Effect of adding magnesium sulfate to intrathecal low-dose of bupivacaine for patients with severe pre-eclampsia undergoing cesarean delivery

Background: Intrathecal magnesium sulfate, an NMDA antagonist, has been shown to prolong analgesia and potentiates spinal anesthesia without significant side effects in parturients. This study aimed to explore the hypothesis that adding magnesium sulfate to intrathecal low-dose of bupivacaine and sufentanil can prolong the spinal analgesia in patients with severe pre-eclampsia. Methods: Sixty patients with severe pre-eclampsia were enrolled in this prospective, double-blinded, placebo-controlled trial. Patients were randomly divided into two groups. Patients in Magnesium group received spinal anesthesia with 0.5% bupivacaine 6 mg + sufentanil 2.5 μg + 25% magnesium sulfate 50 mg and the other patients in Control group received the same dose of bupivacaine and sufentanil only. Characteristic of spinal anesthesia, duration of spinal anesthesia, postoperative analgesia requirements were recorded. Side effects were also recorded. Results: The duration of spinal analgesia was longer (183 ± 32 vs 138 ± 27 min) in Magnesium group than in Control group (P < 0.001). The consumption of postoperative fentanyl was significantly lower in the Magnesium group than that in the Control group (343 ± 42 vs 550 ± 49 μg, P < 0.001). No differences in side effects of spinal anesthesia were found between groups. Conclusion: In parturients with severe pre-eclampsia undergoing caesarean delivery, the addition of intrathecal magnesium sulfate to low-dose of bupivacaine and sufentanil prolongs the duration of analgesia and reduces postoperative analgesic requirements without additional side effects.