الفهرس 
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Abstract
In the immediate postoperative period, the pain is mostly due to tissue injury and inflammation. Surgical intervention generally involves nerve injury which can result in severe chronic pain. Relief of postoperative pain usually is achieved by injection of intermittent doses of opioid drugs. However, extensive use of opioid is associated with a variety of complications as respiratory depression, drowsiness, sedation, nausea, vomiting, urine retention, ileus and constipation. These complications contribute to delayed hospital discharge.
Magnesium ion was the first agent discovered to be an NMDA channel blocker. It inhibits catecholamine release from the adrenal medulla and peripheral nerve endings, and also blocks catecholamine receptors directly. So magnesium causes sympathetic block and indirectly causes dilated blood vessels, and thereby reduces blood pressure
Magnesium sulphate has been used as an adjuvant for perioperative analgesia. Many clinical studies have demonstrated that i.v. magnesium infusion during general anesthesia reduced anesthetic requirement and postoperative analgesic consumption.
The aim of this work was to:
- Compare the effects of two different dose regimens of magnesium on post operative pain relief in inguinal hernia repair surgery.
This study was carried out on sixty adult patients admitted to Alexandria Main University Hospitals for elective inguinal hernia repair under general anaesthesia.
Patients were selected as grade І or ІІ physical status of American Society of Anaesthesiologists (ASA).
Anaesthesia was induced with Fentanyl (2µg/kg) and Propofol (2mg/kg) given as IV bolus followed by Atracurium as a muscle relaxant in an intubating dose of 0.5 mg/kg. Patients were ventilated by 100% oxygen using Bain circuit for 2-3 minutes and were intubated using appropriate size endotracheal tube
Then patients were connected to anesthesia machine maintaining anesthesia by Isoflurane in 50% oxygen in air.
Patients were mechanically ventilated using the following data (Tidal Volume: 6-8 ml/kg, Frequency: 10-12 bpm).
Patients were randomly assigned into three groups (20 each):
group (A): Patients received a magnesium sulfate bolus (40 mg / kg) diluted in 50 ml normal saline 10 minutes before induction followed by (10 mg / kg / hour) magnesium sulfate infusion prepared in 100 ml normal saline started before skin incision.
group (B): Patients received a magnesium sulfate bolus (40 mg / kg) diluted in 50 ml normal saline 10 minutes before induction followed by equal volume of normal saline infusion started before skin incision.
group (C): Patients received equal volumes of normal saline bolus and infusion started before skin incision.
The following data were measured:
- Heart rate in beats/min and mean arterial blood pressure in mmHg were recorded at base line, before intubation, 1min after intubation, 15, 30, 45, 60, 75, 90,105 and 120 minutes intra-operative and 2, 4, 8, 16, 20 and 24hours post-operative.
Intraoperative atracuium consumption in mg.
- Postoperative pain score was recorded immediately after recovery and at 1, 2, 3, 4, 8, 16, 20 and 24 hrs after surgery using visual analogue scale (VAS).
- Postoperative nalbuphine consumption was assessed by recording time of first dose nalbuphine given and total dose of nalbuphine in mg required by the patient during the first 24 hours post-operatively.
- Side effects (hypotension, respiratory depression, nausea and vomiting) were recorded during the first 24 hours postoperatively.
The results of this study showed significant decrease in mean arterial blood pressure and heart rate in group (A) ) relative to group (B) and (C) before intubation, at 1, 15, 30, 45, 60, 75, 90, 105 and at 120 minutes intraoperatively and all through the postoperative period (P value <0.001). Comparison between group (B) and (C) showed significant decrease in the mean heart rate and mean arterial blood pressure in group (B) during the intraoperative period till at 75 minutes then there was no statistical significant difference from this time and all through the post operative period.
When comparing the results of the three groups in VAS there was significant decrease in group (A) compared to the other two groups in these readings immediately after recovery, I, 3, 4, 8, 16, 20 and 24 hours and there were significant decreases in group (B) than group (C) in these readings immediately after recovery, 3 and 24 hours.
When comparing the three groups according to the time of first dose of nalbuphine there was statistically significant decrease in group (A) than the other two groups.
It was found that group (C) significantly consumed more post-operative analgesics (nalbuphine) with a mean of (53.50±8.13 mg /24h) in comparison to group (A) which consumed less nalbuphine with a mean of (22.0±4.10 mg /24h) and group (B) which consumed also less nalbuphine with a mean of (37.0±5.71 mg /24h).
When comparing the results of the three groups in total dose of the muscle relaxant, there was significant decrease in total dose of atracurium in group (A) with a mean of (54.75±5.22 mg) and group (B) a mean of(63.50±6.51 mg) in comparison to group (C) with a mean of (83.25±6.74 mg).
There were no detected postoperative side effects.