الفهرس 
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Abstract
Post-operative pain in laparoscopic cholecystectomy is variable, multifactorial and unpredictable. The use of ultrasound-guided thoracic paravertebral nerve blocks (TPVB) has been explored as part of its multi-modal pain management. Magnesium has the advantage of having anti-nociceptive effects due to its antagonistic effect on the N-methyl D-aspartate (NMDA) receptor, which play a major role in transmitting sensory signals that cause pain, modulation and sensitization in acute and chronic pain conditions. In previous studies, it has been found that adding magnesium sulfate to local anesthetics in various regional anesthetic procedures is safe and efficient, and in our study we used magnesium sulfate as an adjuvant to bupivacaine in ultrasound guided paravertebral block and compared its effect with using bupivacaine alone. Fifty patients of either sex with American Society of Anesthesiologists (ASA) physical status I or II, aged from 20-60 years for patients scheduled for elective laparoscopic cholecystectomy were enrolled in this study and divided into 2 groups equally. These patients were randomly allocated to undergo bilateral ultrasound guided paravertebral block. The two groups were: 1. Control group: Bupivacaine group (B group) N=25 : Included patients who received 17 mL of 0.25% bupivacaine + 3 mL saline 0.9% in a total volume of 20 ml on each side. 2. Magnesium group (M group) N=25 : Included patients who received 17 mL of 0.25% bupivacaine + 3 mL of 75 mg magnesium sulfate diluted in 0.9% saline in a total volume of 20 ml on each side. . All patients were premedicated using midazolam 0.03 mg/kg intravenously. Ultrasound guided thoracic paravertebral block was performed before induction of general anesthesia. General Anesthesia was induced using intravenous propofol (2-3 mg/kg), fentanyl IV (1µ/kg) and atracurium besylate (0.6 mg/kg) to facilitate intubation. Then patient was mechanically ventilated using a volume control mode. Anesthesia was maintained using minimum alveolar concentration of isoflurane 1.2% and 40% air in O2 mixture with maintenance doses of atracurium (0.1 mg/kg). During operation, base line values of HR, SpO2 and non-invasive MAP were collected 1 minute before and 1 minute after paravertebral block, 1 minute after induction of anesthesia, at skin incision, then recording was done every 15 min till the end of the first hour and then every 30min interval till the end of surgery. All patients were extubated at the end of surgery after neuromuscular reversal with administration of neostigmine (0.05 mg/kg) and IV atropine (0.02 mg/kg) and fulfilling the criteria of extubation. Patients were admitted to the PACU then to the ward, all vital data & hemodynamics were recorded at 1, 2, 6, 12 and 24 hours postoperatively. Pain intensity was assessed at rest and during cough with VAS score at 1, 2, 6, 12 and 24 hours postoperatively. The duration of analgesia, amount of opioids used and postoperative complications were recorded in both groups. Our results revealed that there was significant difference between magnesium sulfate group and bupivacaine group as adding magnesium sulfate to bupivacaine in ultrasound guided paravertebral block provided rapid intra-operative sensory block onset, delayed post-operative time of first morphine request by the patient; longer duration of analgesia, less need for post-operative morphine so decrease total dose of morphine used to control pain in 24 hours post-operative , less VAS score at rest and during coughing during post-operative 24 hours and lowered intraoperative and postoperative heart rate (HR) and mean arterial blood pressure (MABP) in magnesium sulfate group when compared with bupivacaine group , with no incidence of PONV in magnesium sulfate group and no postoperative need for atropine or phenylepherine and no incidence of pneumothorax, respiratory depression or chest pain in any patient of both groups. In this study we concluded that the addition of magnesium sulfate (150 mg) to a bupivacaine (25%) for bilateral ultrasound guided thoracic paravertebral block is useful adjuvant to bupivacaine as it improve the quality of the blockade, prolong postoperative analgesia and decrease opioid consumption in the first 24 post-operative hours for patients undergoing laparoscopic cholecystectomy .