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*Pharmacology > Progidy- Local Anesthetics > Flashcards

Progidy- Local Anesthetics Flashcards

1
Q

T/F - LA’s exert their action in the nodes of randvier

A

true

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2
Q

ATP pump =

____ K+ in

______NA++ out

A

2 K in,

3 NA out

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3
Q

Why does a nerve that’s freuqently stimulated get anesthetized quicker with a local anesthetic?

A

Bc the LA’s bind during the active or inactive states; so the more the nerve gets stimulated, the more chances the local anesthetic has to bind to the sodium channels .

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4
Q

What is the longest acting ester local anesthetic

A

Tetracaine

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5
Q

Which ester local has the shortest DOA

A

Chloroprocaine

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6
Q

opioids administered intrathecally provide analgesia through the attenuation of __fiber nociception,

A

C

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7
Q

The potential for LAST correlates with what characteristic of the drug

A

potency (lipid solubility)

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8
Q

initial signs of LAST

A
  • agitation
  • tinnitus
  • circumoral numbness
  • blurred vision
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9
Q

What is most commonly the first arrhythmia seen at toxic levels of a local anesthetic

A

bradycardia

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10
Q

When SpO2 levels are > 70%, the SpO2 will be (under/overestimated)

<70%, SpO2 will be (under/overestimated)

A

> 70% - underestimaded (SpO2 85%)

<70% - overestimated (Spo2 85%)

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11
Q

Transient neurological symptoms typically resolve within _____ days and the incidence is highest after which local anesthetic

A

1-7 days

lidocaine

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12
Q

What layer of skin is the rate-limiting layer for the absorption of eutectic mixture of local anesthetic (EMLA) cream?
A. stratum corneum
B. stratum spinosum
C. stratum granulosum
D. stratum basale

A

A. stratum corneum

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13
Q

Which local anesthetic only exists in a nonionized state?
A. tetracaine
B. benzocaine
C. procaine
D. mepivicaine

A

B. benzocaine

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14
Q

Which syndrome causes persistent paralysis of the nerves, resulting in lower extremity weakness and bladder and bowel dysfunction?
A. Cauda equina syndrome
B. Transient neurologic syndrome
C. Postdural puncture headache syndrome
D. Horner’s syndrome

A

A. Cauda equina syndrome

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15
Q

T/F: Bupivacaine can produce symptoms of cardiotoxicity at lower plasma concentrations in patients taking medications that inhibit cardiac impulse propagation such as digitalis, calcium channel blockers, or beta-blockers.

A

True

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16
Q

T/F: When clonidine is added to a LA, it prolongs the action of both long-acting and intermediate-acting agents equally

A

True- for up to 2 hours

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17
Q

Which of the following respiratory effects may occur with the administration of local anesthetics?

A. Increased bronchiolar smooth muscle tone

B. Decreased ventilatory response to hypoxia

C. Leftward shift in the CO2 response curve

D. Decreased ventilatory response to CO2

A

B. Decreased ventilatory response to hypoxia

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18
Q

Which of the following represents the standard concentration of epinephrine that would be added to a local anesthetic to prolong the duration of an epidural block? (select two)

A. 1:100,000 solution

B. 1:200,000 solution

C. 1 mcg/mL

D. 5 mcg/mL

A

B & D

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19
Q

T/F: The additional of hyaluronidase prolongs the duration of a block

A

false- speeds the onset by increasing the spread of local anesthetics into the tissues

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20
Q

All local anesthetics produce smooth muscle relaxation (vasodilation) except which 3 agents

A

cocaine

lido

& ropi

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21
Q

The duration of which local anesthetic is prolonged the most by the addition of the epinephrine?

A. Lidocaine

B. Etidocaine

C. Bupivacaine

D. Prilocaine

A

A. Lidocaine

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22
Q

T/F: the addition of epi does not significantly affect the duration of BPV

A

True - but perhaps people use it to decrease risk for toxicity by decreasing vascular uptake of the drug ?

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23
Q

Match protein binding with:

Mepivacaine

Lidocaine:

Ropi:

-60%, 80%, 95%

A

Mepivacaine: 80%

Lidocaine: 60%

Ropi: 95%

24
Q

The baricity levels of four local anesthetic mixtures are listed below. Which one would be considered to be isobaric?

A. 0.985

B. 1.0

C. 1.007

D. 1.15

A

B. 1.0

25
Q

Normal Specific gravity of CSF

A

1.004-1.009

26
Q

You have performed a brachial plexus block using bupivacaine with 1:200,000 epinephrine. The patient asks how long the block will last. You inform the patient that the block can last up to

A. 2 hours

B. 7 hours

C. 14 hours

D. 40 hours

A

C. 14 hours

27
Q

Which of the following factors would exert the greatest effect on the duration of action of local anesthetics?

A. Serum alpha-1 acid glycoprotein levels

B. Serum albumin levels

C. pH as determined by arterial blood gas

D. Serum alpha-1 antitrypsin levels

A
28
Q

The addition of sodium bicarbonate to local anesthetics would be responsible for all of the following except:

A. Decreased pain on injection

B. Reduced latency

C. Increased ionization of the local anesthetic

D. Prolonged duration of action

A

C. Increased ionization of the local anesthetic

The addition of bicarbonate to local anesthetics increases the non-ionized portion of the drug which facilitates the drugs passage across the neuronal lipid membrane and speeds onset. It also prolongs the duration of action and reduces pain on injection.

29
Q

A local anesthetic with which of the following pKa values would you expect to have the quickest onset of action?

A. 7.4

B. 7.6

C. 7.8

D. 8.3

A

A. 7.4

The closer the pKa is to physiologic pH, the more of it will exist in nonionized form and be able to cross the lipid membrane of the neuron, thus speeding onset.

30
Q

Onset of 5% Lidocaine in topical form

A. 5 minutes

B. 30 minutes

C. 2 hours

D. 4 hours

A

B. 30 minutes

(think you put your lido cream on an hour before just to be double sure)

31
Q

Which local anesthetic has low potency and short duration?

A. Procaine

B. Tetracaine

C. Bupivacaine

D. Prilocaine

A

A. Procaine

32
Q

Which of the following organs is most responsible for the initial rapid uptake of local anesthetics following intravenous injection?

A. Liver

B. Kidneys

C. Lungs

D. Muscle

A

C. Lungs

33
Q

Local anesthetics exist as:

A. weak acids with a negatively charged amine group

B. weak bases with a negatively charged amine group

C. weak acids with a positively charged amine group

D. weak bases with a positively charged amine group

A

D. weak bases with a positively charged amine group

All local anesthetics are weak bases consisting of a lipophilic group (often a benzene ring) attached to a positively charged amine group by either an amide or ester linkage.

34
Q

The incidence of transient neurologic symptoms following a tetracaine spinal anesthetic is increased by

A. local anesthetic baricity

B. early ambulation

C. increasing the glucose concentration in the anesthetic

D. the addition of phenylephrine to the anesthetic

A

D. the addition of phenylephrine to the anesthetic

(not epi though; and +lithotomy position can increase risk)

35
Q

Which ECG change would you most likely see in a patient with bupivacaine toxicity?

A. ST-T wave changes

B. Atrioventricular block

C. Widened QRS

D. Tachycardia

A

C. Widened QRS

PVCs, widening of the QRS, and ventricular tachycardia are the three most common ECG changes seen in local anesthetic toxicity. Alterations such as ST-T wave changes, tachycardia, and AV block also may occur, but are less common.

36
Q

Following injection of lidocaine during an epidural anesthetic, the patient begins to complain of numbness of her lips, dizziness, and ringing in the ears. Which of the following would be an appropriate intervention?

A. Encourage the patient to hyperventilate

B. Encourage the patient to take slow, shallow breaths

C. Administer thiopental sodium 50-100 mg IV

D. Administer atropine 0.4 mg IV to prevent possible bradycardia

A

A. Encourage the patient to hyperventilate

As the toxic symptoms progress, atropine may be indicated for bradycardia or sodium thiopental 50-100 mg to terminate seizures. In the early stages of toxicity, however, hyperventilation (preferably with 100% oxygen) is the treatment of choice. Acidosis worsens the toxic effects of local anesthetics by causing cerebral vasodilation and delivering more drug to the brain, reducing plasma protein binding which leaves more free drug available in the circulatory system, and by causing ion trapping within the neuron due to increased intracellular acidosis. Hyperventilation with 100% oxygen increases the plasma pH to counteract these effects and denitrogenates the lungs in the event emergency intubation becomes necessary.

37
Q

Plain 2% lidocaine has a specific gravity between 1.0004 and 1.0066. In relation to cerebrospinal fluid, this solution would be

A. Hypobaric

B. Isobaric

C. Hyperbaric

D. There is not enough information to answer this question

A

Hypobaric

CSF has a specific gravity of 1.004 to 1.009. 2% plain lidocaine is hypobaric in relation to CSF.

38
Q

T/F : the threshold for local anesthetic toxicity LOWER when injected intra-arterially than when injected intravenously

A

True

-b/c the lung extracts a signficant amount of LA, so IV injection into venous circulation hits the lungs before the freshly oxygenated arterial blood does

39
Q

You are performing regional anesthesia using lidocaine mixed with 1:200,000 epinephrine. The patient suddenly develops hypotension, tachycardia, and syncope. What is the most likely cause?

A. Allergic reaction to the local anesthetic

B. Allergic reaction to the epinephrine

C. Air embolus

D. Intravascular injection

A

D. Intravascular injection

If local anesthetic injection produces rash, urticaria, bronchospasm, laryngeal edema, and/or hypotension, then the cause is most likely an allergic reaction. Symptoms from the injection of a local anesthetic mixed with epinephrine such as syncope, tachycardia, and hypotension are more likely to be due to inadvertent intravascular injection.

40
Q

Which local anesthetics will produce vasodilation (select two)

A. prilocaine

B. ropivacaine

C. bupivacaine

D. lidocaine

A

Lido & Ropi

(& cocaine)

41
Q

What is the most common local anesthetic selected for subcutaneous infiltration anesthesia?

A. Lidocaine

B. Ropivacaine

C. Cocaine

D. Bupivacaine

A

A. Lidocaine

42
Q

Which local anesthetic exists as a pure S enantiomer?

A. Bupivacaine

B. Ropivacaine

C. Tetracaine

D. Benzocaine

A

B. Ropivacaine

(& Levobupi – makes them less toxic)

43
Q

In in vitro studies, the speed at which nerves are blocked by a local anesthetic is inversely proportional to their fiber size. According to this model, what is the correct order in which nerve function would be lost?

A. Proprioception, motor, autonomic

B. Motor, proprioception, autonomic

C. Motor, autonomic, proprioception

D. Autonomic, motor, proprioception

A

D. Autonomic, motor, proprioception

44
Q

Which local anesthetic is not recommended for use in peripheral nerve anesthesia?

A. ropivacaine

B. lidocaine

C. tetracaine

D. bupivacaine

A

C. tetracaine

b/c of it’s slow onset and increased potential for toxicity

45
Q

Which local anesthetic has the highest potency and longest duration?

A. Tetracaine

B. Procaine

C. Lidocaine

D. Mepivacaine

A

A. Tetracaine

Of the drugs listed, tetracaine has the highest potency and longest duration of action. Lidocaine and mepivacaine are both intermediate in potency and duration, while procaine has low potency and a short duration of action.

46
Q

All local anesthetics slow the maximum depolarization rate of the cardiac action potential via their effects on

A. magnesium channels

B. calcium channels

C. sodium channels

D. NMDA receptors

A

C. sodium channels

All local anesthetics slow the maximum depolarization rate of the cardiac action potential by inhibiting sodium influx through sodium channels.

47
Q

The renal excretion of the unchanged form of most local anesthetics is limited because of their low

A. degree of protein binding

B. degree of water solubility

C. molecular weight

D. volume of distribution

A

B. degree of water solubility

48
Q

Following administration of a spinal anesthetic, a patient exhibits severe bradycardia. What is the first line of treatment you should employ?

A. Ephedrine 25 mg IV

B. Atropine 0.4-0.6 mg IV

C. Intravenous fluids 15 mL/kg IV

D. Propofol 20 mg IV

A

B. Atropine 0.4-0.6 mg IV

If that is insufficient, ephedrine 25-50 mg should be administered. If necessary, epinephrine 0.2 to 0.3 mg may be administered.

49
Q

Which of the following would you expect to be most likely to increase a patient’s ventilatory response to carbon dioxide?

A. A brachial plexus block with bupivacaine

B. The administration of morphine 10 mg IV

C. Administering 100 mg of lidocaine IV

D. Administering a lidocaine spinal

A

A. A brachial plexus block with bupivacaine

Clinically useful levels of lidocaine can depress the ventilatory response to hypoxemia.

The systemic absorption of bupivacaine (as from a brachial plexus block), however, can stimulate the ventilatory response to CO2.

50
Q

Which nerve fibers would you expect to be more resistant to the effects of local anesthetics?

A. Unmyelinated nerve fibers responsible for pain and temperature transmission

B. Myelinated nerve fibers responsible for pain and temperature transmission

C. B fibers

D. A-delta fibers

A

A. Unmyelinated nerve fibers responsible for pain and temperature transmission

Studies have shown that C fibers (which are unmyelinated and transmit pain and temperature impulses) are more resistant to blockade than A-delta fibers and B fibers. Option B describes A-delta fibers, so it is also incorrect.

(perhaps why a patient still feels dull pain)

51
Q

Which local anesthetic has the greatest rate of metabolism?

A. Procaine

B. Tetracaine

C. Liposomal bupivacaine

D. Chloroprocaine

A

D. Chloroprocaine

(Tetracaine is the slowest)

52
Q

Regarding local anesthetics, which of the following are associated with acidosis? (select two)

A. Increased uptake of the local anesthetic into the brain

B. Increased convulsant threshold of the local anesthetic

C. Increased plasma protein binding of the local anesthetic

D. Increased proportion of free drug in the bloodstream

A

A. Increased uptake of the local anesthetic into the brain

D. Increased proportion of free drug in the bloodstream

Acidosis and/or hypercarbia will decrease the convulsive threshold of local anesthetics. Acidosis decreases the plasma protein binding, which increases the free form of the drug in the bloodstream which results in an increased amount available for diffusion into the brain.

53
Q

Hypercarbia and acidosis (increase/decrease) the seizure threshold of local anesthetics

A

Decrease the threshold, making it more likely to occur

54
Q

Which amide anesthetic undergoes the most rapid metabolism?

A. Prilocaine

B. Lidocaine

C. Mepivacaine

D. Etidocaine

A

A. Prilocaine

Then Lido > Mepivicaine.

slowest = bupi, etido, and mepi

55
Q

Select two highly protein-bound local anesthetics.

A. Lidocaine

B. Mepivacaine

C. Tetracaine

D. Bupivacaine

A

C. Tetracaine

D. Bupivacaine

highly protein-bound drugs have a longer duration of action.

56
Q
A

*Pharmacology (25 decks)

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