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thiopentone

thiopentone

introduction

  • thiopentone is an ultra-short acting barbiturate primarily used as an induction agent to aid rapid sequence induction
  • iv use only
    • IM use causes pain/necrosis
    • inadvertent intra-arterial injection of thiopentone → vasospasm
  • consider alternatives if either:
    • hypotensive
    • head injury or acute stroke (secondary brain injury from transient hypotension is a risk)
    • porphyria
    • asthma - it can release histamine

preparation

  • comes as a Pentothal 500mg/2.5% kit:
    • reconstitute by adding the 20ml of supplied sterile water to the powder-containing bottle and dissolve
    • use only if it is clear, free from precipitate and is not discolored
    • solution is 25mg/ml (500mg per 20ml)
    • use within 24 hours.

dosage

  • iv induction dose: 3-5mg/kg
  • reduce dose in elderly or those at risk of hypotension

pharmacology

  • plasma:brain equilibration occurs within 1minute
  • short acting due to redistribution (metabolised @ 12-16%/hr after single dose);
  • large doses ⇒ myocard. depress.& decr. venous tone ⇒ decreased SV & cardiac output ⇒ hypotension
  • potent resp. depressant
  • decreased cerebral metabolism & cerebral blood flow (contrast with inhaled GAs!)
  • may reduce hepatic & renal blood flow
thiopentone.txt · Last modified: 2009/03/18 16:36 (external edit)