Minimum Volume of LA Required to Surround Each of the Branches of the Axillary Brachial Plexus using Ultrasound Guided Technique

Introduction:The minimum volume of LA required to effectively block the four main branches of the axillary brachial plexus is unknown.The main aim of the current study was to determine the minimal volume of LA required to surround each branch of axillary brachial plexus and document its onset and duration of sensory and motor effects.Material and methods: 20 patients with ASA I-II undergoing hand or forearm surgery were selected for this study.USG was used to locate each of the 4 branches of axillary plexus.1.5% of lignocaine with 1:200 000 of adrenaline was loaded into a syringe driver and deposited with a 22 G needle and injection commenced using the bolus function (600 ml h21).Results: The mean (95% of Confidence Interval) volume required for each nerve was: radial 3.32 (2.74-3.89)ml, median 2.65 (2.01-3.19)ml, ulnar 2.48 (2.04-2.93)ml, and musculocutaneous 2.20 (1.86-2.54)ml.The mean (95% of Confidence Interval) onset time for complete sensory block was: radial 21.5 (12.5-30.5)min, median 25.8 (17.5-34.0)min, ulnar 25.6 (16.8-34.4)min, and musculocutaneous 14.8 (7.35-23.2) min.The mean (95% of Confidence Interval) last recorded time with complete block was: radial 136.1 (104.6-158.7)min, median 143.7 (122.4-165.0)min, ulnar 182.2 (157.1-207.2) min, and musculocutaneous 157.3 (130.8-183.9)min. Conclusions:We concluded that it is possible to deposit 2-4 ml of local anaesthetic around each branch of axillary plexus.We also speculate that by increasing the amount of volume of LA would produce anesthesia of quicker onset and with longer.