[Interscalene block for total shoulder arthroplasty: comparative study (ultrasound vs. neurostimulation)].

BACKGROUND Modern anesthesiology has integrated the use of ultrasonography as a tool that has displaced neurostimulation as a technique for locating peripheral nerves. The aim of this study was to determine which procedure is more effective for guiding interscalene block for total shoulder arthroplasty. METHODS We carried out a comparative, prospective non-randomized study comprised of the group guided by neurostimulation interscalene block and the group guided by ultrasound. All patients in both groups were scheduled for total shoulder arthroplasty. Latency, degree of sensory and motor block, success rate, postoperative pain intensity at 6, 12, and 24 h, patient satisfaction and complications were measured. RESULTS We included 110 patients, 55 per group. Patients were placed in beach chair position and the deltopectoral approach was used. There were no differences in demographic characteristics. Results for neurostimulation vs. ultrasound group: latency 19.11 ± 2.27 vs. 17.24 ± 1.42 min, p= 0.23. Block sensitivity in both groups was grade 0 motor block grade 0 in 76.4% and grade 1 in 23.6% vs. grade 0 to 100%. There was 100% success rate for both groups. Postoperative pain at 6 h was 0.13 ± 0.54 vs. 0.11 ± 0.13 p= 0.90, at 12 h 1.67 ± 1.15 vs. 1.65 ± 0.59 p= 0.89 and at 24 h 3.15 ± 1.66 vs. 2.99 ± 1.15 p= 0.78. Satisfaction 54.5% very satisfied and 45.5% satisfied 96.36% vs 3.6% very satisfied and satisfied. Complications 18.18% vs. 3.6% p= 0.023. CONCLUSION Ultrasound-guided interscalene nerve block is the technique of choice in elective total shoulder arthroplasty.