title: Ultrasound-guided low-dose interscalene brachial plexus block reduces the incidence of hemidiaphragmatic paresis.
abstract: OBJECTIVE
  Interscalene brachial plexus block is associated with 100% incidence of hemidiaphragmatic paresis as a result of phrenic nerve block. We examined whether an ultrasound (US)-guided interscalene brachial plexus block performed at the level of root C7 versus a nerve stimulation interscalene brachial plexus block, both using 10 mL of ropivacaine 0.75%, resulted in a lower incidence of hemidiaphragmatic paresis.
  
  
  METHODS
  In a prospective randomized controlled trial, 30 patients scheduled for elective shoulder surgery under combined general anesthesia and interscalene brachial plexus block were included. Interscalene brachial plexus block using the same dose was performed using either US or nerve stimulation guidance of ropivacaine for both groups. General anesthesia was standardized. Ventilatory function was assessed using spirometry, and movement of the hemidiaphragm was assessed by US.
  
  
  RESULTS
  Two patients in the US group showed complete paresis of the hemidiaphragm, but in the nerve stimulation group, 12 patients showed complete and 2 patients had partial paresis of the hemidiaphragm (13% versus 93%, respectively; P < 0.0001). Ventilatory function (forced expiratory volume at 1 second, forced vital capacity, and peak expiratory flow) was significantly reduced in the nerve stimulation group compared with the US-guided group (P < 0.05). One block failure occurred in the nerve stimulation group compared with none in the US group. No adverse effects occurred in either group.
  
  
  CONCLUSIONS
  Ultrasound-guided interscalene brachial plexus block performed at the level of root C7 using 10 mL of ropivacaine 0.75% reduces the incidence of hemidiaphragmatic paresis.
authors.affiliation: Department of Anesthesiology, Radboud University Nijmegen Medical Centre, Ikazia Hospital Rotterdam, the Netherlands.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Renes
authors.forename: Harald C
authors.initials: HC
authors.lastname: Rettig
authors.forename: Mathieu J
authors.initials: MJ
authors.lastname: Gielen
authors.forename: Oliver H
authors.initials: OH
authors.lastname: Wilder-Smith
authors.forename: Geert J
authors.initials: GJ
authors.lastname: van Geffen
mesh_terms: D000328:Adult; D000368:Aged; D000577:Amides / Q000009:adverse effects*; D000779:Anesthetics, Local / Q000009:adverse effects*; D001917:Brachial Plexus / Q000000981:diagnostic imaging*; D003964:Diaphragm / Q000000981:diagnostic imaging / Q000294:innervation* / Q000503:physiopathology; D004558:Electric Stimulation; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000009:adverse effects; D010291:Paresis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D010366:Peak Expiratory Flow Rate; D010791:Phrenic Nerve / Q000187:drug effects*; D011446:Prospective Studies; D000077212:Ropivacaine; D012782:Shoulder / Q000601:surgery; D013147:Spirometry; D013997:Time Factors; D018084:Ultrasonography, Interventional; D014797:Vital Capacity; D055815:Young Adult
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine