EFFECTS OF ADDING MAGNESIUM SULPHATE, MIDAZOLAM ORKETAMINE TO HYPERBARIC BUPIVACAINE FOR SPINAL ANESTHESIA IN LOWER ABDOMINAL AND LOWER EXTREMITY SURGERY

Background: Adequate pain management is essential to accelerate functional recovery and enabling patients to return to their normal activity more quickly. Central sensitization is an activity-dependent increase in the excitability of spinal neurons and is considered to be one of the mechanisms implicated in the persistence of postoperative pain. Purpose: This study investigate the effects of intrathecal magnesium sulfate, midazolam or Ketamine to bupivacaine on the spread, duration, regression of spinal block, and postoperative analgesia in patients undergoing lower abdominal and lower extremity surgery. Methods: This study was designed in a prospective, randomized, and double blinded manner. 80 patients [ASA] I-II status) scheduled for spinal anesthesia were randomly divided into four groups (n=20). S Group: received 1ml of 0.9% normal saline, Mg Group received 50mg (0.5ml of 10% magnesium sulfate), Mid Group received 2mg (0.4ml of 5% midazolam), and K Group received 1.5mg/kg ketamine, All were added to 15mg intrathecal hyperbaric bupivacaine. Data were collected regarding the onset, duration, highest level of dermatomal sensory blockade. Sensory and motor blockade were monitored using pin prick and Bromage score respectively. Time for regression of two segments in the maximum block height was estimated. Duration of pain relief and analgesic consumption within 24 hours was estimated. Vital data and any untoward effects were recorded perioperatively. Results: The addition of intrathecal magnesium (50mg) to spinal anesthesia prolonged the time for regression of two segments in the maximum block height and time to L2 regression, but did not affect maximum sensory level or the time to reach the highest level of sensory block. The same results were collected when adding midazolam or ketamine to intrathecal bupivacaine. Total analgesic consumption in the first 24 hrs was decreased significantly with the addition of magnesium sulphate, midazolam or ketamine to spinal anesthesia in comparison with the control group, but the time to first analgesic requirement was prolonged significantly in the Mg Group (412.5+25.6), Mid Group (357.2±36.5) and Kgroup (.3.3.8+55.9) compared to (110.5+25.6) in S group. Conclusion: This study found that the analgesic effect of intrathecal bupivacaine was potentiated by intrathecal adjuvants as magnesium sulphate, midazolam or ketamine. The addition of one or two of the previous adjuvants in the recommended doses prolonged the postoperative analgesic effect of intrathecal bupivacaine (7±1hrs), and patients used less analgesic drugs in the first 24hrs after surgery.