Flashcards in NM blockers Deck (10)
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1
Why would you use neuromuscular blocking agents?
Muscle relaxation is part of triad of anaesthesia
2
What other ways could you achieve muscle relaxation?
General anaesthesia
Local anaesthesia of peripheral nerve
Local anaesthesia - epidural
3
What are the advantages of using an NMBA?
Provides muscle relaxation
Prevents movement
Whole body
Reduce need for high concentration of inhalational agent
BUT movement is an indicator for anaesthetic depth
4
What problems are associated with NMBA?
Monitoring depth of anaesthesia
Also prevents movement of respiratory muscles
Patients require IPPV
5
What are the indications for use of NMBA?
Intraocular surgery
Facilitate IPPV
Laparotomy
Cardiovascularly unstable patients
Orthopaedics
6
How do NMBA's work?
Block the action potential at the neuromuscular junction
Two types: Depolarising and non-depolarising
7
Describe depolarising NMBA's
Bind reversibly to the Ach receptor
Initial muscle contraction followed by relaxation
8
Describe non-depolarising NMBA's
Also bind reversibly to Ach receptor but…
Do not cause muscle contraction
These are used in veterinary practice
9
Describe reversal of NMBA's
Modern agents short acting so often just left to ‘wear-off’
Reversed with anti-acetylcholonesterase (neostigmine or edrophonium)
-Allows Ach concentration to rise in synaptic cleft so Ach can compete effectively with the NMBA
-Need to give an anticholinergic concurently to prevent bradycardia
-Eg. Atropine or glycopyrrolate
Competitive antagonist so effect can be overcome by increasing the concentration of the agonist.
10
