Presentation Authors: Michael Borofsky*, Minneapolis, MN, Marcelino Rivera, Rochester, MN, Casey Dauw, Ann Arbor, MI, Amy Krambeck, James Lingeman, Indianapolis, IN
Introduction: Most urologists performing percutaneous nephrolithotomy (PCNL) do not obtain access. A steep learning curve with traditional techniques is one possible explanation, indicating a role for new tools to simplify this process. Electromagnetic (EM) guidance is appealing for access as it allows real time, three-dimensional targeting without radiation. Few studies have explored EM guidance for PCNL and no prior work has evaluated whether such technology can potentially decrease the learning curve in gaining access. We sought to determine the feasibility of a new EM guidance system (Auris Health, Redwood City, CA) in obtaining percutaneous access among urologists of different experience levels.
Methods: IRB and IACUC approval was obtained for a pilot study to compare feasibility of EM guided percutaneous access to fluoroscopic guided access in a porcine model. Voluntary participants included urology sub-interns, residents, fellows and faculty. They were categorized into 3 cohorts: Beginner (0-10 prior PCNL cases), Intermediate (10-100) and advanced (>100). Trainees were provided verbal guidance during punctures from mentors with no hands on help. Each participant performed an EM and fluoroscopic guided puncture, the order of which was switched with each subsequent participant. Primary outcome was successful puncture, determined by endoscopic visualization of the needle entering the desired calyx. Secondary outcomes included access time, fluoroscopy time, and number of attempts. Participants were limited to 3 attempts and 10 minutes total to obtain access using each technique.
Results: 14 participants (6 beginner, 4 intermediate, 4 expert) attempted 28 punctures. Overall success using EM guidance was 93% compared to 71% using fluoroscopy (p=0.33). EM guided punctures had shorter overall access times (1.4 vs. 4.2 min, p < 0.01) with fewer number of attempts (1 vs 2, p < 0.01). Median fluoroscopy time was 1.6 min in the fluoroscopy cohort compared to 0 in the EM cohort, excluding the initial retrograde pyelogram (p < 0.01). Beginners showed comparable success rates and outcomes relative to experts despite higher access times (figure 1).
Conclusions: EM guidance is a promising new technique to decrease the learning curve of percutaneous access with high success rates and minimal radiation.
Source of Funding: Auris Health, Redwood City, CA