Superpulsed Thulium Fiber Laser for Stone Dusting: In Search of a Perfect Ablation Regimen-A Prospective Single-Center Study

Objective:To compare the efficacy of the standard and higher frequency regimens for superpulsed thulium fiber laser (SP TFL) retrograde intrarenal surgery (RIRS). Materials and Methods:A prospective study of patients with renal calculi of 10-30 mm was performed. For RIRS, we used the SP TFL (NTO IRE-Polus, Russia) and a 9.5F flexible ureteroscope with 270 degrees deflection and 3.6F working channel. Retropulsion and visibility were assessed based on the surgeon's feedback using three-point Likert scales. The stone-free rate was assessed at 3 months with CT. Results:A total of 40 patients were included in the study with a mean age of 56 years, mean stone density of 880 +/- 381 HU, mean stone size of 16.5 +/- 6.8 mm, and median stone volume of 883 (interquartile range 606-1664) mm(3). Both ablation efficacy and speed were higher in the 200-Hz mode (2.7 J/mm(3)vs3.8 J/mm(3)and 5.5 mm(3)/secondvs8.0 mm(3)/second, respectively); moreover, the higher frequency correlated with increased ablation speed (r = -0.21,p = 0.019). However, both increased energy and frequency did not lead to increase of laser-on time or intraoperative complication rates. Conclusions:SP TFL is able to effectively disintegrate stones during RIRS with minimal complication rates. The use of higher frequency regimens showed higher efficacy and ablation speed and was not associated with increased complication rates.