Neuromuscular Blockers

Question 1

What do neuromuscluar blocking drugs do?

Answer 1

Interrupt nerve impulses at the NMJ

Question 2

What is the result of a neuromuscular block?

Answer 2

Complete paralysis of striated muscles with no analgesia and retained consciousness

Question 3

What are some indications for NMBs?

Answer 3

• Positioning eye centrally
• Relaxation of respiratory muscles (ICU patients)
• Relax muscles for neurological or orthopedic surgeries
• Aid in intubation (humans)

Question 4

What are the components of balanced anesthesia?

Answer 4

1. Unconsciousness
2. Stop reflexive movements/muscle relaxation
3. Analgesia

Question 5

Is mechanical ventilation required when using NMBs?

Answer 5

Yes, due to paralysis of respiratory muscles, spontaneous ventilation ceases

Question 6

What systems need to be monitored when using NMBs?

Answer 6

Cardio, respiratory, oxygenation

Question 7

What are the only two indications of noxious stimulation when using NMBs?

Answer 7

Tachycardia and high blood pressure

Question 8

When should NMBs not be used?

Answer 8

• No ability to ventilate or monitor
• Insufficient analgesia during surgery
• As a sole agent for procedures or euthanasia

Question 9

What is the MOA of depolarizing NMBDs?

Answer 9

Nicotinic ACh receptor agonist causing membrane depolarization

Question 10

What is the MOA of non-depolarizing NMBDs?

Answer 10

Competitive antagonist on nicotinic ACh receptors stabilizing muscle membranes

Question 11

What is the order of muscle relaxation?

Answer 11

Ocular muscles > Everything else (larynx observed esp) > Diaphragm

Question 12

What are some factors that influence the effect of NMBDs?

Answer 12

• Hypothermia
• Electrolyte abnormalitites
• Acid-base disorders
• Age
• Thermal burn

Question 13

What are some drugs that potentiate NMBD effects?

Answer 13

• Inhalation anesthetics
• Aminoglycoside antibiotics
• Local anesthetics
• Cardiac antiarrhythmic drugs
• Diuretics
• Magnesium

Question 14

What is succinylcholine mainly used for?

Answer 14

Human intubation

Historically used as euthanasia drug (inhumane)

Question 15

What is seen in Phase-1 block with succinylcholine?

Answer 15

Muscle fasciculation then paralysis

Question 16

What is seen in Phase-2 block with succinylcholine?

Answer 16

Non-depolarizing blockade after prolonged/high dosages

Question 17

What are some adverse effects of succinylcholine?

Answer 17

• Cardiac arrhythmias
• Hyperkalemia
• Fasciculation, myalgia, myoglobinuria
• Elevated intra-ocular and intra-gastic pressures
• Malignant hyperthemia

Question 18

Cumulative effects are less likely with what type of NMBDs?

Answer 18

Non-depolarizing

Question 19

Which type of NMBDs have less adverse effects?

Answer 19

Non-depolarizing

Question 20

Do non-depolarizing NMBDs have cardiovascular side effects?

Answer 20

Little to none

Question 21

What is the major metabolite in atracurim and what does it do?

Answer 21

Laudanosine, decreases seizure threshold

Question 22

What is atracurium eliminated by?

Answer 22

Plasma esterase enzymes- plasma pH and temp dependent

Question 23

Can atracurium cause histamine release at high doses?

Answer 23

Yes

Question 24

Cisatracurium represents what percentage of atracurium mixtures?

Answer 24

15% oft he 10 isomer mixture

Question 25

How is cistracurium elimated?

Answer 25

80% Hofmann elimination- organ dependent

Question 26

Which NMBD is the first choice in vet med?

Answer 26

Rocuronium

Question 27

What is rocuronium antagonized by?

Answer 27

Sugammadex- usually not needed

Question 28

How is rocuronium eliminated?

Answer 28

Mostly liver, partially kidneys

Question 29

What must be monitored closes when recovering patients with MNBDs on board?

Answer 29

Respiration

Question 30

What are sites of peripheral nerve stimulation in the dog/cat?

Answer 30

Peroneal and ulnar nerves

Question 31

What are sites of peripheral nerve stimulation in the horse?

Answer 31

Facial and peroneal nerves

Question 32

What are the stimulation patterns? (5)

Answer 32

1. Single twitch 2. Train of four 3. Tetanic stimulation 4. Post-tetanic count stimulation 5. Double burst stimulation

Question 33

What is single twitch stimulation used for?

Answer 33

Determine minimum necessary current to evoke maximal movement response prior to injecting NMBDs aka Supramaximal stimulus

Question 34

What is train of four stimulation used for?

Answer 34

Determine how deep the blockade is

Question 35

With train of four: the first twitch is the largest and the last is the smallest What does this indicate?

Answer 35

Partial blockade

Question 36

What will you see on a train of four stimulation with complete blockade?

Answer 36

No response

Question 37

A TOF ratio of what suggests acceptable recovery from blockade?

Answer 37

>0.9

Question 38

What kind of NMBDs are not recommended to antagonize?

Answer 38

Depolarizing NMBDs: succinylcholine

Question 39

What kind of drugs can be used to andtagonize NMBDs?

Answer 39

Ancetylchonlinesterase inhibitors- increased ACh at the NMJ Edrophonium over neostigmine

Question 40

What drug is used to REVERSE rocuronium?

Answer 40

Sugammadex

Question 41

How does sugammedex reverse rocuronium?

Answer 41

Rocuronium binds with sugammadex's lipophilic core