Safety and efficacy of different doses of intrathecal magnesium sulfate on the acute and chronic postoperative pain in patient undergoing pelvic cancer surgeries - a randomized controlled dose finding clinical study.

Background and objectives: Excision of tumors from pelvis causing severe pain postoperatively. Hemodynamic stability, and better analgesia were documented when MgSO4 was used as an adjuvant to local anesthesia. We aimed to investigate the effect of using intrathecal MgSO4 with different doses as an adjuvant to LAs on postoperative acute pain, hemodynamics, and chronic pain. Methods: Ninety patients scheduled for pelvic surgery for excision of tumors have been included in this study and divided into three groups; all patient received general anesthesia (GA) plus intrathecal fentanyl (group A), while the second (group B) and the third (group C) received intrathecal magnesium sulfate 50 mg and 100 mg, respectively; intra- and postoperative outcomes such as hemodynamics, (LANSS) pain score, (NRS) and postoperative complications have been measured. Results: The results revealed that MgSO4 in the (group B) had significant effect on decreasing the postoperative pain during the first 24 hours; the result of the three groups revealed that there was statistically significant difference between the group A and groups (B-C) (P-value >0.05), while there was insignificant statistical difference between the group B and group C. Patients in the fentanyl group requested analgesic after 6 to 8 hours (mean ±SD 8.4817 ± 0.819 mg), while patients in group B after 12 to 14 hours postoperatively (13.7450 ± 0.86477 mg) and patients in group C requested analgesia 16 hours postoperatively (13.7800 ± 1.00272 mg). LANSS score was significantly improved in groups B-C, but fewer complications such as itching, nausea and shorter time of recovery after the surgery in group B than other groups. Conclusion: When comparing IT magnesium sulfate at doses of 50 and 100 to fentanyl 50 mg, we found superiority of MgSO4, in decreasing pain after surgery and ITMgSO4 50 mg achieved a reasonable balance between postoperative analgesia and side effects. In addition, ITMgSO4 has shown significant effect in decreasing the chronic pain postoperatively. [ABSTRACT FROM AUTHOR]