Comparison of impact of adjuvant treatment of midazolam, fentanyl, and magnesium sulfate with intrathecal bupivacaine on block characteristics and postoperative analgesia in knee arthroplasty

Abstract

Objective: To compare the efficacy of midazolam, fentanyl, and magnesium sulfate as adjuvants to intrathecal bupivacaine on both block characteristics and postoperative analgesia in knee arthroplasty. Methods: This randomized double-blind clinical trial recruited spinal anesthesia patients of the American Society of Anesthesiologists class I or II, who needed knee arthroplasty. Patients were stratified into three intervention groups, including the midazolam group, the fentanyl group, and the magnesium sulfate group, and the patients were administered with midazolam, fentanyl, and magnesium sulfate, respectively. Hemodynamic parameters, sensory and motor block, and pain score (Visual Analogue Scale) were measured and compared among the three groups. Results: A total of 105 patients were included in this study with 35 patients in each group. There was no statistically significant difference in terms of oxygen saturation, mean blood pressure, duration of surgery, and postoperative complications, including nausea, vomiting, bradycardia, dizziness, and hypotension, as well as the time of opioid administration among the three groups (P>0.05). Statistically significant differences were found in terms of heart rate at 15, 30, 45, 60, 75, and 105 min after beginning of operation among the three groups, which was lower in the midazolam group (P<0.05). The midazolam group showed a shorter time to achieve sensory block after spinal anesthesia, sensory block to T8 or higher and sensory block to T12 and L1 (P<0.05). Besides, the three groups showed significantly differences in terms of onset of motor block after spinal anesthesia and time to achieve motor block to T8 or higher or Bromage score 3 (P=0.001). No significant difference was noted in pain scores among the three groups (P>0.05). Conclusion: Midazolam resulted in a shorter time to achieve sensory and motor block to T8 or higher, the onset of motor block and sensory block after spinal anesthesia, and time to achieve sensory block to T12 and L1, and the pain scores were not significantly different among the groups. Thus, midazolam can be highly underlined, if a shorter onset of sensory and motor blocks is targeted. [Funded by the research deputy of Arak University of Medical Sciences (No.99258); fa.irct.ir number, IRCT20141209020258N164].