Intrathecal dexamethasone as an adjuvant for spinal anesthesia: a systematic review

Spinal anesthesia is a common anesthetic technique for lower limb and abdominal surgery. Despite its efficacy, its use is limited because of its duration and potential severe side effects, especially in high-risk patients undergoing major surgery. Adjuvants such as dexamethasone offer the potential to prolong the anesthetic effect and reduce the need for local anesthetics while reducing the incidence of serious adverse events. The purpose of this systematic review is to evaluate the efficacy of dexamethasone as an intrathecal adjuvant in prolonging anesthetic duration, delaying pain onset, and minimizing adverse events (PROSPERO registration: CRD42022350218).

We included randomized controlled trials conducted in adult patients undergoing spinal anesthesia for lower limb or abdominal surgery and comparing the performance of dexamethasone with alternative spinal treatments. A comprehensive systematic search was conducted on PubMed/MEDLINE, Scopus, CINAHL, EMBASE, CENTRAL, and Cochrane Library from February to June 2023 without language restriction. Risk of bias was assessed using the Cochrane Risk of Bias Tool (RoB2).

Ten studies, nine of which were at high risk of bias, were included (N.=685 patients). Overall, intrathecal dexamethasone was associated with a longer duration of sensory block, improvement in the duration or extent of postoperative analgesia, and significant shortening of block onset. The role of dexamethasone in prolonging motor block was not clear. The incidence of adverse events was low. Intrathecal dexamethasone has been shown to be a potentially valuable adjuvant to prolong the duration of sensory block and improve postoperative analgesia without increasing adverse events.

Given the wide heterogeneity of methodological approaches, further investigation is needed. Considering the limitations of the included studies and awaiting more conclusive evidence, the prudent use of dexamethasone could be recommended in those specific situations where general anesthesia or higher local anesthetics should be avoided.