nmblockers
Table of Contents
neuro-muscular blockers
see also:
introduction
- neuro-muscular blocking agents (NMBAs) are those that paralyse muscle activity by blocking normal transmission at the neuro-muscular junctions of skeletal muscle.
- there are two main groups of agents:
- depolarising agents:
- mimic acetylcholine and activate nicotinic receptors at neuromuscular junctions and then desensitizes the receptor so it can no longer recieve further action potentials
- these are commonly used at induction of anaesthesia due to their rapid onset of action
- eg. suxamethonium
- non-depolarising agents:
- competitive antagonist of acetylcholine at nicotinic receptors at neuro-muscular junctions, and thus do NOT cause the muscle fasciculation seen in depolarising agents.
- these are mainly used for maintenance of paralysis during anaesthesia although some are used at induction instead of depolarising agents.
- The nondepolarizing NMBAs, unlike suxamethonium, can be reversed by the use of neostigmine (0.06 to 0.08 mg/kg IV) after approximately 40 percent of neuromuscular function has returned
- these can be divided into two groups:
- aminosteroid agents:
- benzylisoquinolinium agents:
- not routinely used in the emergency setting because they more often cause histamine release and some cause autonomic ganglionic blockade
- eg. atracurium and mivacurium
suxamethonium
- see suxamethonium1)
- dose: 1.5 mg/kg intravenous dose
vecuronium
- see vecuronium2)
- usual maintenance adult dose 10mg
- duration of action 25-40min
- use as an induction NMBA:
- a priming dose of 0.01 mg/kg is administered three minutes before an increased intubating dose of 0.15 mg/kg.
- used in this way, vecuronium achieves intubation level paralysis in approximately 75 to 90 seconds
rocuronium
- see rocuronium
- rocuronium has a shorter time to onset and shorter duration of action compared to other agents in its class.
- time to paralysis is approximately 60 seconds, when the recommended dose of 1.2 mg/kg IV is given.
- multiple studies and systematic reviews demonstrate it creates intubating conditions comparable to suxamethonium.
pancuronium
- should not be used for RSI. It can cause tachycardia and histamine release, and has a longer time to onset and duration of action than alternative agents.
nmblockers.txt · Last modified: 2016/08/09 11:04 by 127.0.0.1