Minimum effective volume of local anesthetic for ultrasound-guided supraclavicular brachial plexus block.
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.
Duggan
Edel
E
Department of Anesthesia and Pain Management, Toronto Western Hospital University Health Network, Ontario, Canada.
El Beheiry
Hossam
H
Perlas
Anahi
A
Lupu
Mario
M
Nuica
Alina
A
Chan
Vincent W S
VW
Brull
Richard
R
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
D019162:Anesthetics, Combined; D000779:Anesthetics, Local; D008012:Lidocaine; D002045:Bupivacaine