Muscle relaxants and monitoring

Question 1

The ACh receptor is contained within the motor cell membrane and consists of five glycoprotein subunits

Answer 1

2 - a
1 - B
1 - S
1 - E

Question 2

Which subunit does acetylcholine bind to?

Answer 2

a

Question 3

ACh receptors are found in several areas: (3)

Answer 3

Postjunctional (most Ach receptors found)
Prejunctional
Extrajunctional

Question 4

Which junction influence the release of Ach?

Answer 4

Prejunctional

Question 5

How much receptor channels are open and a threshold potential is reached, a muscle action potential (MAP) is generated.

Answer 5

5 to 20%

Question 6

Half life of mature Ach receptors

Answer 6

2 weeks

Question 7

Half life of immature receptors

Answer 7

24 hours
The immature receptors depolarize more easily in the presence of ACh or SCH and thus are more prone to release potassium.

Question 8

Where is pseudocholinesterase produced?

Answer 8

Liver and circulates in the plasma

Question 9

When added to the serum under study, this inhibits normal plasma cholinesterase by 80%, whereas the atypical plasma cholinesterase is inhibited by only 20%.

Answer 9

Dibucaine

Question 10

Normal dibucaine number

Answer 10

80

Question 11

2 Muscle relaxants with biliary excretion

Answer 11

Vecuronium and rocuronium

Question 12

Like SCH, is metabolized by pseudocholinesterase.

Answer 12

Mivacurium

Question 13

This non-depolarizing muscle blocker does not seem to cause significant histamine release.

Answer 13

Cisatracurium

Question 14

Tachycardia is usually a side effect of this non-depolarizing muscle blocker because of ganglionic stimulation and vagolysis.

Answer 14

Pancuronium

Question 15

What antibiotic appears to have negative prejunctional and postjunctional effects.

Answer 15

Aminoglycoside

Question 16

Discuss important characteristics of a nerve stimulator.

Answer 16

A nerve stimulator should be capable of delivering single-twitch stimulation at 0.1 Hz (1 stimulus every 10 seconds), train of four (TOF) at 2 Hz (2 per second), and tetanic stimulation at 50 Hz (50 per second).

Question 17

Nerve stimulator electrodes (depolarizes or hyperpolarizes)
Black?
Red?

Answer 17

Black - depolarize

Red - Hyperpolarize

Question 18

Which stimulation mode is most commonly used to assess degree of blockade? How is it done?

Answer 18

TOF
Four stimuli are delivered at a frequency of 2 Hz (2 per second), and the ratio of the amplitude of the fourth to the first response in a train (T4:T1) ratio estimates the degree of block.

Question 19

Study

Answer 19

Twitch disapears when
4th twitch : 75% to 80% occupancy
3rd twitch : 85% occupancy
2nd twitch : 85% to 90% occupancy
1st twitch : 90% to 95% occupancy

Question 20

Consists of repetitive, high-frequency stimulation at frequencies of 50 Hz or greater.

Answer 20

Tetanic stimulation

Question 21

Loss of contraction during tetanic stimulation

Answer 21

Tetanic fade

Question 22

Mode of stimulation which involves the application of an initial burst of three 0.2-ms impulses at 50 Hz followed by an identical stimulation in 750 ms.

Answer 22

Double burst

Question 23

Which nerves can be chosen for stimulation?

Answer 23

Adductor pollicis muscle of the thumb

Question 24

What is adequate muscular relaxation?

Answer 24

Adequate relaxation is generally present when one to two twitches of the TOF response are present, correlating with 80% depression of single-twitch height.

Question 25

Discuss the appropriate time to reverse neuromuscular lockade based on nerve stimulation.

Answer 25

Neuromuscular blockade can be reversed when there is at least one twitch with TOF stimulation.