Adjuvant medications to local anesthetics in nerve blockade

Abstract

Peripheral nerve blocks are commonly used for surgical anesthesia, postoperative analgesia, and to reduce opioid requirements. Although these blocks have traditionally been carried out using local anesthetics, singleinjection techniques can be short-lived and limited by the relatively brief duration of action of currently available local anesthetics. Increasing the dose or concentration of local anesthetics may prolong the duration of analgesia, but may also increase the risk such as unwanted motor weakness or systemic toxicity of local anesthetics. Numerous adjuvant medications have been added to local anesthetics to prolong the durations of anesthesia and analgesia achieved by peripheral nerve blocks, and currently, a number of different adjuvants are used to improve quality of the block. This article will review the several nerve block adjuvants used in combination with local anesthetics to provide blockade of peripheral nerves in clinical practice, describing the rationale for their use in peripheral nerve blocks, and the evidence for their effectiveness.