Neuromuscular Blockade(Paralytics)

Question 1

State three indications for a neuromuscular blockade

Answer 1

To facilitate tracheal intubation
To optimise surgical conditions such as intrathoracic, intra abdominal and intracranial
To optimise ventilation in a patient who requires controlled mechanical ventilation

Question 2

Do neuromuscular blockades have anaesthetic and sedative effects?

Answer 2

No, only produce paralysis

Question 3

State a life threatening adverse effect of suxamethonium

Answer 3

Hyperkalemia

Question 4

List 7 contraindications of succinylcholine

Answer 4

Lower motor neuron disease
Third degree burns
Duchene muscular dystrophy
Long term immobility
Intra abdominal sepsis
Hyperkalemia
Malignant Hyperthermia

Note: When used in this condition succinylcholine leads to exaggerated release of potassium causing Hyperkalemia (first 5)

Question 5

Name one adverse effect of succinylcholine choline seen in the postoperative period.

Answer 5

Painful myalgia

Question 6

Is succinylcholine associated with malignant hyperthermia?

Answer 6

Yes, it is a potent trigger

Question 7

Name an enzyme that metabolizes succinylcholine.

Answer 7

Plasma Pseudocholinesterase

Note: Some people have a defective enzyme or insufficient enzymes

Question 8

Does succinylcholine have a rapid onset and short duration of action?

Answer 8

Yes, it is prolonged in people with deficient or defective Pseudocholinesterase

Question 9

Explain the mechanism of action of non depolarising muscle relaxants.

Answer 9

They competitively inhibit the activity of acetylcholine on the postsynaptic nicotinic receptors thus preventing influx of sodium and depolarisation

Question 10

Name a non depolarising muscle relaxant that acts on pre junctional receptors.

Answer 10

Pancuronium

Question 11

Name a non depolarising muscle relaxant with the faster onset of action.

Answer 11

Rocuronium

Note: It is not faster than suxamethonium(succinylcholine)

Question 12

Name three non depolarising muscle relaxants with intermediate duration of action.

Answer 12

Rocuronium
Vecuronium
Cisatracurium

Question 13

Name a muscle relaxant that is long acting.

Answer 13

Pancuronium

Question 14

What is the major way in which Rocuronium and vecuronium are metabolized.

Answer 14

Hepatobiliary system

Note: Prolonged duration in people with severe liver disease

Question 15

Name a byproduct of metabolism of vecuronium excreted by the kidneys.

Answer 15

3-desacetyl vecuronium (it is an active substance)

Note: Note in renal failure duration of action of vecuronium is prolonged.

Question 17

Name an ideal muscle relaxant in people with severe liver and kidney disease and state why.

Answer 17

Cisatracurium
Why: It is cleared via the Hoffman elimination(degradation in plasma at physiologic pH and temperature)

Question 18

What is the mode of excretion of pancuronium?

Answer 18

Renal(80%)

Question 19

State what, is used to monitor the activity of muscle relaxant

Answer 19

Train of four twitches

If the anesthetist can feel the presence of four twitches, then the patient is 75% paralyzed or less.

If he/she feels three twitches, then the patient can be up to 85% paralyzed.

Two twitches indicate that the patient is 95% paralyzed,

One twitch, 99%, and

No twitches indicate that the patient is totally paralyzed, or more (meaning that there is an excess in muscle relaxant).

Question 20

When do you typically measure the degree of muscle relaxation with the train of four?

Answer 20

When there are 1-3 twitches seen.

Note: Four twitches are not to be monitored and no twitch spat all as well as it gives no information as to the likely duration of the existing blockade

Question 21

Name a reversal agent for non depolarising neuromuscular blockers.

Answer 21

Neostigmine

Note: Reversal of the neuromuscular blockade is possible if there is some evidence of spontaneous recovery at the neuromuscular junction, as detected by at least one out of four twitches.

Question 22

Name three important side effects of neostigmine. And state how they are typically prevented.

Answer 22

Bradycardia, bronchospasm and increased gut motility

Prevention: Administration of glycopyrrolate(anticholinergic)

Question 23

What is the best indicator of an adequate reversal of neuromuscular blockade.

Answer 23

Clinical signs.

Question 24

List 3 clinical signs that indicate adequate reversal of neuromuscular blockade.

Answer 24

The patient’s ability to lift the head for 5 seconds, to protrude his or her tongue, and maintain an inspiratory pressure ≥ −21 cm H2O are reliable signs of adequate reversal

Question 25

List 2 reliable clinical signs that indicate inadequate reversal of neuromuscular blockade.

Answer 25

The inability to sustain a prolonged muscle movement (such as extending the arm), and the sensation that one is unable to breathe or handle secretions are signs of aninadequate reversal.

Question 26

Are Tidal volume respiratory mechanics and the Train-of Four responses reliable indicators for adequate reversal of neuromuscular blockade?

Answer 26

Nope

Question 27

A 28-year-old man presents for shoulder surgery. The patient had a documented episode of malignant hyperthermia in a previous surgery under general anesthesia. Which of the following neuromuscular blockers is contraindicated in this patient? A. Vecuronium B. Rocuronium C. Pancuronium D. Succinylcholine E. Cisatracurium

Answer 27

D. Succinylcholine. It has been shown to cause malignant hyperthermia.

Question 28

An 18-year-old man presents to the operating room for an emergency exploratory laparotomy for a gun-shot wound to the abdomen. The patient has been intubated in the emergency room and arrives to the operating room intubated. Initial vital signs: BP 68/22, heart rate (HR) 142. His abdomen is distended, tense, and rigid. Which of the following is the most appropriate NMB for maintenance of paralysis in this patient? A. Vecuronium B. Pancuronium C. Cisatracurium D. Succinylcholine E. Rocuronium

Answer 28

B. Pancuronium has a vagolytic effect leading to tachycardia, which is vital for this patient. With significant intra-abdominal blood loss and severe hypotension, the patient’s cardiac output is dependent on the heart rate which should be maintained at high rates Succinylcholine: It is contraindicated in intra-abdominal sepsis which is likely in this patient who have signs of peritonism.

Question 29

Name a contraindication of pancuronium and state why.

Answer 29

Coronary artery disease. Why: Pancuronium increases the heart rate which can produce myocardial ischemia through increased myocardial work and decreased coronary blood flow.

Question 30

Does the effect of suxamethonium(succinylcholine choline last more than 10 minutes?

Answer 30

Nope, only in people with Pseudocholinesterase deficiency or defects.

Question 32

How many molecules of acetylcholine does suxamethalonium have.

Answer 32

2.

Question 33

List 5 contraindications of suxamethonium(lecture)

Answer 33

Malignant Hyperthermia Scoline apnoea Risk of Hyperkalemia including crush injuries, burns and Rhabdomyolysis and renal failure Drug allergy Unknown myopathies

Question 34

List four life threatening adverse effects of suxamethonium

Answer 34

Hyperkalemia Scoline apnoea Malignant Hyperthermia Anaphylaxis

Question 35

Does suxamethalonium cause bradycardia?

Answer 35

Yes it can.

Question 36

What is the treatment of scoline apnoea?

Answer 36

Supportive treatment with ventilation, sedation and fresh frozen plasma. Note: The condition is inherited and can be heterozygous or homozygous

Question 37

Name the characteristic clinical feature of scoline apnoea.

Answer 37

Muscle paralysis

Question 45

Name two non depolarising neuromuscular blockers that do not cause any histamine release

Answer 45

Cisatracurium Vecuronium

Question 48

Name the toxic metabolite of atracurium

Answer 48

Laudanosine

Question 49

Does reversal of non depolarising neuromuscular blocker mean waking the patient up?

Answer 49

Nope

Question 50

Should reversal of non depolarising neuromuscular blockers be done every after the drug has clinically worn off?

Answer 50

All non depolarising neuromuscular blockers should be reversed when it is safe to do so. Remember even when there is clinical improvement the drug may still be in the body and could bind to the receptors again

Question 51

Should reversal be given for suxamethonium?

Answer 51

Nope, it is not effective and could even prolong it's action

Question 53

Name an anticholinergic added when reversing the effects of neuromuscular blockers that does not cross the blood brain barrier

Answer 53

Glycopyrrolate

Question 54

When is it safe to reverse the non depolarising neuromuscular blockers?

Answer 54

When there is at least 3 twitches present Or if the patient is already breathing adequately Note: Early reversal is pointless as acetylcholine will not be able to effectively displace the muscle relaxant

Question 57

State an adverse effect of neostigmine when given in large doses.

Answer 57

Weakness

Question 58

Outline the management of inadequate reversal of neuromuscular blockade.5

Answer 58

Exclude another cause Maintain ventilation Reverse any potentiators Use PNS Repeat dose neostigmine

Question 59

Name 5 causes of inadequate reversal of non depolarising neuromuscular blockade.

Answer 59

Inadequate drug or giving it too early. Anaesthetic agents Stroke Analgesia Hypo or Hypercarbia

Question 60

List two commonest potentiators of inadequate reversal of non depolarising neuromuscular blockade.

Answer 60

Hypothermia Electrolyte abnormalities mainly magnesium, potassium and calcium

Question 61

Name a newest drug used to reverse effects of Rocuronium.

Answer 61

Sugarmmadex Note: It is a modified sugar that “mops up” any rocuronium by encasing it in its molecular structure; this is excreted renally

Question 62

State why sugarmmadex is better than neostigmine when it comes to reversal of Rocuronium.

Answer 62

It can be used at any time It has no muscarinic side effects Note: It is very expensive and not available in state