Effect of Local Anaesthetic Volume on Axillary Brachial Plexus Block Duration

Axillary brachial plexus block is an safe, effective and widely used technique for providing surgical anesthesia at and below the elbow. Inadvertent intraneural and intravascular injections are the only significant risks. Traditionally, greater volumes of local anaesthetic have been administered to achieve successful axillary brachial plexus block, but recent studies have demonstrated that this can be achieved with even very low volumes of 2-4 mL lidocaine 1.5% per nerve or ultra low volume of 1 mL lidocaine 2% per nerve. Administration of 30mL (vs 10 mL) lidocaine 2% with epinephrine 1:200 000 prolongs the sensory and motor block duration of ultrasound guided axillary brachial plexus block for elective upper limb surgical procedures. Primary Outcome: The primary outcome will be the overall duration of sensory block. Secondary Outcomes: Duration of motor block Time to onset of the block. The quality of block intraoperatively Time to first request of postoperative opioid analgesia. Total opioid consumption at 24 hours. The incidence of adverse effects perioperatively: nausea, dizziness, tinnitus, vomiting, convulsions or arrhythmia.