Dexmedetomidine versus Magnesium Sulphate as an Adjuvant to Local Anesthesia in Single-Injection Percutaneous Peribulbar Anesthesia for Cataract Extraction

Abstract

R egional anesthesia is most used for ophthalmic procedures. Various techniques and combinations for local anesthetics and adjuvants have been established and frequently used over the years with the aim of establishing a better block. As a day case procedure, cataract extraction needs anesthetic management that is effective, safe, economic, and not time consuming. This improves patient satisfaction and assures minimal exhaustion of hospital resources and facilities. The single injection peribulbar block utilized in this study is a recent modification of the peribulbar techniques previously used. It offers extended safety due to the use of short needles and the need for a single injection only. It also requires less total volume of local anesthetics which may be of little benefit on single patient bases but would be more cost efficient on a larger scale. Magnesium is a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist decreasing the excitatory post-synaptic currents produced by NMDA receptors activation and it inhibits voltage-gated calcium channels. Dexmedetomidine is centrally acting highly specific α2-agonist commonly used as sedative. Both have been used as adjuvants to local anesthetic mixtures in different regional anesthesia techniques, including the peribulbar anesthesia to improve the quality and duration of the block.