Neuromuscular agents

Question 1

What are the features of succinylcholine?

Answer 1

Best intubation conditions, rapid access, inimaltime to sperate with a full stomach

The only depolarising neuromuscular blocking agent.
Mimic the affect of ACh but only one molecule needs to bind.
Actually an agonist but it blocks subsequent stimulations. Prevents repolarisation. Results n fasciculations followed by relaxation.
Remains in the cleft until breakdown by pseudocholineesterases.

Onset is fast 60 seconds
Duration is short - 5 mins
Elimintion half life - 1 min

Side effects: Cardiac dysarethias
Increased intrcranial pressure
Increased intragastric pressure
Increased intraoccular pressure
Malignant hyperpyrexia

Question 2

How do non-depolarising agents work?

Answer 2

They bind the AChR and are an antagonist for ACh. Only one needs to bind so favours drug.
>70% receptors occupied - start of relxation
>90% complete relaxation

Question 3

What are three aminosteroids?

Answer 3

Pancuronium (long acting 40 - 90 mins)
Rocuronium (intermediate acting 20-45 mins)
Vecuronium (intermediate acting 20-45 mins)

Question 4

What are three benzylisoquinolones?

Answer 4

Atracurium (intermediate acting 20-45 mins)
Cisatracurium
Mivacurium (short acting 10-15 mins)

Question 5

What are the features of atracurium?

Answer 5

It is a benzylisoquinolone.
Intermediate acting 20-45 mins
Onset 3-5 mins (slow)
Breaks down in a temp and pH dependednt mechanism

Hypotension
Tachycardia
Histamine release

Question 6

What are the features of mivacurium?

Answer 6

Benzylisoquinolone
3x potency of atracurium
Sow onset 3-4 mins
Sort duration of action 10-15 mins
Hydrolysed by pseudocholinesterases
Some histamine release

Question 7

What are the features of rocuronium?

Answer 7

Aminosteriod
Intermeduate duration - 40 minutes
Fast onset
Can be use for rapid intubation
Liver elimination
Minimal cardiac effects

Question 8

What are the features of vecuronium?

Answer 8

Aminosteriod
Intermeduate duration - 40 minutes
Slow onset
Active metabolites secreted in urine so increased duration in renal failure.
Minimal cardiac effects and minimal chance for anaphylaxis

Question 9

What are the features of pancuronium?

Answer 9

Aminosteroid
High potency
slow onset
Long duration - 90 mins
Increases heart rate, blood pressure and cardiac output
Good for long cardiac surgical procedures
Excreted by the liver and the kidney

Question 10

Which neuromuscular blockers are reversible?

Answer 10

The non-depolarisin drugs
Can reveres by increasingthe amount of ACh for competation - anti-cholinesterase drugs (neostigmine). But these cause ANS effects such as bradycardia so need to give atropine too.

Or by decreasing the amount of the drug.
Sugammadex - binds rocuronium and vecuronium - 2 mins

Question 11

How do you tell if your neuromuscular block is working?

Answer 11

TOF. TOF of 4 with 50%

Ventilatory response to hypoxia is impaired below a TOF 4 with 90% - risk of airway collapse below this point