Does circumferential spread of local anaesthetic improve the success of peripheral nerve block?

The relation between the pattern of local anaesthetic (LA) spread and the quality of peripheral nerve block is unclear. Twenty-one volunteers were randomized to receive a median nerve block with intended circumferential or intended non-circumferential spread of LA. Different predetermined volumes an...

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Bibliographic Details
Published in:British journal of anaesthesia : BJA 2014-07, Vol.113 (1), p.177-185
Main Authors: Marhofer, D., Karmakar, M.K., Marhofer, P., Kettner, S.C., Weber, M., Zeitlinger, M.
Format: Article
Language:English
Subjects:
Adolescent
Adult
anaesthetic techniques, regional
Anesthetics, Local - administration & dosage
Anesthetics, Local - pharmacokinetics
Cross-Over Studies
Double-Blind Method
Drug Administration Schedule
equipment, ultrasound machines
Humans
Image Interpretation, Computer-Assisted - methods
Imaging, Three-Dimensional - methods
Median Nerve - diagnostic imaging
Median Nerve - metabolism
Mepivacaine - administration & dosage
Mepivacaine - pharmacokinetics
Middle Aged
Nerve Block - methods
regional anaesthesia
Ultrasonography, Interventional - methods
Young Adult
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Summary:The relation between the pattern of local anaesthetic (LA) spread and the quality of peripheral nerve block is unclear. Twenty-one volunteers were randomized to receive a median nerve block with intended circumferential or intended non-circumferential spread of LA. Different predetermined volumes and needle placement techniques were used to produce the different patterns of LA spread. Volumetric, multiplanar 3D ultrasound imaging was performed to evaluate the pattern and extent of LA spread. Sensory block was assessed at predetermined intervals. Complete circumferential spread of LA was achieved in only 67% of cases in the intended circumferential study group and in 33% of cases in the intended non-circumferential group. Block success was similar (90%) and independent of whether circumferential or non-circumferential spread of the LA was achieved. All block failures (n=4) occurred in the intended non-circumferential group with low volumes of LA. The onset of sensory block (independent of group allocation) was faster with circumferential spread of LA [median (IQR) onset time, 15 (8; 20) min] compared with non-circumferential spread of LA [median (IQR) onset time, 20 (15; 30) min]. More LA was used for circumferential blocks [median (IQR) volume of LA 2.8 (1.3; 3.6) vs 1.3 (1.1; 2.4) ml]. Even under optimal conditions, it was not possible to achieve circumferential spread of LA in all intended cases. The success of median nerve block seems to be independent of the pattern of LA spread. DRKS 00003826.
ISSN:0007-0912
1471-6771
DOI:10.1093/bja/aeu002