LAUSR

PURPOSE Digital ureteroscopes employ "chip-on-the-tip" technology which allows for significant improvement in image resolution. However, image distortion often occurs during laser lithotripsy due to acoustic wave production. We sought to compare image distortion using different laser power settings and distances from the laser fiber tip to the scope for the Super Pulsed Thulium Fiber (SPTF) laser and high power Holmium:YAG (Ho:YAG) laser. MATERIALS AND METHODS Ureteroscopy was simulated using a silicone kidney-ureter-bladder model fitted with a 12/14F access sheath and the Lithovue™ (Boston Scientific), disposable digital flexible ureteroscope. At defined laser parameters (10, 20, 30 and 40W, short pulse), a 200-μm laser fiber was slowly retracted toward the tip of the ureteroscope during laser activation. Image distortion was identified, and distance from the laser tip to the scope tip was determined. Data from the two lasers were compared utilizing t-tests. RESULTS After controlling for frequency, power, and laser mode, utilizing 1.0J of energy was significantly associated with less feedback than 0.5J (-0.091mm, p ≤ 0.05). Increased power was associated with larger feedback distance (0.016mm, p ≤ 0.05); however, increase in frequency did not have a significant effect (-0.001mm, p = 0.39). The SPFT laser had significantly less feedback when compared to all Holmium laser modes. CONCLUSIONS Increased total power results in image distortion occurring at greater distances from the tip of the ureteroscope during laser activation. Image distortion occurs further from the ureteroscope with Ho:YAG laser than with SPTF fibers at the same laser settings. In clinical practice, the tip of the laser fiber should be kept further away from the tip of the scope during ureteroscopy as the power increases as well as when utilizing the Ho:YAG system compared to the SPTF laser platform. The SPTF laser may have a better safety profile in terms of potential scope damage.