which aids in fat removal and provides extended postoperative analgesia.

Question 145

What is the recommended dosage of lidocaine with epinephrine for regional anesthesia in tumescent liposuction?
A. 5 mg/kg
B. 7 mg/kg
C. 35 to 55 mg/kg
D. 100 mg/kg

Answer 145

Answer: B. 7 mg/kg
Rationale: For regional anesthesia using lidocaine with epinephrine, the recommended dosage is 7 mg/kg. This dosage takes into account the “mega-dose” approach of the tumescent technique, which allows for the use of higher total doses of lidocaine due to its slow systemic absorption and “tissue buffering system.”

Question 146

What is the recommended dosing range for lidocaine when using the tumescent technique for liposuction?
A. 5 to 7 mg/kg
B. 7 to 10 mg/kg
C. 35 to 55 mg/kg
D. 100 to 200 mg/kg

Answer 146

Answer: C. 35 to 55 mg/kg
Rationale: The tumescent technique for liposuction utilizes a “mega-dose” of highly diluted lidocaine, often ranging from 35 to 55 mg/kg. This high dosage is possible because the lidocaine is infused into the subcutaneous tissue and absorbed slowly, thereby reducing peak plasma concentrations and minimizing the risk of toxicity. However, close monitoring is still essential due to the delayed peak plasma levels.