SUMMARY
When compared with intermittent bolus administration, continuous
infusion of intravenous anesthetic drugs provides greater control of anesthetic depth,
thus ensuring (1) better hemodynamic control with fewer episodes of hemodynamic instability,
(2) smaller total drug doses, and (3) more rapid return to an awake state. Improved
drug administration techniques combined with several new intravenous anesthetic agents
have provided greater impetus for the use of intravenous anesthesia in clinical practice.
Devices for the administration of intravenous anesthesia are continuing to evolve.
The introduction of pumps designed specifically for continuous intravenous anesthetic
drug delivery has enhanced intravenous anesthesia. Automated drug delivery is becoming
routine in many countries. Pharmacokinetic model-driven infusion has several theoretical
advantages over manual infusion systems, such as further improvements in hemodynamic
control and a more predictable rapid awakening. Studies comparing outcomes after
automated drug delivery of intravenous anesthetics versus manual methods or inhaled
anesthesia have either demonstrated improved results or been equivocal. No studies
have identified clinical or safety problems with automated anesthetic drug delivery.
It thus appears that pharmacokinetic model-driven infusion systems, though limited
by the same biologic variability that affects manual drug delivery, are safe and
effective in clinical use.
The introduction of commercial TCI systems has grown to an extent
that in many institutions, such systems are an everyday part of anesthesia practice.
We predict that with the increased emphasis on reducing human error in medicine,
especially drug delivery, TCI systems will ultimately replace manual methods. With
the advent of monitors of hypnosis and increased understanding of the components
of anesthesia, closed-loop drug delivery of anesthesia is showing promise in providing
further advantages. Many hurdles still need to be overcome before such devices will
come into routine use. However, present knowledge and the results of recent studies
are sufficiently encouraging to pursue this goal.
