[Retrograde intrarenal surgery using a 1.94 m superpulsed thulium fiber laser].

INTRODUCTION: surgical treatment of urinary stone disease plays an important role in urological practice. Stone fragmentation can be performed using various lithotripters, from which Holmium fiber laser (Ho: YAG) has currently taken the main place. According to the current literature, a superpulsed thulium fiber laser with a wavelength of 1.94 m and a maximum power output of 40 W showed in vitro higher efficiency compared to Ho: YAG, while having the same safety profile. The use of a thulium fiber laser with a pulse energy of 0.025-6 J and a high repetition rate (up to 1600 Hz) allows to most effectively perform stone dusting during retrograde intrarenal surgery (RIRS). AIM: to improve the performance of RIRS using the 1.94m superpulsed thulium fiber laser. MATERIALS AND METHODS: a total of 152 patients with renal stones who were treated during the period from February 2018 to July 2019 were included in the study. The analysis of the laser settings, their effect on retropulsion and visibility when performing RIRS using a superpulsed thulium fiber laser with a wavelength of 1.94 m and a maximum power output of 40 W, a peak power of 500 W, as well as an assessment of the stone-free rate the first postoperative day and 3 months after the procedure was done. RESULTS: The most frequently used settings were as following: 0.5 J, 30 Hz, 15 W (No. 1), 0.15 J, 200 Hz, 30 W (No. 2), 0.8 J, 31.25 Hz, 25 W (No. 3), 0.8 J, 37.5 Hz, 30 W (No. 4). The statistical analysis of the influence of the settings on the quality of endoscopic imaging and retropulsion was carried out. In addition, the features of each settings were analyzed. The stone-free rate on the first postoperative day was evaluated using low-dose CT. CONCLUSION: A superpulsed thulium fiber laser with a wavelength of 1.94 m and a maximum power of 500 W has shown high efficiency in clinical practice when performing RIRS, since it allows to have good endoscopic imaging, minimal retropulsion, and to perform stone dusting, which had a positive effect on the stone-free rate. Optimization of the settings of thulium fiber lithotripsy may improve the results of surgical treatment of urinary stone disease.

[Experimental verification of thulium lithotripsy].

AIM: Experimental evaluation of the efficacy and safety of lithotripsy using a new pulsed thulium fiber laser operating at a wavelength of 1.94 microns, peak power of 500 watts (maximum average power of 50 watts) by comparing it with a holmium laser operating at a wavelength of 2.1 microns (average maximum power 100 W and 120 W). RELEVANCE: The proportion of minimally invasive surgery in the management of urolithiasis, including retrograde intrarenal surgery, is steadily growing. The most appropriate tool for stone destruction is a laser. To date, the gold standard of minimally invasive surgical treatment of nephrolithiasis is holmium laser lithotripsy, which uses a laser on yttrium-aluminum-garnet activated by holmium ions (Ho: YAG) operating at a wavelength of 2.1 m. However, in recent years, lasers on a Tm-activated fiber with a wavelength of 1.94 m have become increasingly popular since the water absorption coefficient for the Tm radiation of a fiber laser is 5.5 times higher than for a Ho: YAG laser and in 2.2 times higher than for the Tm: YAG laser. This difference may translate into greater effectiveness and speed of stone crushing, which in turn leads to shorter operating time. MATERIALS AND METHODS: This article describes physical foundations of holmium and thulium laser radiation, the mechanisms of stone fragmentation, data from a series of experiments comparing the efficiency and safety of ex-vivo lithotripsy using a holmium solid-state laser with a wavelength of 2.1 m and a thulium fiber laser with a wavelength of 1.94 m. RESULTS: The study findings suggest that the STA IRE-Polyus thulium fiber laser operating at a wavelength of 1.94 microns and a maximum power of 500 watts has several advantages over the holmium laser in the stone fragmentation in urological practice. CONCLUSION: The results of the experimental work allow us to conclude that the use of a thulium fiber laser operating at a wavelength of 1.94 m and a maximum peak power of 500 W enables highly effective and safe lithotripsy.