Endoscopic lithotripsy with a SuperPulsed thulium-fiber laser for ureteral stones: A single-center experience.

Abstract

To estimate the efficacy and safety of SuperPulsed thulium-fiber laser ureteral lithotripsy and to identify optimal laser settings. Patients with solitary stones were prospectively included. Lithotripsy was performed with a SuperPulsed thulium-fiber laser (NTO IRE-Polus, Fryazino, Russia) using a rigid ureteroscope 7.5 Ch (Richard Wolf, Knittlingen, Germany). We analyzed the efficacy of lithotripsy by measuring total energy required for stone disintegration, "laser-on" time, ablation speed, ablation efficacy, and energy consumption. Stone retropulsion and visibility were assessed using a three-point Likert scale. Complications were assessed using the Clavien-Dindo classification system. A total of 149 patients were included. The mean stone density was 985±360 Hounsfield units, the median (interquartile range) stone volume was 179(94-357) mm3 . The median (interquartile range) total energy was 1 (0.4-2)kJ, and laser-on time 1.2 (0.5-2.7)min. The median (interquartile range) stone ablation speed was 140(80-279) mm3 /min, energy for ablation of 1mm3 was 5.6 (3-9.9)J/mm3 and energy consumption was 0.9 (0.6-1)J/min. A correlation was found between retropulsion and the energy used (r=0.5, P<0.001). Multivariable analysis showed energy to be a predictor of increased retropulsion (odds ratio 65.7, 95% confidence interval 1.6-2774.1; P=0.028). No predictors for worse visibility were identified. The SuperPulsed thulium-fiber laser provides effective and safe lithotripsy during ureteroscopy regardless of stone density. Fiber diameter and laser frequency do not influence visibility or safety. Optimal laser settings are 0.5J×30Hz for fragmentation and 0.15J×100Hz for dusting.