[Comparative study of the efficacy and safety of a new generation of thulium fiber lasers for ureteroscopy and lithotripsy].

INTRODUCTION

The development and implementation in clinical practice of a 3rd generation thulium fiber laser with the possibility of computer control (modulation) of the shape, amplitude and pulse repetition rate opens up new possibilities for thulium fiber laser lithotripsy.

AIM

To carry out a comparative study of the efficacy and safety of thulium fiber laser lithotripsy using a of the 2nd (FiberLase U3) and 3rd generation devices (FiberLase U-MAX).

MATERIALS AND METHODS

A total of 218 patients with solitary ureteral stones, who underwent to ureteroscopy with lithotripsy using 2nd and 3rd generation thulium fiber lasers (IRE-Polus, Russia) from January 2020 to May 2022 with the same peak power (500 W), laser settings of 1 joule, 10 Hz and with a laser fiber diameter of 365 m, were included in the prospective study. For lithotripsy using FiberLase U-MAX laser a new original modulated pulse, which was found and optimized in a preclinical study, was used. Depending on the laser, the patients were divided into 2 groups. In 111 patients, stone fragmentation was performed on FiberLase U3 (2nd generation), while 107 patients were undergone to lithotripsy on a new laser device FiberLase U-MAX (3rd generation). Stone size ranged from 6 mm to 28 mm (11+/-4 mm). The duration of procedure and lithotripsy, the quality of the endoscopic picture during fragmentation (from 0 to 3 points, 0-bad, 3-excellent), the frequency of retrograde migration of stones, as well as damage to ureteral mucosa (of 1-3 degrees) were evaluated.

RESULTS

The time of lithotripsy was significantly lower in the group 2 than in the group 1 (12.3+/-4.6 vs. 24.7+/-6.2 min; p<0.05). The average quality of the endoscopic picture was significantly better in the group 2 (2.5+/-0.4 vs. 1.8+/-0.2 points; p<0.05). Clinically significant retrograde migration of stone or its fragments (the need for additional ESWL, flexible ureteroscopy) was noted in 16% vs. 8% of patients in group 1 and 2, respectively (p<0.05). Damage to ureteral mucosa of the 1st and 2nd degree due to laser exposure in the group 1 was noted in 24 (22%) and 8 (7%) cases, compared to 21 (20%) and 7 (7%) cases in group 2, respectively. Stone-free state was 84% in group 1 and 92% in group 2.

CONCLUSION

Modulation of the laser pulse shape allowed to improve endoscopic visibility, increase the speed of lithotripsy, reduce the frequency of retrograde stone migration without increasing the trauma to ureteral mucosa.