D Marhofer1, M K Karmakar2, P Marhofer3, S C Kettner1, M Weber4, M Zeitlinger4. 1. Department of Anaesthesia and Intensive Care Medicine and. 2. Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China. 3. Department of Anaesthesia and Intensive Care Medicine and peter.marhofer@meduniwien.ac.at. 4. Department of Clinical Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
Abstract
BACKGROUND: The relation between the pattern of local anaesthetic (LA) spread and the quality of peripheral nerve block is unclear. METHODS: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. RESULTS: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]. CONCLUSIONS: 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. CLINICAL TRIAL REGISTRATION: DRKS 00003826.
RCT Entities:
BACKGROUND: The relation between the pattern of local anaesthetic (LA) spread and the quality of peripheral nerve block is unclear. METHODS: 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. RESULTS: 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]. CONCLUSIONS: 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. CLINICAL TRIAL REGISTRATION: DRKS 00003826.
Authors: Jane R Schubart; Eric Schaefer; Piotr Janicki; Sanjib D Adhikary; Amber Schilling; Alan J Hakim; Rebecca Bascom; Clair A Francomano; Satish R Raj Journal: J Dent Anesth Pain Med Date: 2019-10-30