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Contents: General Propofol has largely replaced thiopentone as the intravenous induction agent of choice. Detailed PDF reviews of the intravenous induction agenst are available from AnesthesiologyNews, ICU Adelaide and the Royal College of Anaesthetists. Alan Palmer has a set of slides. The UK Society for Intravenous Anaesthesia includes a substantial abstracts database as well as useful abstracts from previous meetings. Also check out the European Society for Intravenous Anaesthesia (EuroSIVA). The Journal of Consciousness Studies discusses the metaphysics of consciousness. WFSA Update on Induction Agents. Widely used anaesthetic induction agent with slightly slower onset than thiopentone, a greater tendency to drop blood pressure. The rapid, pleasant offset makes it suitable for monitored sedation, maintenance of anaesthesia, and patient sedation in ICU. Pain on injection is probably pH related and can be ameliorated by addition of plain lignocaine (2-5ml of 1% to 20ml propofol works fine. New target controlled infusion (TCI) technique makes continuous administration easier.
The old favourite has almost totally been replaced by propofol in most markets. The main advantage of thiopentone is rapid onset, but it has a narrower safety margin. Has well documented cerebral protective effects at burst suppression doses, though propofol is probably just as good. Can cause acute episode of porphyria in susceptible patients.
An induction agent presented in propylene glycol with less cardiovascular depression than thiopentone. Causes pain on injection, occasional involuntary movements, suppresses cortisol production. Depresses cerebral metabolism but conflicting evidence for cerebral protection.
An intravenous NMDA-receptor antagonist anaesthetic agent with analgesic, intoxicating and dissociative hallucinatory properties. Associated catecholamine output which masks cardiac depression. Potent analgesic properties, mild respiratory depression and some maintenance of muscle tone. Can be used as a total intravenous anaesthetic, particularly useful for trauma or field situations. Also useful in low doses (eg 0.05mg/kg/hr) by infusion with general anaesthesia to inhibit NMDA-receptor associated nocioceptive 'wind-up' and reduce intra-operative opioid requirements. Management of post-operative pain, especially in patients already using opioids, maybe be markedly improved by maintaining a ketamine infusion for a few days (adjust rate to results vs side-effects, often starting at 0.02 mg/kg.hr). Limited cerebral protection. Recreationally abused ("Special-K") for intoxicating and hallucinatory effects. Confusion and disorientation are undesirable after anaesthesia.
TCI means 'Target Controlled Infusion' in which a microprocessor-controlled syringe pump automatically and variably controls the rate of infusion of a drug to attain a user defined target level in an effect site in the patient (usually blood). This greatly simplifies maintenance of a steady blood level. Thousands of papers can be found with google. At present commercial TCI systems are only available for propofol.
TIVA means 'Total intravenous Anaesthesia'. In its pure form this means no inhalational agents of any kind. It can be done without TCI pumps, however they certainly make it a lot easier. Information about benzodiazepines from MetroHealth. Flumazenil product info from Roche USA.
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