title: IV and Perineural Dexmedetomidine Similarly Prolong the Duration of Analgesia after Interscalene Brachial Plexus Block: A Randomized, Three-arm, Triple-masked, Placebo-controlled Trial.
abstract: BACKGROUND
  Perineural and IV dexmedetomidine have each been suggested to prolong the duration of analgesia when administered in conjunction with peripheral nerve blocks. In the first randomized, triple-masked, placebo-controlled trial to date, the authors aimed to define and compare the efficacy of perineural and IV dexmedetomidine in prolonging the analgesic duration of single-injection interscalene brachial plexus block (ISB) for outpatient shoulder surgery.
  
  
  METHODS
  Ninety-nine patients were randomized to receive ISB using 15 ml ropivacaine, 0.5%, with 0.5 μg/kg dexmedetomidine administered perineurally (DexP group), intravenously (DexIV group), or none (control group). The authors sequentially tested the joint hypothesis that dexmedetomidine prolongs the duration of analgesia and reduces the 24-h cumulative postoperative morphine consumption. Motor blockade, pain severity, hemodynamic variations, opioid-related side effects, postoperative neurologic symptoms, and patient satisfaction were also evaluated.
  
  
  RESULTS
  Ninety-nine patients were analyzed. The duration of analgesia was 10.9 h (10.0 to 11.8 h) and 9.8 h (9.0 to 10.6 h) for the DexP and DexIV groups, respectively, compared with 6.7 h (5.6 to 7.8) for the control group (P < 0.001). Dexmedetomidine also reduced the 24-h cumulative morphine consumption to 63.9 mg (58.8 to 69.0 mg) and 66.2 mg (60.6 to 71.8 mg) for the DexP and DexIV groups, respectively, compared with 81.9 mg (75.0 to 88.9 mg) for the control group (P < 0.001). DexIV was noninferior to DexP for these outcomes. Both dexmedetomidine routes reduced the pain and opioid consumption up to 8 h postoperatively and did not prolong the duration of motor blockade.
  
  
  CONCLUSIONS
  Both perineural and IV dexmedetomidine can effectively prolong the ISB analgesic duration and reduce the opioid consumption without prolonging motor blockade.
authors.affiliation: From the Department of Anesthesia, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada (F.W.A.); and Department of Anesthesia (F.W.A., V.W.S.C., A.U.N., S.O., R.P., J.O., R.B.) and Department of Surgery, Division of Orthopedic Surgery (T.D., D.J.O.-H.), Women's College Hospital, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Faraj W
authors.initials: FW
authors.lastname: Abdallah
authors.forename: Tim
authors.initials: T
authors.lastname: Dwyer
authors.forename: Vincent W S
authors.initials: VW
authors.lastname: Chan
authors.forename: Ahtsham U
authors.initials: AU
authors.lastname: Niazi
authors.forename: Darrell J
authors.initials: DJ
authors.lastname: Ogilvie-Harris
authors.forename: Stephanie
authors.initials: S
authors.lastname: Oldfield
authors.forename: Rajesh
authors.initials: R
authors.lastname: Patel
authors.forename: Justin
authors.initials: J
authors.lastname: Oh
authors.forename: Richard
authors.initials: R
authors.lastname: Brull
mesh_terms: D000328:Adult; D000698:Analgesia / Q000379:methods / Q000639:trends*; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage*; D065527:Brachial Plexus Block / Q000379:methods / Q000639:trends*; D020927:Dexmedetomidine / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000175:diagnosis / Q000517:prevention & control; D011446:Prospective Studies; D013997:Time Factors
chemical_list: D018712:Analgesics, Non-Narcotic; D020927:Dexmedetomidine