title: Will the Real Benefits of Single-Shot Interscalene Block Please Stand Up? A Systematic Review and Meta-Analysis.
abstract: BACKGROUND
  Interscalene block (ISB) can provide pain relief after shoulder surgery, but a reliable quantification of its analgesic benefits is lacking. This meta-analysis examines the effect of single-shot ISB on analgesic outcomes during the first 48 hours after shoulder surgery.
  
  
  METHODS
  We retrieved randomized and quasirandomized controlled trials examining the analgesic benefits of ISB compared with none in shoulder surgery. Severity of postoperative pain measured on a visual analog scale (10 cm scale, 0 = no pain, 10 = worst pain) at rest at 24 hours was the designated primary outcome. Secondary outcomes included pain severity at rest and with motion at 2, 4, 6, 8, 12, 16, 32, 36, 40, and 48 hours postoperatively. Opioid consumption, postoperative nausea and vomiting, patient satisfaction with pain relief, and postanesthesia care unit and hospital discharge time were also assessed.
  
  
  RESULTS
  A total of 23 randomized controlled trials, including 1090 patients, were analyzed. Patients in the ISB group had more severe postoperative pain at rest by a weighed mean difference (95% confidence interval) of 0.96 cm (0.08-1.83; P = 0.03) at 24 hours compared with no ISB, but there was no difference in pain severity beyond that point. The duration of pain relief at rest and with motion after ISB were 8 and 6 hours, respectively, with a corresponding weighed mean difference in visual analog scale pain scores (99% confidence interval) of -1.59 cm (-2.60 to -0.58) and -2.20 cm (-4.34 to -0.06), respectively, with no additional pain relief benefits beyond these points. ISB reduced postoperative opioid consumption up to 12 hours, decreased postoperative nausea and vomiting at 24 hours, and expedited postanesthesia care unit and hospital discharge. The type, dose, and volume of local anesthetic used did not affect the results.
  
  
  CONCLUSIONS
  ISB can provide effective analgesia up to 6 hours with motion and 8 hours at rest after shoulder surgery, with no demonstrable benefits thereafter. Patients who receive an ISB can suffer rebound pain at 24 hours but later experience similar pain severity compared with those who do not receive an ISB. ISB can also provide an opioid-sparing effect and reduce opioid-related side effects in the first 12 and 24 hours postoperatively, respectively. These findings are useful to inform preoperative risk-benefit discussions regarding ISB for shoulder surgery.
authors.affiliation: From the Department of Anesthesia, University of Toronto, Toronto, Ontario, Canada; Department of Anesthesia and the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada; Division of Obstetric Anesthesia, Department of Anesthesia, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Department of Anesthesia, Hospital for Sick Children, Toronto, Ontario, Canada; Department of Anesthesia, Women's College Hospital, Toronto, Ontario, Canada; and Department of Anesthesia, Toronto Western Hospital, University Health Network, Toronto, Canada.
authors.forename: Faraj W
authors.initials: FW
authors.lastname: Abdallah
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Halpern
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Aoyama
authors.forename: Richard
authors.initials: R
authors.lastname: Brull
mesh_terms: D000701:Analgesics, Opioid / Q000627:therapeutic use; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000009:adverse effects; D006801:Humans; D007267:Injections; D009407:Nerve Block / Q000009:adverse effects / Q000379:methods*; D016017:Odds Ratio; D019637:Orthopedic Procedures / Q000009:adverse effects*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D017060:Patient Satisfaction; D012720:Severity of Illness Index; D012782:Shoulder / Q000294:innervation / Q000601:surgery*; D020069:Shoulder Pain / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid; D000779:Anesthetics, Local
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