title: Low dose intravenous dexamethasone (4 mg and 10 mg) significantly prolongs the analgesic duration of single-shot interscalene block after arthroscopic shoulder surgery: a prospective randomized placebo-controlled study.
abstract: BACKGROUND
  Although intravenous dexamethasone prolongs the analgesic duration of interscalene brachial plexus block, it is uncertain whether this effect can be observed using lower doses of dexamethasone. This study evaluated the impact of intravenous dexamethasone (4 mg and 10 mg) on the analgesic duration of single-shot interscalene block after arthroscopic shoulder surgery. We hypothesized that both doses would prolong the analgesic duration compared with placebo.
  
  
  METHODS
  This was a prospective double-blind randomized placebo-controlled study in patients undergoing elective arthroscopic shoulder surgery under regional anesthesia with a single-shot interscalene block (0.5% ropivacaine 20 mL). Patients received dexamethasone 4 mg (D4), dexamethasone 10 mg (D10), or a placebo (normal saline [NS]) intravenously at the time of block completion. The primary outcome was the duration of analgesia, defined as the time from the onset of sensory blockade to the first analgesic request. The primary outcome was first analyzed with a Kruskal-Wallis test and then with a Mann-Whitney test for pairwise between-group comparison.
  
  
  RESULTS
  Sixty-nine patients completed the study. The median [interquartile range] duration of analgesia was significantly different between the three groups (D4, 19.7 [16.9-23.3] hr; D10, 19.1 [11.5-22.8] hr; and NS, 11.8 [9.3-14.0] hr; P = 0.001). This difference was statistically significant for D4 and D10 compared with placebo (median difference [MD], 7.8 hr; 95% confidence interval [CI], 4.6 to 11.1 hr; P < 0.001; and MD, 7.4 hr; 95% CI, 4.2 to 10.5 hr; P = 0.001, respectively) but not for D4 compared with D10 (MD, 0.5 hr; 95% CI, -2.8 to 3.7 hr; P = 0.38).
  
  
  CONCLUSIONS
  Low doses of intravenous dexamethasone (4 mg and 10 mg) significantly prolong the analgesic duration of interscalene block. This trial was registered at ClinicalTrials.gov (NCT02412657).
authors.affiliation: Department of Anesthesiology, Hôpital Maisonneuve-Rosemont, Université de Montréal, 5415 boulevard Assomption, Montréal, QC, H1T 2M4, Canada. f.chalifoux@umontreal.ca.
authors.forename: Frédéric
authors.identifier: http://orcid.org/0000-0003-4704-0184
authors.initials: F
authors.lastname: Chalifoux
authors.affiliation: Department of Surgery, Hôtel-Dieu de Sorel and Hôpital Pierre-Boucher, Sorel-Tracy and Longueuil, QC, Canada.
authors.forename: François
authors.initials: F
authors.lastname: Colin
authors.affiliation: Department of Anesthesiology, Hôpital Pierre-Boucher, Longueuil, QC, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: St-Pierre
authors.affiliation: Department of Anesthesiology, Hôpital Maisonneuve-Rosemont, Université de Montréal, 5415 boulevard Assomption, Montréal, QC, H1T 2M4, Canada.
authors.forename: Nadia
authors.initials: N
authors.lastname: Godin
authors.affiliation: Department of Anesthesiology, Hôpital Maisonneuve-Rosemont, Université de Montréal, 5415 boulevard Assomption, Montréal, QC, H1T 2M4, Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Brulotte
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001182:Arthroscopy; D003907:Dexamethasone / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D010149:Postoperative Pain / Q000517:prevention & control*; D011446:Prospective Studies; D012782:Shoulder / Q000601:surgery*; D013997:Time Factors
chemical_list: D003907:Dexamethasone