Dexmedetomidine 150 mcg significantly extends the duration of ropivacaine interscalene block by almost 30% without significant adverse effect.

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• Gerhard Fritsch, Thomas Danninger, Karl Allerberger, Alexander Tsodikov, Thomas K Felder, Monika Kapeller, Peter Gerner, and Chad M Brummett.
• From the *Department of Anesthesiology, Perioperative Medicine, and Critical Care Medicine, Paracelsus Medical University, Salzburg, Austria; †Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, MI; ‡Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, Austria; and §Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI.
• Reg Anesth Pain Med. 2014 Jan 1; 39 (1): 37-47.

Background And ObjectivesResearch suggests that the addition of dexmedetomidine to local anesthetics can prolong peripheral nerve blocks; however, clinical safety data are limited, and interscalene blocks have not been studied. The present study was designed to test the hypothesis that dexmedetomidine added to ropivacaine would safely enhance the duration of analgesia without adverse effects when compared with ropivacaine alone.MethodsWe conducted a single-center, prospective, randomized, triple-blind, controlled trial of 62 patients undergoing elective shoulder surgery under general anesthesia with an interscalene block. Patients underwent ultrasound-guided interscalene blocks using either 12 mL of 0.5% ropivacaine or 0.5% ropivacaine plus 150-µg dexmedetomidine. The primary outcomes were self-reported duration of the nerve block and safety assessment (adverse effects and neurological sequelae). Data were analyzed in a blinded fashion.ResultsThe median duration of the nerve block was 18 hours (95% confidence interval, 18-20) in the dexmedetomidine group and 14 hours (95% confidence interval, 14-16) in the ropivacaine group (P = 0.0001). Dexmedetomidine also lowered pain scores for the first 14 hours postoperatively and significantly hastened the time to sensory (P = 0.04) and motor (P = 0.002) block onset. Dexmedetomidine lowered heart rate but blood pressures were stable. Plasma levels of ropivacaine were not different between groups, and plasma dexmedetomidine levels were relatively low. There were no adverse events or neurological sequelae.ConclusionsDexmedetomidine added to ropivacaine for interscalene blocks increased the duration of the nerve block and improved postoperative pain. These additional efficacy and safety data should encourage further study of peripheral perineural dexmedetomidine in humans.

This article appears in the collections: Perioperative & Regional Dexmedetomidine and Regional Anaesthesia.

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