Effect Of Dexmedetomidine As An Adjuvant In Erector Spinae Plane Block On Postoperative Analgesia In Thoracolumbar Spine Surgery With An Opioid Free Anaesthesia Technique: A Prospective Randomized Clinical Trial

Opioid Free Anaesthesia (OFA) is a multimodal nonopioid analgesic technique wherein use of opioids in any form is completely eliminated during anaesthesia. This  new concept has emerged secondary to potential adverse effects of opioids.In light of the known adverse effects, there have been concerted efforts to reduce opioid exposure by utilising the non-opioid based alternatives analgesic techniques. These non-opioid based techniques are either administered systemically or at nerve root levels.Ketamine is a well-established anaesthetic agent which acts as NMDA receptor in addition to opioid receptors. It provides intense analgesia by reducing glutamate release due to its antagonist action on NMDA receptors and by binding to sigma-opioid receptors. Subanaesthetic doses of ketamine (0.5 mg/kg or less) is very effective in reducing postoperative pain score.Few studies have documented use of ESP block  in spine surgery and observed lower pain scores postoperatively in ESP block group compared with systemic opioids. Dexmedetomidine, an alfa 2 receptors agonist, produces analgesia by acting on locus ceruleus of central nervous system and on both presynaptic and postsynaptic alfa 2 receptors at peripheral nervous system.We hypothesize that the addition of dexmedetomidine to local anaesthetic agent (ropivacaine) as an adjuvant in the ESP block will increase the duration of postoperative analgesia in spine surgery in ketamine based OFA technique.In this study, the effect of dexmedetomidine will be assessed as an adjuvant to ropivacaine in ESP block in thoracolumbar spine surgery done under ketamine based OFA on postoperative pain management.