Effects of adding dexmedetomidine, fentanyl, and verapamil to 0.5% ropivacaine on onset and duration of sensory and motor block in forearm surgeries: a randomized controlled trial

This study was aimed to compare the onset and duration of axillary block with ropivacaine 0.5% plus either dexmedetomidine, fentanyl, or verapamil in forearm surgeries. This double-blind clinical trial enrolled three equal-sized block-randomized groups of patients (n = 105) scheduled for hand and forearm surgery at Arak, Iran in 2019, who received: (i) ropivacaine (40 mL/0.5%) + dexmedetomidine (1 μg/kg), (ii) ropivacaine (40 mL/0.5%) + fentanyl (1 μg/kg), and (iii) ropivacaine (40 mL/0.5%) + verapamil (2.5 mg), respectively. We recorded some vital signs such as mean arterial pressure, heart rate and oxygen saturation, onset of complete sensory and motor block, duration of the block, opioid use, as well as pain score at recovery and certain time points (2, 4, 6, 12, and 24 hours post-operation). Adding dexmedetomidine to ropivacaine (40 mL/0.5%) prolonged the duration of sensory (P = 0.001) and motor block (P = 0.001) in compared to adding fentanyl and verapamil and it also shortens the time to onset of sensory (P = 0.001) and motor block (P = 0.001). There is a significant difference between three groups in terms of visual analog scale mean and the lowest pain score was obtained in the dexmedetomidine group (P = 0.001), significant time trend (P = 0.001), as well as the time and groups interaction (P = 0.001). Dexmedetomidine was concluded to be associated with alleviated pain; reduced opioid use; short onset of sensory block; and prolonged duration of sensory and motor block. It hence is recommended to lengthen the duration of axillary block and to help relieve postoperative pain and ultimately to move to cut down the postoperative opioid use in forearm surgery. The study was approved by the Ethical Committee of Arak University of Medical Sciences (approval No. IR.ARAKMU. REC.1397.266), and registered on Iranian Registry of Clinical Trials (registration No. IRCT20141209020258N111) on May 9, 2019.