Axillary brachial plexus anesthesia: electrical versus cold saline stimulation

The aim of this study was to investigate which of two methods of nerve stimulation, cold saline-induced paresthesia or use of a nerve stimulator, was more effective in increasing the successful brachial plexus block rate by the axillary approach. Twenty patients were randomly assigned to Group A (saline below 11 degrees C), and 20 patients to Group B (nerve stimulator). All blocks were performed by the same anesthesiologist using 40 mL of 1.5% mepivacaine and 4 mL of 8.4% sodium bicarbonate. Successful block was defined using Vester-Andersen et al.'s criteria. Cold saline-induced paresthesiae in the hand or forearm were obtained in 19 patients (95%) during one of four attempts allowed, and in 15 patients (75%) on the first attempt. A motor response was evoked by a nerve stimulator in 17 patients (85%). Two patients (10%) had a paresthesia in the hand without a motor response with the current at less than 1 mA. A successful block was achieved in 19 patients in each group.