Grant CRNA Local Anesthetics Quiz Review
Are you a nurse anesthetist and want to put your knowledge to the test? The Grant CRNA local anesthetics quiz review below is set to help advance and gauge your knowledge. Take it up and see how it goes.
Questions and Answers
- 1.
Nerve conduction is determined mainly by 2 factors: nerve fiber diameter and the degree of ________, which determines conduction velocity.
Explanation
Nerve conduction is determined mainly by two factors: nerve fiber diameter and the degree of myelination. Myelination refers to the presence of a myelin sheath, which is a fatty substance that surrounds and insulates nerve fibers. This insulation allows for faster and more efficient conduction of electrical impulses along the nerve fibers. Therefore, the degree of myelination directly affects the conduction velocity of the nerve.Rate this question:
- 2.
Various concentrations of local anesthetics will provide various types of blocks. For example: –0.125% Bupivicaine only blocks _______ while 0.5% blocks sensory and motor
Explanation
Different concentrations of local anesthetics can produce different types of blocks. In this case, a concentration of 0.125% Bupivicaine only blocks sensory function, while a concentration of 0.5% blocks both sensory and motor function.Rate this question:
- 3.
Which of the following describes the correct order of nerve fiber blockade?
- A.
Autonomic, sensory, then motor.
- B.
Sensory, autonomic, then motor.
- C.
Sensory, motor, then autonomic.
- D.
Motor, autonomic, then sensory.
Correct Answer
A. Autonomic, sensory, then motor.Explanation
The correct order of nerve fiber blockade is autonomic, sensory, then motor. This means that the autonomic nerves, which control involuntary bodily functions, are blocked first. Then, the sensory nerves, responsible for transmitting sensations such as pain, are blocked. Finally, the motor nerves, which control movement, are blocked. This order ensures that the patient does not feel pain or discomfort during a procedure, while still allowing them to maintain some motor function.Rate this question:
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- 4.
Local anesthetics produce reversible binding at the site of sodium channels in nerves in all of the following states EXCEPT:
- A.
Closed/Resting
- B.
Open
- C.
Inactivated
Correct Answer
A. Closed/RestingExplanation
Local anesthetics work by binding to sodium channels in nerves, blocking the conduction of nerve impulses and producing a reversible loss of sensation. They primarily bind to the open and inactivated states of the sodium channels, preventing the influx of sodium ions and inhibiting nerve cell depolarization. However, they do not bind to the closed/resting state of the sodium channels, as this is the state in which the channels are not actively conducting impulses. Therefore, local anesthetics do not have an effect on the closed/resting state of sodium channels.Rate this question:
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- 5.
Local anesthetics must bind with at least ______ successive nodes of Ranvier to be effective.
Correct Answer
3
threeExplanation
Local anesthetics need to bind with a minimum of three successive nodes of Ranvier in order to be effective. The nodes of Ranvier are small gaps in the myelin sheath that surrounds nerve fibers. By binding to these nodes, local anesthetics can block the transmission of nerve signals, effectively numbing the area. Binding to fewer than three nodes may not provide enough coverage to fully block the nerve signals, resulting in incomplete anesthesia.Rate this question:
- 6.
The non-ionized form diffuses into the nerve axon while the ionized form binds to receptors on sodium channels when the channel is in the inactivated state.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The explanation for the given correct answer is that the non-ionized form of a substance is able to easily pass through the cell membrane and diffuse into the nerve axon. On the other hand, the ionized form of the substance binds to specific receptors on sodium channels, but only when the channel is in the inactivated state. This means that both forms of the substance have different mechanisms of action, but they are both involved in the transmission of signals within the nerve axon. Therefore, the statement is true.Rate this question:
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- 7.
Voltage gated Na+ channels are found only in the nerve’s _____.
- A.
Axon
- B.
Dendrites
- C.
Soma
Correct Answer
A. AxonExplanation
Voltage gated Na+ channels are found only in the nerve's axon. This is because the axon is responsible for transmitting electrical signals, known as action potentials, from one neuron to another. Voltage gated Na+ channels play a crucial role in generating and propagating these action potentials. They open in response to a change in voltage, allowing Na+ ions to flow into the axon and depolarize the membrane. This depolarization triggers the opening of voltage gated K+ channels, leading to repolarization and the propagation of the action potential along the axon. Therefore, voltage gated Na+ channels are specifically located in the axon to facilitate efficient and rapid transmission of electrical signals.Rate this question:
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- 8.
The Cm (minimum blocking concentration) or motor fibers is about ____ that of sensory fibers.
- A.
2x
- B.
1/2
- C.
1/4
- D.
10x
Correct Answer
A. 2xExplanation
The minimum blocking concentration (Cm) for motor fibers is approximately twice that of sensory fibers. This means that it takes a higher concentration of a blocking agent to inhibit the function of motor fibers compared to sensory fibers.Rate this question:
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- 9.
}The Cmin for local anesthetics can be defined as the lowest concentration of drug that is needed for blocking impulse propagation. The Cmin value can very depending on the temperature, pH or _____ concentration of the bathing solution.
Correct Answer
Calcium
CaExplanation
Cm requirements go up with temperature and hypercalcemia.Rate this question:
- 10.
Chemically, local anesthetics have three characteristic traits:1. An intermediate carbon group separates2. an unsaturated “aromatic” ring system from3. a tertiary amine. The aromatic ring provides lipophilic characteristics, whereas the amine gives hydrophilicity to the molecule.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
This type of linkage is important clinically because it has implications for metabolism and allergic potentialRate this question:
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- 11.
Lipid solubility will ______ potency and duration of action.
- A.
Increase
- B.
Decrease
- C.
Not affect
Correct Answer
A. IncreaseExplanation
Direct correlationRate this question:
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- 12.
When considering duration of action, the lipid solubility of a drug is more important than its protein binding.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Protein binding, however, is more important than lipid solubility when it comes to duration of action
When a drug is bound to protein it is not available to be metabolized by the liver or plasmaesterases.Rate this question:
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- 13.
Local Anesthetics that have a longer duration of action preferentially bind to the _____ protein chain of the nerve and less to albumin
Correct Answer
alpha
Alpha 1-acidExplanation
Alpha 1-acid glycoprotein (remember – weak base)
Therefore, less metabolism of the drug since it is staying at the site of action (less likely cleared by blood flow)
Ester local anesthetics usually have a shorter duration of action than amidesRate this question:
- 14.
Which of the following local anesthetics is 95% protein bound and has the greatest duration of action?
- A.
Bupivicaine
- B.
Mepivicaine
- C.
Lidocaine
- D.
Chloroprocaine
Correct Answer
A. BupivicaineExplanation
Chloroprocaine has NO (0%) protein binding – very short DOA – half life is 6 minutesRate this question:
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- 15.
Increased lipid solubility correlates with increased protein binding, increased potency, longer duration of action and a higher tendency for severe _______ (especially cardiac).
- A.
Toxicity
- B.
Anaphylaxis
- C.
Great outcomes
- D.
Cases of the Monday's
Correct Answer
A. ToxicityExplanation
Increased lipid solubility allows a drug to easily cross cell membranes and distribute throughout the body, leading to increased protein binding. This binding can enhance the drug's potency and prolong its duration of action. However, it also increases the drug's potential for toxicity, particularly in organs such as the heart. Therefore, drugs with high lipid solubility are more likely to cause severe toxicity, especially cardiac toxicity.Rate this question:
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- 16.
If a local anesthetic is injected into venous system, less drug gets to systemic circulation due to uptake by the _____ (first pass uptake).
Correct Answer
LungsExplanation
When a local anesthetic is injected into the venous system, it bypasses the liver, which is responsible for metabolizing drugs before they enter systemic circulation. Instead, the drug travels directly to the lungs, where it undergoes first-pass uptake. This means that a significant amount of the drug is taken up by the lungs before it can enter systemic circulation, resulting in less drug reaching the rest of the body.Rate this question:
- 17.
The addition of epinephrine or, less commonly, phenylephrine causes ______ rate of absorption and of peak plasma concentrations.
- A.
Decreased
- B.
Increased
- C.
No change to
Correct Answer
A. DecreasedExplanation
Toxicity is based on peak plasma levels.
The addition of vasoconstrictors facilitates neuronal uptake, enhancing the quality of analgesia, and limits toxic side effects.
**Always assume you could accidentally inject into the blood stream.Rate this question:
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- 18.
The addition of epinephrine to bupivacaine, ropivacaine, or etidocaine has which effect on their duration of action?
- A.
Increase
- B.
Decrease
- C.
No change
Correct Answer
C. No changeExplanation
Epi is effective for increasing DOA of short acting and intermediate acting drugs, clinically does not really effect DOA of long acting drugs because they are already longRate this question:
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- 19.
What is the max dose of epinephrine your are able to mix with your local anesthetic?
- A.
200-250 mcg or 3-5 mcg/kg
- B.
100-175 mcg or 1.5-2.5 mcg/kg
- C.
50-100 mcg or 0.5-1 mcg/kg
- D.
250-500 mcg or 5-10 mcg/kg
Correct Answer
A. 200-250 mcg or 3-5 mcg/kgExplanation
Use the 1:200,000 concentration (5 mcg/mL)Rate this question:
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- 20.
Higher max doses of local anesthetic are allowed with vasoconstrictor added.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The addition of a vasoconstrictor to a local anesthetic allows for higher maximum doses to be used. Vasoconstrictors, such as epinephrine, constrict blood vessels at the site of administration, reducing blood flow and delaying the systemic absorption of the local anesthetic. This reduces the risk of toxicity and allows for higher doses to be used safely.Rate this question:
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- 21.
Which of the following are contraindications to the addition of epi to your LA?
- A.
Unstable angina
- B.
Cardiac dysrhythmias
- C.
Uncontrolled HTN
- D.
Uteroplacental insufficiency
- E.
Areas that lack collateral blood flow such as the fingers/toes
Correct Answer(s)
A. Unstable angina
B. Cardiac dysrhythmias
C. Uncontrolled HTN
D. Uteroplacental insufficiency
E. Areas that lack collateral blood flow such as the fingers/toesExplanation
The addition of epi to local anesthesia should be avoided in patients with unstable angina, cardiac dysrhythmias, uncontrolled hypertension, uteroplacental insufficiency, and areas that lack collateral blood flow such as the fingers/toes. These conditions can increase the risk of adverse cardiovascular events or compromise blood flow to vital organs or extremities, making the use of epi in local anesthesia contraindicated.Rate this question:
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- 22.
Ropivacaine, lidocaine, and cocaine are vasoconsctrictors
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Ropivacaine, lidocaine, and cocaine are all drugs that have vasoconstrictor properties. Vasoconstrictors are substances that cause the narrowing of blood vessels, leading to a decrease in blood flow. This can be beneficial in certain medical procedures, such as local anesthesia, as it helps to reduce bleeding and prolong the effects of the anesthetic. Therefore, the statement that ropivacaine, lidocaine, and cocaine are vasoconstrictors is true.Rate this question:
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- 23.
Cocaine has vasoconstrictive properties because of its ability to block the reuptake of _________.
Correct Answer
norepinephrine
norepi
NEExplanation
Cocaine has vasoconstrictive properties because it blocks the reuptake of norepinephrine. Norepinephrine is a neurotransmitter that plays a role in regulating blood vessel constriction. When cocaine inhibits its reuptake, norepinephrine remains in the synaptic cleft for a longer period, leading to increased stimulation of alpha-adrenergic receptors and causing vasoconstriction. This narrowing of blood vessels can result in increased blood pressure and reduced blood flow to certain areas of the body.Rate this question:
- 24.
The pKa's of local anesthetics range from 7.6-9.1 with one exception of chloroprocaine which has a really high pKA. Chloroprocaine still has a very fast onset of action due to being used in high concentrations (3%).
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Locals are weak bases prepared as hydrochloride salts.Rate this question:
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- 25.
How do we increase the pH of a local anesthetic in order to increase the amount of drug in the nonionized form when injected into tissue?
- A.
The addition of sodium bicarbonate
- B.
Hyperventilate the patient
Correct Answer
A. The addition of sodium bicarbonateExplanation
Another benefit of adding NaHCO3 = less pain on injection.
Bupivicaine may precipitate with NaHCO3 addition
Use lower amounts of bicarb
0.1mEq/20 mL of bup vs. 1 mEq/10 mL of lido – not on test but for regionalsRate this question:
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- 26.
Which of the following receives the greatest amount of LA from distribution due to its greater tissue mass?
- A.
Brain
- B.
Liver
- C.
Muscle
- D.
Fat
Correct Answer
C. MuscleExplanation
Increased lipid solubility = greater plasma protein binding and greater tissue uptakeRate this question:
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- 27.
Metabolites of prilocaine, which accumulate after large doses of drug (>10mg/kg), convert hemoglobin to __________.
Correct Answer
methemoglobinExplanation
Benzocaine can also cause methemoglobinemia.Rate this question:
- 28.
The rate of metabolism of amides is agent dependent.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Prilocaine>lidocaine>mepivacaine>ropivacaine>bupivacaine
Mnemonic:
Please lease my rusty bus.Rate this question:
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- 29.
Esters are mostly eliminated via metabolism by:
- A.
Pseudocholinesterase
- B.
Kidneys
- C.
Lungs
- D.
Liver
Correct Answer
A. PseudocholinesteraseExplanation
Cocaine is also metabolized by liver esterases
Avoid the use of ester LA's with pseudocholinesterase deficiency.Rate this question:
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- 30.
Pregnancy, liver diseases, the 1st 6 months of life, and atypical plasma cholinesterase all ________ the DOA of ester local anesthetics.
- A.
Increase
- B.
Decrease
- C.
Have no effect
Correct Answer
A. IncreaseExplanation
Via decreasing plasma cholinesterase activity.Rate this question:
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- 31.
Echthiophate, neostigmine, pyridostigmine, and edrophonium are for drugs that ________ ester LA activity.
- A.
Prolong
- B.
Shorten
- C.
Have no effect
Correct Answer
A. ProlongExplanation
The drugs mentioned in the question, echthiophate, neostigmine, pyridostigmine, and edrophonium, are known to prolong ester LA (local anesthetic) activity. This means that these drugs increase the duration of the effects of local anesthetics, making them last longer.Rate this question:
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- 32.
Esters are metabolized almost exclusively in the liver by the microsomal cytochrome-P-450
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
This describes amides.
Patients w/liver disease or reduced liver blood flow may have prolonged effects.
P450 is INHIBITED by anesthesia gases, propanolol, and cimetidine.Rate this question:
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- 33.
What is the MOST LIKELY cause of local anesthetic toxicity?
- A.
Accidental intravascular injection
- B.
Inclusion of a vasoconstrictor
- C.
Tracheal injection site
- D.
Using a large dose
Correct Answer
A. Accidental intravascular injectionExplanation
The other three are factors that can produce LA toxicity but most likely due to an accidental IV injection.Rate this question:
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- 34.
Symptoms of LOCAL local anesthetic toxicity include all of the following except:
- A.
Pain, hematoma, and abscess
- B.
Ecchymosis
- C.
Tissue necrosis
- D.
Visual disturbances
Correct Answer
D. Visual disturbancesExplanation
Symptoms of local anesthetic toxicity can include pain, hematoma, abscess, ecchymosis, and tissue necrosis. However, visual disturbances are not typically associated with local anesthetic toxicity. Visual disturbances may be a side effect of other medications or conditions, but they are not a characteristic symptom of local anesthetic toxicity.Rate this question:
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- 35.
All of the following increase the risk of LA toxicity except?
- A.
Pregnancy
- B.
Hypoxemia
- C.
Respiratory acidosis
- D.
Respiratory alkalosis
Correct Answer
D. Respiratory alkalosisExplanation
Respiratory alkalosis does not increase the risk of LA (local anesthetic) toxicity. Local anesthetics are weak bases, and they exist predominantly in the ionized form in an alkaline environment. In respiratory alkalosis, there is a decrease in carbon dioxide levels, resulting in increased blood pH. This alkalotic state decreases the ionization of local anesthetics, reducing their toxicity. On the other hand, pregnancy, hypoxemia, and respiratory acidosis increase the risk of LA toxicity as they all lead to an acidic environment, promoting the ionization of local anesthetics and increasing their toxicity.Rate this question:
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- 36.
The greatest systemic absorption of local anesthetics occurs with _______ nerve blocks followed by caudal then epidural.
Correct Answer
intercostalExplanation
Peripheral nerve blocks are a less likely source of systemic absorption unless accidentally injecting IV - always aspirate prior to injection.Rate this question:
- 37.
In regards to CNS LA toxicity, it has been noted that _____ of the associated symptoms are seen when plasma concentrations increase slowly.
- A.
More
- B.
Less
Correct Answer
A. MoreExplanation
A sudden increase in plasma concentration may result in convulsions being the first symptom as opposed to circumoral numbness, etc.
75-80% of CNS toxicity occur within the first 5 minutes of the block being administered.Rate this question:
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- 38.
CNS depression associated with CNS toxicity reflects selective depression of inhibitory cortical neurons, leaving excitatory pathways unopposed.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The statement is true because CNS depression associated with CNS toxicity occurs when inhibitory cortical neurons are selectively depressed, which means they are not functioning properly. This leads to excitatory pathways being unopposed, meaning they are not balanced or regulated by the inhibitory neurons. As a result, there is an increase in excitatory activity in the CNS, leading to symptoms of CNS toxicity.Rate this question:
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- 39.
You are performing a nerve block on your patient when they begin having a tonic clonic seizure. Initial seizure treatment includes providing O2, airway control, midazolam and ________ their respiratory rate.
- A.
Increasing
- B.
Decreasing
Correct Answer
A. IncreasingExplanation
Hyperventilation helps to decrease the chance of ion trapping the LA in the brain.Rate this question:
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- 40.
0.5-2mg/kg of _______ terminates seizure activity.
Correct Answer
propofolExplanation
Propofol is a medication commonly used for anesthesia induction and maintenance, as well as for terminating seizure activity. It is administered intravenously in a dose range of 0.5-2mg/kg. This dosage is effective in stopping seizures and restoring normal brain activity. Propofol works by enhancing the inhibitory effects of gamma-aminobutyric acid (GABA), a neurotransmitter that reduces neuronal excitability. By increasing GABA's activity, propofol helps to control and terminate seizure activity.Rate this question:
- 41.
Containing a preservative is an absolute contraindication to administering a LA into a neuraxial compartment.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Administering a local anesthetic (LA) into a neuraxial compartment, such as the epidural or intrathecal space, is contraindicated if it contains a preservative. Preservatives can cause neurotoxicity and other adverse effects when injected into these compartments. Therefore, it is important to ensure that the LA being administered is preservative-free to avoid potential harm to the patient.Rate this question:
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- 42.
Your patient you were performing a regional block on suddenly becomes profoundly hypotensive and bradycardic. You suspect cardiovascular toxicity, after strongly reconsidering your career choice, you anticipate doing all of the following except:
- A.
Administer systemic epinephrine
- B.
High quality chest compressions
- C.
Activate ECMO
- D.
Administer 20% lipid emulsion
Correct Answer
A. Administer systemic epinephrineExplanation
Systemic epinephrine absorption following use with local anesthetics will most likely cause arrhythmias.Rate this question:
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- 43.
_____________ is the most cardiac toxic LA.
Correct Answer
BupivacaineExplanation
Also: etidocaine and ropivacaine (dissociates faster)Rate this question:
- 44.
The arrhythmogenic effect of bupivacaine is probably a result of the ________ of both fast Na+ and slow Calcium channels.
- A.
Inhibition
- B.
Excitation
Correct Answer
A. InhibitionExplanation
Typically will cause v-fib/v-tachRate this question:
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- 45.
________ is the most toxic ester due to it being hydroloyzed more slowly than other esters.
Correct Answer
TetracaineExplanation
Tetracaine is the most toxic ester because it undergoes hydrolysis at a slower rate compared to other esters. Hydrolysis is a chemical reaction in which a compound is broken down by water. In the case of esters, hydrolysis leads to the release of toxic byproducts. Since tetracaine is hydrolyzed more slowly, it remains in the body for a longer time, increasing its toxicity.Rate this question:
- 46.
This type of local anesthetics are broken down to para-aminobenzoic acid (PABA) which is a known allergen potentially causing localized edema, urticaria, bronchospasm, and anaphylaxis.
- A.
Esters
- B.
Amides
Correct Answer
A. EstersExplanation
Esters are a type of local anesthetics that are broken down into para-aminobenzoic acid (PABA), which is a known allergen. This can potentially cause localized edema, urticaria, bronchospasm, and anaphylaxis. Therefore, the correct answer is Esters.Rate this question:
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- 47.
____________ is ideally suited for topical anesthesia. It has a pKa of 3.5, making it completely ionized in a pH of 7.4 It comes in a 20% solution, delivering 200-300 mg per brief spray. Methemoglobinemia may occur with doses over 300 mg.
Correct Answer
Benzocaine
hurricane sprayExplanation
Benzocaine is ideally suited for topical anesthesia because it has a pKa of 3.5, which means it is completely ionized in a pH of 7.4. This allows it to easily penetrate the skin and provide effective anesthesia. Additionally, it comes in a 20% solution, delivering 200-300 mg per brief spray, which is a suitable dosage for topical anesthesia. However, it is important to note that doses over 300 mg can lead to methemoglobinemia, a condition where the blood is unable to carry oxygen effectively.Rate this question:
- 48.
All of the following are symptoms of methemoglobinemia EXCEPT:
- A.
Brownish-gray cyanosis
- B.
Tachypnea
- C.
Bradycardia
- D.
Metabolic acidosis
Correct Answer
C. BradycardiaExplanation
Causes tachycardia.
Patients w/severe anemia or heart failure cannot tolerate the reduced O2 carrying capacity.
Tx w/1-2 mg/kg of 1% methylene blue.Rate this question:
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- 49.
LA _______ non-depolarizing muscle relaxant blockade.
- A.
Potentiate
- B.
Inhibit
Correct Answer
A. PotentiateExplanation
The word "potentiate" means to increase the effect or strength of something. In the context of the given question, the blank is asking for a word that completes the sentence and relates to the non-depolarizing muscle relaxant blockade. By choosing "potentiate" as the correct answer, it suggests that the action being described is the enhancement or strengthening of the blockade caused by the non-depolarizing muscle relaxant.Rate this question:
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- 50.
Chloroprocaine and procaine share the same maximum dose which is ___ mg/kg.
Correct Answer
12Explanation
Chloroprocaine and procaine have the same maximum dose of 12 mg/kg. This means that for every kilogram of body weight, the maximum amount of these medications that can be administered is 12 milligrams. This ensures that the dosage remains within safe limits and prevents potential adverse effects or toxicity.Rate this question:
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