Mixed-Reality Simulation for Needle Tracking Skills in Ultrasound-Guided Regional Anesthesia: An Evaluator-Blinded, Randomized Controlled Trial

Abstract

Abstract Background: Ultrasound-guided regional anesthesia (UGRA) is the preferred technique for peripheral nerve blockade, and failure to maintain needle tip visualization underlies most procedural complications. UGRA is still taught in most residency programs through didactic instruction and limited phantom exposure. The comparative effectiveness of mixed-reality simulation against conventional instruction is poorly characterized. Objective: To evaluate whether a one-hour mixed-reality simulation session with formative deliberate practice improves needle handling and tracking skills, compared with a didactic session, in simulated settings and during clinical UGRA procedures, in anesthesiology residents at a large academic center. Methods: A prospective, evaluator-blinded, randomized controlled trial was conducted at Beth Israel Deaconess Medical Center between August 2025 and March 2026 (IRB 2025P000229). Thirty-six anesthesia residents (CA1–CA3) were block-randomized 1:1 with stratification by training level. All received the didactic lecture; intervention residents additionally completed a structured mixed-reality session on the PERC Mentor Suite Mixed-Reality Simulator (SurgicalScience). The primary outcome was change in phantom Needle Tip Visibility Ratio (NTVR) from pre- to post-session, analyzed using a linear mixed-effects model. Secondary outcomes included clinical NTVR, Regional Anesthesia Procedural Skills (RAPS) ratings, NASA-Task Load Index, and perceived usefulness. Results: The intervention arm showed larger improvement in phantom NTVR than control (arm-by-phase interaction 0.094, 95% CI 0.042 to 0.146, p = 0.001; d = 1.18). The effect was largest in CA1 (d = 1.80) and CA2 (d = 1.70), and not detected in CA3 (d = 0.13); three-way arm-by-phase-by-level interaction p = 0.003. Clinical NTVR was numerically higher overall (d = 0.42, p = 0.22), with the largest stratum effect in CA1 (d = 1.25, p = 0.038). Cognitive load did not differ between arms overall. Eighty-two percent of intervention residents rated the training as very or extremely useful. Conclusions: A brief mixed-reality simulation session produced large improvements in phantom needle tip visualization, transferring most clearly to clinical performance in junior residents. Effects attenuated with increasing training level, raising questions about year-appropriate training formats. Keywords: ultrasound-guided regional anesthesia; simulation-based education; mixed reality; needle tip visibility; cognitive load; medical education.