Investig Clin Urol.  2020 Nov;61(6):594-599. 10.4111/icu.20200130.

Influence of the laser pulse shape in the treatment of stones in the upper urinary tract

• Alghamdi A
• Kretschmer A
• Stief CG
• Strittmatter F

• KMID: 2508191
• DOI: http://doi.org/10.4111/icu.20200130

Abstract

Purpose
Urinary stones can be successfully treated using a Holmium: Yttrium-Aluminum-Garnet (Ho: YAG) laser. Regarding success rates, laser pulse energy, frequency, and pulse width are well-known contributing factors. Whether the pulse shape might be a further factor influencing the laser efficiency is unclear. This study aimed to evaluate different modes of laser pulse shapes in a realworld setting.
Materials and Methods
The Dornier Medilas^® H Solvo (Weßling, Germany) was used in the treatment of ureter and kidney stones. Patients were randomized into standard pulse shape (SPS) and new pulse shape groups (NPS1; ureter) and (NPS2; kidney pelvis), depending on the stone localization. The primary endpoint was laser efficiency defined as mm³ stone destruction per overall operating time. Secondary endpoints encompassed number of stone recoveries and stone-free rate.
Results
Altogether 145 patients (24 SPS vs. 32 NPS1; 51 SPS vs. 38 NPS2) were included. No differences in sex, age, body mass index, stone localization and stone composition were found, except for preoperative stone size (133±95 [SPS] vs. 197±139 [NPS1] mm³ ; p=0.023) and (348±298 [SPS] vs. 525±429 [NPS2] mm³ ; p=0.042). Regarding the primary endpoint, a significant increase in laser efficiency could be detected for the NPS1 and NPS2 groups compared to the SPS groups (39.9±44.9 vs. 28.8±30.2 and 51.7±61.3 vs. 22.4±24.2 mm³ /min [mean±standard deviation]). No statistically significant differences were found for secondary endpoints and perioperative complication rates.
Conclusions
Efficiency of the Ho: YAG laser can be positively influenced by different pulse shapes. This adds the variable of individualized intraoperative decision making.

Keyword

Lasers; Operative; Pulse; Surgical procedures; Urinary calculi