Muscle Relaxants Flashcards

0
Q

What is phase 1 block?

A

High proportion of Ach (I.e. Succinylcholine) to be activated at once

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1
Q

Acetylcholine binds what receptor at the neuromuscular junction? What subunit?

A

Nicotinic (2 Ach needed). Alpha subunits

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2
Q

Myasthenia gravis and depolarizing NMB vs. non-depolarizing NMB

A

Depolarizing: decreased sensitivity

Non-depolarizing: increased sensitivity

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3
Q

Best place to put twitch monitor that mimics diaphragm and larynx muscles?

A

Occuli orbicularis (innervated by facial nerve)

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4
Q

Absence of 4th twitch on ToF = what percentage of receptors blocked?
3rd twitch? 2nd twitch? No twitches?

A

75-80%
85%
90%
None: 95%

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5
Q

Twitch monitor on adductor pollicus longus or occuli orbicularis is more resistant to non-depolarizing NMB?

A

Occuli orbicularis

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6
Q

Succinylcholine duration of action with ecothiophate use? Atropine use? Cirrhosis? Pregnancy?

A

Cholinesterase inhibitor so prolonged duration
Atropine increases Ach so decreases duration
Decreased pseudocholinesterase so prolongs duration
Dilutional decrease of pseudocholinesterase so prolongs duration

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7
Q

Dibucaine number of 20%? 50% 80%?

A

20%: Homozygous for abormal pseudocholinesterase so prolonged action of succinylcholine (4-8 hours)
50%: Heterozygous so prolonged action (30 min)
80%: Normal

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8
Q

Time frame and type of injury to worry about with succinylcholine use

A

24 hours after injury up until 1 year

Burns, prolonged sepsis, spinal cord injuries, myopathies, major trauma

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9
Q

Succinylcholine and what side effect(s) are most associated with fasciculations? Increased ICP, increased IOP, masseter spasms, myalgias, increased abdominal pressures

A

Increased ICP and abdominal pressures

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10
Q

Effect on duration of non-depolarizing NMB: volatile anesthetics, hypercalcemia, hypermagnesemia, hyperthermia, acidosis, hyperkalemia.

A
Prolonged
Shortened/normal
Prolonged
Shortened/normal 
Prolonged
Shortened/normal
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11
Q

General side effects of benzylisoquinolone muscle relaxants (-curium) vs. steroid muscle relaxants (-curonium)

A

Curium: histamine release (mostly atracurium and mivacurium)
Curonium: vagolytic (mostly pancuronium)

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13
Q

Non-depolarizing NMB and left sided hemiparesis, myasthenia gravis, cerebral palsy, 3rd degree burns 2 weeks ago, SLE.

A

Resistance to non-depolarizing NMB on left (proliferation of extra-junctional AchR)
Increased sensitivity to depolarizing and resistance to non-depolarizing
Resistance to non-depolarizing and normal to depolarizing
Resistance to non-depolarizing, hyperkalemia with succ
Sensitivity to both

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14
Q

What do you worry about with atracurium & cisatracurium?

A

Laudanosine is a breakdown product metabolized by the liver and excreted by kidneys; can results in CNS excitation if built up (atracurium is more likely to cause problems because you need larger doses than cis-)

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15
Q

What NMB can cause a polyneuropathy with weakness with prolonged drip usage?

A

Vecuronium

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16
Q

Non-depolarizing NMB with the most liver metabolism

A

Pancuronium

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17
Q

Non-depolarizing NMB with the greatest renal excretion

A

Pancuronium

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18
Q

How is rocuronium metabolized and excreted?

A

No metabolism, cleared by the liver via bile

19
Q

How is vecuronium excreted?

A

25% renal, 75% bile

20
Q

Which NMB can precipitate with thiopental?

A

Rocuronium and vecuronium

21
Q

Full dose of naloxone?

A

0.4 mg

22
Q

Which would you not see with glycopyrrolate? Bronchodilation, tachycardia, decreased GI motility, decreased salivation, mydriasis?

A

Mydriasis; glycopyrolate has a quaternary structure and cannot cross the BBB

23
Q

What is recurization?

A

Rocuronium is excreted via bile with no metabolism and can reabsorbed again, causing residual NMB actions

24
Q

Neostigmine onset time and peak effect time?

A

Onset: 5 min
Peak: 10 min

25
Q

Does neostigmine cross the placenta? Can glycopyrolate cross the placenta?

A

Neo: Yes
Glyco: No

26
Q

75yo male given scopolamine is confused and disoriented, what is the treatment?

A

Physostigmine (crosses the BBB to increase Ach - since scopolamine is an anti-cholinergic)

27
Q

Most hemodynamically stable non-depolarizing NMB?

A

Vecuronium (no vagolysis and no histamine release) - Rocuronium has vagolysis

28
Q

Intubating dose of Succinylcholine?

A

1.5 mg/kg

29
Q

Intubating dose of Rocuronium?

A
  1. 6 mg/kg

1. 2 mg/kg (RSI)

30
Q

Intubating dose of Cisatracurium?

A

0.2 mg/kg

31
Q

Intubating dose of Vecuronium?

A

0.1 mg/kg

32
Q

Intubating dose of Pancuronium?

A

0.1 mg/kg

33
Q

Non-depolarizing NMB with the longest duration of action?

A

Pancuronium

34
Q

Non-depolarizing NMB with the most vagolytic side effect?

A

Pancuronium

35
Q

When should you avoid succ in children?

A

Men younger than 5 years (undiagnosed Duchenne muscular dystrophy)

36
Q

Difference in cardiac side effects seen with succinylcholine in adults vs. children?

A

Children: sympathotonic so they will brady after succ
Adults: vagotonic so they will become tachy

37
Q

What is the best clinical indicator of adequate muscle function after NMB use?

A

Sustained head lift (at least 70% function has returned)

38
Q

What T4/T1 ratio ensure the patient can maintain adequate ventilation?

A

0.9

39
Q

What is the gold standard of monitoring NMB?

A

Mechanomyography

40
Q

How is the duration of action of esmolol affected by a patient with a dibucaine number of 20%?

A

Not affected at all. Esmolol is metabolized by esterases in the RBCs (different from pseudocholinesterase that breaks down succinylcholine in this homozygous)

41
Q

How are NMB’s affected by Lambert-Eaton Syndrome?

A

Increased sensitivity to depolarizing and non-depolarizing NMBs (decreased ACh at the junction -> increased sensitivity to non-depolarizing -> increased extra-junctional receptors -> increased sensitivity to depolarizing)

42
Q

Does cerebral palsy increase the risk of hyperkalemia with succinylcholine use?

A

No since there is no increase in the extra-junctional receptors

43
Q

How do you calculate the RSBI (rapid shallow breathing index)? What is a good value for extubation?

A

RSBI = RR / TV (in liters)

RSBI