Neuromuscular Blocking Agents

Question 1

What is the triad of anesthesia with NMB agents?

Answer 1

Unconsciousness (hypnosis)
Analgesia
Muscle relaxation (loss of reflex)

Question 2

What are NMB agents recommended for in vet med?

Answer 2

Intra-ocular surgeries
Intra-cranial surgeries
Thoracotomy
Mechanical ventilation

Question 3

What are the 2 families of cholinergic receptors?

Answer 3

Muscarinic

Nicotinic

Question 4

What is the neurotransmitter for cholinergic receptors?

Answer 4

Acetylcholine

Question 5

True or False: somatic nicotonic receptors are different than autonomic nicotinic receptors

Answer 5

False, they are identical

Question 6

What is required to stimulate a nicotinic receptor?

Answer 6

2 Ach (α subunits) molecules

Question 7

What is an example of a non-competitive, depolarizing NMB?

Answer 7

Succinylcholine

Question 8

What is the first phase of non-competitive, depolarizing NMBs? Second phase?

Answer 8

1: muscle depolarization (> [K])
2: muscle relaxation

Question 9

When are non-competitive depolarizing NMBs unsafe?

Answer 9

With conditions predisposed to high serum K such as renal disease, HYPP horses, and burn victims

Question 10

What can non-competitive depolarizing NMBs cause?

Answer 10

Acute increase in IOP and ICP

Question 11

How do competitive, non-depolarizing NMBs work?

Answer 11

Takes one molecule to block somatic nicotinic receptors, interferes with Ach binding

Question 12

What is the clinical effect of competitive, non-depolarizing NMBs?

Answer 12

At least 70% somatic nicotinic receptors blocked results in clinical loss of somatic muscle tone

Question 13

What happens if NMB > Ach?

Answer 13

Paralysis

Question 14

What happens if Ach > NMB?

Answer 14

Muscle tone

Question 15

What are examples of benzylisoquinolones?

Answer 15

Curare

cis-Atracurium

Question 16

What was the first known NMB alkaloid?

Answer 16

Curare

Question 17

How is curare eliminated?

Answer 17

Hofmann elimination- temperature and pH dependent

Question 18

What are examples of steroids that are NMB agents?

Answer 18

Pancuromium
Vencuronium
Rocuronium

Question 19

What should be done once a patient is paralyzed?

Answer 19

Ventilate

Monitor the degree of block

Question 20

What is NM block monitoring done via?

Answer 20

Peripheral nerve stimulator

Question 21

What are the peripheral nerves stimulated with monitoring a NM block?

Answer 21

Common peroneal
Ulnar
Facial

Question 22

What is muscle contraction/movement directly proportional to?

Answer 22

Number of active somatic nicotonic receptors

Question 23

True or False: it is important to determine normal peripheral nerve stimulation prior to giving NMB agent

Answer 23

True

Question 24

What are the modes of nerve stimulation?

Answer 24

Tetanic

Single twitch

Question 25

What is the train of four?

Answer 25

4 single twitches 0.5 seconds apart (2 seconds)
2 Hz
Compare T4:T1 ratio; 1 = no block, smaller ratio, the greater the block
T4 fades first and recovers last
Used to determine/adjust dose regimen, recovery

Question 26

What are examples of NMB reversal agents ?

Answer 26

Acetylcholinesterase inhibitors: neostigmine, edrophonium

Rocuronium specific reversal: Sugammadex

Question 27

What do Ach-esterase inhibitors do?

Answer 27

Results in decrease in Ach metabolism thus increase in numbers of Ach molecule receptor interaction
Outcompetes with NMB agent
Return of muscular tone

Question 28

What is required for Ach-esterase inhibitors?

Answer 28

Some muscular tone already present

Question 29

True or False: Ach-esterase inhibitors are nicotinic cholinergic specific

Answer 29

False, the result is an increase in Ach interaction at both nicotinic and muscarinic receptors

Question 30

What are side effects of Ach-esterase inhibitors?

Answer 30

Salivation

Bradycardia

Question 31

How can the side effects associated with Ach-esterase inhibitors be prevented?

Answer 31

Anticholinergic administration prior to Ach-esterase administration

Question 32

What must the patient be able to do prior to ending controlled ventilation?

Answer 32

They must be able to ventilate sufficiently