Background: Ultrasound (US)-guided supraclavicular or infraclavicular blocks are commonly used for upper extremity surgery. The aims of this randomized study were to compare the block performance and onset times, effectiveness, incidence of adverse events and patient's acceptance of US-guided supraclavicular or infraclavicular blocks. We hypothesized that the supraclavicular approach, being more superficial and easier to visualize using a 10 MHz transducer, will produce a faster and a more extensive sensory block. Methods: One hundred and twenty patients were randomized to two equal groups: supraclavicular (S) and infraclavicular (I). Each patient received a mixture containing equal volumes of ropivacaine 7.5 mg/ml and mepivacaine 20 mg/ml with adrenaline 5 mg/ml, 0.5 ml/kg body weight (minimum 30 ml, maximum 50 ml). The sensory score (anaesthesia -2 points, analgesia -1 point and pain -0 point) of the seven terminal nerves was assessed every 10 min. Patients were declared ready for surgery when they had an effective surgical block -anaesthesia or analgesia of the five nerves below the elbow. Thirty minutes after the block, the unblocked nerves were supplemented. The block performance and latency times, surgical

In the hands of anaesthetists experienced in nerve electrolocation, the MNS technique of an initial axillary block by four separate injections of 10 mL of mepivacaine produces faster and more extensive block than the TA technique by two separate injections of 20 mL. Hence, the MNS technique requires fewer supplementary blocks and results in faster patient readiness for surgery than the TA technique.

Infraclavicular block by single injection caused less discomfort and fewer adverse events than axillary block by multiple injections. Block effectiveness, onset time and patients' acceptance were similar.