Preventive Analgesia by Local Anesthetics

Abstract

U sing local anesthetics to reduce acute postoperative pain has a long history, but recent reports have not been systematically reviewed. Also, the need to include only those clinical studies that meet minimum standards for randomization and blinding must be followed. Stringent study design standards were applied to identify publications regarding the use of perioperative local anesthetics. Several types of peripheral nerve blocks were examined that covered a variety of surgical procedures, and the effects of an intentionally administered intravenous (IV) local anesthetic (lidocaine) to suppress postoperative pain were examined. Publications in which vascular concentrations of local anesthetics were measured at different times after peripheral nerve block procedures were investigated as well, noting the incidence of when those levels reached ones attained during intentional IV administration. It is important to note that a very large number of studies using neuraxial blockade techniques (epidural, spinal) has not been included in this review but will be examined in a later, separate review. The overall results demonstrated a strongly positive effect of local anesthetics by either route for suppressing postoperative pain scores or analgesic (opiate) consumption. There were a few situations in which the effects were equivocal. Enhanced effectiveness of adding adjuvants was not uniformly apparent. The differential benefits of drug delivery before, during, or immediately after a surgical procedure are not obvious, and a general conclusion is that marked antihyperalgesic effects are realized when local anesthetic is present during the acute postoperative period, and its presence during surgery is not required for this action to occur.