Comparison of the Effects of 3 Methods of Intrathecal Bupivacaine, Bupivacaine-Fentanyl, and Bupivacaine-Fentanyl-Magnesium Sulfate on Sensory Motor Blocks and Postoperative Pain in Patients Undergoing Lumbar Disk Herniation Surgery

Abstract

Background: The aim of this study was to investigate the effects of adding intrathecal (IT) fentanyl and magnesium sulfate (MgSO4) to bupivacaine on sensory motor blocks and postoperative pain in patients undergoing lumbar disk herniation surgery. Methods: In a double-blind randomized clinical trial, the patients undergoing lumbar disk herniation surgery were allocated to receive hyperbaric bupivacaine (A), or hyperbaric bupivacaine and fentanyl (B), hyperbaric bupivacaine, fentanyl and MgSO4 (C) IT. Data were collected regarding the onset of sensory block and time to regression to T10, time to complete motor block and full motor recovery, time to first analgesic requirement, postoperative pain score, and analgesic consumption and side effects. P< 0.05 was considered to be statistically significant. Results: A total of 105 patients were randomized and assigned to 3 groups (n= 35 in each groups). There were no significant differences between groups in regard to time to reach the T10 level of sensory block (P= 0.82), time to regression to T10 (P= 0.11), and the time to complete motor block (P= 0.58). Meanwhile, the time to complete recovery of motor function was significantly longer in group C (116.4 +/- 18.4, 126.4 +/- 25.5, 130.2 +/- 15.7 min, respectively, P= 0.016). Time to first analgesic requirement was also significantly longer in group C (3.26 +/- 1.12, 5.57 +/- 0.92, 6.91 +/- 1.27 h, respectively, P< 0.001). Total morphine consumption was significantly less in group C (14.3 +/- 4.3, 8.3 +/- 3.5, 6 +/- 3.6 mg, respectively, P< 0.001). The severity of pain was significantly less in C group (P< 0.001). Conclusion: In patients undergoing lumbar disk herniation surgery, IT MgSO4 in combination with bupivacaine-fentanyl can decrease severity of postoperative pain and analgesic consumption without additional side effect.