PD37-09 THE LASER-DARRT: A NOVEL DIRECT ALIGNMENT REDUCED RADIATION TECHNIQUE FOR PERCUTANEOUS RENAL ACCESS

INTRODUCTION AND OBJECTIVES: The traditional bullseye technique for obtaining renal access in percutaneous nephrolithotomy (PCNL) utilizes continuous fluoroscopy and accounts for substantial radiation exposure. In an attempt to minimize the radiation dose, we describe a novel laser-DARRT (Direct Alignment Reduced Radiation Technique) using direct alignment of the percutaneous access needle with the laser beam from the fluoroscopic C-arm system. METHODS: In the laser-DARRT technique, fluoroscopy was used to select the needle entry site above the calyx of interest. The Carm was positioned with the laser beam on the skin over the desired access site at a 30 degree angle. The access needle was placed such that the needle tip and hub were both aligned with the laser beam. The needle was inserted into the renal calyx using tactile feedback while maintaining alignment with the laser. Needle depth and successful calyceal puncture were confirmed both fluoroscopically and under direct vision. A randomized-controlled study was performed using a benchtop kidney model. Twenty medical personnel were tested using both the bullseye and laser-DARRT techniques and the results were stratified by subject experience level. Each subject obtained needle access to the upper, middle, and lower pole of the kidney model using both techniques. The primary endpoint was total fluoroscopy time. Secondary endpoints included insertion time, number of puncture attempts, number of course corrections, and subjective procedural difficulty. Paired samples Wilcoxon signed rank tests were used for statistical analysis with significance at p<0.05. RESULTS: A total of 120 needle placements were recorded by the 20 study subjects (60 conventional and 60 Laser DARRT). The fluoroscopy time required to obtain needle access using the LaserDARRT technique was significantly reduced compared to the conventional technique in all groups, including the attendings/fellows (7.09 vs. 18.51 sec; p<0.001), residents (6.55 vs. 13.93 sec; p1⁄40.001), and medical students (6.69 vs. 20.22 sec; p<0.001). The medical students also rated the Laser DARRT technique easier to use (2.56 vs. 4.89; p<0.001). No difference was seen in total access time, puncture attempts, or course corrections between techniques. CONCLUSIONS: The laser-DARRT for percutaneous renal access reduced fluoroscopy time by 63% compared with a conventional bullseye technique. The least experienced users found the laserDARRT significantly easier to learn. This is a promising new technique that merits additional testing in animal and human models.