Initial clinical experience with the pulsed solid-state thulium YAG laser from Dornier during RIRS: first 25 cases

Effect of Pulse Modulation on Diode-Pumped Laser Lithotripsy

Introduction: This study addresses pulse modulation for kidney stone lithotripsy using diode-pumped thulium yttrium aluminum garnet (Tm:YAG, λ = 2.02 µm) and thulium fiber lasers (TFLs, λ = 1.94 µm). Three research questions were investigated: (1) What are the effects of varying pulse duration and energy of the first pulse and varying the interpulse delay in a pulse modulation sequence to increase energy transfer across saline to a stone? (2) Does an optimal pulse modulation profile exist in a single-pulse sequence to provide highest percent radiant energy transfer? (3) Does a higher effective energy transfer to the stone using pulse modulation produce greater stone volumetric removal? Materials and Methods: We measured radiant energy transmission efficiency (RETE) and ablation volumes in phantom and human stones. RETE was utilized to compare the pulse energy transmission through air and saline media. We recorded fast camera traces and vapor bubble collapse pressures. Craters were created at fiber standoff distances (SDs) of 0.0 mm, 0.5 mm, and 1.0 mm, and volumes were measured using optical coherence tomography. Results: For Tm:YAG laser irradiation, dual-pulse mode significantly increased RETE by as much as 75% at 1 mm SD compared with single-pulse mode. With the Tm:YAG laser, an optimal "dual-pulse" modulation resulted in greater volumetric removal compared with a "single-pulse" across all stone cohorts (p < 0.05) except for calcium oxalate monohydrate stones (p = 0.38) at a 1 mm SD. TFL yielded similar results, but showed heterogeneity across stone compositions. Conclusions: Pulse-modulated diode-pumped Tm:YAG and TFL can deliver higher photon count through a saline layer if the first pulse is optimized. An optimal pulse modulation profile where the second pulse is synchronized with the vapor bubble dynamics of the first pulse results in the highest percent RETE and increased stone volumetric removal.

Propensity Score Matched Analysis of Thulium Fiber vs Pulsed Thulium:Yttrium Aluminum Garnet Laser Lithotripsy in Flexible Ureteroscopy for Kidney Stone Disease Using a Flexible and Navigable Suction Ureteral Access Sheath: Results From a Prospective, Multicenter Study of the EAU Section of Endourology

OBJECTIVE

To evaluate outcomes after flexible ureteroscopy (F-URS) for renal stone(s) using a flexible and navigable suction ureteral access sheath (FANS-UAS) comparing Thulium fiber (TFL) vs pulsed Thulium:Yttrium aluminum garnet (p-Thulium:YAG) laser.

METHODS

Data from adults who had F-URS in 5 centers were prospectively collected (April 2023-January 2024). All patients had a preoperative and within 30days CT scan. Stone-free: grade A: zero fragments; grade B: single fragment ≤2mm; grade C: single fragment 2.1-4mm; grade D: single/multiple fragments >4 mm. One-to-one propensity score-matching for age, gender, prestenting, stone volume, stone location, and Hounsfield units was performed. Within 6months after surgery, an intravenous urography or CT urography scan was performed in all patients.

RESULTS

Of 179 included patients, TFL was employed in 115 patients. After matching, 64 patients from each group with comparable baseline characteristics were included. Median lasing time was significantly longer in the TFL group (15.5 [10,23] minutes vs 13 [10,15] minutes, P=.02), while total surgical time did not differ. There was no case of blood transfusion and sepsis. Overall stone-free rate (SFR) was significantly different between the groups with a higher proportion of patients in p-Thu:YAG laser group undergoing reintervention for residual fragments (17.2% vs 3.1%). There was no case of new-onset hydronephrosis, ureteropelvic junction/ureteral stenosis, impaired urinary drainage, or altered pelvicalyceal anatomy at a median follow-up of 13weeks.

CONCLUSION

F-URS using FANS-UAS showed negligible serious adverse events and good SFR using both lasers. p-Thu:YAG laser showed shorter lasing time, marginal better grade A+B SFR but higher reintervention rate for residual fragments.

Endoscopic treatment of renal and ureteral stones using the new Cyber Ho generator with Magneto technology: the first clinical experience from a multicenter study

PURPOSE

A novel Ho: YAG laser generator incorporating Magneto pulse modulation technology has been developed to enhance lithotripsy performance. This study evaluates the safety and effectiveness of the Holmium: YAG Cyber Ho generator with Magneto technology (Quanta System®) for the endoscopic treatment of renal and ureteral stones.

MATERIALS AND METHODS

An observational multicentric study was conducted on 55 prospectively enrolled patients with ureteral and renal stones who underwent endoscopic lithotripsy using the new Ho: YAG laser with Magneto pulse modulation technology. Recorded parameters included stone volume, density, laser-on time (LOT), and laser settings optimized for Magneto use. Outcome metrics included ablation speed (mm³/s) and energy consumption (J/mm³), while the stone-free rate (SFR) and complication rate were also assessed. The perceived effectiveness of lithotripsy and retropulsion were evaluated using a 5-point Likert scale.

RESULTS

Included patients had a median age of 57 years (IQR 48-65). The median stone volume was 948 mm³ (IQR 107-3091), and the median stone density was 900 HU (IQR 750-1105). Stones were located in the ureter in 21 cases (38%), in the lower calyx in 13 cases (24%), and in the upper/mid calyx in 21 cases (38%). The median laser-on time was 16 min (IQR 5-17). Laser settings showed consistent performance, with a median energy of 0.8 J (IQR 0.8-0.8), a frequency of 10 Hz (IQR 10-10), and an average power of 8 W (IQR 8-10). Lithotripsy performance was reflected by a median energy consumption of 14.8 J/mm³ (IQR 11.9-24.3) and an ablation speed of 0.6 mm³/s (IQR 0.4-0.7). The stone-free rate (SFR) was 94.5%. 3.6% of patients experienced Clavien-Dindo grade 1-2 complications, and no severe complications (grade 3-4) were reported. Subjective efficacy was rated as "outstanding" and "very good" in 58.2% and 36.4% of cases, respectively, while retropulsion was subjectively evaluated as "absent" and "very low" in 91.0% and 9.0% of cases, respectively.

CONCLUSIONS

Endoscopic treatment of renal and ureteral stones using the Cyber Ho generator with the new Magneto pulse modulation technology is safe and effective in this preliminary report. High ablation efficiency and a satisfying anti-retropulsion effect have been reported, potentially leading to faster treatment, higher stone-free rates (SFR), and a lower need for second-stage procedures. Further studies are required to fully evaluate this technology.

New Techniques and Technologies in Flexible Ureteroscopy

This article provides a step-by-step guide to flexible ureteroscopy (URS), with focus on some of the newer techniques and technologies available to facilitate treatment of complex stones. In it we review indications, preoperative evaluation, surgical steps, postoperative care, troubleshooting methods, and complication management. Furthermore, we will explore advances in laser technologies, the integration of suction mechanisms, and the incorporation of intrarenal pressure measurement systems in flexible URS.

Pulsed Thulium: YAG laser for the management of Urolothiasis: a systematic review from the EAU section of endourology

INTRODUCTION

In an effort to address the limitations of current lasers, pulsed-waved Thulium: YAG laser devices were released. The purpose of this systematic review is to present all existing data, arising exclusively from human studies and clinical practice, regarding the endourological applications of the new pulsed-waved Thulium: YAG laser technology in stone disease management.

PATIENTS AND METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement, three databases (PubMed, Scopus and Cochrane) were thoroughly investigated from inception to 30 December 2024. The following search string was utilized: (pulsed OR hybrid) AND (thulium: YAG OR Tm: YAG).

RESULTS

In total eight studies satisfied all inclusion criteria and were finally included in the qualitative analysis. Six studies reported the use of the pulsed-waved Thulium: YAG laser during ureteroscopic lithotripsy (URSL) or retrograde intrarenal surgery (RIRS) and two studies reported its use during percutaneous nephrolithotomy (PCNL). In included studies, the lasing time ranged from 6.7 (2.7-13.9) to 36 (11-52) minutes. Stone-free rates (SFRs) ranged from 82 to 95%, while the Grade I-II and III-IV complications, based on the Clavien-Dindo Classification System, ranged from 3.3 to 30% and from 0 to 2%, respectively.

CONCLUSION

The purely pulsed Thulio® and hybrid RevoLix® Thulium: YAG lasers demonstrate promising safety and efficacy for RIRS and PCNL, with high peak power enabling efficient stone disintegration and effective dusting. However, the evidence is limited by small sample sizes, heterogeneity, and a lack of high-quality comparative trials. Further robust studies are needed to confirm these findings and draw reliable conclusions.

Differences in lasers and laser technologies: what does a clinician need to know?

PURPOSE OF REVIEW

This review focuses on recent advancements in laser technologies used in urology, particularly in enucleation, vaporization, lithotripsy, and focal laser ablation (FLA). The growing use of the thulium fiber laser (TFL) and the development of pulsed thulium lasers (p-Tm:YAG) highlight the relevance of this review, as these innovations aim to improve precision and outcomes in urological procedures.

RECENT FINDINGS

Recent studies have shown the advantages of TFL in achieving precise tissue ablation, reduced retropulsion offered by the Moses technology in holmium lasers, and the potential of pulsed thulium lasers for more precise control of the effects on tissues. Additionally, FLA is gaining traction for its ability to treat localized prostate cancer with minimal collateral damage. These technologies not only optimize procedural accuracy but also reduce complications, making them safer for high-risk patients, including those receiving anticoagulants.

SUMMARY

The advancements in laser technology, including TFL, Moses technology, and pulsed thulium lasers, are improving outcomes in urological surgeries by increasing precision, reducing operative time, and minimizing complications. FLA represents a promising alternative for minimally invasive cancer treatments. Ongoing research should focus on optimizing laser parameters and exploring broader clinical applications.

Rise in intraluminal temperature during ureteroscopy: Is this a concern?

The global increase in urolithiasis prevalence has led to a shift towards minimally invasive procedures, such as retrograde intrarenal surgery, supported by advancements in laser technologies for lithotripsy. Pulsed lasers, particularly the holmium YAG and the newer thulium fiber laser, have significantly transformed the management of upper urinary tract stones. However, the use of high-power lasers in these procedures introduces risks of heat-related injury. Laser lithotripsy works through photothermal and photomechanical effects to fragment stones, but up to 96% of the laser energy is converted into heat, increasing the risk of thermal damage to the surrounding urothelial mucosa. Studies show that even at low-power settings, intrarenal temperatures can exceed the threshold for cellular injury, particularly in confined spaces like the ureter. This narrative review explores strategies to mitigate thermal injury, including optimizing laser settings, improving irrigation flow rates, and incorporating novel methods such as cold irrigation, controlling outflow resistance, and using suction. Understanding these approaches is crucial to enhancing patient safety during high-power laser lithotripsy procedures.

Innovative use of the new pulsed-thulium: YAG laser for ureteroscopic lithotripsy: can the "kidney stone calculator" predict lithotripsy duration?

To assess the accuracy of Kidney Stone Calculator(KSC), a software designed for surgical planning, in predicting the duration of lithotripsy during flexible ureteroscopy(FURS) when using the novel pulsed-Thulium: YAG(p-Tm: YAG) laser. From February to August 2023, a single-center prospective study was conducted, including patients with kidney or ureteral stones through non-contrast computed tomography(NCCT), who underwent FURS with p-Tm: YAG laser lithotripsy. KSC used three-dimensional segmentation of the stones from NCCT images, along with an interactive user interface for laser settings, to estimate the stone volume(SV) and the lithotripsy duration(LD). The correlation between the estimated(esLD) and effective(efLD) lithotripsy duration was evaluated. A multiple linear regression analysis was conducted to identify preoperative and intraoperative factors affecting discrepancies between esLD and efLD. Twenty-eight patients were included with a median age of 55(48-74) years and 71% of men. Stone were located in the renal cavities(71%), ureter(21%) or both locations(8%). Median maximum stone diameter(MSD) and SV were respectively 14(11-30)mm and 1239(294, 2000)mm3. Nine patients had a SV equal to or greater than 2000mm3. EsLD and efLD did not differ(28 vs. 32 min, p = 0.8892), and were highly and positively correlated(r = + 0.90,p-value = < 0.001). Multivariate analysis indicated that the difference between estimated and effective lithotripsy were correlated with the stone volume(> 2000mm3), the use of ureteral access sheath and for struvite stones. "Kidney Stone Calculator" can accurately estimate LD during FURS with the p-Tm: YAG laser. Variables such as stone volumes over 2000mm3 and stone composition could be integrated the estimation. KSC is the only software that estimates LD with Holmium: YAG, Thulium Fiber and p-Tm: YAG lasers.

Simulation of the temperature distribution of kidney stones induced by thulium fiber laser and Ho: YAG laser lithotripsy

Simulation studies on temperature distribution in laser ablation help predict ablation rates, laser settings, and thermal damage. Despite the limited number of reported numerical studies on the temperature distribution of kidney fluid, there is no simulation study for kidney stone temperature distribution. We employ a numerical approach to study the kidney stone temperature distribution and predict ablation rates, which is an important parameter for clinical lithotripsy. The study looked at how the thulium fiber laser and the Ho:YAG laser differ in terms of temperature profile and ablation depth of kidney stones like calcium oxide monohydrate. The ablation depth increased from 152.7 µm to 489.7 µm when the TFL laser (operated at 10 Hz repetition rate and 1 ms pulse width) fluence increased from 764 J/cm2 to 1146 J/cm2. Correspondingly, the depth increased from 21 µm to 68 µm for the Ho: YAG laser operated at 3 Hz and 0.22 ms pulse width. We attribute this to an increase in temperature with laser energy. We further investigated the effect of pulse width on ablation depth by considering three different TFL pulse widths: 0.5 ms, 0.75 ms, and 1 ms. There was a decrease in ablation depths from 402.5 µm to 242.6 µm when the pulse width increased from 0.5 ms to 1 ms. Because of lower water absorption coefficients, the Ho:YAG laser (70 mJ/10 Hz) produced a smaller ablation depth and temperature profile than the thulium fiber laser (70 mJ/10 Hz). Experimental results from the literature validated the simulation. We found that the Ho:YAG laser worked better for ablation when it was set to 0.2 J/100 Hz for the Ho:YAG laser and 0.4 J/50 Hz for the TFL laser, which were clinical laser settings that we found in the literature. This indicates that, in addition to laser absorption by water, the laser parameters also significantly influence temperature distribution and ablation.

Thulium fiber laser versus pulsed Thulium:YAG for laser lithotripsy during flexible ureteroscopy

To compare the pulsed-Thulium: YAG(p-Tm: YAG) and Thulium Fiber(TFL) lasers in terms of efficiency and safety profiles during flexible ureteroscopy(fURS) and endocorporeal laser lithotripsy(ELL). A prospective single-center open-label comparative study included consecutive patients with ureteral and renal stones who underwent fURS using Thulio(p-Tm: YAG, Dornier©,Germany) or TFL Drive(TFL, Coloplast©,Danemark), with 270 μm and 150/200μm laser fibers(LF), respectively. fURS were performed by a single operator in each group. Demographics, stone size, stone density, laser-on time(LOT) and laser settings were recorded. Ablation speed(mm3/s), energy consumption(J/mm3) values for each procedure were also assessed. Stone-free rate(SFR, <3 mm fragments) and zero fragment rate(ZFR) on non-contrast computed tomography within 3 months postoperatively were also recorded. 36 and 39 patients were included in p-Tm: YAG and TFL group, respectively. Groups presented similar demographics but for high blood pressure(53vs23%,p = 0,005), anatomical abnormalities(8vs33%,p = 0,03), lower pole(8vs26%,p = 0,04) and pelvic stones(25vs13%,p = 0,04) for p-Tm: YAG and TFL, respectively. The median stone maximum diameter was higher in the p-Tm: YAG group(17.3vs13.8 mm, p = 0,001) but stone volume was similar among groups(1514vs1347mm3,p = 0,6). Laser settings were similar among groups(0,6-15 Hz,10-12 W). Shorter LOT(< 0,001) and lower UAS insertion(0,01) rates were reported for TFL compared to p-Tm: YAG. The median J/mm3 was similar(14vs17,p = 0,2) but p-Tm: YAG presented higher ablation speed(0,91vs0,73mm3/s, p = 0,04). SFR were similar among groups(75vs77%,p = 0,8) but ZFR was higher in TFL group(39vs64%,p = 0,008). No difference in complications was reported. Both p-Tm: YAG and TFL are safe and effective for ELL during fURS. SFR were similar between TFL and p-Tm: YAG but the latter presented lower ZFR, traducing its lower ability to dust. Using 200 μm laser fibers with p-Tm: YAG could nuance these findings.

In Vitro Comparison of Pulsed-Thulium:YAG, Holmium:YAG, and Thulium Fiber Laser

Objective: To characterize the pulse characteristics and risk of fiber fracture (ROF) of the pulsed-Thulium:YAG (p-Tm:YAG) laser and to compare its ablation volumes (AVs) against Holmium:Yttrium-Aluminium-Garnet (Ho:YAG) laser and Thulium fiber laser (TFL). Materials and Methods: p-Tm:YAG (100 W-Thulio, Dornier-Medtech©, Germany) was characterized using single-use 272 μm core-diameter-fibers. p-Tm:YAG characterization included pulse shape, duration, and peak power (PP) studies. ROF was assessed after 5 minutes of continuous laser activation (CLA) at five decreasing fiber bend radii (1, 0.9, 0.75, 0.6, and 0.45 cm). p-Tm:YAG, Ho:YAG (120 W-Cyber-Ho, Quanta®, USA), and TFL (60 W-TFLDrive, Coloplast®, Denmark) AVs were compared using a 20-mm linear CLA at 2 mm/second velocity in contact with 20 mm3 hard stone phantoms (HSP) and soft stone phantoms (SSP) (15:3 and 15:5 water to powder ratio, respectively) fully submerged in saline at 0.5 J-20 Hz or 1 J-10 Hz. After CLA, phantoms underwent three-dimensional (3D) micro-scanning (CT) and subsequent 3D segmentation to estimate the AVs, using 3DSlicer©. Each experiment was performed in triplicate. Results: p-Tm:YAG presents a uniform pulse profile in all of the available preset modes. PP ranged from 564 to 2199 W depending on pulse mode. No laser fiber fracture occurred at any bend radius. p-Tm:YAG achieved similar mean AVs to TFL and Ho:YAG for HSP (8.96 ± 3.1 vs 9.78 ± 1.1 vs 8.8 ± 2.8 mm3, p = 0.67) but TFL was associated with higher AVs compared with p-Tm:YAG and Ho:YAG (12.86 ± 1.85 vs 10.12 ± 1.89 vs 7.56 ± 2.21 mm3, p = 0.002) against SSP. AVs for HSP increased with pulse energy for p-Tm:YAG and Ho:YAG and (11.56 ± 1.8 vs 6.36 ± 0.84 mm3 and 11.27 ± 1.98 vs 6.34 ± 0.55 mm3, p = 0.03 and p = 0.02), whereas AVs for SSP were similar across laser settings for all laser sources. AVs with TFL were similar across laser settings for both phantom types. Conclusion: p-Tm:YAG combines intermediate PP between Ho:YAG and TFL, a uniform pulse profile, no ROF with increasing deflection and effective ablation rates. Further clinical studies are needed to confirm these in vitro results.

Assessment of Holmium:YAG, Pulsed-Thulium:YAG and Thulium Fiber Lasers for Urinary Stone Ablation. In Vitro Study

Objective: To evaluate the ablation speed (AS), laser efficiency and direct thermal lesions during urinary stone lithotripsy with the current available laser technologies: Holmium:YAG (Ho:YAG), pulsed-Thulium:YAG (p-Tm:YAG) and thulium fiber laser (TFL) in vitro using different laser settings. Materials and Methods: Ho:YAG, p-Tm:YAG, and TFL laser system were used in an in vitro ureteral model with a volume of 125 mm3 Begostone. The following parameters were tested across all laser devices: 0.6J/10 Hz (6 W), 0.6 J/20 Hz (12 W), 1.5 J/10 Hz (15 W), and 1.5 J/20 Hz (30 W), employing short pulse width for all lasers and long pulse width for Ho:YAG and p-Tm:YAG. Ten participants conducted the experimental setup during 3-minutes laser on time, combining the laser technology, settings, and pulse widths, with a total of 20 different combinations. The efficiency, AS and ureteral damage resulting from each intervention were analyzed. Results: p-Tm:YAG and TFL demonstrated significantly higher efficiency compared with Ho:YAG (0.049 ± 0.02 Δgr/KJ and 0.042 ± 0.01 Δgr/KJ vs 0.029 ± 0.01 Δgr/KJ; p < 0.05). In all laser sources, as the power increases, the AS also increases (p < 0.05). Furthermore, only at high-energy settings (1.5 J) higher frequency led to increase AS (p < 0.05). Both, p-Tm:YAG and TFL exhibited higher AS compared to Ho:YAG (0.64 ± 0.33 Δgr/s and 0.62 ± 0.31 Δgr/s vs 0.44 ± 0.22 Δgr/s; p < 0.05). Regarding ureteral injuries, as the power increases, there is a higher chance of ureteral damage (p = 0.031). No differences were observed between laser technologies (p = 0.828). Conclusions: Both, p-Tm:YAG and TFL exhibited superior performances during laser lithotripsy compared with Ho:YAG, as they demonstrated higher efficiency and ablation speed. Thermal damage did not appear to be associated with specific laser equipment, but higher grades of lesions are described by increasing power.

Flexible Ureteroscopic Lithotripsy with the Pulsed Thulium:Yttrium Aluminum Garnet Laser Thulio: Preliminary Results from a Prospective Study

Background and objective

Recently, the new pulsed thulium:yttrium aluminum garnet (p-Tm:YAG) laser technology has been introduced in endourology for lithotripsy. The aim of this study was to assess and validate the clinical laser performance and safety profile of p-Tm:YAG laser in a series of patients with renal and ureteral stones who underwent flexible ureteroscopy (fURS).

Methods

Prospective data were collected for patients who underwent fURS with the p-Tm:YAG laser Thulio (Dornier MedTech Systems GmbH, Wessling, Germany) at our institution by using two different laser fiber core diameters (270 and 200 μm). The primary endpoint of the study was stone-free rate (SFR), and the secondary endpoints were Clavien-Dindo complications grade ≥1 and the comparison between laser fibers of different diameters in all the parameters analyzed. Descriptive statistics relied on medians and interquartile ranges for continuous covariates, and on frequencies and percentages for categorical covariates. After stratification according to fiber types, differences between groups were tested with Wilcoxon and chi-square tests as appropriate. All the analyses and graphics were performed using R software (version 4.2.2).

Key findings and limitations

The SFR was 82% at 1-mo follow-up. In six out of 50 procedures (12%), Clavien-Dindo grade I-II complications were recorded. There were no differences regarding all the laser parameters considered between patients who were treated with 270 or 200 μm laser fibers (p > 0.05). Limitations of the study include small sample size in a single center and the lack of comparative groups.

Conclusions and clinical implications

In this prospective study of 50 patients who underwent fURS for ureteral and renal stones, the p-Tm:YAG laser Thulio was both effective and safe in a short-term follow-up. More prospective randomized studies in larger populations using different laser sources are required to confirm the clinical laser performance and safety of p-Tm:YAG laser for urinary stones treatment.

Patient summary

In this report, we looked at the outcomes for the pulsed thulium:yttrium aluminum garnet laser Dornier Thulio in patients who underwent flexible ureteroscopy for ureteral and renal stones. We found that this new laser technology is effective and safe, representing a good alternative to the other laser machines available for stone lithotripsy. We need more studies with larger populations to establish the superiority of this laser technology over the others.

Pulsed Thulium:YAG laser - What is the lithotripsy ablation efficiency for stone dust from human urinary stones? Results from an in vitro PEARLS study

BACKGROUND

The novel pulsed thulium:yttrium-aluminum-garnet (p-Tm:YAG) laser was recently introduced. Current studies present promising p-Tm:YAG ablation efficiency, although all are based on non-human stone models or with unknown stone composition. The present study aimed to evaluate p-Tm:YAG ablation efficiency for stone dust from human urinary stones of known compositions.

METHODS

Calcium oxalate monohydrate (COM) and uric acid (UA) stones were subjected to lithotripsy in vitro using a p-Tm:YAG laser generator (Thulio®, Dornier MedTech GmbH, Germany). 200 J was applied at 0.1 J × 100 Hz, 0.4 J × 25 Hz or 2.0 J × 5 Hz (average 10W). Ablated stone dust mass was calculated from weight difference between pre-lithotripsy stone and post-lithotripsy fragments > 250 µm. Estimated ablated volume was calculated using prior known stone densities (COM: 2.04 mg/mm3, UA: 1.55 mg/mm3).

RESULTS

Mean ablation mass efficiency was 0.04, 0.06, 0.07 mg/J (COM) and 0.04, 0.05, 0.06 mg/J (UA) for each laser setting, respectively. This translated to 0.021, 0.029, 0.034 mm3/J (COM) and 0.026, 0.030, 0.039 mm3/J (UA). Mean energy consumption was 26, 18, 17 J/mg (COM) and 32, 23, 17 J/mg (UA). This translated to 53, 37, 34 J/mm3 (COM) and 50, 36, 26 J/mm3 (UA). There were no statistically significant differences for laser settings or stone types (all p > 0.05).

CONCLUSION

To our knowledge, this is the first study showing ablation efficiency of the p-Tm:YAG laser for stone dust from human urinary stones of known compositions. The p-Tm:YAG seems to ablate COM and UA equally well, with no statistically significant differences between differing laser settings.

Thulium:YAG laser: a good compromise between holmium:YAG and thulium fiber laser for endoscopic lithotripsy? A narrative review

PURPOSE

To provide a technological description of the new pulsed solid-state Thulium:YAG laser (Tm:YAG). In addition, current available literature on Tm:YAG lithotripsy is also reviewed.

MATERIALS AND METHODS

Medline, Scopus, Embase, and Web of Science databases were used to search for Tm:YAG operating mode articles.

RESULTS

Tm:YAG technology works with a laser cavity with thulium-doped YAG crystal, pumped by laser diodes. Laser beam operates at 2013 nm, with an adjustable peak power (≥ 1000 W) and the minimal fiber laser diameter is of 200 µm. It has an intermediate water absorption coefficient and peak power-pulse duration. Various pulse modulations are proposed, aiming to minimize stone retropulsion. Multiple comparative in vitro studies suggest that Tm:YAG's ability to fragment stones is similar to the one of the Ho:YAG laser; on the contrary, its ability to dust all stone types is similar to the one of the TFL, with a low retropulsion. A single in vivo study assessed Tm:YAG lithotripsy feasibility.

CONCLUSIONS

The new pulsed solid-state thulium:YAG laser could represent a safe and effective compromise between Ho:YAG laser and TFL for endoscopic lithotripsy, either in retrograde intra-renal surgeries or in percutaneous nephrolithotomy.

Pulsed thulium:YAG laser-ready to dust all urinary stone composition types? Results from a PEARLS analysis

PURPOSE

To evaluate whether stone dust can be obtained from all prevailing stone composition types using the novel pulsed thulium:YAG (p-Tm:YAG), including analysis of stone particle size after lithotripsy.

METHODS

Human urinary stones of 7 different compositions were subjected to in vitro lithotripsy using a p-Tm:YAG laser with 270 µm silica core fibers (Thulio®, Dornier MedTech GmbH®, Wessling, Germany). A cumulative energy of 1000 J was applied to each stone using one of three laser settings: 0.1 J × 100 Hz, 0.4 J × 25 Hz and 2.0 J × 5 Hz (average power 10 W). After lithotripsy, larger remnant fragments were separated from stone dust using a previously described method depending on the floating ability of dust particles. Fragments and dust samples were then passed through laboratory sieves to evaluate stone particle count according to a semiquantitative analysis relying on a previous definition of stone dust (i.e., stone particles ≤ 250 µm).

RESULTS

The p-Tm:YAG laser was able to produce stone dust from lithotripsy up to measured smallest mesh size of 63 µm in all seven stone composition types. Notably, all dust samples from all seven stone types and with all three laser settings had high counts of particles in the size range agreeing with the definition stone dust, i.e., ≤ 250 µm.

CONCLUSION

This is the first study in the literature proving the p-Tm:YAG laser capable of dusting all prevailing human urinary stone compositions, with production of dust particles ≤ 250 µm. These findings are pivotal for the broader future implementation of the p-Tm:YAG in clinical routine.

Controversies in ureteroscopy: lasers, scopes, ureteral access sheaths, practice patterns and beyond

Ureteroscopy has become an increasingly popular surgical intervention for conditions such as urinary stone disease. As new technologies and techniques become available, debate regarding their proper use has risen. This includes the role of single use ureteroscopes, optimal laser for stone lithotripsy, basketing versus dusting, the impact of ureteral access sheath, the need for safety guidewire, fluoroscopy free URS, imaging and follow up practices are all areas which have generated a lot of debate. This review serves to evaluate each of these issues and provide a balanced conclusion to guide the clinician in their practice.