ISSN: 2469-5742 Solakhan. Int Arch Urol Complic 2019, 5:061 DOI: 10.23937/2469-5742/1510061 Volume 5 | Issue 2 International Archives of Open Access Urology and Complications RESEARCH ARTICLE Holmium Laser Lithotripsy: In-Vitro Investigation of Optimum Power Settings in Fragmentation, Dusting and Propulsion and Stone Breaking Times Mehmet Solakhan* Department of Urology, Bahcesehir University School of Medicine, Istanbul, Turkey Check for updates *Corresponding author: Mehmet Solakhan, MD, Department of Urology, Bahcesehir University School of Medicine, Mücahitler Neigborhood, 52063 st. 27090. Şehitkamil-Gaziantep, Istanbul, Turkey, Tel: +90-532-778-50-68, Fax: +90- 342-324-88-60, Orcid id: 0000-0001-9123-9196 Abstract stone breaking settings made with different fiber diameters and stone displacement distances. The lowest fragment Background: In this study, we aimed to determine the size was at low energy low-high frequency settings (0.2 J-20 appropriate energy-frequency settings in fragmentation, Hz). As the amount of energy increased, the length of the dusting and propulsion during stone crushing with holmium- fragmented fragments of the stone increased. Additionally, YAG laser. at low energy-low or high frequency settings, the stone Materials and methods: An experimental urinary system propulsion rate was the least (P < 0.0001). model was created. Stones previously taken during the Conclusion: If we want dusting the stone, we need to use operation were used for the procedure. For this purpose, low energy high frequency settings, and if we want to break stones with Ca-oxalate and Ca-phosphate were used. up the small fragments, we need to use high energy low Kidney and ureter model was prepared under laboratory frequency settings. The operation time is prolonged when conditions. Irrigation catheter with a lumen of 15 mm low energy is used. was used for the ureter model. 9F rigid ureterorenoscope (Storz/Germany) was used to reach the stone. DORNIER Keywords MEDILAS H SOLVO/30 W-Germany laser was used for Ho:yag laser, Stone fragmentation, Dusting, Breaking time, stone crushing. 275 and 550 microfibers were used for Experimental study stone crushing as laser fiber. Eight different stone crushing settings were determined and tested (0.2 J-2 J/5-20 Hz). Abbreviations In each adjustment, stone crushing was applied until the 0.5 cm stone was completely broken. It was tested how Ho: YAG: Holmium: Yttrium - Aluminum Garnet; PE: Pulse far the stone was pushed according to the laser power Energy; HiFr: High Frequency; URS: Ureterorenoscopy applied, especially during stone crushing. For both the kidney and the ureter, the optimum power value (J/Hz) and the breaking time of the stone were tested according to the Introduction desired fragmentation model of the stone. Especially in our country (Turkey), surgical opera- Results: With or without stabilization, low energy-low or tions are done quite a lot because of the high preva- high frequency settings resulted in an increase in total lence of stone. With the advancement of technology, fragmentation and dusting time (p = 0.001). At high energy, the stone breaking time was significantly lower than the many different treatment alternatives are brought to time at low energy. Fragmentation of stone was achieved the agenda and a different endoscopic instrument is in- in less time in all frequency settings with stabilization (p troduced each year. While flexible ureteroscope is used < 0.0001). No significant difference was found in stone for kidney stones, holmium: yttrium - aluminum garnet crushing settings made with different fiber diameters (p = (Ho: YAG) laser is generally used with it [1]. The Ho: YAG 0.659). No significant difference was determined between laser is widely used for this application because of its Citation: Solakhan M (2019) Holmium Laser Lithotripsy: In-Vitro Investigation of Optimum Power Set- tings in Fragmentation, Dusting and Propulsion and Stone Breaking Times. Int Arch Urol Complic 5:061. doi.org/10.23937/2469-5742/1510061 Accepted: October 12, 2019: Published: October 14, 2019 Copyright: © 2019 Solakhan M. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Solakhan. Int Arch Urol Complic 2019, 5:061 • Page 1 of 4 • DOI: 10.23937/2469-5742/1510061 ISSN: 2469-5742 high absorption coefficient at the corresponding wave and higher frequency, stone migration is less and frag- length. In this way, it provides thermo-mechanical ab- mentation occurs as dusting [4]. lation on the stone surface and provides photo thermal The main objective of our study was to determine fragmentation with the expansion of the water in the the most effective power settings on the rate of frag- urinary stones [2]. One of the most important issues in mentation, dusting and propulsion and stone breaking the Ho: YAG-laser research is to facilitate urinary excre- times using an experimental laser system. tion of fragments and allowing the average stone frag- ment size to be reduced to increase treatment success. Method This process is called ‘stone dusting’. With the change in An experimental urinary system model was creat- laser settings (pulse energy, pulse duration, repetition ed. Stones previously taken during the operation were rate), stone fragmentation, stone crushing time and used for the procedure. For this purpose, stones with stone propulsion distance are significantly affected. Ca-oxalate and Ca-phosphate were used. Kidney and Different experimental systems have been used to com- ureter model was prepared under laboratory condi- pare different laser systems and laser parameters [3-5]. tions (Figure 1A, Figure 1B, Figure 1C and Figure 1D). Such installations are generally used to measure the Two separate experimental setups were used. In the fragmentation rate and dusting efficiency of the stone. first one, the fragmentation and dusting parameters of Migration to the kidney occurs in the stones in the ure- the stone were evaluated and in the other arrangement ter with both the introduction of the endoscope and the the propulsion distances of the stone were evaluated. effect of laser power. This leads to a longer treatment Irrigation catheter with a lumen of 15 mm was used for period in the patient. Both the fragmentation and the the ureter model. 9 F rigid ureterorenoscope (Storz/ propulsion rates of the stone are greatly influenced Germany) was used to reach the stone. DORNIER ME- by the selected laser parameters [5]. The stone breaks DILAS H SOLVO/30 W-Germany laser was used for stone down better at high energy and low frequency, but the fragmentation. 275 and 550 microfibers were used for migration is greater in this application at lower energy stone crushing as laser fiber. Eight different stone crush- A B C D Figure 1: A-D) Images of the process. Solakhan. Int Arch Urol Complic 2019, 5:061 • Page 2 of 4 • DOI: 10.23937/2469-5742/1510061 ISSN: 2469-5742 ing settings were determined and tested (0.2 J-2 J/5-20 Discussion Hz). In each adjustment, stone crushing was applied With this study, the most appropriate settings of until the 0.5 cm stone was completely broken. Saline was used for image clarity during the procedure (100 dusting, fragmentation and propulsion during stone ml/min). It was tested how far the stone was pushed crushing were determined. The optimal setting for pro- according to the laser power applied, especially during pulsion and dusting was 0.6 J 20 Hz, and for fragmen- stone crushing. For both the kidney and the ureter, the tation 2 J 10 Hz. The difference of our study from other optimum power value (J/Hz) and the fragmentation studies in the literature; the use of real kidney stones in time of the stone were tested according to the desired the process and the time taken for the stone crushing fragmentation model of the stone. process measured at exactly different settings. Results URS with holmium laser allows surgeons to use a va- riety of strategies to treat ureteral and kidney stones. With or without stabilization, low energy-low or There are two most commonly used techniques in this high frequency settings caused increase in total frag- field: first, fragmentation using low frequencies and mentation and dusting time (p = 0.001). At high ener- high pulse energy (PE) to break stones into small piec- gy, the stone breaking time was significantly lower than es, the other is dusting. This is then done using high the time at low energy (Table 1). Stone breaking was frequency (HiFr) and low PE to form fine dust particles achieved in less time in all frequency settings with sta- that pass through the ureter spontaneously [6]. To set bilization (p < 0.0001). There were no significant differ- the dusting parameters, the frequency and PE can be ences in stone breaking times in stone breaking settings changed. PE and frequency multiplication indicate total with different fiber diameters (p = 0.659). No signifi- performance in watts. Frequencies between 10 and 40 cant difference was detected between stone breaking MHz are used in conventional (low PE) dusting settings. settings made with different fiber diameters and stone Dusting with a frequency of at least 40 Hz (usually low propulsion distances (Table 1). The lowest fragment size PE around 0.2-0.5 J used) is called HiFr dusting. In frag- was at low energy high frequency settings (0.2 J-20 Hz). mentation settings higher PE around 0.6 to 2.0 J and As the amount of energy increased, the length of the lower Fr around 6 to 10 Hz is used [7]. HiFr stone crush- fragmented fragments of the stone increased. Stone ing, known as dusting has become an accepted meth- propulsion rate was found to be the least at low ener- od in the treatment of urolithiasis with flexible URS.