title: The effect of continuous interscalene brachial plexus block with 0.125% bupivacaine vs 0.2% ropivacaine on pain relief, diaphragmatic motility, and ventilatory function.
abstract: OBJECTIVE
  Outpatient continuous interscalene brachial plexus blocks containing bupivacaine or ropivacaine are commonly used to control pain after shoulder surgery. Interscalene blocks cause hemidiaphragmatic paresis. Because ropivacaine preferentially blocks sensory fibers, it may cause less blockade of the phrenic nerve. The purpose of this study was to evaluate the effects of 2 common continuous interscalene brachial plexus infusions: 0.125% bupivacaine vs 0.2% ropivacaine. The study hypothesis is that respiratory function will be less attenuated using ropivacaine than bupivacaine without affecting pain relief.
  
  
  METHODS
  Study design was a prospective randomized double-blind study, registered (NCT 02059070), with institutional review board approval and written informed consent.
  
  
  METHODS
  The setting was the preoperative and postoperative area in an orthopedic teaching hospital.
  
  
  METHODS
  Outpatients scheduled for shoulder arthroscopic surgery were included.
  
  
  METHODS
  All patients underwent baseline measurements and interscalene catheter placement, then randomized to receive pumps containing either 0.2% ropivacaine or 0.125% bupivacaine.
  
  
  METHODS
  Study measurements included preoperative and postoperative bedside spirometry and ultrasonographic evaluations of diaphragmatic excursion, postoperative pain scores, and postdischarge oral opioid (oxycodone) consumption.
  
  
  RESULTS
  There were no statistically significant differences between bupivacaine vs ropivacaine in outcomes of forced expiratory volume at 1 second change (-22% ± 18.3% vs -29% ± 14.9%), diaphragmatic excursion (-81.4% ± 37.95% vs -75.5% ± 35.1%), VAS pain scores at rest (4.9 ± 2.9 vs 3.5 ± 2.8), or oral opioid consumption (33.7 ± 24.3 mg vs 35.1 ± 33.9 mg).
  
  
  CONCLUSIONS
  There was no difference in respiratory dysfunction or opioid requirements between interscalene continuous peripheral nerve blocks with 0.125% bupivacaine or 0.2% ropivacaine. Further study is required to identify anesthetic infusates that will control pain while decreasing the attenuation of pulmonary function.
authors.affiliation: Detroit Medical Center/Wayne State University. Electronic address: dchoroma@med.wayne.edu.
authors.forename: Dominik W
authors.initials: DW
authors.lastname: Choromanski
authors.affiliation: Detroit Medical Center/Wayne State University. Electronic address: ppate@med.wayne.edu.
authors.forename: Pranav S
authors.initials: PS
authors.lastname: Patel
authors.affiliation: Detroit Medical Center/Wayne State University. Electronic address: jfrederi@med.wayne.edu.
authors.forename: Joel M
authors.initials: JM
authors.lastname: Frederick
authors.affiliation: Detroit Medical Center. Electronic address: slemos@dmc.org.
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Lemos
authors.affiliation: Detroit Medical Center/Wayne State University. Electronic address: echidiac@med.wayne.edu.
authors.forename: Elie J
authors.initials: EJ
authors.lastname: Chidiac
mesh_terms: D000328:Adult; D000368:Aged; D000577:Amides / Q000008:administration & dosage*; D000701:Analgesics, Opioid / Q000008:administration & dosage; D000779:Anesthetics, Local / Q000008:administration & dosage*; D001182:Arthroscopy / Q000379:methods; D065527:Brachial Plexus Block / Q000379:methods*; D002045:Bupivacaine / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D006784:Hospitals, Teaching; D006801:Humans; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000188:drug therapy; D011446:Prospective Studies; D000077212:Ropivacaine; D012785:Shoulder Joint / Q000601:surgery; D013147:Spirometry
chemical_list: D000577:Amides; D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D000077212:Ropivacaine; D002045:Bupivacaine
keywords: Bupivacaine; Continuous peripheral nerve blocks; Hemidiaphragmatic paresis; Interscalene blocks; Phrenic nerve paresis; Ropivacaine