The Pharmacology Of Intravenous Anesthetic Induction Agents: A Primer

their optimal clinical utilization. History and Principles Whereas inhaled anesthetics are useful for the induction of anesthesia, particularly in the absence of IV access as occurs commonly in pediatric anesthesia, IV anesthetics have become the primary agents for the induction of general anesthesia. The development of IV anesthetics followed the late 19th-century introduction of hollow needles, syringes, and IV fluid therapy, which provided direct access to the bloodstream for the rapid administration of drugs. These innovations paved the way for the introduction of rapidly acting IV anesthetics. Prior to the development of IV anesthetics, induction of general anesthesia required inhalation of gases and vapors (including nitrous oxide, ether, and chloroform) that often resulted in slow, unpleasant, and occasionally dangerous inductions. Hexobarbital, the first ultrashort-acting barbiturate—and considered to be the first successful and widely used IV anesthetic—was introduced by Weese in Germany in 1932. This was followed in 1935 by the introduction of thiopental by Lundy in Minnesota and Waters in Wisconsin. Thiopental became widely accepted, largely because of the lack of excitatory myoclonic movements that were seen with hexobarbital; 75 years later, thiopental is still in use. In 1926, Lundy introduced the concept of “balanced anesthesia” to describe a polypharmaceutical combination of premedication, local anesthesia, and general anesthesia to reduce the dose of each agent and thereby improve safety. Dr. Hemmings has no relevant financial conflicts to disclose.