Characteristics of anesthetic agents used for induction and maintenance of general anesthesia

The characteristics of ideal intravenous (i.v.) and inhaled anesthetic agents; the rationale for inducing anesthesia with i.v. anesthetics (particularly propofol); the rationale for inducing and maintaining anesthesia with inhaled anesthetics; and the advantages and disadvantages of specific inhaled anesthetics, namely, nitrous oxide, desflurane, halothane, isoflurane, and sevoflurane, are discussed.Propofol has many characteristics of the ideal i.v. anesthetic, including a rapid, smooth induction of anesthesia and rapid clearance from the body. The use of an i.v. anesthetic such as propofol avoids the claustrophobia associated with the inhaled route. Inhaled anesthetics are preferred for maintenance of anesthesia because they allow a more precise control of the anesthetic state and do so at low cost. The ideal inhaled anesthetic agent has ample potency and a low solubility in blood and tissues (rapid recovery from anesthesia), resists physical and metabolic degradation, and protects and does not injure vital tissues. It also does not cause seizures, respiratory irritation, or circulatory stimulation or deplete the ozone layer. It has a low acquisition cost. Nitrous oxide potency is too small to produce anesthesia by itself. Halothane is too soluble and poses a risk of severe hepatotoxicity. Desflurane, isoflurane, and sevoflurane are preferred because they have an adequate potency, appropriate solubility, and minimal to no risk for hepatotoxicity.The utilization choice among desflurane, isoflurane, and sevoflurane is made by weighing specific advantages and disadvantages of each agent. The primary determining factors for use are anesthetic potency and control, rate of anesthesia induction, clearance from the body, and adverse effects.