Alfentanil and midazolam: new anesthetic drugs for continuous infusion and an automated method of administration.

New drugs like alfentanil and midazolam have the primary advantage of metabolizing faster than existing compounds in their class. Because of shorter plasma half-lives, the drugs are well suited for continuous infusion. In our hands, CACI is a valuable clinical instrument and research tool. Although some anesthetic drugs can be given safely and effectively by bolus injection, whenever a titrated continuous infusion is appropriate (and physiologically closed-loop delivery is not possible), use of a CACI-type instrument should be the preferred method of administration. With the availability for continuous infusion of alfentanil and midazolam, with their highly desirable pharmacodynamic properties and relatively effervescent pharmacokinetics, we believe that computerized pharmacokinetic model-driven infusion devices will play a significant role in future anesthetic practice.