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Flashcards in NM blockers Deck (10)
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Why would you use neuromuscular blocking agents?

Muscle relaxation is part of triad of anaesthesia


What other ways could you achieve muscle relaxation?

General anaesthesia

Local anaesthesia of peripheral nerve

Local anaesthesia - epidural


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


What problems are associated with NMBA?

Monitoring depth of anaesthesia

Also prevents movement of respiratory muscles

Patients require IPPV


What are the indications for use of NMBA?

Intraocular surgery

Facilitate IPPV


Cardiovascularly unstable patients



How do NMBA's work?

Block the action potential at the neuromuscular junction

Two types: Depolarising and non-depolarising


Describe depolarising NMBA's

Bind reversibly to the Ach receptor

Initial muscle contraction followed by relaxation


Describe non-depolarising NMBA's

Also bind reversibly to Ach receptor but…

Do not cause muscle contraction

These are used in veterinary practice


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.


Describe monitoring of NMBA's

Requires a peripheral nerve stimulator

Need to attach and check placement BEFORE administer the NMBA

Peripheral nerve stimulator gives information on how effective the block is

Heart rate, blood pressure and pupil dilation should be monitored as indicators of anaesthetic depth