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nmblockers

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
    • 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

vecuronium

  • 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

  • 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.
1)
aka succinylcholine / sux / Anectine / Scoline
2)
Norcuron
nmblockers.txt · Last modified: 2016/08/09 21:04 (external edit)