Inhalational Anesthesia

Abstract

Pharmacists have traditionally had little involvement with inhalational anesthetic agents. As the popularity of operating room pharmaceutical care increases, the need for the pharmacist's understanding of the uses and actions of anesthetic agents becomes necessary. This review provides an introduction to inhalational anesthesia, delivery systems, and the agents commonly used in anesthetic practice. Inhalational agents have long been used to provide general anesthesia through combined pharmacological actions. Nitrous oxide and oxygen are delivered as sole gasses or as carrier vehicles for the more potent inhalational anesthetics: halothane, enflurane, isoflurane, sevoflurane, and desflurane. The minimum alveolar concentration (MAC) of anesthetics is a measurement of concentrations that will prevent reflex movement in 50% of patients. A low blood/gas solubility coefficient for inhalational agents is desirable and is equated with low metabolism, rapid onset, and short duration of action. The inhalational agents are depressants to the nervous and respiratory systems and have variable effects on the cardiovascular system. Potent volatile agent induced renal toxicity may be a result of fluorine produced as a byproduct of hepatic metabolism. Newer agents favorably show lower solubility characteristics and increased physical and metabolic stability.