Effects of dexmedetomidine, fentanyl and magnesium sulfate added to ropivacaine on sensory and motor blocks in lower abdominal surgery: a randomized clinical trial

This study aimed to compare the effects of intrathecal dexmedetomidine, fentanyl and magnesium sulfate added to ropivacaine on the onset and duration of sensory and motor blocks in lower abdominal surgery. This double-blind randomized clinical trial included 90 patients scheduled for lower abdominal surgery at Vali-Asr Hospital in Arak, Iran. The enrolled patients were randomly divided into three equal groups and then underwent spinal anesthesia. The first group received 10 mu g of dexmedetomidine, the second group received 50 mu g of fentanyl, and the third group received 200 mg of 20% magnesium sulfate intrathecally in addition to 15 mg of 0.5% ropivacaine. In the dexmedetomidine group, the mean arterial blood pressure was lower than the other two groups (P = 0.001). Moreover, the time to onset of sensory block (P = 0.001) and the mean duration of sensory block (P = 0.001) were shorter and longer, respectively, in the dexmedetomidine group than in the other two groups. In the dexmedetomidine group, the mean time to onset of motor block (P = 0.001) and the mean duration of motor block (P = 0.001) were lower and higher than in the other two groups, respectively. There was no significant difference in visual analog scale score, heart rate, administered opioid, and drug side effects among the three groups. Dexmedetomidine caused early sensory and motor blocks while prolonging the duration of sensory and motor blocks compared with the other two groups. In addition, dexmedetomidine reduced mean arterial blood pressure in patients. Based on the findings of this study, it is recommended that dexmedetomidine can be used in order to enhance the quality of sensory and motor block in patients.