Exam 2 Neuromuscular Blocking Drugs (NMBDs)

Question 1

Action of NMBDs

Answer 1

• interrupt transmission of nerve impulses at the neuromuscular junction (NMJ)
• results complete paralysis of striated muscles while:

1. Consciousness is retained
2. No analgesia
3. Spontaneous respiration ceases

Question 2

What is the most common indication of NMBDs in vet med?

Answer 2

Position the eyeball centrally without traction

Question 3

What is the primary reason for using inhalational

anesthetics in vet med?

a) Analgesia
b) Immobility
c) Unconsciousness

Answer 3

b) Immobility

Question 4

What 2 things are the only signs that show in response to noxious stimulation?

Answer 4

Tachycardia and high blood pressure

Question 5

NMBDs must not be used as a sole agent for any
kind of procedure or euthanasia

True or False?

Answer 5

True

Question 6

5 Functions of NMJ

Answer 6

1. An impulse arrives at the motor nerve terminal (Ca2+ influx)
2. Release of acetylcholine (ACh) neurotransmitter
3. ACh binds to nicotinic ACh receptors on the postjunctional
   membranes (opening K+ and Na+ channels)
4. The resulting ion flux triggers an action potential that leads
   to muscle contraction
5. ACh is rapidly metabolized by the enzyme
   acetylcholinesterase in the synaptic cleft

Question 7

Which drugs bind to muscarinic ACh receptors?

a) Alfaxalone
b) Dexmedetomidine
c) Glycopyrrolate

Answer 7

c) Glycopyrrolate

Question 8

Depolarizing NMBDs act as ____ on nicotinic ACh receptors

Non-depolarizing NMBDs act as ___ on nicotinic ACh receptors

Answer 8

Depolarizing NMBDs act as agonist on nicotinic ACh receptors

Non-depolarizing NMBDs act as competitive antagonist on nicotinic ACh receptors

Question 9

Order of muscle relaxation?

Answer 9

Eyes > larynx > diaphragm

• Ocular muscles are the most sensitive
• Diaphragm is the most resistant

Question 10

Which drugs most potentitates NMBD effect?

Answer 10

Inhalational anesthetics

Question 11

3 Main factors that influence the depth of NMBD effect

Answer 11

1) Hypothermia
2) Electrolyte abnormalities
3) Age

Question 12

Treatment for histamine release

Answer 12

Low dose epinephrine

Question 13

4 non-depolarizing intermediate NMBDs

Answer 13

1) Atracurium
2) Cisatracurium
3) Rocuronium
4) Vecuronium

Question 14

What is the only depolarizing NMBD used in clinics?

Answer 14

Succinylcholine

Question 15

Which drugs can trigger malignant hyperthermia?

a) Fentanyl
b) Isoflurane
c) Ketamine
d) Propofol

Answer 15

b) Isoflurane

Question 16

Which intermediate acting non-depolarizing NMBD may cause seizures and histamine release at high doses?

Answer 16

Atracurium

Question 17

Sites of stimulation:

Dogs and cats?

Horses?

Answer 17

Dogs and cats -> peroneal nerve & ulnar nerve

Horses -> peroneal nerve & facial nerve

Question 18

_____ used for reversal of
neuromuscular blockade caused by
rocuronium

Answer 18

Sugammadex