Preprocedural ultrasound-assisted midline continuous spinal anesthesia in older patients: is there an advantage over the conventional landmark-guided paramedian technique? A randomized controlled trial

Abstract Background Preprocedural neuraxial ultrasonography improves the technical performance of spinal anesthesia, and ultrasound-assisted paramedian approaches may be particularly efficient. However, the paramedian technique requires a distinct entry point and needle trajectory that may be less familiar to some operators, whereas the midline approach remains familiar and widely used. Whether preprocedural ultrasound can enhance this familiar midline strategy compared with landmark-guided paramedian puncture in older patients remains uncertain. Methods In this single-center randomized trial, 110 patients aged ≥ 65 years were allocated 1:1 to landmark-guided paramedian (PML) or preprocedural ultrasound-assisted midline (MUS) continuous spinal anesthesia for hip-fracture surgery. The primary outcome was needle passes. Secondary outcomes included insertion attempts, first-pass success, identification and procedure times, complications, and puncture level. Between-group comparisons used Mann–Whitney U, χ², or Fisher exact tests as appropriate. Results Needle passes were lower with MUS than PML (2 [1–3] vs. 3 [2–5]; Hodges–Lehmann difference, − 1 pass; 95% CI, − 1 to 0; P = 0.004). First-pass success was higher with MUS (34.5% vs. 16.4%; risk difference, 18.2% points; 95% CI, 1.9–33.4; P = 0.029). Identification time was longer with MUS (130 [99–185] vs. 27 [15–41] s; difference, 100 s; 95% CI, 86–119; P < 0.001), whereas procedure time did not differ significantly (39 [23–68] vs. 48 [30–84] s; P = 0.072). Complications were uncommon. Conclusions Ultrasound-assisted midline puncture reduced needle passes and increased first-pass success compared with landmark-guided paramedian puncture, although identification time was longer. These findings demonstrate a technical benefit of the overall MUS strategy; nevertheless, its patient-centered clinical significance remains uncertain. Trial registration ClinicalTrials.gov, NCT06740994. Registered December 14, 2024; retrospectively registered.