RESUMO
BACKGROUND: There are few data comparing the onset time of interscalene brachial plexus block performed using ultrasound (US) guidance or nerve stimulation (NS) technique for elective coracoacromial ligament repair. METHODS: Fifty ASA I-III patients were randomly allocated to receive a continuous interscalene brachial plexus block with 20 ml of 1% ropivacaine with either NS or US guidance. The time of block performance, number of skin punctures and needle redirections, inadvertent vascular punctures, and procedure-related pain scores were recorded. The onsets of sensory and motor blocks in the distribution of radial, axillary, and musculocutaneous nerves were blindly assessed every 5 min until 30 min from the end of local anaesthetic (LA) injection. Intraoperative fentanyl, general anaesthesia (GA) requirements, postoperative pain scores, LA consumption, and patients' requirements for subcutaneous morphine during the first 24 h were compared. RESULTS: Block onset times were similar. The time to complete the block and the number of skin punctures and vascular punctures were significantly lower in Group US. There were no differences in needle redirections, incidence of paraesthesiae, intraoperative fentanyl consumption, and requirements for GA or postoperative morphine. The US group required significantly less LA only at 16 h after surgery and had lower pain scores at rest at 24 h after surgery. CONCLUSIONS: Block onset times and success rate were similar whether NS or US was used, although US guidance allowed shorter procedural times, fewer needle punctures, and fewer vascular punctures.