title: Extrafascial injection for interscalene brachial plexus block reduces respiratory complications compared with a conventional intrafascial injection: a randomized, controlled, double-blind trial.
abstract: BACKGROUND
  Hemidiaphragmatic paresis after ultrasound-guided interscalene brachial plexus block is reported to occur in up to 100% of patients. We tested the hypothesis that an injection lateral to the brachial plexus sheath reduces the incidence of hemidiaphragmatic paresis compared with a conventional intrafascial injection, while providing similar analgesia.
  
  
  METHODS
  Forty ASA I-III patients undergoing elective shoulder and clavicle surgery under general anaesthesia were randomized to receive an ultrasound-guided interscalene brachial plexus block for analgesia, using 20 ml bupivacaine 0.5% with epinephrine 1:200 000 injected either between C5 and C6 within the interscalene groove (conventional intrafascial injection), or 4 mm lateral to the brachial plexus sheath (extrafascial injection). The primary outcome was incidence of hemidiaphragmatic paresis (diaphragmatic excursion reduction >75%), measured by M-mode ultrasonography, before and 30 min after the procedure. Secondary outcomes were forced vital capacity, forced expiratory volume in 1 s, and peak expiratory flow. Additional outcomes included time to first opioid request and pain scores at 24 h postoperatively (numeric rating scale, 0-10).
  
  
  RESULTS
  The incidences of hemidiaphragmatic paresis were 90% (95% CI: 68-99%) and 21% (95% CI: 6-46%) in the conventional and extrafascial injection groups, respectively (P<0.0001). Other respiratory outcomes were significantly better preserved in the extrafascial injection group. The mean time to first opioid request was similar between groups (conventional: 802 min [95% CI: 620-984 min]; extrafascial: 973 min [95% CI: 791-1155 min]; P=0.19) as were pain scores at 24 h postoperatively (conventional: 1.6 [95% CI: 0.9-2.2]; extrafascial: 1.6 [95% CI: 0.8-2.4]; P=0.97).
  
  
  CONCLUSIONS
  Ultrasound-guided interscalene brachial plexus block with an extrafascial injection reduces the incidence of hemidiaphragmatic paresis and impact on respiratory function while providing similar analgesia, when compared with a conventional injection.
  
  
  BACKGROUND
  NCT02074397.
authors.affiliation: Department of Anaesthesia.
authors.forename: N
authors.initials: N
authors.lastname: Palhais
authors.affiliation: Department of Anaesthesia, Toronto Western Hospital and Women's College Hospital, University of Toronto, Toronto, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Brull
authors.affiliation: Department of Anaesthesia.
authors.forename: C
authors.initials: C
authors.lastname: Kern
authors.affiliation: Department of Anaesthesia.
authors.forename: A
authors.initials: A
authors.lastname: Jacot-Guillarmod
authors.affiliation: Department of Anaesthesia.
authors.forename: A
authors.initials: A
authors.lastname: Charmoy
authors.affiliation: Department of Orthopaedic, Lausanne University Hospital, Lausanne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Farron
authors.affiliation: Department of Anaesthesia eric.albrecht@chuv.ch.
authors.forename: E
authors.initials: E
authors.lastname: Albrecht
mesh_terms: D000328:Adult; D000779:Anesthetics, Local; D065527:Brachial Plexus Block / Q000379:methods*; D002045:Bupivacaine; D002968:Clavicle / Q000000981:diagnostic imaging / Q000601:surgery; D004311:Double-Blind Method; D005205:Fascia / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control*; D053208:Kaplan-Meier Estimate; D008297:Male; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000453:epidemiology; D012120:Respiration Disorders / Q000209:etiology* / Q000517:prevention & control*; D015656:Respiratory Mechanics / Q000187:drug effects; D012133:Respiratory Paralysis / Q000139:chemically induced / Q000453:epidemiology; D012782:Shoulder / Q000000981:diagnostic imaging / Q000601:surgery; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional
chemical_list: D000779:Anesthetics, Local; D002045:Bupivacaine
keywords: analgesia; anesthesia, regional; brachial plexus block; diaphragm; postoperative pain