Intravenous anaesthesia: new drugs, new concepts, and clinical applications

Abstract

During the course of the past decade, three distinct developments have resulted in the widespread clinical application of intravenous anaesthesia: (a) the world-wide introduction of propofol and alfentanil in the late 1980s; (b) enhanced understanding of the pharmacodynamics and pharmacokinetics of iv anaesthetic drugs (e.g., context-sensitive half-times); (c) commercial availability of programmable ,syringe infusion pumps for intravenous infusion techniques While many of the advantages and some of the limitations of iv anaesthesia are now well-apparent, further refinement and establishment of techniques employing predominantly iv anaesthetic drugs are focusing upon several important areas. These include continued development of new, short-acting drugs which have minimal side-effects and increasingly predictable durations of action; quantitation of drug interactions; research in the area of drug delivery systems; and pharmacoeconomic evaluation of iv anaesthetic techniques. While the last two issues constitute entities unto themselves, this Refresher Course Lecture will focus primarily on new iv drugs, new methods to predict recovery from iv anaesthesia, drug interactions, and practical applications of these principles. Objectives(i) To review how the characteristics of an "ideal" iv anaesthetic drug apply to the new opioid analgesic, remifentanil. (ii) To predict the potential clinical applications of an ultra-short acting opioid analgesic. (iii) To compare and contrast three predictors of recovery from iv anaesthetics: relevant effect-site decrement time, context-sensitive half-time, and mean effect time. (iv) To review basic principles of drug interaction, and to apply these to benzodiazepine/propofol, and propofol/opioid combinations. (v) To establish optimal infusion regimens for iv anaesthetic drugs. (vi) To review practical applications and techniques for obtaining maximum benefit from iv infusion anaesthesia. New drugsPropofol has been available in Canada for more than five years, and while many of its desirable attributes and limitations are now well-defined, t studies related to pharmacological interactions, and cost-effectiveness of this drug are ongoing. However, propofol, which has provided a major advance in clinical anaesthesia, can no longer be considered "new," and the search continues for even better sedative-hypnotics and opioid analgesics. The characteristics desirable of an "ideal" iv anaesthetic drug are listed in Table I. While many of these characteristics may appear obvious, they highlight the necessary attributes for drug development in the cost-conscious 1990s.For new drugs to be incorporated into clinical practice, they must have unique pharmacokinetic and pharmacodynamic properties, a high therapeutic index and favourable side effect profile, while at the same time providing either a comparable, or improved cost-benefit compared with existing drugs of the same class. 2.3In the area of sedative-hypnotics, eltanolone is being evaluated in Europe, although it appears that this drug lack...

I.v. anaesthesia and EEG burst suppression in rats: bolus injections and closed-loop infusions

“…Large increases, an order of magnitude larger than seen with propofol or etomidate shown here, would indicate serious, unacceptable accumulation and dominating redistribution of the drug. [2][3][4] During stable anaesthesia, established using a closed-loop system, other measures to assess depth of anaesthesia could be tested and cardiorespiratory and other variables could be measured easily. We found that paw withdrawal during propofol anaesthesia was less pronounced than the response during etomidate anaesthesia.…”

“…Performance was also assessed quantitatively in each individual experiment. For this purpose the standard deviation (SD) of the BSR distribution around the BSR target during the 10-50-min time interval (2400 s) was determined according to equation (3). The first 10 min were excluded because of the initial fluctuations, and the last 10 min because in some experiments the paw pressure stimulus influenced BSR stability.…”

“…These advances are illustrated in the clinical use of target-controlled infusion (TCI) systems based on population variables 1 but also in articles addressing clinical predictors such as context-sensitive half-time, relevant effect-site decrement time and mean effect time. [2][3][4] Development of new i.v. anaesthetics should build on knowledge of current drugs and determine key characteristics at an early stage.…”

Comparison Of The Direct Costs, Length Of Recovery, And Incidence Of Post Operative Anti Emetic Use After Anesthesia Induction With Propofol Or A 1:1 Mixture Of Thiopental And Propofol

“…Propofol was one of the first agents to directly challenge thiopental as the standard induction agent (Miller, 1996).…”

Outcome of large angle exotropia treated by single stage adjustable strabismus surgery with monitored conscious anesthesia

“…fentanyl, and midazolam. [ 15 16 17 ] Further surgery/adjustment is done based on the correction achieved. The purpose of this study was to determine if this allows us to optimize the number of rectus muscles operated and achieve good motor alignment.…”