Anesthetic Considerations: Local Versus Regional

Local anesthesia is defined as a loss in the perception of pain over a small area of the body. Regional anesthesia is also a loss in the perception of pain, but in a larger anatomical area or region. Both local and regional anesthesia are usually achieved by pharmacological use of local anesthetic agents. There are two types of local anesthetic agents, amino-amides and amino-esters, defined by their chemical structures. Both classes achieve their effects by deactivating the sodium channels responsible for the inward flux of sodium during the depolarization phase of the action potential. The net result is an increase in the amount of stimulus required to generate an action potential as well as decreased propagation of any action potentials across the anesthetized neuron. This chapter will discuss the history, pharmacology, pharmacokinetics, metabolism, toxicities, chemical structures, as well as the clinical utility of using local anesthetics in localized and regional fashions.