TIVA and TCI in Modern Anesthesia

General anesthesia is characterized by reversible depression of central nervous system functions, with the goal of inducing loss of consciousness, analgesia, amnesia, abolition of neurovegetative responses to stimuli, immobility, and, in some cases, abolition of muscle tone. Over the years, the pharmacological toolbox available to the anesthesiologist has increased considerably. There are a variety of drugs that can be used, some administered by inhalation because they are in the gas or vapor state under ambient conditions, and others administered intravenously. Totally intravenous anesthesia (TIVA: Total IntraVenous Anesthesia) uses only intravenous anesthetics; inhalational anesthesia employs anesthetic vapors; balanced anesthesia, the most widely used, uses both routes. Target-Controlled Infusion (TCI) is a technique for administering intravenous anesthetics that uses advanced infusion pumps, which can autonomously vary the infusion rate to maintain a constant concentration of anesthetic set by the operator in the plasma or effector site; the software with which the pump is equipped continually reevaluates the amount of drug to be infused based on a pharmacokinetic model. Closed-Loop Anesthesia is an anesthesia technique using the TCI method, in which the anesthesiologist does not set the concentration of the anesthetic but the magnitude of the desired effect, e.g., the level of depth of anesthesia as measured by the Bispectral index (BIS). In this mode, the software changes the target plasma concentration based on data from the monitoring system. Table 1.1 shows some important dates in the development of intravenous anesthesia [1].