REGIONAL ANAESTHESIA Minimum volume of local anaesthetic required to surround each of the constituent nerves of the axillary brachial plexus, using ultrasound guidance: a pilot study

Methods. We enrolled 19 ASA I–II patients undergoing hand or forearm surgery. The four nerves of the axillary plexus were identified with ultrasound guidance. Lidocaine 1.5% with epinephrine 1:200 000 was loaded into a syringe driver. A 22 G needle was inserted in the long axis to each nerve and injection commenced using the bolus function (600 ml h). The needle was repositioned until the nerve was completely surrounded. The bolus dose in millilitres displayed on the syringe driver was recorded. This was repeated for each nerve. The degree of sensory and motor block was recorded as secondary outcomes.