Neuromuscular Blocking Agents

Question 1

What are the 2 types of NMB?

Answer 1

Non depolarising

Depolarising

Question 2

What do they facilitate?

Answer 2

Tracheal intubation
Muscle relaxation for surgery
Mechanical ventilation

Question 3

Suxamethonium is what type of NMB

Answer 3

Depolarising
Succinylcholine related to acetylcholine. Activates muscle fibres first hence twitches.
Metabolised by plasma pseudocholinesterases

Question 4

Depolarising muscle relaxant characteristics?

Answer 4

Fast onset, see twitching there activation before full blockade, fast offset, no reversal required

Question 5

Non depolarising NMB characteristics?

Answer 5

Competitive antagonist of ACh at NMJ.

Slower onset and offset, no activation before block, may require reversal

Question 6

Why do RSI favour short acting NMB?

Answer 6

Minimises time between induction and intubation

Wears off quickly after a few minutes allowing respiration to restart and oxygen reserve to increase

Question 7

What is sux apnoea?

Answer 7

Genetic abnormality in cholinesterases so that the effects of sux are prolonged
Must use nerve stimulator prior to further relaxant

Question 8

Intubation dose and properties of atracurium?

Answer 8

Benzylisoquinolium
Hofmann degradation (spontaneous but temp dependent) 
Histamine release (worse in asthmatics or quick dose admin)

0.5mg/kg
35mg for 70kg
Maintain with 10-30mg boluses
Comes as 10mg/ml in 5ml ampules liquid in fridge 
More potent that sux

Question 9

Vecuronium properties and Induction dose?

Answer 9

Aminosteroid
Met liver, exc urine and bike
Prolonged effects in liver and renal disease
Induction of liver enzymes shortens duration of action, higher dose requirement

0.1mg/kg
Maintain with 1-2mg boluses
Comes as powder 10mg mix with sterile water 2mg/ml
More potent than atracurium

No effect of CV or RS

Question 10

Suxamethonium induction dose?

Answer 10

1-1.5mg per kg
100mg avg
Liquid in fridge

Question 11

CI to Suxamethonium

Answer 11

MH
anaphylaxis 
Sux apnoea 
Widespread denervation injury - burns, spinal cord injury (high potassium from extra junctions receptors)
Open/ penetrating eye injury 

Bradycardia
Raised ocular pressure/ stomach pressure/ ICP
Cause Sux pains!

Question 12

What potentiates effects of agents?

Answer 12

Acidosis
High dose gentamicin
Magnesium

Question 13

What shortens duration of action if vecuronium?

Answer 13

Phenytoin

Carbamazepine