Evalution of the Effect of Addition of Magnesium Sulfate to Local Anesthetics for Peribulbar Block: a Meta-Analysis for Randomized Trials

Abstract

Background: Magnesium sulphate has been used along with local anesthetics in different regional blocks and found to be have agreat effect in decreasing the time of onset of the block , IOP and increasing the duration of the block. To evaluate the effect of addition of magnesium sulfate to local anesthetics mixture on the time for onset of the globe and lid akinesia ,IOP and duration of peribulbar block in differnet ophthalmic surgeries . A systematic literature search that performed to identify randomized controlled trials that compared addition of magnesium sulphate to local anaesthetics in peribulbar block against standard local anaesthetic in different eye surgeries . Using the random effects model, risk ratio (for binary variables), weighted mean difference (for continuous variables) and 95% confidence intervals were calculated.We applied trial sequential analysis to assess the risks of type I and II error, meta-regression for the study of the doseresponsive relationship, and the Grading of Recommendations Assessment, Development, and Evaluation system.We identified 13 randomized controlled trials .When using conventional meta_analysis of nine low risk of bias trials, we found a statistically significantly longer duration of analgesia,. 1.Introduction: Regional anesthesia is a preferred technique for ophthalmic surgery. It is safe, inexpensive and provides efficient ocular anesthesia for ophthalmic surgery. Among regional blocks, It has shown high success rate and safety in different ocular procedures including difficult and extended time surgeries. .[1] Peribulbar block is safer in comparison to retrobulbar block due to a lesser incidence of serious complications such as brainstem anesthesia, globe perforation, and retrobulbar hemorrhage.[2] However, the development of ocular akinesia with peribulbar block takes longer time in comparison to retrobulbar block, and the occurrence of inadequate analgesia is also more frequent in peribulbar block.[3] The peribulbar block is a needle-based technique that varies from the retrobulbar block in terms of the depth and angulation of needle placement within the orbit [2]. The rate of major complications under peribulbar anesthesia was reported to be 0.006%. However, its main disadvantage is the need for a larger volume of local anesthetic agent resulting increase in IOP .[4] Magnesium has been used with a local anesthetic solution in different regional anesthesia techniques to decrease the onset time of block and to increase the quality and duration of anesthesia.[5] Magnesium is a physiological calcium channel blocker and noncompetitive antagonist of N-methyl-D-aspartate (NMDA) receptors. [6] Magnesium has been used with a local anesthetic solution in different regional anesthesia technique to decrease the onset time of block and to increase the quality and duration of anesthesia.[6] 2.Literature search: 2.1.Study design: Meta-analysis study. 2.2.Review of literature: We performed a systematic electronic literature search in the databases MEDLINE, Epub,NCBI ,Cochrane Central, Web of Science, and Google Scholar on August 4, 2019 in order to identify trials that used magnesium sulphate as adjuvant to local anaesthetics in peribulbar block in different eye surgeries. Search was limited to randomized trials published in English language, conducted on humans over the last 13 years. All protocols were approved by the local ethics committee or institutional review board of their respective institution. 2.3.Screening and evaluation of articles: The following screening was used to screen the articles yielded by review of literature after ranking the articles according to authors and journal of publication. Only articles fulfilling the inclusion criteria was included for further steps of data collection, analysis and reporting.