title: Minimum effective volume of local anesthetic for ultrasound-guided supraclavicular brachial plexus block.
abstract: OBJECTIVE
  The aim of this study was to determine the minimum effective anesthetic volume required to produce an effective supraclavicular block for surgical anesthesia using an ultrasound (US)-guided technique.
  
  
  METHODS
  Twenty-one adults undergoing elective upper limb surgery received a US-guided supraclavicular block. The initial volume of local anesthetic (LA; 50:50 mixture of lidocaine 2% and bupivacaine 0.5% with epinephrine) injected was 30 mL, which was subsequently varied by 5 mL for each consecutive patient according to the response of the previous patient. The minimum effective anesthetic volume in 50% of patients was determined using the Dixon and Massey up-and-down method. The effective volume in 95% of patients (ED95) was calculated using probit transformation and logistic regression.
  
  
  RESULTS
  The minimum effective anesthetic volume in 50% and calculated effective volume in 95% of patients were 23 mL (95% confidence interval, 13-39 mL) and 42 mL (95% confidence interval, 19-65 mL), respectively. Seven patients received supplemental LA, with no patient requiring a general anesthetic.
  
  
  CONCLUSIONS
  In this study, the minimum volume required for US-guided supraclavicular block in 50% of patients was 23 mL, and in 95% of patients was 42 mL. Under the present study conditions, the calculated volume of LA required for US-guided supraclavicular block does not seem to differ from the conventionally recommended volume required for supraclavicular blocks using non-US-based nerve localization techniques.
authors: Department of Anesthesia and Pain Management, Toronto Western Hospital University Health Network, Ontario, Canada.
authors: Edel
authors: E
authors: Duggan
authors: Hossam
authors: H
authors: El Beheiry
authors: Anahi
authors: A
authors: Perlas
authors: Mario
authors: M
authors: Lupu
authors: Alina
authors: A
authors: Nuica
authors: Vincent W S
authors: VW
authors: Chan
authors: Richard
authors: R
authors: Brull
mesh_terms: D000328:Adult; D000368:Aged; D019162:Anesthetics, Combined / Q000008:administration & dosage*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D001917:Brachial Plexus / Q000000981:diagnostic imaging*; D002045:Bupivacaine / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008012:Lidocaine / Q000008:administration & dosage*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D011446:Prospective Studies; D012684:Sensory Thresholds / Q000187:drug effects; D018084:Ultrasonography, Interventional
chemical_list: D019162:Anesthetics, Combined; D000779:Anesthetics, Local; D008012:Lidocaine; D002045:Bupivacaine