Total intravenous anaesthesia

Abstract

Driven by better understanding of the pharmacokinetic principles involved and improvements in infusion pump technology, total intravenous anaesthesia (TIVA) has become more popular and has many potential advantages. Safe and effective use of TIVA requires the practitioner to have a sound understanding of the pharmacokinetics involved and the pharmacokinetic behaviour of many drugs can be described by a three-compartment model. Mathematical modelling can be used to calculate the blood and theoretical effect-site concentrations of anaesthetic drugs for a given dosing regimen. Following consideration of the three-compartment model, manual regimes were developed to permit TIVA, but such regimes were insufficiently flexible to provide adequate anaesthesia for all patients in all circumstances. Target controlled infusion (TCI) systems are computerized infusion systems capable of delivering variable infusion regimes based on a complex mathematical solution to the pharmacokinetic models. Such systems allow the anaesthetist to achieve and maintain any desired target drug concentration appropriate to an individual patient and level of surgical stimulation. TCI systems have facilitated the increased use of TIVA over the past decade such that this technique has become ‘mainstream’ throughout much of the world.