Minimum effective volume of local anesthetic for ultrasound-guided supraclavicular brachial plexus block

Reg Anesth Pain Med. 2009 May-Jun;34(3):215-8. doi: 10.1097/AAP.0b013e31819a9542.

Abstract

Background and objectives: 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.

Conclusion: 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.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Anesthetics, Combined / administration & dosage*
  • Anesthetics, Local / administration & dosage*
  • Brachial Plexus / diagnostic imaging*
  • Bupivacaine / administration & dosage*
  • Female
  • Humans
  • Lidocaine / administration & dosage*
  • Logistic Models
  • Male
  • Middle Aged
  • Nerve Block / methods*
  • Prospective Studies
  • Sensory Thresholds / drug effects
  • Ultrasonography, Interventional*

Substances

  • Anesthetics, Combined
  • Anesthetics, Local
  • Lidocaine
  • Bupivacaine