Effects of Clonidine as an Adjuvant to Lidocaine with Epinephrine in Ultrasound Guided Axillary Brachial Plexus Block: A Randomised Controlled Trial

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.

Minimum effective volume of 0.2% ropivacaine for ultrasound-guided axillary brachial plexus block in preschool-age children

Ultrasound-guided axillary brachial plexus block is increasingly used in preschool-age patients. However, the minimum effective volume of local anaesthetics has not been determined. With ethical committee approval and written informed consent from the guardians of all paediatric patients, we studied 27 consecutive patients aged 3 to 6 years who were scheduled for hand surgery. After general anaesthesia, eligible patients received a set volume of ultrasound-guided axillary brachial plexus block. We determined the volume of 0.2% ropivacaine for consecutive patients from the preceding patient’s outcome. The initial volume was 0.4 ml/kg. The testing interval was set at 0.05 ml/kg, and the lowest volume was 0.1 ml/kg. The following conditions were defined as a successful block: no heart rate changes, body movement, or ventilatory disorders during the operation; no use of fentanyl in the PACU; and a postoperative sensory block score < 3. The sequences of positive and negative blocks in consecutive patients were recorded. Using probit regression analysis, the 50% effective volume was 0.185 ml/kg (95% CI 0.123–0.234), and the 95% effective volume was 0.280 ml/kg (95% CI 0.232–0.593). EV50 and EV95 values of 0.2% ropivacaine for ultrasound-guided axillary brachial plexus block were 0.185 ml/kg and 0.280 ml/kg, respectively.

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

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.

Peripheral Nerve Stimulator (PNS) Versus Trans-Arterial (TA) Techniques for Axillary Brachial Plexus Block

Background: Axillary brachial plexus block is one of the widely used techniques for upper extremity surgery. Peripheral nerve blocks (PNB) provide optimal surgical conditions while providing prolonged post-operative analgesia. The transarterial (TA) technique of axillary brachial plexus block is a well established method of producing regional anaesthesia for surgeries at or below elbow. In this prospective randomized study we compared, “peripheral nerve stimulator (PNS) versus trans-arterial (TA) techniques for axillary brachial plexus block” Methods: In this prospective, randomized study 80 patients, age>18 year, ASA-I & II, were divided randomly into two groups PNS and TA. In PNS groups 40 patients received axillary approach of brachial plexus block with the help of peripheral nerve stimulator, and rest TA group received axillary block through transarterial approach. Local anaesthetic 0.25% bupivacaine 15ml+1% lignocaine with adrenaline (1:200,000) 20 ml was used. Then success rate of two different methods of block were compared. Other parameters of comparison was block performance time of block, onset of sensory and motor block, failure rate, analgesia required etcetera. Results: The success rate of the block in PNS group was 90% and the success rate of TA group was 85% and there was no significant difference in success rate. Performance time was significantly low in trans-arterial axillary approach of brachial plexus block (p<0.005). There was no significant difference in onset of motor and sensory block. The sensory and motor functions returned properly in all patients. Conclusion: In our study we found that the PNS guided axillary block and TA injection axillary brachial plexus block provide similar success rate, and onset of block when musculocutaneous nerve blocked separately in the both techniques. Keywords: Axillary brachial plexus block, Trans-arterial approach, Peripheral nerve stimulator.