Selecting the ideal adjuvant to improve neuraxial and regional analgesia: A narrative review

Abstract

Introduction: The aim of this review was to systematize known facts about the effects of adjuvants to local anesthetics for neuraxial and regional analgesia in order to determine the adjuvant with the best effect among all others. More precisely to consider the time to onset, the strength of the effect, duration of the motor and sensory block and some additional effects such as 'marker of intravascular injection', safety and toxicity profile. We aimed to find an ideal adjuvant which has all these properties to a good degree. Methodology: For this narrative review we searched the information in Medline, PubMed, Scopus, and Embase databases. 105 articles were identified regarding the topic, published since 1989 to 2020. Data from 105 articles about adjuvants to local anesthetics was analyzed and synthesized in this review. Results: Regional methods of analgesia are becoming a crucial part of anesthesiologists' practice and the knowledge about adjuvants is developing alongside with it, so there are more and more studies devoted to it. All of them try to find the “ideal” adjuvant, having sufficient necessary effects, but we think that due to the difference in various classes of adjuvants, some may be better than others. However, use of combination of adjuvants is not desirable at all times. Conclusion: A variety of adjuvants to local anesthetics are available now, yet the data about most of them remains inconclusive, so more studies are required to found out the best adjuvants with the most desirable profile and the least adverse effects.