Advanced | NMB Agent and clinical application

Question 1

Describe the “Single Twitch Method”

Answer 1

A single supramaximal stimulus is delivered at a frequency of between 0.1 and 1 Hz.

Response amplitude is inversely proportional to the degree of blockade, as the blockade intensifies the response diminishes. Response returns as recovery occurs.

Question 2

A patient taking cyclophosphamide would have which of the following effect on pseudocholinesterase?

A. Inhibition

B. Augmentation

Answer 2

A. Inhibition

It is a pseudocholinesterase inhibitor so it causes prolonged apnea after succinylcholine administration.

Question 3

Which volatile anesthetic potentiates NMB the most?

A. Sevoflurane

B. Desflurane

C. Halothane

D. Isoflurane

Answer 3

B. Desflurane

The rank order of potentiation is desflurane > sevoflurane > isoflurane > halothane > nitrous oxide.

Stoelting Pharma | 6th edit

Question 4

TOFC 4
TOF ratio <0.4

The values presented may be interpreted as:

A. Shallow block

B. Deep block

C. Minimal block

D. Recovered

Answer 4

A. Shallow block

Question 5

READ

Answer 5

READ

• Response to TOF versus Response to PTC as illustrated below.

Question 6

Fade after Suxamethonium blockade indicates:

A. adequate blockade

B. onset of Phase II blockade

C. overdosage of suxemethonium

D. priming with an intubating dose

Answer 6

B. onset of Phase II blockade

Phase I block with Suxamethonium doesn’t exhibit fade, the TOF responses demonstrate diminished but equal amplitude.

• Fade after Suxamethonium blockade indicates onset of a Phase II block.

Describe the train of four method?

• Four supramaximal stimuli are delivered at 2 Hz (occurs over 1.5 seconds).

NDNMB demonstrates ‘fade’ in response to TOF stimuli.
The TOF Ratio is the ratio of the magnitude of the fourth response to the first response. Normal TOF response with no blockade = 1.0.

Question 7

This is the dose of succinylcholine causing an average 95%
suppression of twitch height (the ED95)?

A. 0.3 mg/kg

B. 1mg/kg

C. 1.5mg/kg

D. 2mg/kg

Answer 7

A. 0.3 mg/kg

For example, a 65 kg otherwise healthy patient would need a 19.5mg succinylcholine to yield a 95% suppression of twitch height.

Question 8

What is the estimated percentage of receptor occupancy when the depth of block is DEEP:

A. 95-100%
B. 90-95%
C. more than or equal 70%
D. 50%

Answer 8

B. 90-95%

Question 9

Which of the following statements provides the most accurate explanation behind the “faster onset” of rocuronium as compared with cis-atracurium?

A. Rocuronium is less potent
B. Rocuronium is more potent
C. Rocuronium is ultrashort acting
D. Rocuronium is long acting

Answer 9

A. Rocuronium is less potent

Question 10

Why is it relevant to achieve a TOF ratio of 0.9 and its implication in extubation?

Answer 10

0.7 - 0.75 is enough to say that reversal is enough however 0.8 - 0.9 excludes clinically important residual neuromuscular blockade.
At ratios less than 0.9, residual NMB blunts chemoreceptor sensitivity to hypoxia and hypercarbia and there is functional impairment to upper pharyngeal and esophageal muscles predisposing to regurgitation and aspiration.

Question 11

This NMB agent undergoes no clinically significant metabolism and is cleared primarily by the liver via BILE EXCRETION:

A. Rocuronium
B. Pancorunium
C. Cis-atracurium
D. Mivacurium

Answer 11

A. Rocuronium

Question 12

During induction of anesthesia for cesarean delivery in a 22-year-old female, rocuronium is inadvertently substituted for succinylcholine. The neonate does not show any sign of muscle relaxation because rocuronium is:

A. Highly protein bound
B. “Unaffected by ion trapping”
C. Lipid soluble
D. Highly ionized

Answer 12

D. Highly ionized

Neuromuscular-blocking drugs (NMBDs) are highly charged molecules because of the presence of a quaternary ammonium group in their structure. This makes them poorly lipid soluble so that they do not cross biologic membranes like blood–brain
barrier, renal tubular epithelium, and placenta.

Administration of these drugs thus does not produce central nervous system effects; renal tubular reabsorption is minimal, and maternal administration does not adversely affect the fetus. Issue of ion trapping can only develop if a drug gets trapped in the acidic environment of fetal blood after it has crossed the placenta.

Question 13

The effect of Ach at the neuromuscular junction (NMJ) is terminated by which
of the following mechanisms?

A. Break down by acetylcholinesterase
B. Break down by pseudocholinesterase
C. Degradation by tissue esterase
D. Reuptake into the nerve terminal

Answer 13

A. Break down by acetylcholinesterase

After depolarization of the motor nerve and a rise in intracellular Ca+2 at the nerve
terminal, vesicles containing Ach are released into the synaptic cleft. Binding of
Ach to nAchRs on muscle cells induces muscle contraction. Ach is then rapidly
hydrolyzed by acetylcholinesterase into choline and acetic acid in the synaptic cleft
as well as at the basement membrane. Choline is subsequently reabsorbed at the
presynaptic nerve terminal.

Pseudocholinesterase is an enzyme responsible for the degradation of
succinylcholine, mivacurium, as well as ester local anesthetics. Similarly, tissue
esterases are responsible for the degradation of other pharmacologic agents, such as remifentanil and atracurium.

Neither of these enzymes plays a role in the
degradation of Ach, resulting in termination of its action at the NMJ.

Question 14

What is the role of Ca++ in muscle contraction?

Answer 14

Ca+2 binds to and induces a conformational change in troponin which leads to formation of actin-myosin cross-bridge.

Depolarization of the skeletal muscle –> release of Ca+2 from the sarcoplasmic reticulum as well as entry of extracellular Ca+2 –> Ca+2 binds to and
induces a conformational change in troponin –> formation of actin-myosin cross-bridge –> activation of the myosin motor –> thereby producing mechanical contraction.

Question 15

This NMB agent has an active metabolite that is almost as potent as its parent drug. In ESRD patients, accumulation of the active metabolite can be a problem.

A. Rocuronium

B. Vecuronium

C. Pancuronium

D. Mivacurium

Answer 15

VECURONIUM

• Vecuronium is simply pancuronium without the quaternizing methyl
  group in the 2-piperidino substitution.
• Vagolytic means, inhibition of the action of the vagus nerve. Just like the effect of atropine and other anticholinergics.
• increased lipid solubility gives it a greater biliary elimination.
• Excretion is via LIVER(majority) and KIDNEY.

Stoelting | 6th edit

Question 16

When given with Thiopental, this aminosteroid NMB can potentially precipitate.

A. Rocuronium

B. Vecuronium

C. Pancuronium

D. Mivacurium

E. Atracurium

Answer 16

B. Vecuronium

Vecuronium is prepared as a lyophilized powder because it is less stable in solution.

Vecuronium is a quaternary aminosteroid with only one metabolite, 3-
desacetylvecuronium. It precipitates out of solution if administered concurrently
with thiopental.

Vecuronium cannot be prepared as a ready-to-use solution with
a sufficient shelf life, even as a buffered solution. In contrast, pancuronium, the 2- piperidine is quaternized and no longer basic (charged). Thus, it does not participate in catalysis of the 3-acetate hydrolysis.

Panco DO NOT precipitate. Vecuronium does!!

Question 17

TRUE or FALSE

Onset is faster for the less potent NMB agent.

Answer 17

TRUE

Succinylcholine and rocuronium is less potent compared to Cis-atracurium and Vecuronium, hence they have FASTER ONSET.

Dictum:

• “The less POTENT, the more FASTER”

Question 18

IOP increase after a single dose succinylcholine?

Answer 18

up to 15mmHg (ONLY lasts 5 minutes)

Normal intraocular pressure is
12 to 20 mmHg with a diurnal variation of 2 to 3 mmHg, whereas changes in position may induce increases of up to 6 mmHg.

Intraocular pressure increases up to 15 mmHg transiently (5 minutes duration) after administration of succinylcholine

Question 19

Which of the following has a vagolytic property thus causing tachycardia?

A. Mivacurium
B. Cis-atracurium
C. Atracurium
D. Pancuronium

Answer 19

D. Pancuronium

Pancuronium produces tachycardia through a vagolytic mechanism, as well as by direct sympathomimetic actions.

This is due to its ability to block the reuptake of norepinephrine and butyrylcholinesterase-inhibiting properties.

Question 20

A 19-year-old man is brought to the emergency department with burns to 50% of his body after an accident. His SpO2 is 85% with a respiratory rate of 30 breaths/minute. He requires endotracheal intubation and mechanical ventilation for respiratory failure. Which of the following is MOST likely to result from administration of succinylcholine 1 mg/kg IV?

A. Trismus

B. Bradycardia

C. Adequate relaxation

D. Hyperkalemia

Answer 20

C. Adequate relaxation

The administration of succinylcholine results in a temporary increase in serum potassium levels. The average increase in serum potassium of 0.5 mEq/L is normally well tolerated.

The degree of increase can be dramatic in patients with major burns, multiple trauma, prolonged immobility, upper motor neuron disorders, or denervation injuries. This is thought to be secondary to increased expression of extrajunctional nicotinic acetylcholine receptors.

After a burn injury, it takes approximately 24 hours for extrajunctional nicotinic acetylcholine receptors to appear. This effect peaks seven days following the injury and is also accompanied by decreased sensitivity to nondepolarizing muscle relaxants. Thus, because this patient sustained the burn less than 24 hours before presentation, it is safe to use succinylcholine to achieve neuromuscular relaxation for rapid sequence induction and intubation.

• Adequate relaxation would be the expected response from succinylcholine 1 mg/kg IV. Succinylcholine is the drug of choice for rapid sequence induction and intubation providing excellent intubating conditions within 45-60 seconds.

Question 21

The intubating dose of NonDepo NMB should be 2x the ED95?

Answer 21

TRUE

Larger intubating dose SPEEDS the onset and LENGTHENS the duration

Question 22

Clinical vignette:

While doing a PACU rounds, you noticed that a patient is desaturating to an O2 sat of 70-80%. Upon thorough assessment, your clinical judgement is to secure the airway using RSI technique. However, the patient underwent GA-GETA and neostigmine was used as reversal agent from his previous surgery an hour ago.

What muscle relaxant are you going to use this time and why?

Answer 22

ROCURONIUM 1.2mg/kg

Neostigmine, but not edrophonium, inhibits pseudocholinesterase (in addition to acetylcholinesterase) which leads to a prolonged effect of succinylcholine. Therefore, it is not recommended to administer succinylcholine in cases where surgical muscle relaxation is required
immediately after neostigmine has been administered.

Reference: Barash 9th edit | pp 1613

Question 23

A patient on succinylcholine infusion has a TOF ratio of 0.3. What does this tell about the patient’s degree of paralysis?

A. Patient is in phase I block.
B. Patient is in phase II block.
C. Patient is recovering from block.
D. Cannot tell from given information.

Answer 23

B. Patient is in phase II block

Phase I, or accommodation, block is characterized by a uniform decrease in the
amplitude of twitches compared with baseline. There is no fade with TOF on phase I block, and adequate recovery will demonstrate return of all 4 twitches. Phase II block is characterized by fade on TOF, tetanic fade, and post-tetanus potentiation.

Question 24

Which of the following is PAINLESS?

A. TOF Stimulation

B. Tetanic stimulation

Answer 24

A. TOF Stimulation

Can be interpreted without a pre-operative twitch response for comparison (as is required for Single Twitch).

• Doesn’t antagonize the NMB as tetanic stimulation does.

Question 25

Which mechanism best explains the fasciculations often seen preceding a phase I block by succinylcholine? A. Activation of presynaptic nAchR B. Activation of postsynaptic nAchR C. Prolonged muscle depolarization D. Prolonged muscle repolarization

Answer 25

A. Activation of presynaptic nAchR Binding of succinylcholine to presynaptic nAchR activates those receptors, stimulating repetitive firing and Ach release from the motor nerve terminal, which are manifested as fasciculations. Succinylcholine competes with Ach for binding to the postsynaptic nAchR and is not metabolized by the acetylcholinesterase present at the synaptic cleft, producing prolonged activation of the nAchR and muscle depolarization. As the depolarized muscle membrane locks voltage-gated sodium channels in the inactivated confirmation, junctional neurotransmission is blocked and flaccid paralysis ensues. This is called a phase I, or accommodation, block. This block is terminated by unbinding and diffusion of succinylcholine away from the NMJ back into the plasma and subsequent hydrolysis by plasma cholinesterases. Fasciculations can produce myalgia, and pretreatment with a small dose of nondepolarizing NMBs or NSAIDs has been shown to be effective for myalgia prophylaxis.

Question 26

The four most common neuromuscular blocking drugs currently used in clinical practice have an ED95 of either 0.3 or 0.05! .

Answer 26

TRUE ED95 for SUX and ROC is 0.3 ED95 for CIS and VEC is 0.05 * There is a highly significant variation between patients in response to all neuromuscular blocking drugs

Question 27

Nondepolarizing neuromuscular blocking drugs bind and inhibit:

Answer 27

presynaptic α3β2 acetylcholine receptors BIND - -> INHIBIT - -> MUSCLE RELAX!

Question 28

TRUE or FALSE Glycopyrrolate has onset and offset times similar to neostigmine.

Answer 28

TRUE For these reasons, glycopyrrolate is preferred with neostigmine (dose one-fifth that of neostigmine, 0.2-mg glycopyrrolate for every 1-mg neostigmine)

Question 29

Intubating dose of ATRACURIUM:

Answer 29

0.5 mg/kg twice the ED95!

Question 30

For all neuromuscular blockers the usual intubating dose is 2× or 3× the ED95

Answer 30

TRUE

Question 31

Which of the following statements provides the most accurate explanation behind the “faster onset” of rocuronium as compared with cisatracurium? A. Rocuronium is less potent B. Rocuronium is more potent C. Rocuronium is ultrashort acting D. Rocuronium is long acting

Answer 31

****A. Rocuronium is less potent The rate of onset of nondepolarizing NMBs generally depends on their potency. Less potent agents, such as rocuronium (ED95 0.3 mg/kg), have a faster onset of action as compared with more potent agents, such as cisatracurium (ED95 0.05 mg/kg). Rocuronium and cisatracurium are both intermediate-acting NMBs and have a duration of action of approximately 30-50 minutes. **LESS POTENT, FAST ONSET **

Question 32

Psuedocholinesterase activity is increased in which of the following conditions? A. Pregnancy B. Liver failure C. Obesity D. Malignancy

Answer 32

C. Obesity Pseudocholinesterase degrades succinylcholine (SCh), mivacurium, and certain local anesthetics. Intrinsic levels can be affected by certain physiologic and pharmacologic factors, such as alcoholism or obesity, which both increase butyrylcholine (aka pseudocholinesterase) levels. Butyrylcholinesterase levels may decrease to 75% of normal during pregnancy and to 67% of normal during immediate postpartum period; this degree of decrease is not usually clinically significant, but occasional prolonged apnea from SCh administration may result. Similarly, significant decrease of synthetic liver function may also result in prolonged apnea. In addition, plasma butyrylcholinesterase may be inhibited by exogenous compounds, such as organophosphates (eg, insecticides, chemical warfare agents, and echothiophate, a topical glaucoma agent), anticholinesterase agents (eg, neostigmine, pyridostigmine, and edrophonium), and monoamine oxidase inhibitors (MAOIs).

Question 33

Conditions with nAChR Upregulation:

Answer 33

SENSITIVE to succinylcholine RESISITANT to NMBA

Question 34

According to BARASH, the high-dose of ROCURONIUM is:

Answer 34

0.9 to 1.2 mg/kg

Question 35

What is ED 95?

Answer 35

The average dose to ACHIEVE 95% suppression of twitch height in 50% of population.

Question 36

The “defasciculating” dose of a nondepolarizing neuromuscular blocking drug: A. 5 - 10% of ED95 B. 15 - 30% of ED95 C. 50 - 75% of ED95

Answer 36

5 - 10% of ED95

Question 37

Which muscle relaxant undergoes biliary excretion? A. Vecuronium B. Pancuronium C. Rocuronium D. Succinylcholine E. Both A and C

Answer 37

A. Both A and C

Question 38

Nondepolarizing neuromuscular blocking drugs are:

Answer 38

Ionized Hydrophilic compounds Quaternary ammonium - exhibit limited lipid solubility CANNOT CROSS BBB and PLACENTA

Question 39

Only when the residual neuromuscular block is minimal (e.g., train-of-four count of 4 without fade or train-of-four ratio ≥0.4) is neostigmine a highly effective reversal agent.

Answer 39

TRUE NEO is 0.4! dial 0.4 to get in!!!

Question 40

Which of the following structures of the skeletal muscle does not change in length as the muscle contracts? A. A band B. I band C. H zone D. Z line

Answer 40

A. A band Skeletal muscle myofibril is composed of densely organized actin (thin) and myosin (thick) filaments. Histologically, A band contains overlapping actin and myosin, whereas I band contains actin only. The distance between 2 Z lines is defined as a sarcomere. When muscle cell is depolarized, rising intracellular Ca+2 leads to formation of actin-myosin cross-bridges in the A band and myosin motor activation pulls the actin filaments closer together. Thus, the spaces occupied by I band, H zone, and between the Z lines become shorter. The A band width remains unchanged.

Question 41

TRUE or FALSE Following an intubating dose of a nondepolarizing drug, and once a clinical neuromuscular block is established, about 50% to 75% of the intubating dose is required to reestablish a deeper block.

Answer 41

**FALSE ** Following an intubating dose of a nondepolarizing drug, and once a clinical neuromuscular block is established, ***only 10% to 25%*** of the intubating dose is required to reestablish a deeper block (i.e., 0.05 to 0.15 mg/kg for rocuronium).

Question 42

Does succinylcholine reduces the RISK of aspiration in patients with intact and competent esophageal sphincter? How?

Answer 42

YES Although succinylcholine may increase intragastric pressure, the lower esophageal sphincter tone is also increased, such that the intragastricesophageal pressure gradient remains the same. Therefore, in patients with an intact and competent esophageal sphincter, there is not an increased risk of aspiration from the use of succinylcholine.

Question 43

TRUE or FALSE The speed of onset is inversely related to the potency.

Answer 43

TRUE The less potent, the faster ONSET

Question 44

SEQUENCE of NEUROMUSCULAR TRANSMISSION

Answer 44

Action potential depolarizes --> Ca++ INFLUX --> Fusions in Vesicles --> RELEASE of Ach --> Ach DIFFUSES across synaptic cleft --> binds ALPHA(not beta) subunit of NICOTINIC receptors When Ach binds both ALPHA --> receptor ION channel OPENS: Na+Ca++ pasok K+ alalabas

Question 45

The metabolism of this NMB agent is INDEPENDENT of liver function thus making it ideal for patients with advanced liver pathology? A. Cisatracurium B. Atracurium C. Mivacurium D. Pancuronium

Answer 45

A. Cisatracurium Cisatracurium is the cis-cis isomer of atracurium and represents 15% of the atracurium mixture by weight but over 50% in potency. It is also metabolized by Hofmann elimination but, unlike atracurium, it does not release histamine. **Metabolism is independent of liver function.**

Question 46

TRUE or FALSE Nondepolarizing neuromuscular blocking drugs bind to one or both alpha subunits of the nicotinic acetylcholine receptor WITHOUT causing any activation of these ion receptor channels

Answer 46

TRUE

Question 47

TRUE or FALSE Succinylcholine should be avoided in GBS due to the danger of hyperkalemia, a risk that can persist after recovery from GBS.

Answer 47

TRUE If NMB is needed for surgical exposure, then a short-acting NMB should be used. Depending on the phase of the disease, patients may be resistant or sensitive to these drugs, so objective nerve function monitoring is important

Question 48

Where is pseudocholinesterase produced? A. Liver B. Lung C. Kidney D. Plasma

Answer 48

A. Liver Pseudocholinesterase is produced in the liver and circulates in the plasma.

Question 49

The SHORT duration of succinylcholine is due to: A. Lipid Metabolism B. Rapid Hydrolysis C. ED50 D. ED95

Answer 49

B. Rapid Hydrolysis

Question 50

TRUE or FALSE In patients with type II diabetes the duration of ROCURONIUM is prolonged and residual paralysis risk is increased.

Answer 50

TRUE

Question 51

TRUE or FALSE Hoffman elimination is faster when the pH is higher and the temperature is lower?

Answer 51

FALSE **Low pH, High Temperature = FASTER ELIMINATION via Hoffman elimination ** During a Hofmann elimination reaction, quaternary ammonium groups are converted to tertiary amines by cleavage of a carbon nitrogen bond. The Hofmann reaction is both pH- and temperature-dependent, with higher pH and temperature favoring elimination.

Question 52

Compared with the phase I block elicited by succinylcholine, the phase II block has which of the following characteristics? A. Same twitch strength with repetitive stimulation B. Posttetanic potentiation C. Similarity with depolarizing block D. Posttetanic depression

Answer 52

B. Posttetanic potentiation Usually, administration of intubating doses of succinylcholine produces a short, depolarizing neuromuscular blockade referred to as the phase I block. The force of muscle contractions is reduced; however, the twitch strength does not change in response to repetitive stimulation (eg, TOF or tetany). Administration of large doses of succinylcholine (>3-5 mg/kg), prolonged exposure (>30 min), or the presence of abnormal/atypical plasma cholinesterases can lead to a phase II block, which resembles the level of paralysis generated by nondepolarizing NMBs. Fade of twitch strength is observed after repetitive stimulation and potentiation, or stronger twitches, is produced after a period of tetany.

Question 53

ROUTE of SUX can be thru EXCEPT: A. intravenously B. Intraosseous C. Intralingual D Intramuscular E. Endotracheal

Answer 53

E. Endotracheal Succinylcholine is usually administered intravenously, but intraosseous, intralingual, and intramuscular routes have been reported when intravenous access is unavailable.

Question 54

TRUE or FALSE Succinylcholine depolarizes both postsynaptic and extrajunctional receptors

Answer 54

TRUE SUX --> POST & EXTRAJUNCTIONAL --> MUSLCE RELAX!

Question 55

TRUE of succinylcholine: A. Induces maximum blockade within 1 minute and lasts for approximately 45 minutes to 1 hour B. Despite paralysis at the adductor pollicis muscle, the diaphragm may start to contract, and spontaneous breathing may resume as fast as 2 minutes after 1 mg/kg C. About 75% of the original intravenous dose reaches the neuromuscular junction D. If pretreatment is used, it is recommended to INCREASE the dose of succinylcholine (up to 2 mg/kg).

Answer 55

D. If pretreatment is used, it is recommended to INCREASE the dose of succinylcholine (up to 2 mg/kg). Statement A is wrong because succinylcholine blockade lasts for up to 15 minutes. Spontaneous breathing may resume as fast as 5 minutes after the dose of 1mg/kg About 10% of the original intravenous dose reaches the NMJ

Question 56

The lowest train-of-four count for depth of block is called “shallow,” TOF count: ____ TOF ratio: ____

Answer 56

TOF count of 4 TOF ratio of < 0.4

Question 57

Contraindications to administering succinylcholine:

Answer 57

Burn more than 24 hrs AKI with Uremia Conditions with Upregulated receptors MH-susceptible

Question 58

Succinylcholine-induced HYPERKALEMIA happens in these following condition EXCEPT: A. Acute renal failure B. Sepsis C. Encephalitis D. Severe trauma E. Burn <12 hrs

Answer 58

E. Burn <12 hrs These are the conditions that can result to hyperkalemia: ACUTE renal failure with Uremia Sepsis Encephalitis Severe trauma Chronic denervation states (SPINAL CORD INJURY, PROLONGED BED REST, BURN of > 24 hours) Open globe (anterior chamber)

Question 59

A patient was maintained on a succinylcholine infusion for 8 hours during surgery and does not regain spontaneous ventilation 30 minutes after the infusion was discontinued. TOF yields 1 twitch. Which of the following is the best course of action? A. Give neostigmine. B. Send pseudocholinesterase activity test. C. Give naloxone. D. Wait for spontaneous recovery.

Answer 59

D. Wait for spontaneous recovery WHY? This patient likely has a phase II block as a result of a prolonged succinylcholine infusion. The recommended course of action at this time would be to continue sedation and mechanical ventilation until spontaneous recovery of muscle strength has occurred. Although theoretically anticholinesterase drugs can antagonize phase II block by increasing the amount of Ach available in the synaptic cleft, the response is difficult to predict because those drugs will also prevent the degradation of succinylcholine and are therefore best avoided in this situation. Atypical pseudocholinesterase or pseudocholinesterase deficiency may be suspected if the patient developed a phase II block and prolonged paralysis after a single dose of succinylcholine. Naloxone is a reasonable choice if patient has full motor recovery (no fade on TOF) and still fails to initiate spontaneous ventilation, pointing to other causes of apnea, such as opioid overdose.

Question 60

Bradycardia observed after a single dose of Succinylcholine to children is attributed to what mechanism? A. Muscarinic stimulation B. Nicotinic stimulation

Answer 60

MUSCARINIC stimulation at the sinus node

Question 61

Which of the following Non-depolarizing NMB has the highest VAGOLYTIC effect: A. Mivacurium B. Vecuronium C. Atracurium D. Pancuronium

Answer 61

D. Pancuronium Vagolytic effects from highest to lowest: PAN > ROC > VECU

Question 62

What is the NMB of choice for a patient with GBS? A. Non-depolarizing B. Depolarizing

Answer 62

Succinylcholine SHOULD be avoided in patients with GBS due to danger of hyperkalemia. If NMB is needed for surgical exposure, short acting non-depolarizing agent should be used.

Question 63

SUCCINYLCHOLINE and DIBUCAINE number: DIBUCAINE NUMBER - % of NORMAL pseudocholinesterase INHIBITED by dibucaine(NOT ABNORMAL pseudo)

Answer 63

Dibucaine - amide local anesthetic; inhibits normal plasma pseudocholinesterase by about 80% or greater. Normal - 80% homozygous atypical - 20% heterozygous atypical - 40 to 60% HOMO --> Paralysis extend up to 4-8 hrs HETERO --> Paralysis extend 50% up to 100%

Question 64

Succinylcholine short duration is due to: A. Rapid hydrolysis B. Volume of distribution C. Liver extraction ratio D. Diffusion to ECF

Answer 64

A. Rapid Hydrolysis

Question 65

Ca+2 binding to which component of the NMJ induces muscle contraction? A. Actin B. Thin filaments C. Troponin D. Nicotinic acetylcholine receptor

Answer 65

C. Troponin Binding of Ach to nAchRs causes a conformational change that lets Na+ into the cell while K+ out of the cell, depolarizing skeletal muscle. Depolarization leads to release of Ca+2 from the sarcoplasmic reticulum as well as entry of extracellular Ca+2. Ca+2 binds to and induces a conformational change in troponin, allowing formation of actin-myosin cross-bridge and activation of the myosin motor, thereby producing mechanical contraction. Ca+2 DOES NOT directly bind to actin, also known as thin filaments. Calcium kay TROPONIN

Question 66

Which of the following muscle relaxant is metabolized by pseudocholinesterase? A. Cis-atracurium B. Vecuronium C. Pancuronium D. Mivacurium

Answer 66

D. Mivacurium

Question 67

Which statement regarding the phase II block that can be associated with succinylcholine administration is TRUE? A. Phase II block occurs only after prolonged exposure to succinylcholine. B. Receptor desensitization is a mechanism responsible for phase II block. C. Inhalation anesthetics delay the onset of phase II block. D. Phase II block results in train-of-four (TOF) fade but not tetanic fade.

Answer 67

B. Receptor desensitization is a mechanism responsible for phase II block. Phase II block occurs after repeated boluses or prolonged infusion of succinylcholine. It can also occur after a single bolus of succinylcholine in patients with pseudocholinesterase deficiency. Phase II block is characterized by fade of the TOF twitch response, tetanic fade, and posttetanic potentiation. Several mechanisms have been proposed to explain the phase II block, including succinylcholine binding and inhibition of the presynaptic nAchR, postsynaptic receptor desensitization (locking of the receptor in an inactivated state unresponsive to further agonist binding), and membrane potential repolarization by activation of Na/K ATPase. Inhaled anesthetics accelerate, not delay, the onset of a phase II block.

Question 68

TRUE or FALSE The most important level of block is “recovered,” where the train-of-four count is 4 and the train-of-four ratio is ≥0.9.

Answer 68

TRUE

Question 69

Which of the following is the correct sequence of signals, leading to skeletal muscle contraction? A. Release of Ach → ligand-gated Na+ channels → motor nerve depolarization → voltage-gated Ca++ channels → muscle depolarization B. Motor nerve depolarization → voltage-gated Ca++ channels → release of Ach → ligand-gated Na+ channels → muscle depolarization C. Motor nerve depolarization → ligand-gated Na+ channels → release of Ach → voltage-gated Ca++ channels → muscle depolarization D. Ligand-gated Na+ channels → voltage-gated Ca++ channels → release of Ach → motor nerve depolarization → muscle depolarization

Answer 69

B. Motor nerve depolarization → voltage-gated Ca++ channels → release of Ach → ligand-gated Na+ channels → muscle depolarization

Question 70

Approximately what percent of the original intravenous dose reaches the neuromuscular junction when succinylcholine is given? A. 10% B. 50% C. 75% D. 100%

Answer 70

A. 10% Pseudocholinesterase has a great capacity to hydrolyze succinylcholine and only a small fraction, approximately 10%, of the original intravenous dose reaches the neuromuscular junction.

Question 71

All of the following are side effects of anticholinesterase drugs, EXCEPT: A. Excessive salivation B. Increased bowel motility C. Bradycardia D. Bronchodilation

Answer 71

D. Bronchodilation Administration of anticholinesterase agent leads to accumulation of acetylcholine, manifesting increased cholinergic actions in the body. Vagal stimulation causes bradycardia and, if not antagonized by concomitant administration of a cholinergic agent, may lead to cardiac standstill. Anti-sialagogue actions of these agents are also helpful in reducing the excessive salivation induced by parasympathetic overactivity of acetylcholine generated by inhibition of cholinesterase. Disruption of gastrointestinal anastomosis is another consideration, secondary to increased peristalsis of the bowel. Cholinergic activity may also lead to bronchospasm and not bronchodilation.

Question 72

In obese patients who need RSI, the dose of succinylcholine should be calculated based on: A. actual body weight B. ideal body weight C. total body weight

Answer 72

A. actual body weight Depo - ACTUAL body weight NonDepo - IDEAL body weight

Question 73

In an otherwise healthy patient, the increase of serum K after an intubating dose of succinylcholineis limited to approximately: A. 0.5 mEq/L B. 0.05 mEq/L C. 5 mEq/L D. 1.5 mEq/L

Answer 73

0.5 mEq/L

Question 74

TOF of > 2 would need which of the following dose of sugammadex in order to reverse it within 2 - 4 mins? A. 2mg/kg B. 4mg/kg C. 16mg/kg D. 8mg/kg

Answer 74

A. 2mg/kg SUGAMADEX 2mg/kg will reverse the paralysis in 2 minutes up to 4 minutes!

Question 75

This NMB agent undergoes no clinically significant metabolism and is cleared primarily by the liver via BILE EXCRETION: A. Rocuronium B. Succinylcholine C. Mivacurium D. Atracurium

Answer 75

ROCURONIUM

Question 76

incidence of anaphylaxis is very high with the use of which of the following? A. Cis-atracurium B. Succinylcholine C. Mivacurium D. Atracurium

Answer 76

B. Succinylcholine Incidence is1:10,000 VERY COMMON! High yield tip: AGENTS implicated in ALLERGIC REACTION during GENERAL ANESTHESIA Muscle relaxant is the most common culprit of allergic reaction intraoperatively.

Question 77

The substantial release of acetylcholine that occurs with tetanic stimulation—which floods the neuromuscular junction and presynaptic receptors with acetylcholine and serves to potentiate subsequent muscle responses is THE BASIS of which of the following pattern of nerve stimulation? A. POTC B. Double-burst stimulation C. TOF count D. Single twitch

Answer 77

A. POTC

Question 78

A 40 year old male is on tetracycline antibiotic coverage. If this patient is to be given NMB agent, the mechanism by which tetracyclines prolong NMB is thru? A. Pre-junctional B. Post-junctional C. Passive diffusion D. Active transport

Answer 78

B. Post-junctional Some antibiotics can also potentiate neuromuscular blockade. The aminoglycoside antibiotics, the polymyxins, and lincomycin and clindamycin primarily inhibit the prejunctional release of acetylcholine and also depress postjunctional nicotinic acetylcholine receptor sensitivity to acetylcholine. * The tetracyclines, on the other hand, exhibit postjunctional activity ONLY. Stoelting Pharma | 6th edit

Question 79

A 35 year old male is on clindamycin antibiotic coverage. If this patient is to be given NMB agent, the effect of clindamycin on NMB will be? A. Prolonged duration of NMB B. Shortened duration of NMB C. No effect on duration

Answer 79

A. Prolonged duration of NMB Prevents prejunctional release of Ach and decreases postjunctional nicotinic Ach receptors to Ach ---> Prolonged duration!!

Question 80

Which of the following will LEAST likely potentiate the action of NMB agent? A. Quinidine B. High dose local anesthetic C. Mg sulfate D. Hyperparathyroidism

Answer 80

D. Hyperparathyroidism

Question 81

A 40 year old female is scheduled for Laparoscopic procedure. She is known to have Bronchial asthma and have had an exacerbation few weeks ago. In order to avoid the potential development hyperactive airway, the MOST likely NMB agent that should be used is: A. Cis-atracurium B. Rocuronium C. Succinylcholine D. Mivacurium

Answer 81

A. Cis-atracurium The administration of benzylisoquinolinium NMBDs (with the exception of cisatracurium) is associated with histamine release, which may result in increased airway resistance and bronchospasm in patients with hyperactive airway disease. Stoelting Pharma | 6th edit

Question 82

All of the following will potentiate the effect of NMB agent EXCEPT: A. Aminoglycosides B. Tetracyclines C. Lithium D. Anticonvulsant E. Droperidol

Answer 82

Droperidol DRUGS that can potentiate the effect of NMB agents: Aminoglycosides Tetracyclines Clindamycin Lincomycin Polymixin * Volatile * Lithium * Anticonvulsant

Question 83

Which of the following side effect of succinylcholine cannot be blunted with a defasciculating dose of rocuronium? A. Increased IOP B. Increased ICP C. Myalgia

Answer 83

A. Increased IOP

Question 84

How would you reverse succinylcholine apnea in a patient with abnormal pseudocholinesterase?

Answer 84

Low dose neostigmine after phase II blocks occurs * low dose because neostigmine preferentially inhibits acetylcholinesterase, but higher dose inhibits pseudocholinesterase which would impair metabolism of sux even further. True Learn

Question 85

What does a phase II block mean?

Answer 85

It means that the postjunctional membrane has become repolarized, but it is desensitized to acetylcholine. A phase II block occurs after administration of a single large dose of succinylcholine (≥10 × ED95), repeated doses, or a prolonged continuous infusion.

Question 86

TRUE/FALSE Myasthenia Gravis is very sensitive to Non-depolarizing NMB agents. Therefore, about 1/2 to 2/3 of the dose should be used if and when paralysis is needed.

Answer 86

TRUE

Question 87

TRUE or FALSE Myotonic dystrophy (Myotonia) should be given depolarizing NMB when and if needed to avoid exaggerated contracture and CICO scenario.

Answer 87

FALSE!! NO Sux! It will lead to exaggerated contracture and CICO scenario.

Question 88

TRUE or FALSE Succinylcholine is relatively contraindicated in DMD (Duchenne Muscular Dystrophy)

Answer 88

TRUE

Question 89

TRUE or FALSE Non-depolarizing NMB (rocuronium) is not contraindicated in cases with upper motor neuron lesion.

Answer 89

TRUE!

Question 90

The effect of neomycin at the neuromuscular junction is: (A) decreased by depolarizing relaxants (B) partially reversed by calcium (C) potentiated by anticholinesterases (D) prevented by pretreatment with magnesium (E) primarily prejunctional

Answer 90

(B) partially reversed by calcium