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Apex > Neuromuscular Blockers > Flashcards

Neuromuscular Blockers Flashcards

1
Q

What is the difference between extrajunctional receptors and regular nicotinic receptors?

A

A gamma subunit replaces the epsilon subunit or it consists of 5 alpha subunits

They are far more sensitive to sux

Remain open longer

Resistant to nondepolarizers

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2
Q

What are some contraindications to Sux?

A

Burns
Spinal cord injury
Upper/lower motor neuron dx
CVA
Tetanus
Severe sepsis
Muscular dystrophy
Prolonged chemical denervation

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3
Q

How much does Sux increase serum potassium?

A

Transiently (10-15 mins) by 0.5-1.0 mEq/L

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4
Q

When should sux be avoid (and for how long) following a denervation injury?

A

24-48hrs after for at least 1 year

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5
Q

What is the tx for sux-induced hyperkalemia?

A

Calcium chloride
Insulin + glucose
Hyperventilation
Sodium bicarb

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6
Q

What is a phase 1 block?

A

When sux stimulates the presynaptic nicotinic receptor it produces mobilization Ach in the nerve terminal as usual so there is ample supple of Ach

(No fade ~ normal sux response)

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7
Q

What is a phase 2 block?

A

Nondepolarizers competitively antagonize the presynaptic nicotinic receptor. The mobilization of Ach is impaired so the nerve terminal can only release what is immediately available, which exhausts quickly.

High doses of Sux can also produce this.

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8
Q

What two situations increase the risk of a phase 2 block with Sux?

A

Dose > 7-10 mg m/kg
Infusion of greater than 30-60 minutes

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9
Q

Where is the best location of measure onset of blockade?

A

Orbicularis oculi or corrugator supercilii

(This assess the facial nerve)

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10
Q

Where is the best place to measure recovery?

A

Adductor pollicis
Flexor hallucis

(These measure the ulnar nerve or posterior tibial nerve)

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11
Q

What TOF ratio suggests full recovery?

A

> 0.9

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12
Q

What are some acceptable clinical endpoints for neuromuscular blockade?

A

Tidal volume: > 5 mL/kg
TOF: no fade
Vital capacity: > 20 mL/kg
Inspiratory force: > than a - 40 cm H2O (more negative ~ the better)
Head lift > 5 seconds
Hand grip > 5 seconds

*** tongue blade against force is the best qualitative test of neuromuscular function

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13
Q

How does sux cause bradycardia and asystole?

A

By stimulating the M2 receptor in the SA node

(Kids are more susceptible to bradycardia due to their higher baseline vagal tone.

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14
Q

How does sux cause tachycardia and hypertension?

A

Mimicking the action of Ach at the sympathetic ganglia

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15
Q

What are some side effects of sux?

A

Increased intraocular pressure
Risk of MH
Bradycardia
Tachycardia
HTN
K+ release
Increased intracranial pressure
Increased intra gastric pressure

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16
Q

What enzyme (or enzymes) metabolizes acetylcholine?

A

Acetylcholinesterase
Genuine cholinesterase
Type 1 cholinesterase
True cholinesterase
Specific cholinesterase

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17
Q

What metabolizes Succinylchokine, mivacurium and Ester anesthetics

A

Butyrlcholinesterase
Pseudocholinesterase
Type 2 cholinesterase
False cholinesterase
Plasma cholinesterase

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18
Q

What are some drugs that reduce pseudocholinesterase activity? Aka prolong the duration of Sux

A

Metoclopramide
Esmolol
Neostigmine
Echothiopate
Oral contraceptives
Cyclophosphamide
MOAs
Nitrogen mustard

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19
Q

What are some co-existing diseases that may reduce pseudocholinesterase activity? Aka prolong sux

A

Atypical PChe
Severe liver disease
Chronic renal disease
Burns
Neoplasm
Advanced age
Malnutrition
Pregnancy

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20
Q

What is a Normal Dibucaine test?

A

It inhibits normal pseudocholinesterase

Normal number is 80 or dibucaine has inhibited 80% of the pseudocholinesterase.

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21
Q

What is an abnormal Dibucaine test?

A

Dibucaine does NOT inhibit atypical pseudocholinesterase. If the patient has a number of 20, this mean the Dibucaine did not inhibit the patient’s PChE

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22
Q

What is typical homozygous Dibucaine number? What is the sux duration?

A

Typical homozygous: 70-80
Duration: 5-10 mins

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23
Q

What is heterozygous Dibucaine number? What is the sux duration?

A

50-60
Duration: 20-30 mins

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24
Q

What is atypical homozygous Dibucaine number? What is the sux duration?

A

20-30
Duration: 4-8 hours

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25
Q

In atypical plasma cholinesterase, is there an insufficient number of quantity of pseudocholinesterase or is the enzyme not functional?

A

Not functional

26
Q

Why does Sux have a black box warning for kids?

A

Risk of cardiac arrest and/or sudden death secondary to hyperkalemia in children with undiagnosed skeletal muscle myopathy

27
Q

What does mild hyperkalemia present with?

A

Peaked T waves and PR prolongation

28
Q

What are the 3 goals if hyperkalemia results following administration of Sux to a child?

A

Stabilize the myocardium (give calcium 20 mg/kg or 60 mg/kg)

Shift K+ into cells (hyperventilation, glucose and insulin)

Enhance K+ excretion (lasix, volume, hemodialysis)

29
Q

Who has the highest incidence of myalgia?

A

Young adults (girls > boys) undergoing ambulatory surgeries

30
Q

What can be administered to lessen myalgia following Sux administration?

A

2 mg Roc, 0.3 mg Vec

31
Q

What is Duchenne’s muscular dystrophy response to sux and/or a nondepolarizer?

A

Sux: hyperkalemia/rhabdo
Roc: sensitive

32
Q

What is guillain-barre response to sux and/or a nondepolarizer?

A

Sux: hyperkalemia
Roc: sensitive

33
Q

What is multiple sclerosis response to sux and/or a nondepolarizer?

A

Sux: hyperkalemia
Roc: sensitive

34
Q

What is amyotrophic lateral sclerosis response to sux and/or a nondepolarizer?

A

Sux: hyperkalemia
Roc: sensitive

35
Q

What is up regulation of AChRs response to sux and/or a nondepolarizer?

A

Sux: hyperkalemia
Roc: resistant/normal

36
Q

What is Charcot-Marie Tooth response to sux and/or a nondepolarizer?

A

Sux: hyperkalemia
Roc: normal

37
Q

What is hyperkalemic periodic paralysis response to sux and/or a nondepolarizer?

A

Sux: hyperkalemia
Roc: normal

38
Q

What is hypokalemic periodic paralysis response to sux and/or a nondepolarizer?

A

Sux: MH?
Roc: normal

39
Q

What is MH response to sux and/or a nondepolarizer?

A

Sux: MH
Roc: normal

40
Q

What is myotonic dystrophy response to sux and/or a nondepolarizer?

A

Sux: contractures (not hyperkalemia)
Roc: normal or sensitive

41
Q

What is Huntington Chorea response to sux and/or a nondepolarizer?

A

Sux: sensitive
Roc: sensitive

42
Q

What is myasthenia Gravis response to sux and/or a nondepolarizer?

A

Sux: resistant
Roc: sensitive

43
Q

What is a short acting nondepolarizing neuromuscular blocker?

A

Mivacurium

Dose (0.15 mg/kg)
Duration: 16.8 mins

44
Q

What are the intermediate-acting neuromuscular blockers?

A

Cisatracurium (0.1 mg/kg)
Duration: 45 mins

Vecuronium (0.1 mg/kg)
Duration: 45 mins

Atracurium ( 0.5 mg/kg)
Duration: 45 mins

Rocuronium (0.6 mg/kg)
Duration 35 mins

45
Q

What is a long-acting nondepolarizing neuromuscular blocker?

A

Pancuronium (0.08 mg/kg)
Duration: 85 mins

46
Q

How is Atracurium metabolized?

A

Hofmann elimination and non-specific esterases

47
Q

How is cisatracurium metabolized?

A

Hoffman elimination

48
Q

How is Mivacurium metabolized?

A

Pseudocholinesterase

49
Q

How does temperature and pH affect Hofmann elimination?

A

Reaction is faster with alkalosis and HYPERthermia

Reaction is slower with acidosis and HYPOThermia

50
Q

What is Laundanosine?

A

Metabolite of both Atracurium and cisatracurium

This metabolite can produce seizures

51
Q

How is rocuronium metabolized?

A

Biliary excretion

Renal: 10-25%

52
Q

How is vecuronium metabolized?

A

Hepatic clearance

Renal elimination: 50-60%

53
Q

How is pancuronium metabolized?

A

Hepatic clearance
Renal Elimination: 85%

54
Q

In what order do the volatile agents potentiate neuromuscular blockers?

A

Des > Sevo > Iso > N2O > propofol

55
Q

What other medications may potentiate neuromuscular blockade?

A

Dantrolene
Lasix
Local anesthetics
Verapamil, amlodipine
Aminoglycosides, Clindamycin, tetracycline

56
Q

What electrolyte imblanaces potentiate the neuromuscular blockade?

A

^ Lithium
^ Magnesium
Decrease in calcium
Decrease in Potassium

57
Q

How does temperature affect neuromuscular blockade?

A

Hypothermia ^ duration

58
Q

What neuromuscular blockers have a histamine release?

A

Sux, Mivacurium, Atracurium

59
Q

Which neuromuscular blocker has a vasolytic effect?

A

Pancurium

60
Q

What type of patient should kit receive pancuronium?

A

A patient with hypertrophic cardiomyopathy

61
Q

What are the most common cause of perioperative allergic reactions?

A

Neuromuscular blockers

62
Q

Which NMB has the highest rate of anaphylaxis?

A

Sux (but roc is also shown a bunch in the literature)

Apex (47 decks)

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