Comparative analgesic, hemodynamic, pain and duration of sensory and motor block effects of dexmedetomidine, granisetron, and nitroglycerin added to ropivacaine in intravenous anesthesia for forearm surgeries: a randomized clinical study

This trial-based paper strives to address the comparative efficacy of some ropivacaine adjuvant options, comprising dexmedetomidine, granisetron, and nitroglycerin, on pain and hemodynamic changes in intravenous anesthesia for forearm surgeries. This double-blind, placebo-controlled study enrolled four block-randomized eligible groups with patients (overall, n=128) undergoing orthopedic forearm surgeries in the dexmedetomidine, nitroglycerin, granisetron, and placebo groups. Intra- and post-operative vital signs (mean arterial pressure/heart rate/ oxygen saturation) were monitored at baseline and captured every 10 minutes until the end of the surgery, as well as the onset of sensory and motor block and length and duration of the block and mean opioid use within 24 hours. Lastly, pain was noted after tourniquet inflation (at 15, 30, and 45 minutes every 15 minutes until the end of surgery) and after deflation (every 30 minutes to 2 hours at 30, 60, 90, and 120 minutes), as well as 6, 12, and 24 hours after the tourniquet was deflated. The dexmedetomidine-sedated subjects appeared to demonstrate quicker onset and longer length and duration of sensory and motor block, plus less pain and opioid use at all scheduled times (both P = 0.0001). Dexmedetomidine is recommended as an adjuvant to regional anesthesia (Bier's block), while being coupled with the rapid onset and prolonged length and duration of sensory and motor blocks, in addition to soothed pain and diminished opioid use within postoperative 24 hours. The study was approved by Ethics Committee of Arak University of Medical Sciences (approval No. IR.ARAKMU.REC.1398.112) on July 21, 2019, and registered at Iranian Registry of Clinical Trials (registration number IRCT20141209020258N123) on November 2, 2019.