COMPARATIVE STUDY OF THE EFFECTS OF INTRAOPERATIVE INFUSION OF LOW DOSE KETAMINE AND MAGNESIUM ON CONTROLLING POST OPERATIVE PAIN AND POST OP OPIOID CONSUMPTION AMONG THE PATIENTS UNDERGOING ORTHOPAEDIC SURGERIES AT DGH TRINCOMALEE SUPERVISOR Dr. Herath R. M. H. M. A. I. Consultant Anaesthetist. DGH Trincomalee INVESTIGATORS Dr. Rimaz S. N. A. Dr. Nusra M. A. F Dr. Amarasooriya S.C. Dr. Cowshika K.TABLE OF CONTENTS1. INTRODUCTION 1.1 Background Pain is defined as “An unpleasant sensory and emotional experience associated with actual orp otential tissue damage”. Postoperative pain is the commonest reason for delayed discharge and unanticipated hospital admission after ambulatory surgery.1 When pain is not treated accordingly it will become persistent, a vicious cycle of increasing disability and distress can occur2.Therefore alleviating the surgical pain from perioperative period will break the vicious cycle. Provision of multimodal analgesia with conventional opioids, non-steroidal an