The Influence of Intraoperative Magnesium Sulfate Administration on Postoperative Morphine Requirement in Living Donor During Orthotopic Liver Transplantation

Introduction A lot of recent trials emphasized that perioperative magnesium sulfate (MgSO4) infusion has general anesthetic properties that could reduce anesthetic drug consumption and postoperative analgesia requirements in several types of surgery. Optimal post-operative pain control is necessary for early mobilization, improved respiratory function, and deep venous thrombosis. Administration of multimodal analgesics could limit the excessive use of systemic opioid analgesia especially (morphine), which has a high rate of postoperative side effects as sedation, respiratory depression, ileus, nausea, vomiting, constipation, urine retention, and itching. Therefore, medications and adjuvant drugs reducing the need for opioids have become widely used as parts of multimodal analgesia. Post-operative pain management begins with pre-operative planning and formulating a pain management plan that is tailored to an individual patient's liver function, respiratory and coagulation status, comorbidities and extent of resection.

Anesthetic technique:

Patients will be premedicated with tablet of alprazolam 0.25 mg the night before and 2 hours before surgery. Upon arrival in operating room usual monitoring will be established including heart rate, blood pressure, electrocardiogram (ECG),and temperature. After induction of anesthesia, an arterial line will be inserted for continuous monitoring of blood pressure and frequent blood gas analysis. End-tidal carbon dioxide (capnography) will be attached. General anesthesia will be administered using propofol 2 mg/kg, morphine 0.1 mg/kg and atracurium besylate 0.5 mg/kg followed by oral endotracheal intubation. Maintenance of general anesthesia with a mixture of isoflurane and 50% oxygen in air, morphine 2 mg/ h, mechanical ventilation will be adjusted to keep arterial oxygen saturation < 95 % and end-tidal carbon dioxide between 35 and 40 mmHg. Atracurium (0.15 mg/kg) will be administered every 30 min.

Baseline intravenous infusion rate of lactated ringers solution will be set at (6ml/ kg/h) in both groups, additional solution will be infused if required. Magnesium sulfate infusion and anesthetic agents will be discontinued at the end of operation. The postoperative residual neuromuscular blockade will be reversed by using neostigmine 0.04 mg/kg and atropine 0.02 mg/kg. Then the patient will be extubated and transferred to the post-anesthesia care unit (PACU) for 1-hour observation.

Statistical analysis: