Facilitatory Effects of Perineural Dexmedetomidine on Neuraxial and Peripheral Nerve Block

Abstract

Abstract Background DXM is an anxiety reducing, sedative, and pain medication. It has been used as adjunct to local anesthetics to improve the quality of perioperative analgesia and prolong its duration. Alpha2-adrenergic agonists have expanded the horizons of regional anesthesia. DXM is a highly selective α-2 agonist similar to clonidine but with a greater affinity for the α-2 receptor. It is the pharmacologically active d-isomer of medetomidine, a full agonist of α-2 adrenergic receptors. Objective The aim of this study is to evaluate the efficacy of DXM as an adjuvant to local anesthetics for intrathecal and supraclavicular blocks compared to LA alone. Methods This is a meta-analysis study. Searches were conducted in PubMed, Ovid/MEDLINE and Embase using free text and controlled vocabulary terms relating to Dexmedetomidine (MeSH). Results will be combined using Boolean operator “AND” with search terms analgesia, anesthesia, adjuvant, local anesthetics, nerve block, perineural, and terms designating route of administration such as neuraxial, intrathecal, supraclavicular, arm, and brachial plexus. Additional non-indexed articles will be retrieved using Google Scholar; and reference sections of retrieved trials will be hand-searched for additional relevant studies. Search will be limited to randomized trials published in English language, conducted on humans over the last 15 years. All protocols were approved by the local ethics committee or institutional review board of their respective institution. Results Throughout the studies reviewed, the dose of DXM was either given through a lumbar puncture performed in lateral or sitting position (range 3ug – 10ug) or via the supraclavicular approach in supine position with arm adducted (range 30ug – 100ug). DXM has been shown to prolong sensory and motor block duration in spinal and supraclavicular blocks. However, sensory and motor block onset has varied greatly from one study to another. DXM has also proved to have no significant adverse effects in the short term. Conclusion The study results indicate that the use of dexmedetomidine as a local anesthetic adjuvant prolongs sensory and motor block duration when administered intrathecally as part of spinal anesthesia or peripherally as part of a supraclavicular block.