title: Reduction in sodium content of local anesthetics for peripheral nerve blocks: a comparative evaluation of saline with 5% dextrose--a randomized controlled double-blind study.
abstract: BACKGROUND
  Commercially available local anesthetic drugs when diluted with normal saline have high sodium content. High perineural sodium concentration has been implicated in antagonizing the analgesic effects of local anesthetics by preventing and/or delaying neural blockade. Five percent dextrose is not known to cause any short- or long-term injury when injected around neural tissue. In this study, we prospectively compared and evaluated block characteristics when local anesthetic drug was diluted with these 2 different agents.
  
  
  METHODS
  Patients scheduled for upper limb surgery were randomly assigned to receive axillary brachial plexus block with 0.5% ropivacaine (1% diluted with either 5% dextrose or normal saline). Motor and sensory block were tested every 5 minutes for 30 minutes. Postoperatively, a telephone interview was conducted after 24 hours and 7 days along with surgical follow-up at days 3, 10, and/or 14 to 28 days to document side effects, patient satisfaction, and time for block resolution. Any nerve deficits were followed until resolution. The primary outcome was time to onset of sensory nerve block.
  
  
  RESULTS
  Five hundred fifty patients were recruited for this study. The mean time to complete sensory block was 18.3 ± 6.1 minutes in the dextrose group and 22.5 ± 6.4 minutes in the saline group (P < 0.001, 95% confidence interval for mean difference 3.0-5.4 minutes). There were 5 patients with clinical nerve deficits (no statistical difference between groups).
  
  
  CONCLUSIONS
  Dilution with 5% dextrose provides earlier onset of axillary brachial plexus block with ropivacaine.
authors.affiliation: Department of Anesthesia and Perioperative Medicine, University of Western Ontario, London, Ontario, Canada. sdhir2@uwo.ca
authors.forename: Shalini
authors.initials: S
authors.lastname: Dhir
authors.forename: Luminita
authors.initials: L
authors.lastname: Tureanu
authors.forename: Amir
authors.initials: A
authors.lastname: Bouzari
authors.forename: Amna
authors.initials: A
authors.lastname: Masood
authors.forename: Mario
authors.initials: M
authors.lastname: Francispragasam
authors.forename: Sugantha
authors.initials: S
authors.lastname: Ganapathy
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000577:Amides / Q000008:administration & dosage* / Q000009:adverse effects / Q000737:chemistry; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000009:adverse effects / Q000737:chemistry; D001917:Brachial Plexus; D002626:Chemistry, Pharmaceutical; D004311:Double-Blind Method; D004339:Drug Compounding; D005260:Female; D005947:Glucose / Q000008:administration & dosage* / Q000009:adverse effects / Q000737:chemistry; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000187:drug effects; D009407:Nerve Block / Q000009:adverse effects; D009864:Ontario; D017288:Pain Threshold / Q000187:drug effects; D014677:Pharmaceutical Vehicles / Q000008:administration & dosage* / Q000009:adverse effects / Q000737:chemistry; D011446:Prospective Studies; D000077212:Ropivacaine; D012964:Sodium / Q000032:analysis*; D012965:Sodium Chloride / Q000008:administration & dosage* / Q000009:adverse effects / Q000737:chemistry; D013997:Time Factors; D055815:Young Adult
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D014677:Pharmaceutical Vehicles; D012965:Sodium Chloride; D000077212:Ropivacaine; D012964:Sodium; D005947:Glucose