Perioperative pharmacology

Pharmacokinetic and pharmacodynamic principles have been developed to describe how a desired blood level and effect of a medication is achieved. These principles usually must be modified during the perioperative period because many medications given to patients in the operating room and in the intensive care unit are frequently not given to the point at which steady- state drug concentrations are achieved. Furthermore, because many patients have altered renal and hepatic function, either because of the effects of anesthetics, the surgical procedure, or of disease, pharmacokinetic and pharmacodynamic principles are further altered. In managing patients in the operating room or in the intensive care unit, it is probably easiest when dosing to effect, and when appropriate, to guide dosing schedules by measuring serum drug levels.