Muscle Relaxants

Question 1

What do muscle relaxants do?

Answer 1

Neuromuscular blocking agents that interrupt transmission of impulses from motor nerve to muscle synapse
They act at the nicotinic receptor to block release acetylcholine

Question 2

What are the two kinds of muscle relaxants

Answer 2

Depolarising and non-depolarising

Question 3

What do depolarising muscle relaxants do?

Answer 3

Cause initial surge at neuromuscular followed by refractory period where muscle dose not respond - binds straight to post synaptic receptors

Question 4

Name a depolarising muscle relaxant

Answer 4

Succinylcholine

Suxamethonium

Question 5

What do non-polarising muscle relaxants do

Answer 5

Block receptors at the muscle end plates

Question 6

Name a non-polarising drug

Answer 6

vescuronium

atracurium

Question 7

Which kind of muscle relaxant can be reversed?

Answer 7

Non-polarising

Question 8

Do muscle relaxants affect consciousness

Answer 8

no - they do not cross the blood brain barrier

Question 9

Do muscle relaxants provide analgesia

Answer 9

no

Question 10

Why use muscle relaxants? (name 2 reasons)

Answer 10

• facilitate controlled IPPV
• During intraocular surgery
• Where good muscle relaxation is required to facilitate the surgery
• As part of a balanced anaesthesia technique for high risk patients

Question 11

Name 2 disadvantages of muscle relaxants

Answer 11

• hypothermia due to decreased muscle tone
• difficult to assess anaesthetic depth
• some drugs in this group may cause hypotension
• Increased effects if used with aminoglycosides
• Increased susceptibility if used alongside halothan, isoflurane, corticosteroids, some diuretics, and epinephrine
• Very vigilant monitoring is necessary during and post anaesthetic period due to laryngeal muscles