Magnesium Preliminary Study On The Efficacy Of Postoperative Patient-controlled Analgesia And Opioid Receptor-mediated Adenylate Cyclase Activity

PART IPostoperative pain management with intravenouspatient-controlled morphine: comparison of the effect of addingsulphate magnesiumOBJECTIVETo investigate whether the addition of magnesium to morphine for intravenous patient-controlled analgesia will improve analgesic efficacy compared with morphine intravenous patient-controlled analgesia alone after major abdominal surgery. And to test the change of serum magnesium and calcium ion concentrations between pre- and post-major abdominal surgery.METHODSSixty patients were randomly allocated to receive either morphine O.Olmg.kg^-1.ml^-1 (Group M) by intravenous patient-controlled analgesia (PCIA), or morphine 0.01mg.kg^-1.ml^-1+MgSO₄ 0.6mg.kg^-1.ml^-1 (Group MM). Postoperative analgesia was started when the verbal rating scale (VAS) was more than 2. There was no loading dose of the study solution. They were then allowed to use bolus doses of this solution (1.5ml every 5 min, 36ml limited within 4 hours). Discomfort, sedation, pain scores, cumulative morphine consumption and adverse effects were recorded up to 48h after the start of the patient-controlled analgesia. To determine serum magnesium and calcium ion concentrations, blood samples were collected before anesthesia induction, at the end of operation and at the end of patient-controlled analgesia.