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Effects of age on minimum effective volume of local anesthetic for ultrasound‐guided supraclavicular brachial plexus block
Author(s) -
PAVIČIĆ ŠARIĆ JADRANKA,
VIDJAK VINKO,
TOMULIĆ KATARINA,
ZENKO JELENA
Publication year - 2013
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/aas.12109
Subject(s) - medicine , brachial plexus , local anesthetic , lidocaine , anesthesia , confidence interval , ultrasound , brachial plexus block , surgery , radiology
Background Involutional changes of peripheral nervous system occur with aging. The aim of the study was to determine the minimum effective volume of local anesthetic required to offer an effective ultrasound‐guided supraclavicular brachial plexus block in 50% of middle‐aged (< 50 years) and elderly (> 65 years) patients. We hypothesized reduced minimum effective volume of local anesthetic in elderly patients. Methods Middle‐aged ( n = 22) and elderly ( n = 22) patients undergoing upper limb surgery received an ultrasound‐guided supraclavicular brachial plexus block. Structural analysis of the brachial plexus in supraclavicular region was obtained by measuring the cross‐sectional area. The prospective, observer‐blinded study method is a previously validated step‐up/step‐down sequence model where the local anesthetic volume for the next patient is determined by the outcome of the previous block. The starting volume was 30 ml (50 : 50 mixture, 0.5%wt/vol levobupivacaine, 2%wt/vol lidocaine). The minimum effective volume of local anesthetic was determined using D ixon and M asey method. Results The minimum effective local anesthetic volume significantly differed between middle‐aged and elderly [23.0 ml, 95% confidence interval ( CI ) 13.7–32.3 vs. 11.9 ml, 95% CI 9.3–14.6; 95% CI of the difference 1.6–20.6, P = 0.027]. The cross‐sectional area of brachial plexus was 0.95 ± 0.15 in middle‐aged and 0.51 ± 0.06 cm 2 in elderly patients ( P < 0.001). Conclusions Within the present study, we report a reduced minimum effective anesthetic volume for ultrasound‐guided supraclavicular block in elderly patients. Additionally, smaller cross‐sectional surface area of brachial plexus in the supraclavicular region was observed.