Background and Objectives Research 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.
Methods We 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.
Results The 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.
Conclusions Dexmedetomidine 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.
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Dr Brummett is a consultant for Purdue Pharma L.P. (Stamford, CT). The University of Michigan holds a patent covering the use of perineural dexmedetomidine in regional anesthesia. Brummett CM, Inventor; The Regents of the University of Michigan, Assignee; Anesthetic Methods and Compositions; US patent application US 12/791,506; Issue date 04/02/2013.
The other authors declare no conflict of interest.
Primary study funding for this study came from the Department of Anesthesiology, Perioperative Medicine and Critical Care Medicine, Paracelsus Medical University, Salzburg, Austria. Dr Brummett receives research funding from R01 AR060392 from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIH, Bethesda, MD; Co-PIs Brummett and Clauw), the American Society of Regional Anesthesia and Pain Medicine Chronic Pain Research Grant (PI Brummett), and the Department of Anesthesiology, University of Michigan.
Study conducted at the Department of Anesthesiology, Perioperative Medicine, and Critical Care Medicine, Paracelsus Medical University, Salzburg, Austria.
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