Evaluation of analgesic effect of adding mag nesium to lidocaine in patient-controlled regional analgesia (PCRA) after foot surgery

At the first 48 hours after orthopedic surgery opioids are used for analgesia.Continuous popliteal nerve block has been performed with increasing frequency for postoperative analgesia after foot surgery and provide better analgesia than traditional systemic opioid-based analgesia.Several additives have been combined with local anesthetics for peripheral nerve blocks. Magnesium is well known as an antagonist of N-methyl-d-aspartate receptors and has some analgesic property.The aim of this study was addition of magnesium to lidocaine in patient- controlled regional analgesia (PCRA) through the popliteal catheter. Forty four patients scheduled for hospital admission after foot surgery entered into this study and divided two group,control(I) and magnesium(II).In control group lidocaine %1(5ml/h) and group II lidocaine %1(5ml/h) + magnesium (5mg/h) infused with (PCRA) pump. Patient characteristics, pain scores (VAS), use of analgesic medications (iv morphine), and side effects of analgesic therapy were recorded for 48 hours after surgery. Pain score (VAS) was more in control group than group II (P=0.001).there was no ignificant difference between two groups in morphin consumption and nausea and vomiting (P=0.12). There were significant difference between two groups in Sedation score(P=0.007) and motion (P=0.001). This study showed addition of magnesium to lidocaine %1 in patient-controlled egional analgesia (PCRA) through the popliteal nerve block catheter have advantages for post operative pain, sedation, motion, reductionof morphin consumption and nausea and vomitig after the foot surgery.