Construct validity of a novel assessment tool for ultrasound-guided axillary brachial plexus block

This study evaluated the effects of adding adjuvant clonidine to lidocaine with epinephrine on the characteristics of ultrasound-guided axillary brachial plexus block (ABPB) for upper extremity surgery. Twenty-four patients were randomised to receive an ultrasound guided ABPB with 20 mL of lidocaine 2% with 1:200,000 epinephrine plus 2 mL of either normal saline 0.9% (Group 1) or a mixture of clonidine 1 µg/kg and normal saline 0.9% (Group 2). The outcome measures that were recorded were the overall onset time and the duration of sensory and motor block. The median (IQR) overall onset time of sensory and motor block was significantly shorter in Group 2 vs. Group 1 (5 (5–7.5) min vs. 10 (8.8–12.5) min; p < 0.001) and (5 (2.5–7.5) min vs. 7.5 (6.3–7.5) min; p = 0.001), respectively. The median (IQR) overall duration of sensory and motor block was significantly longer in Group 2 vs. Group 1 (225 (200–231) min vs. 168 (148–190) min; p < 0.001) and (225 (208–231) min vs. 168(148–186) min; p < 0.001), respectively. In ultrasound-guided ABPB, the addition of clonidine to lidocaine with epinephrine resulted in shorter onset time and prolonged duration of sensory and motor block.

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Effects of local anaesthetic dilution on the characteristics of ultrasound guided axillary brachial plexus block: a randomised controlled study

Medical Ultrasonography ◽

10.11152/mu-3069 ◽

2021 ◽

Author(s):

Anil Ranganath ◽

Osman Ahmed ◽

Gabriella Iohom

Keyword(s):

Brachial Plexus ◽

Local Anaesthetic ◽

Brachial Plexus Block ◽

Onset Time ◽

Ultrasound Guided ◽

Performance Time ◽

Axillary Brachial Plexus Block ◽

Group 2 ◽

Plexus Block ◽

Group 1

Aims: Ultrasound guidance has led to marked improvement in the success rate and characteristics of peripheral nerve blocks. However, effects of varying the volume or concentration of a fixed local anaesthetic dose on nerve block remains unclear. The purpose of our study was to evaluate whether at a fixed dose of lidocaine, altering the volume and concentration will have any effect on the onset time of ultrasound-guided axillary brachial plexus block.Material and methods: Twenty patients were randomised to receive an ultrasound-guided axillary brachial plexus block with either lidocaine 2% with epinephrine (20 ml, Group 2%) or lidocaine 1% with epinephrine (40 ml, Group 1%). The primary endpoint was block onset time. Secondary outcomes included duration of the block, performance time, number of needle passes, incidence of paraesthesia and vascular puncture.Results: The median [IQR] onset time of surgical anaesthesia was shorter in Group 1% when compared to Group 2% (6.25 [5-7.5] min vs 8.75 [7.5-10] min; p=0.03). The mean (SD) overall duration of surgical anaesthesia was significantly shorter in Group 1% compared to Group 2% (150.9±17.2 min vs 165.1±5.9 min; p=0.02). Group 1% had a shorter performance time with fewer needle passes. The incidence of vascular puncture and paraesthesia was similar in the two groups.Conclusion: Ultrasound-guided axillary brachial plexus blocks performed using a higher volume of lower concentration lidocaine was associated with shorter onset time and duration of surgical anaesthesia.

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