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Contents: General Alan Palmer has a really nice set of slides illustrating most aspects of intravenous induction agents. The UK Society for Intravenous Anaesthesia includes a substantial bibliography linked to abstracts. Also check out the European Society for Intravenous Anaesthesia (EuroSIVA). The Journal of Consciousness Studies discusses the metaphysics of consciousness. The old favourite, steadily losing ground to propofol in most markets, mostly because of propofol's recovery characteristics. Main advantage of thiopentone is rapid onset and lesser tendency than propofol to drop blood pressure. Has well documented cerebral protective effects at burst suppression doses. 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. Recreationally abused ("Special-K") for intoxicating and hallucinatory effects. These same effects are undesirable after anaesthesia. Some interest in use of low doses with general anaesthesia to inhibit NMDA-receptor associated nocioceptive 'wind-up'. Limited cerebral protection.
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.
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. Product information PDF from Roche.
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