Ketamine Versus Magnesium as Analgesic Adjuvants in Pediatric Adenotonsillectomy

Adeno-tonsillectomy is one of the most common surgeries in children. The most common complication associated is postoperative pain. If not well controlled, especially in preschool children, it can lead to a longer recovery period, delayed discharge, and nutritional deficiencies resulting in dehydration. These factors will increase hospitalization period and the need for intravenous fluids. For this purpose, a large number of studies has been designed to evaluate the analgesic effects of various drugs during the perioperative period. Opioids are associated with sedation and respiratory depression, NSAIDs increase the risk of reoperation for bleeding while local anesthetics may cause vasoconstriction of the operation site. For several years, N-methyl-D-aspartate (NMDA) receptors antagonists, such as ketamine and magnesium, have been used successfully to decrease postoperative pain and analgesic requirements in adult patients undergoing a number of different procedures. Ketamine reduces the needed analgesia after tonsillectomy. Most studies have shown that ketamine administration has no side effects such as hemodynamic, respiratory complications and airway problems. Magnesium is a physiological antagonist of the NMDA receptor ion channel that plays a key role in central sensitization. Many studies have investigated the effect of magnesium sulphate on postoperative pain and opioid consumption. However, results of those studies were variable. Whereas most studies describe the reduction of postoperative analgesic requirements after magnesium sulfate, a few studies show insignificant beneficial effects. A previous study evaluated the effect of low dose ketamine (0.15 mg/kg) and magnesium sulfate (30 mg/kg) on post tonsillectomy pain in children, which did not demonstrate a decrease in pain or analgesic consumption in children undergoing tonsillectomy. In this study, the investigators will increase the dose of ketamine to (0.5 mg/kg) and magnesium sulfate to (40 mg/kg)