High power holmium:YAG versus thulium fiber laser treatment of kidney stones in dusting mode: ablation rate and fragment size studies

Ablation efficiency and laser safety of a novel superpulsed thulium fiber laser: a in vitro study

PURPOSE

To assess the ablation efficiency of the Superpulsed Thulium Fiber Laser (SP-TFL) and investigate the thermal effects of SP-TFL.

METHODS

A SP-TFLwas employed to evaluate ablation efficiency. Fresh ex-vivo pig kidneys and ureters were utilized to evaluate the renal pelvis and ureter temperature changes, different irrigation rates(0, 15, 38mL/min) and a long pulse width were used.

RESULTS

The research indicated that as laser output power increased, ablation rates significantly increased. Ablation rates(mg/min) were higher and the energy per ablated mass(J/mg) was lower at lower frequencies(10-50 Hz). Under the same frequency and single pulse energy, super short and short pulse widths demonstrated higher ablation rates at higher frequencies (exceeding 100 Hz). The temperature of the renal pelvis and ureter decreased with increasing irrigation rates. In the renal pelvis, without irrigation, the temperature quickly reached the critical threshold of 43℃. The irrigation rate was 15 ml/min and power was no more than 18 W, the renal pelvis temperature did not reach 43℃. When the irrigation rate were 38 ml/min, the temperature did not risen to 43℃. In the ureter, without irrigation, the temperature also quickly reached 43℃. The temperature reached 43℃ when the power exceeded to12W with an irrigation rate of 15 ml/min. With an irrigation rate of 38 ml/min, the temperature reached 43℃ at a laser power of 30 W.

CONCLUSIONS

The SP-TFL demonstrated promising ablation effectiveness especially for lower frequencies and super short and short pulse widths model. Proper irrigation rates, single pulse energy, frequency and pulse width are crucial during lithotripsy.

Comparing thulium fiber versus high power holmium laser in bilateral same sitting retrograde intrarenal surgery for kidney stones: Results from a multicenter study

PURPOSE

Traditionally, bilateral urolithiasis treatment involved staged interventions due to safety concerns. Recent studies have shown that same-sitting bilateral retrograde intrarenal surgery (SSB-RIRS) is effective, with acceptable complication rates. However, there's no clear data on the optimum laser for the procedure. This study aimed to assess outcomes of SSB-RIRS comparing thulium fiber laser (TFL) and high-power holmium:yttrium-aluminum-garnet (Ho:YAG) laser in a multicenter real-world practice.

MATERIALS AND METHODS

Retrospective analysis was conducted on patients undergoing SSB-RIRS from January 2015 to June 2022 across 21 centers worldwide. Three months perioperative and postoperative outcomes were recorded, focusing on complications and stone-free rates (SFR).

RESULTS

A total of 733 patients were included, with 415 in group 1 (Ho:YAG) and 318 in group 2 (TFL). Both groups have similar demographic and stone characteristics. Group 1 had more incidence of symptomatic pain or hematuria (26.5% vs. 10.4%). Operation and lasing times were comparable. The use of baskets was higher in group 1 (47.2% vs. 18.9%, p<0.001). Postoperative complications and length of hospital stay were similar. Group 2 had a higher overall SFR. Multivariate regression analysis indicated that age, presence of stone at the lower pole, and stone diameter were associated with lower odds of being stone-free bilaterally, while TFL was associated with higher odds.

CONCLUSIONS

Our study shows that urologists use both lasers equally for SSB-RIRS. Reintervention rates are low, safety profiles are comparable, and single-stage bilateral SFR may be better in certain cases. Bilateral lower pole and large-volume stones have higher chances of residual fragments.

Steady-state versus burst lasing techniques for thulium fiber laser

OBJECTIVE

To evaluate the stone ablation rate and direct thermal damage from thulium fiber laser (TFL) lithotripsy using continuous (C) and burst (B) lasing techniques on an in vitro ureteral model.

METHODS

The TFL Drive (Coloplast, Humlebaek, Denmark) was used in an in vitro saline-submerged ureteral model. Ten participants, including five junior and five experienced urologists, conducted the experimental setup with 7 different settings comparing two lasing techniques: steady-state lasing (0.5 J/10 Hz = 5W for 300 s and 0.5 J/20 Hz = 10W for 150 s) and burst, intermittent 5 s on/off lasing (0.5 J/20 Hz, 0.5 J/30 Hz, 0.5 J/60 Hz, 0.1 J/200 Hz, and 0.05 J/400 Hz) with a target cumulative energy of 1500 J using cubic 125 mm3 phantom BegoStonesTM. Ureteral damage was graded 1-3 based on the severity of burns and holes observed on the surface of the ureteral model.

RESULTS

The were no significant differences in stone ablation mass neither between C and B lasing techniques, nor between expertise levels. At C lasing technique had only mild ureteral lesions with no significant differences between expertise levels (p: 0.97) or laser settings (p: 0.71). At B lasing technique, different types of thermal lesions were found with no expertise (p: 0.11) or setting (p: 0.83) differences. However, B laser setting had higher grade direct thermal lesions than C (p: 0.048).

CONCLUSION

Regarding efficacy, C and B lasing techniques achieve comparable stone ablation rates. Safety-wise, B lasing mode showed higher grade of direct thermal lesions. These results should be further investigated to verify which of the lasing mode is the safest in vivo. Until then and unless proven otherwise, a C mode with low frequency should be recommended to avoid ureteral wall lesions.

Comparative study of thulium fiber laser versus holmium:yttrium-aluminum-garnet laser for ureteric stone management with semi-rigid ureteroscopy: A prospective, single-center study

Objective

To compare the efficacy and safety of thulium fiber laser (TFL) and holmium:yttrium-aluminum-garnet (Ho:YAG) laser for ureteric stone management with semi-rigid ureteroscopy.

Methods

In a prospective study from January 2020 to December 2021, we compared 40 patients in each group who underwent semi-rigid ureteroscopic lithotripsy with TFL and that with Ho:YAG laser. Stone volume, stone density, stone fragmentation rates, total lasing time, total operative time, endoscopic vision, retropulsion and stone free rates were analyzed in both groups and compared.

Results

Mean stone volume was comparable in the TFL group and the Ho:YAG laser group (282.45 [standard deviation, SD 139.79] mm3 vs. 279.49 [SD 312.52] mm3; p=0.964). Mean stone density was also comparable in the TFL group and the Ho:YAG laser group (1135.30 [SD 317.04] Hounsfield unit vs. 1131.75 [SD 283.03] Hounsfield unit; p=0.959). The mean stone fragmentation rates calculated as stone volume divided by lasing time were 25.85 (SD 10.61) mm3/min and 21.37 (SD 14.13) mm3/min in the TFL group and the Ho:YAG laser group, respectively (p=0.113). The mean total lasing time (10.15 [SD] 4.69 min vs. 11.43 [SD 4.56] min; p=0.222), mean operative time (25.13 [SD 9.51] min vs. 25.54 [SD 10.32] min; p=0.866), and mean total hospital stay (2.62 [SD 0.77] days vs. 2.61 [SD 0.84] days; p=0.893) were comparable in the TFL group and in the Ho:YAG group. The vision was better and retropulsion was less in the TFL group. The stone-free rate at 1 month postoperatively was slightly better in the TFL group (100% vs. 90%; p=0.095).

Conclusion

TFL technology was associated with the comparable total surgical time, total lasing time, and stone fragmentation rate with Ho:YAG laser. However, TFL had better endoscopic vision, lesser stone retropulsion, and slightly better stone-free rates.

What is the definition of stone dust and how does it compare with clinically insignificant residual fragments? A comprehensive review

PURPOSE

During endoscopic stone surgery, Holmium:YAG (Ho:YAG) and Thulium Fiber Laser (TFL) technologies allow to pulverize urinary stones into fine particles, ie DUST. Yet, currently there is no consensus on the exact definition of DUST. This review aimed to define stone DUST and Clinically Insignificant Residual Fragments (CIRF).

METHODS

Embase, MEDLINE (PubMed) and Cochrane databases were searched for both in vitro and in vivo articles relating to DUST and CIRF definitions, in November 2023, using keyword combinations: "dust", "stones", "urinary calculi", "urolithiasis", "residual fragments", "dusting", "fragments", "lasers" and "clinical insignificant residual fragments".

RESULTS

DUST relates to the fine pulverization of urinary stones, defined in vitro as particles spontaneously floating with a sedimentation duration ≥ 2 sec and suited for aspiration through a 3.6Fr-working channel (WC) of a flexible ureteroscope (FURS). Generally, an upper size limit of 250 µm seems to agree with the definition of DUST. Ho:YAG with and without "Moses Technology", TFL and the recent pulsed-Thulium:YAG (pTm:YAG) can produce DUST, but no perioperative technology can currently measure DUST size. The TFL and pTm:YAG achieve better dusting compared to Ho:YAG. CIRF relates to residual fragments (RF) that are not associated with imminent stone-related events: loin pain, acute renal colic, medical or interventional retreatment. CIRF size definition has decreased from older studies based on Shock Wave Lithotripsy (SWL) (≤ 4 mm) to more recent studies based on FURS (≤ 2 mm) and Percutaneous Nephrolithotomy(PCNL) (≤ 4 mm). RF ≤ 2 mm are associated with lower stone recurrence, regrowth and clinical events rates. While CIRF should be evaluated postoperatively using Non-Contrast Computed Tomography(NCCT), there is no consensus on the best diagnostic modality to assess the presence and quantity of DUST.

CONCLUSION

DUST and CIRF refer to independent entities. DUST is defined in vitro by a stone particle size criteria of 250 µm, translating clinically as particles able to be fully aspirated through a 3.6Fr-WC without blockage. CIRF relates to ≤ 2 RF on postoperative NCCT.

Analyzing global research trends and focal points in the utilization of laser techniques for the treatment of urolithiasis from 1978 to 2022: visualization and bibliometric analysis

Laser lithotripsy is gaining global prominence and is a dynamically progressing field marked by a continual influx of new and comprehensive research each year. Recently, there has been a noticeable shift toward the adoption of various kinds of lasers, such as holmium: yttrium-aluminum-garnet (Ho:YAG) and thulium fiber (TFL) lasers. Consequently, we aim to conduct a bibliometric analysis to analyze key areas of research activity within scientific publications that center on the utilization of laser techniques in urolithiasis. A search of the literature spanning from 1978 to 2022 was carried out on 25 December 2023 using the Scopus database to explore research related to the application of laser techniques for urolithiasis treatment. Visualization analysis was performed using VOSviewer software (version 1.6.20). We examined 962 publications that met the specified criteria, 791 (82.22%) of which were original articles. The analysis of the retrieved publications indicated a consistent increase in research output from 1978 to 2022; a particularly noteworthy surge occurred after 2003. In particular, the U.S. claimed the leading position as the most productive country, contributing 211 articles (21.93%). However, India had the highest research productivity according to the adjustment index of 19.08. In the European region, 324 publications (33.68% of the total) originated from 25 countries. The Journal of Endourology contributed the most between 1978 and 2022 (n = 96, 9.98%). The most cited paper examined the effectiveness of holmium: yttrium-aluminum-garnet (Ho:YAG) lasers, while a subsequent study focused on the use of a thulium fiber laser (TFL), an emerging laser technology that has gained increased recognition. Co-occurrence analysis revealed three distinct clusters focusing on the types of laser technology, minimally invasive approaches, and success rate/postoperative complications. This comprehensive investigation delves into the global landscape of laser use for the treatment of urolithiasis. This review supports the emerging clinical concept of using various types of laser technology for urolithiasis treatment. Moreover, the hot issues that researchers should focus on based on the findings of this study are the use of different types of laser lithotripsy in view of the surgical approach, success rate and complications.

Comparison of Thulium Fiber Laser versus Holmium laser in ureteroscopic lithotripsy: a Meta-analysis and systematic review

OBJECTIVES

To compare the efficacy and safety of thulium fiber laser (TFL) to holmium: YAG (Ho: YAG) laser in ureteroscopic lithotripsy for urolithiasis.

METHODS

PubMed, Web of Science, Embase, CENTRAL, SinoMed, CNKI database, VIP and Wanfang Database were systematically searched for all relevant clinical trials until September 2023. References were explored to identify the relevant articles. Meta-analysis was carried out for the retrieved studies using RevMan5.4.1 software, and the risk ratio, mean difference and 95% confidence interval were expressed. Statistical significance was set at p < 0.05. The main outcomes of this meta-analysis were stone-free rate (SFR), perioperative outcomes and intraoperative or postoperative complications.

RESULTS

Thirteen studies, including 1394 patients, were included. According to the results of pooled analysis, TFL was associated with significantly higher stone-free rate (SFR) [0.52, 95% CI (0.32, 0.85), P = 0.009], shorter operation time [-5.47, 95% CI (-8.86, -2.08), P = 0.002], and less stone migration [0.17, 95% CI (0.06, 0.50), P = 0.001]. However, there was no significant difference in terms of the laser time, duration of hospital stay, drop of hemoglobin level, total energy, postoperative ureteral stenting, the incidence of intraoperative complications or postoperative complications between TFL and Ho: YAGs.

CONCLUSION

The findings of this study demonstrated several advantages of TFL in terms of higher SFR, shorter operative time and less stone migration.

TRIAL REGISTRATION

The protocol of this systematic review was listed in PROSPERO ( www.crd.york.ac.uk/PROSPERO ) (Protocol number: CRD42022362550).

Outcomes of ureteroscopy and laser fragmentation using a 60 W MOSES laser: a 3-year prospective study from a University Teaching Hospital

Introduction

Modulated optics enhancement system (MOSES) holmium lasers use "pulse modulation" to increase the efficacy of laser lithotripsy. As the clinical evidence on the efficacy of 60 W holmium laser with MOSES technology is scarce, we analyzed the outcomes of patients treated with this laser at our institution.

Methods

A total of 96 consecutive patients with urinary stones (72 renal stones and 24 ureteral stones) were treated with the 60 W MOSES laser from 2019 until 2022 and were included in our analysis. Patient data and outcomes were prospectively collected, and analysis was performed regarding patient demographics, stone parameters, as well as stone-free rate, operating time, length of stay, and perioperative and postoperative complications.

Results

With a median age of 55 (IQR: 35-69.25) years, the male:female ratio was 53:43. The median stone size was 12 mm (IQR: 7-19), with a mean number of urinary stones of 1.82 (SD ± 1.4). While 36 (35%) patients were pre-stented, a ureteral access sheath was inserted in 36 (37.5%) patients. The median operative time was 44 min (IQR: 22.5-59.5), and 63 (65.5%) patients received postoperative stenting. Perioperative complications (all Clavien ⩽ II complications) were observed in 5 (5.2%) patients (four urinary tract infections and one acute urinary retention), and after the first procedure, 90 (93.8%) patients were stone-free. The median length of hospital stay was 1 day (IQR: 1-1).

Conclusion

This study demonstrated that the 60 W MOSES laser was safe and efficient for the treatment of urinary stones with high stone-free rates and a small risk of minor complications. More studies with larger cohorts are necessary in the future to confirm our results.

Use of artificial stones in training and laboratory studies, have we found the right material? Outcomes of a systematic review from the European School of Urology

Objective

In this review, we investigated the current literature to find out which artificial stones (AS) are available in endourology, and in which experimental and training schemes they are used.

Materials and Methods

A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Twenty-one out of 346 studies met our inclusion criteria and are presented in the current review. The inclusion criteria were the existence of AS and their use for laboratory and training studies.

Results

There is a wide variety of materials used for the creation of AS. BegoStone powder (BEGO USA, Lincoln, Rhode Island) and plaster of Paris™ were used in most of the studies. In addition, Ultracal-30 (U. S. Gypsum, Chicago, IL) was also used. Other materials that were used as phantoms were AS created from plaster (Limbs and Things, UK), standardized artificial polygonal stone material (Chaton 1028, PP13, Jet 280; Swarovski), model stones consisting of spheres of activated aluminum (BASF SE, Ludwigshafen am Rhein, Deutschland), Orthoprint (Zhermack, Badia Polesine, Italy), and a combination of plaster of Paris, Portland cement, and Velmix (calcium sulfate powder). Many experimental settings have been conducted with the use of AS. Our research demonstrated nine studies regarding testing and comparison of holmium: yttrium-aluminum-garnet laser devices, techniques, and settings. Six studies were about extracorporeal shock wave lithotripsy testing and settings. Three experiments looked into treatment with percutaneous nephrolithotomy. Additionally, one study each investigated imaging perioperatively for endourological interventions, stone bacterial burden, and obstructive uropathy.

Conclusion

AS have been used in a plethora of laboratory experimental studies. Independent of their similarity to real urinary tract stones, they present a tremendous potential for testing and training for endourological interventions.

The Saudi urological association guidelines on urolithiasis

Aims

The Saudi Urolithiasis Guidelines are a set of recommendations for diagnosing, evaluating, and treating urolithiasis in the Saudi population. These guidelines are based on the latest evidence and expert consensus to improve patient outcomes and optimize care delivery. They cover the various aspects of urolithiasis, including risk factors, diagnosis, medical and surgical treatments, and prevention strategies. By following these guidelines, health-care professionals can improve care quality for individuals with urolithiasis in Saudi Arabia.

Panel

The Saudi Urolithiasis Guidelines Panel consists of urologists specialized in endourology with expertise in urolithiasis and consultation with a guideline methodologist. All panelists involved in this document have submitted statements disclosing any potential conflicts of interest.

Methods

The Saudi Guidelines on Urolithiasis were developed by relying primarily on established international guidelines to adopt or adapt the most appropriate guidance for the Saudi context. When necessary, the panel modified the phrasing of recommendations from different sources to ensure consistency within the document. To address areas less well covered in existing guidelines, the panel conducted a directed literature search for high quality evidence published in English, including meta analyses, randomized controlled trials, and prospective nonrandomized comparative studies. The panel also searched for locally relevant studies containing information unique to the Saudi Arabian population. The recommendations are formulated with a direction and strength of recommendation based on GRADE terminology and interpretation while relying on existing summaries of evidence from the existing guidelines.

Shock waves generated by toroidal bubble collapse are imperative for kidney stone dusting during Holmium:YAG laser lithotripsy

Holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy (LL) has been the treatment of choice for kidney stone disease for more than two decades, yet the mechanisms of action are not completely clear. Besides photothermal ablation, recent evidence suggests that cavitation bubble collapse is pivotal in kidney stone dusting when the Ho:YAG laser operates at low pulse energy (Ep) and high frequency (F). In this work, we perform a comprehensive series of experiments and model-based simulations to dissect the complex physical processes in LL. Under clinically relevant dusting settings (Ep = 0.2 J, F = 20 Hz), our results suggest that majority of the irradiated laser energy (>90 %) is dissipated by heat generation in the fluid surrounding the fiber tip and the irradiated stone surface, while only about 1 % may be consumed for photothermal ablation, and less than 0.7 % is converted into the potential energy at the maximum bubble expansion. We reveal that photothermal ablation is confined locally to the laser irradiation spot, whereas cavitation erosion is most pronounced at a fiber tip-stone surface distance about 0.5 mm where multi foci ring-like damage outside the thermal ablation zone is observed. The cavitation erosion is caused by the progressively intensified collapse of jet-induced toroidal bubble near the stone surface (<100 μm), as a result of Raleigh-Taylor and Richtmyer-Meshkov instabilities. The ensuing shock wave-stone interaction and resultant leaky Rayleigh waves on the stone surface may lead to dynamic fatigue and superficial material removal under repeated bombardments of toroidal bubble collapses during dusting procedures in LL.

Super pulsed thulium fiber laser outcomes in retrograde intrarenal surgery for ureteral and renal stones: a systematic review and meta-analysis

BACKGROUND

Laser lithotripsy using a thulium fiber laser (TFL) has become an effective treatment option for small renal stones with low complication rates. TFL has a higher absorption coefficient, smaller fibers, and better pulse rate capability.

METHODS

We conducted a systematic review and meta-analysis to evaluate the published evidence regarding TFL's lithotripsy performance in retrograde intrarenal surgery (RIRS), for which we primarily assessed the outcomes of stone-free rate, operation time, and complications. We searched different databases from inception to April 2023. We assessed the methodological quality and risk of bias using the Cochrane Risk of Bias tool for randomized trials and the ROBINS-I tool for non-randomized studies. We used a random-effects model for meta-analysis and assessed heterogeneity using the I2 statistic.

RESULTS

Twelve published studies evaluated the efficacy of RIRS using a TFL for treating renal and ureteral stones. The meta-analysis revealed a predicted stone-free rate of 89.37% (95% CI: 83.93% to 93.12%), indicating that, on average, approximately 89.37% of patients achieved a stone-free state after treatment. The substantial heterogeneity among the studies was evident, as shown by a Q-value of 33.1174 and a p-value of 0.0003. The I2 value of 69.80% (95% CI: 25.91% to 92.02%) highlighted the proportion of variability attributed to genuine heterogeneity across the studies. Moreover, the H2 value 3.31 (95% CI: 1.35 to 12.53) indicated significant heterogeneity beyond random chance. The estimated overall effect size (logit-transformed) of 2.1289 was highly statistically significant (z = 8.7648, p < 0.0001) with a confidence interval of 1.6528 to 2.6049. The reported complications varied across studies, encompassing Clavien grade I-II complications in most cases, with a subset experiencing more severe Clavien grade III-V complications. Additionally, other studies noted a range of complications, such as haematuria, fever, transient creatinine elevation, and postoperative issues like bleeding, pain, and sepsis.

CONCLUSION

This meta-analysis suggests that RIRS using TFL is an effective and safe treatment option for renal and ureteral stones, with high stone-free and low complication rates. The included studies exhibited a low risk of bias and were of high quality. However, more extensive randomized controlled trials with extended follow-up periods are needed to investigate this technique's efficacy and safety.

In vitro investigation of stone ablation efficiency, char formation, spark generation, and damage mechanism produced by thulium fiber laser

To investigate stone ablation characteristics of thulium fiber laser (TFL), BegoStone phantoms were spot-treated in water at various fiber tip-to-stone standoff distances (SDs, 0.5 ~ 2 mm) over a broad range of pulse energy (Ep, 0.2 ~ 2 J), frequency (F, 5 ~ 150 Hz), and power (P, 10 ~ 30 W) settings. In general, the ablation speed (mm3/s) in BegoStone decreased with SD and increased with Ep, reaching a peak around 0.8 ~ 1.0 J. Additional experiments with calcium phosphate (CaP), uric acid (UA), and calcium oxalate monohydrate (COM) stones were conducted under two distinctly different settings: 0.2 J/100 Hz and 0.8 J/12 Hz. The concomitant bubble dynamics, spark generation and pressure transients were analyzed. Higher ablation speeds were consistently produced at 0.8 J/12 Hz than at 0.2 J/100 Hz, with CaP stones most difficult yet COM and UA stones easier to ablate. Charring was mostly observed in CaP stones at 0.2 J/100 Hz, accompanied by strong spark-generation, explosive combustion, and diminished pressure transients, but not at 0.8 J/12 Hz. By treating stones in parallel fiber orientation and leveraging the proximity effect of a ureteroscope, the contribution of bubble collapse to stone ablation was found to be substantial (16% ~ 59%) at 0.8 J/12 Hz, but not at 0.2 J/100 Hz. Overall, TFL ablation efficiency is significantly better at high Ep/low F setting, attributable to increased cavitation damage with less char formation.

2022 Recommendations of the AFU Lithiasis Committee: Laser - utilization and settings

Endocorporeal lithotripsy has progressed thanks to the development of lasers. Two laser sources are currently available: Holmium:YAG (Ho:YAG) and more recently Thulium Fiber Laser (TFL). The settings generally used are dusting, fragmentation, and "pop-corning". These are the first recommendations on laser use for stone management and their settings. Settings must be modulated and can be changed during the treatment according to the expected and obtained effects, the location and stone type that is treated. METHODOLOGY: These recommendations have been developed using two methods: the Clinical Practice Recommendation (CPR) method and the ADAPTE method, depending on whether or not the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis [EAU Guidelines on urolithiasis. 2022]) and their adaptability to the French context.

Photonic Lithotripsy: Near-Infrared Laser Activated Nanomaterials for Kidney Stone Comminution

Near-infrared activated nanomaterials have been reported for biomedical applications ranging from photothermal tumor destruction to biofilm eradication and energy-gated drug delivery. However, the focus so far has been on soft tissues, and little is known about energy delivery to hard tissues, which have thousand-fold higher mechanical strength. We present photonic lithotripsy with carbon and gold nanomaterials for fragmenting human kidney stones. The efficacy of stone comminution is dependent on the size and photonic properties of the nanomaterials. Surface restructuring and decomposition of calcium oxalate to calcium carbonate support the contribution of photothermal energy to stone failure. Photonic lithotripsy has several advantages over current laser lithotripsy, including low operating power, noncontact laser operation (distances of at least 10 mm), and ability to break all common stones. Our observations can inspire the development of rapid, minimally invasive techniques for kidney stone treatment and extrapolate to other hard tissues such as enamel and bone.

Ablation rates with Holmium:YAG and Thulium Fiber Laser: Influence of the stone phantom homogeneity. An in vitro study

OBJECTIVES

The lithotripsy efficiency (LE) in vitro study requires artificial or human stone samples (AS, HS). With the development of dusting lithotripsy, less ex vivo HS are available. We aimed to compare Thulium Fiber Laser (TFL) and Holmium:YAG (Ho:YAG)'s LE and define the most accurate LE parameter.

METHODS

Hard and soft homogenous- and heterogenous-AS (Ho-AS, He-AS) were made to reproduce calcium-oxalate monohydrate and uric acid stones, respectively by a rapid or slow brewing of BegostonePlus (Bego) and distilled water. One hundred and fifty and 272μm-laser fibers, connected to 50W-TFL and 30W-HoYAG generators, compared three settings for TFL (FD: 0.15J/100Hz; D: 0.5J/30Hz; Fr: 1J/15Hz) and two for Ho:YAG (D-Fr). An experimental setup consisted in immerged 10mm cubic stone phantoms with a 20 seconds' lasing spiral, in contact mode, repeated four times. Stones were dried, weighted and μ-scanned (ablation weight and volume [AW and AV]).

RESULTS

With He-AS, dusting AV were four- and three-fold higher with TFL compared to Ho:YAG against hard and soft (P<0.05). In fragmentation, AV were two-fold higher with TFL compared to Ho:YAG against hard (P<0.05) and soft (P<0.05). Experiments with Ho-AS were associated with non-significant differences when comparing TFL-150μm and TFL-272μm. The ablation weight-volume correlation coefficients was higher with Ho-AS than with He-AS (P<0.0001), and with hard than soft AS. If the LE can be estimated by the AW with hard AS, this approximation is not consistent for soft AS.

CONCLUSION

TFL presented higher ablation rates than Ho:YAG, significant with He-AS. If the AW is acceptable and less expensive for hard Ho-AS, AV are more accurate for He-AS, which are suggested to imitate closely HS.

Ureteroscopic lithotripsy by thulium fiber laser versus holmium laser: A single-center prospective randomized study

Objective

Laser lithotripsy has been the standard of care for lower and mid-ureteric calculi. Thulium fiber laser (TFL) is a new introduction to this field, which has been extensively studied for retrograde intrarenal surgery. We have done a prospective randomized study of ureteroscopic lithotripsy between TFL and holmium: Yttrium-aluminum-garnet (HO: YAG) laser to know the efficacy of stone fragmentation, stone-free rate, and complications.

Methodology

A prospective randomized study was done in our hospital from March 2021 to May 2022 on patients planned for ureteroscopic laser lithotripsy. Patients with distal and mid-ureteral stones from 4 mm to 15 mm were included. The laser was used to fragment the stone. All the stones were fragmented from the center to periphery. The setting used was up to 10 W (6-10 Hz, 1J) for TFL and up to 10 W for HO: YAG (5-10 Hz, 0.5-1J). Once the stones were fragmented, they were retrieved until complete visual clearance. Demographic data and stone parameters such as stone size, volume, density, laterality, laser usage time, total operative time, and total energy used were recorded. Operative time, lasering time, retropulsion rate, ablation speed, and visibility score were recorded.

Results

Each group had 90 randomized patients. Both the groups had similar kinds of patient and stone profiles. The mean operating time was 18.5 ± 1.5 min (95% confidence interval [CI] 16.2-25.6) in the TFL group, which was shorter than the holmium group 31.6 ± 1.2 min (95% CI 18.4-38.5), and it was statistically significant (P = 0.024,). Lasering time was also statistically significant with less lasering time with TFL group 7.4 ± 1.8 min (95% CI 5.2-10.3) versus holmium group 14.8 ± 1.5 min (95% CI 12.3-18.4) (P = 0.011). Laser efficacy and ablation speed were better in the TFL group compared to the HO: YAG group and were statistically significant. The visual score was better in HO: YAG group compared to the TFL group.

Conclusion

TFL is more efficacious and faster than Holmium: Yag laser. Complications were similar between the groups. Stone-free rate was also similar between both the groups.

Comparing dusting and fragmenting efficiency using the new SuperPulsed thulium fiber laser versus a 120 W Holmium:YAG laser

PURPOSE

Holmium:YAG laser lithotripsy requires high amperage power and has an upper limit of frequency and a minimal fiber size. The technology utilizing thulium-doped fiber offers low pulse energy settings and high pulse frequencies up to 2,400 Hz. We compared the novel SuperPulsed thulium fiber laser (SOLTIVE™; Olympus) to a commercially available 120 W Ho:YAG laser.

MATERIALS AND METHODS

Bench-top testing was conducted with 125 mm³ standardized BegoStones (Bego USA). Time to ablate the stone into particles <1 mm was recorded for efficiency calculations. Finite energy was delivered, and resulting particle sizes were measured to determine fragmentation (0.5 kJ) and dusting (2 kJ) efficiencies. Remaining mass or number of fragments were measured to compare efficacy.

RESULTS

SOLTIVE™ was faster at ablating stones to particles <1 mm (2.23±0.22 mg/s, 0.6 J 30 Hz short pulse) compared to Ho:YAG laser (1.78±0.44 mg/s, 0.8 J 10 Hz short pulse) (p<0.001). Following 0.5 kJ of energy in fragmentation testing, fewer particles >2 mm remained using SOLTIVE™ than Ho:YAG laser (2.10 vs. 7.20 fragments). After delivering 2 kJ, dusting (1.05±0.08 mg/s) was faster using SOLTIVE™ (0.1 J 200 Hz short pulse) than 120 W 0.46±0.09 mg/s (0.3 J 70 Hz Moses) (p=0.005). SOLTIVE™ (0.1 J 200 Hz) produced more dust particles <0.5 mm (40%) compared to 24% produced by the P120 W laser at 0.3 J 70 Hz Moses and 14% at 0.3 J 70 Hz long pulse (p=0.015).

CONCLUSIONS

The efficacy of SOLTIVE™ is superior to the 120 W Ho:YAG laser by producing smaller dust particles and fewer fragments. Further studies are warranted.

Thulium fibre laser vs holmium: yttrium-aluminium-garnet laser lithotripsy for urolithiasis: meta-analysis of clinical studies

OBJECTIVE

To compare and assess the clinical outcomes between thulium fibre laser (TFL) and holmium: yttrium-aluminium-garnet (Ho:YAG) laser endoscopic lithotripsy of urolithiasis through a meta-analysis of comparative clinical studies.

METHODS

A systematic literature search was performed in May 2022, grey literature search in July 2022. Comparative clinical studies were evaluated according to Cochrane recommendations. Assessed outcomes include the stone-free rate (SFR), complication rate, operative time (OT), laser utilisation time (LUT), ablation rate (stone volume/laser time), ablation efficiency (energy use/stone volume), total energy usage, degree of retropulsion, and hospital stay. Risk ratios (RRs) and standardised mean differences (SMDs) were extrapolated. Subgroup analyses, heterogeneity, publication bias, and Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) assessment were performed. International Prospective Register of Systematic Reviews (PROSPERO) registration: CRD42022300788.

RESULTS

A total of 15 studies with 1698 cases were included in this review. The outcome of SFR showed no significant between-group difference (RR 1.09, 95% confidence interval [CI] 0.99-1.20). However, subgroup analysis of TFL vs Ho:YAG with no pulse modulation showed a SFR favouring TFL (RR 1.11, 95% CI 1.01-1.23). The composite postoperative complication rate was comparable between the two intervention groups (RR 0.97, 95% CI 0.66-1.43). OT, LUT and ablation rate were significantly better for TFL than Ho:YAG (SMD -1.19, 95% CI -1.85 to -0.52; SMD -1.67, 95% CI -2.62 to -0.72; SMD 0.59, 95% CI 0.15-1.03; respectively). The degree of retropulsion was significantly lower for TFL than Ho:YAG without pulse modulation (SMD -1.23, 95% CI -1.74 to -0.71). Ablation efficiency, total energy usage, and hospital stay were all comparable. Based on GRADE criteria, the evidence certainty was determined to be very low.

CONCLUSION

Overall, there was no between-group difference for the SFR. However, compared to Ho:YAG with no pulse modulation, TFL rendered a better SFR. Shorter OT and LUT, a lesser degree of retropulsion, and a better ablation rate were noted in favour of the TFL. There was no overall between-group difference for composite postoperative complication rate, ablation efficiency, total energy usage, and hospital stay. Currently, the available clinical evidence was assessed to be of very low certainty.

Thulium fiber laser in endourology: current clinical evidence

PURPOSE OF REVIEW

To review and summarize preclinical and clinical data on thulium fiber laser's (TFL) effectiveness (ablation rate, stone-free rate etc.) and safety in terms of laser injuries and thermal damage. This enables us to assess how the in-vitro evidence translates into the clinical real-life scenario.

RECENT FINDINGS

In this analysis, a total of 21 preclinical trials have been included. Most of the trials use conventional Holmium:YAG laser as a comparator, with only a few assessing lasers with pulse modulation. Most of the trials focus on the superior ablation rate and superior dusting features of TFL, as well as comparison of retropulsion (both in conventional Ho:YAG and in a pulse modulation), with a few studies assessing safety aspects. A total of 13 trials assessed TFL, clinically, in percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS). The clinical data obtained suggest that lithotripsy by TFL is safe, facilitates effective stone fragmentation, and results in a reduction of retropulsion. Unfortunately, most of the clinical trials lack a direct comparator, and so no clear-cut comparisons are possible.

SUMMARY

During in-vitro studies, TFL demonstrated to be a new energy source with a great potential for improved ablation, lower retropulsion and improved dusting. These claims are supported in contemporary clinical studies, reporting superior ablation and negligible retropulsion in both PCNL and RIRS. However, it should be noted that the data regarding clinical results compared with conventional Ho:YAG is still limited.

Understanding the ablation rate of Holmium:YAG and thulium fiber lasers. Perspectives from an in vitro study

This study sought to analyze the ablation rates of Holmium:YAG (Ho:YAG) and thulium fiber laser (TFL) under different settings combinations. Lasering was carried out by a computed spiral pattern through a stepper motor bearing a laser fiber. BegoStones were placed inside a water container and lasered therein and the ablation rate was calculated. Different combinations were tested for ~12 Watts (W) for Ho:YAG and TFL lasers. Further 25 W combination for TFL were conducted testing higher frequencies. One-hundred-one experiments were conducted. Under ~12 W, the highest ablation rate for Ho:YAG was obtained with 40 Hz/0.3 J, and Virtual Basket™ (VB) emission mode [114.35 (88.30 - 126.40) mg/min] whereas for TFL, using 40 Hz/0.3 J, and long pulse [143.40 (137.40 - 146) mg/min]. A matched-comparison for 12 Hz/1 J settings showed that TFL outperformed Ho:YAG using medium pulse [63.30 (55.30 - 81.30) vs 132.00 (115.70 - 228.60) mg/min, p=0.016] and long pulse [62.90 (51.60 - 78.90) vs 134.70 (110.60 - 149.30) mg/min, p=0.016]. In the 40 Hz/0.3 J settings, TFL outperformed Ho:YAG (p=0.034). Nonetheless, Ho:YAG with VB's ablation rate increased [114.35 (88.30 - 126.40)], being comparable to that of TFL with medium pulse [127.5 (88.90 - 141.70)] (p=0.400). In TFL 25 W experiments, the ablation rate of 500 Hz / 0.05 J, was higher than those of 1000 Hz / 0.025 J (p=0.049). TFL ablation rate is higher than that of Ho:YAG. Moreover, the Virtual Basket™ emission mode, increased Ho:YAG ablation rates, resulting reaching similar to that of TFL in certain modalities.

Thulium fiber laser lithotripsy: Is it living up to the Hype?

Objective

The holmium:yttrium-aluminium-garnet laser (Ho:YAG) has been the gold standard for laser lithotripsy over the last three decades. After demonstrating good in vitro efficacy, the thulium fiber laser (TFL) has been recently released in the market and the initial clinical results are encouraging. This article aims to review the main technology differences between the Ho:YAG laser and the TFL, discuss the initial clinical results with the TFL as well as the optimal settings for TFL lithotripsy.

Methods

We reviewed the literature focusing on the technological aspects of the Ho:YAG laser and TFL as well as the results of in vitro and in vivo studies comparing both technologies.

Results

In vitro studies show a technical superiority of TFL compared to the Ho:YAG laser and encouraging results have been demonstrated in clinical practice. However, as TFL is a new technology, limited studies are currently available, and the optimal settings for lithotripsy are not yet established.

Conclusion

TFL has the potential to be an alternative to the Ho:YAG laser, but more reports are still needed to determine the optimal laser for lithotripsy of urinary tract stones when considering all parameters including effectiveness, safety, and costs.

Thulium fiber laser's dust for stone composition analysis: Is it enough?

Introduction: We aimed to evaluate if the biochemical composition of urinary stones can be determined by analyzing the stone dust only, and whether a photo taken during the surgery could be useful for completing the morpho-constitutional analysis. Materials and methods: 20 patients went through a retrograde intrarenal surgery (RIRS) for renal stone treatment with TFL (Fiber Dust, Quanta, 2020) using 150 µm silica core laser fibers. After laser lithotripsy, residual fragments (RF) were removed with a basket (ZeroTip, Boston Scientific) and spontaneously floating stones particles were considered stone dust and were aspirated through the working channel. Pairs of RF and stone dust were labelled and sent to analysis by scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR). Photos of the stone (surface and section) were taken from videos recorded during the surgery. Results: A total of 20 patients were included in the study. Mean age was 49,8 years old with metabolic and genetic disorders. Mean stone volume was 750 mm3 for ureteral stones and 2334 mm3 for renal stones. Mean stone density was 1187 HU. Positive urine culture was found in 25% patients. In 2/20 (10%) the biochemistry differed only in the relative proportions of each constituent, whilst 5/20 (25%) only one component was missing. Laser crystalline conversion was found in 3/20 (15%). Whewellite and weddellite layers were found in photos thus adding missing information from dust stone analysis. Conclusion: Analyzing aspirated dust through the ureteroscope's working channel by physical techniques, we can understand the lithogenic process of the urinary stone, without needing to analyze the stone fragment. Morphological analysis, given by a proper stone picture, adds missing information in specific cases.

Lithotripsy devices for percutaneous nephrolithotomy (PNL) - new developments

PURPOSE OF REVIEW

Percutaneous nephrolithotomy (PNL) is the mainstay of surgery for renal calculi>2 cm or complex multiple calculi and is a technique that has been around since 1976. We review recent literature surrounding novel lithotripsy devices and technology used in PNL.

RECENT FINDINGS

At present, the Holmium:yttrium-aluminum-garnet (Ho:YAG) laser is widely accepted as the gold standard laser lithotripsy for PNL. SwissLithoClast Trilogy offers a range of probes with a trifecta of electromagnetic, ultrasonic energy with surgeon-controlled suction. The Olympus Shockpulse-SE is a similar lithotripter that relies on continuous ultrasonic energy with pulsed ballistic energy to break stones. Thulium Fiber Laser (TFL) offers an alternative laser energy source to the Holmium laser, which has been shown to be very effective at producing small stone fragments and dust. The Moses technology is another addition in a long list of improvements to the Ho:YAG laser, forming vaporization bubble through which more effective energy can be applied to stones.

SUMMARY

Trilogy, Shockpulse, TFL and Moses pulse modulation technology for the Holmium laser all provide improvements compared with older lithotripsy devices. In particular, they convey a safer, efficient and more effective way to manage and clear stones.

The future of laser technology in kidney stones

PURPOSE OF REVIEW

The aim of this study was to present the recent and promising innovations of the new laser technologies used for the treatment of renal stones.

RECENT FINDINGS

Taking advantage of pulse modulation, new technologies such as the Moses effect, the Virtual basket and the Vapor tunnel have been introduced. These technologies seem to improve lithotripsy efficacy by reducing retropulsion and increasing the stone ablation rate.High-power laser lithotripsy has arisen in everyday clinical practice in some centres. The combination of equal efficacy and safety levels compared with the low-power laser lithotripsy and significantly reduced operative time could explain this trend.Thulium fibre laser is an innovative type of laser-emitting machine that offers a lot of advantages compared with its predecessors. The different mechanism of creating the laser pulse offers new possibilities in laser lithotripsy and perhaps in the future thulium fibre laser could replace Ho:YAG as the golden standard for laser lithotripsy.

SUMMARY

Laser lithotripsy is heavily based on technological equipment. The continuous improvement of available lasers increases the endoscopic lithotripsy levels of efficacy and safety.

Holmium with MOSES technology or Thulium Fiber Laser in Miniperc with suction - A new curiosity

PURPOSE

To present initial clinical comparison between high-power Holmium with MOSES technology(HPH-M) and Thulium Fiber laser(TFL) during mini-PCNL for renal calculi with specific emphasis on fragmentation efficiency, fragment size distribution and stone-free rates(SFR).

MATERIAL AND METHODS

Between Aug2018-Dec2019, we performed mini-PCNL for renal calculi <3cm using HPH-M(Lumenis, Israel) or TFL(Urolase SP, IPG Photonics). Data was collected prospectively in our institutional stone registry. Propensity score matching(1:1) was performed using stone size and density as predictors resulting in matched cohort of 51 patients in each group. MiniPCNL with active suction sheath was standard across all patients. Primary end-point was SFR at immediate post-procedure and 1month using CT/Xray KUB. Stone fragments were retrieved and segregated to assess proportion of dust(<1mm), small(1-3mm) and large(>3mm) fragments.

RESULT

Both groups were comparable in terms of stone size(p=0.74), volume(p=0.17) and density(p=0.69). SFR at 48 hours was 78.43% in HPH-M group and 68.63 % in TFL group. Patients with residual fragments were completely clear at 1month. Lasing time(678.6v/s551.95 seconds;p=0.17), stone fragmentation rate(4.6v/s5.2 mm3/s;p=0.23) and total laser energy(21.9v/s16.3KJ;p=0.09) were comparable in both arms. Both groups produced similar dusting (46.8v/s46.41%;p=0.93). TFL produced a greater proportion of fragments >3mm(36%v/s22.68%, p=0.002). On sub-set analysis based on stone density, all outcome parameters were comparable except a shorter total operative time with TFL (p=<0.05).

CONCLUSION

HPH-M and TFL showed similar SFR. Within constraints of the laser fiber size and energy settings, both modalities were equivalent in terms of fragmentation efficiency and proportion of dusting across stone densities.

Does the Novel Thulium Fiber Laser Have a Higher Risk of Urothelial Thermal Injury than the Conventional Holmium Laser in an In Vitro Study?

INTRODUCTION AND OBJECTIVE

The novel thulium fiber laser (TFL) has been shown to break stones more rapidly than the holmium:YAG laser (HL). However, some evidence suggests that the TFL generates more heat. The purpose of this study is to compare ureteral temperatures generated by these lasers during ureteroscopic laser lithotripsy in a benchtop model.

METHODS

A 1-cm BegoStone was manually impacted in the proximal ureter of a 3D printed kidney-ureter model and submerged in 35.5°C saline. Lithotripsy was performed using a 7.6 French flexible ureteroscope and a 200µm laser fiber without a ureteral access sheath. The Dornier 30W HL, Olympus 100W HL, and Olympus 60W TFL were compared. A needle thermocouple to measure temperature was inserted 2 mm from the laser tip. Irrigation was maintained at 35cc/min at room temperature using the Thermedx FluidSmart System. Intraluminal temperature was continuously recorded for 60 seconds of laser activation. 5 trials were performed for each of 4 different power settings: 3.6, 10, 20, and 30 Watts. ANOVA and Mann-Whitney U tests were performed with p<0.05 considered significant.

RESULTS

Intraureteral fluid temperature increased as laser power settings increased for all lasers (p<0.05). The TFL generated higher average ureteral fluid temperatures than the Dornier and Empower HL at all power settings tested (p<0.001). The maximum temperature for the TFL was higher than the Dornier and Empower HL at all power settings tested (p<0.001), except at 20W with the Empower HL. At 30W, the TFL exceeded 43°C, the threshold for tissue damage.

CONCLUSIONS

The TFL generated more heat at all settings tested. Supraphysiologic ureteral temperatures may be generated with extended use at high energy settings and low irrigation rates. Understanding the heat generation properties of both lasers could help improve the safety of ureteroscopic laser lithotripsy.

Thulium fiber laser in urology: physics made simple

PURPOSE OF REVIEW

In this narrative review, we will focus on a novel thulium fiber laser's physical properties in terms of its clinical applicability.

RECENT FINDINGS

TFL has successfully moved forward from the preclinical trials into clinical practice and now is being widely used in clinics around the world. The available data suggest that the device effectively operates in soft tissues - benign prostate hyperplasia (BPH) and bladder tumors, as well as in lithotripsy. Also, the first promising results were obtained from laparoscopic surgery showing its possible applicability in the management of renal cell carcinoma. The constructional changes in fiber laser's design, lead to alteration of laser-tissue interactions, which resulted in clinical advantages of the device. Yet, the exact mechanism often is considered complex for understanding. With this work, we are aiming to build a bridge between biophysics and clinical practice and give a simple explanation of how the devices is working and why the knowledge of it is important for a clinician.

SUMMARY

The more effective wavelength (closer to the water absorption peak), favorable beam profile, different modes of action allowing to decrease carbonization on one hand and retropulsion on the other, all this makes TFL an evolution in urologic surgery. Further trials investigating on the possible pros and cons of the device are awaited.

In vitro fragmentation performance of a novel, pulsed Thulium solid-state laser compared to a Thulium fibre laser and standard Ho:YAG laser

The aim of this work was to compare the fragmentation efficiency of a novel, pulsed Thulium solid-state laser (p-Tm:YAG) to that of a chopped Thulium fibre laser (TFL) and a pulsed Holmium solid-state laser (Ho:YAG). During the fragmentation process, we used a silicone mould to fixate the hemispherical stone models under water in a jar filled with room-temperature water. Each laser device registered the total energy applied to the stone model to determine fragmentation efficiency. Our study examined laser settings with single pulse energies ranging from 0.6 to 6 J and pulse frequencies ranging from 5 to 15 Hz. Similar laser settings were applied to explicitly compare the fragmentation efficiency of all three devices. We experimented with additional laser settings to see which of the three devices would perform best. The fragmentation performance of the three laser devices differed statistically significantly (p < 0.05). The average total energy required to fragment the stone model was 345.96 J for Ho:YAG, 372.43 J for p-Tm:YAG and 483.90 J for TFL. To fragment the stone models, both Ho:YAG and p-Tm:YAG needed similar total energy (p = 0.97). TFL’s fragmentation efficiency is significantly lower than that of Ho:YAG and p-Tm:YAG. Furthermore, we found the novel p-Tm:YAG’s fragmentation efficiency to closely resemble that of Ho:YAG. The fragmentation efficiency is thought to be influenced by the pulse duration. TFL’s shortest possible pulse duration was considerably longer than that of Ho:YAG and p-Tm:YAG, resulting in Ho:YAG and p-Tm:YAG exhibiting better fragmenting efficiency.

Dusting Efficiency of a Novel Pulsed Thulium:Yttrium Aluminum Garnet Laser vs a Thulium Fiber Laser

Background: Holmium:yttrium aluminum garnet laser (Ho:YAG) is still considered the gold standard in laser lithotripsy. There is a large body of literature comparing the capabilities of Ho:YAG and thulium fiber lasers (TFLs). The novel, pulsed thulium:yttrium aluminum garnet laser (p-Tm:YAG) evaluation model has only been compared with Ho:YAG in terms of its dusting performance to date. It was this study's aim to compare the p-Tm:YAG's dusting efficiency with that of a chopped TFL. Materials and Methods: During the laser ablation procedure, while the laser device was emitting light, the laser fiber was spiraled across the surface of a uniform kidney stone model via software. We relied on the stone model's difference in weight before and after the dusting procedure to assess the dusting efficiency and assessed each laser device's dusting efficiency at various preset laser configurations and laser fiber-motion speeds. We compared both laser devices' laser configurations, which were identical in pulse energy and frequency, while keeping in mind that the pulse duration differed significantly. In addition, we tested each laser device's capability. Results: The average ablated weight across all laser configurations was 0.61 g (standard deviation [SD] = 0.44 g) for p-Tm:YAG and 0.76 g (SD = 0.51 g) for TFL. After statistical analysis, we found no significant difference in ablated weight between the laser devices (U = 1715.5, p-value = 0.11). The maximum permissible frequency configuration for TFL was 1600 Hz, which resulted in the worst overall dusting output. Conclusions: We observed that the p-Tm:YAG's dusting efficiency resembled that of TFL in the identical pulse energy and frequency laser configurations. The ablation efficiency did not seem to be affected by the laser devices' differences in pulse duration. Slower laser fiber-motion speeds resulted in more efficient ablation. When using the maximum preset frequency and power configuration, TFL's dusting efficiency appeared to be inefficient.

Current status of thulium fibre laser lithotripsy: an up-to-date review

OBJECTIVE

To perform an up-to-date review to scope the current status of the thulium fibre laser (TFL) in the setting of stone lithotripsy and provide a guide for the clinical urologist.

METHODS

A review of world literature was performed to identify original articles on TFL for stone lithotripsy. Our clinical experiences of using the technology have also been shared.

RESULTS

To date there have been 11 clinical studies published on TFL for stone lithotripsy. Three of these have been in the setting of miniaturised percutaneous nephrolithotomy (mini-PCNL) and the remainder have been on ureteroscopy (URS). There has only been one randomised study on this technology, which has been for URS. For URS, the range of settings has been 0.1-4 J × 7-300 Hz for both URS and mini-PCNL. Stones ranging from 0.4-3.2 and 1.5-3 cm have been treated with URS and mini-PCNL, respectively. The final stone-free rate for TFL has ranged from 66.6% to 100% and 85-100% for URS and mini-PCNL, respectively. The average length of stay ranged from 0.5 to 2.4 days in the URS group, but no studies have been reported this for mini-PCNL. Operative times in all the studies (both URS and mini PCNL) were <60 min.

CONCLUSION

Initial clinical studies reveal that TFL appears to be efficacious in the setting of stone lithotripsy. However, further randomised trials are warranted to delineate its formal position, as well as determine the optimal settings for use in clinical practice.

Managing Urolithiasis with Thulium Fiber Laser: Updated Real-Life Results-A Systematic Review

Thirty-three years ago, pulsed lasers marked the beginning of a new era in endoscopic lithotripsy, and the one that was highlighted because of its potential was the Holmium: YAG laser, which became and still is the gold standard in endourology. Recently, a new laser technology has been accepted for clinical use in lithotripsy: the thulium fiber laser (TFL), showing appealing characteristics not seen before in several preclinical studies. A review of the literature was performed and all relevant in vitro studies and clinical trials until April 2021 were selected. The search came back with 27 clinical experiences (7 full-text clinical trials and 20 peer-reviewed abstracts) and 33 laboratory studies (18 full-text articles and 15 peer-reviewed abstracts). The clinical experiences confirmed the clinical safety of using the wide parameter range of the TFL. This technology demonstrated the performance at a higher ablation speed, the higher ablation efficiency, and the better dust quality of the TFL, as well as reduced stone retropulsion, thus helping to maintain an optimal visibility. No thermal or radiation damage was found. Given the current evidence, we may be facing the future gold standard laser in endoscopic lithotripsy.

A Systematic Review of Thulium Fiber Laser: Applications and Advantages of Laser Technology in the Field of Urology

Laser technology is widely used in urological surgery, from lithotripsy, prostate surgery to en-bloc resection of tumours. While Holmium:YAG has been widely employed over the last two decades, in recent years, there has been a surge of interest in Thulium Fiber Laser (TFL), which offers theoretical advantages of better water absorption and lower stone ablation thresholds. A systematic review was conducted to assess the evidence from clinical research on TFL's application for lithotripsy and prostate surgery. It identified 357 articles and 8 (1506 patients) were selected, of which 4 clinical studies each investigated TFL enucleation of prostate (ThuFLEP) and TFL lithotripsy. For flexible ureteroscopic lithotripsy (FURSL), stone ablation settings ranged from 0.1-4 J, and 7-300 Hz, mean operative time ranged from 23.4-39.8 minutes and lasing time ranged from 1.2-10 minutes. For stone dusting in percutaneous nephrolithotomy (PCNL), settings of 0.2 J and 125-200 Hz were found to be optimal. For ThuFLEP, all studies showed a significant improvement in IPSS (International Prostate Symptom Score), urinary flow rate (Qmax), quality of life measures, and post-void residual volume, with mean operative time ranging from 67-104.5 minutes. Our review shows that there is limited evidence on the use and clinical outcomes of TFL. ThuFLEP might suggest equivalence to the widely used HoLEP in the available evidence so far. TFL lithotripsy shows promising results but further prospective, randomized trials are required to properly assess its usability, clinical effectiveness and standardisation of the settings for successful adoption of the technology.

Photothermal nanoparticles for ablation of bacteria associated with kidney stones

OBJECTIVE

To determine whether photothermal polymer nanoparticles (NPs) can interface with bacteria associated with kidney stones, generate heat when stimulated with near infrared (NIR) light, and aid in reducing bacterial burden.

METHODS

Two types of kidney stones, artificial, and those removed during percutaneous nephrolithotomy (PCNL), were inoculated with Escherichia coli (E. coli) and then incubated with NPs composed of FITC-labeled Poly[4,4-bis(2-ethylhexyl)-cyclopenta[2,1-b;3,4-b']-dithiophene-2,6-diyl-alt-2,1,3-benzoselenadiazole-4,7-diyl] (PCPDTBSe). Association of the PCPDTBSe NPs was evaluated using fluorescence microscopy. Infected stones were incubated with NPs and exposed to 800 nm light to generate temperature increases from 25.4 to 68.6 °C on the stones. Following photothermal treatment, the stones were homogenized and the bacteria was enumerated via colony counting assays to evaluate the bactericidal effect. The photothermal effect was also evaluated using scanning electron microscopy of the treated biofilms.

RESULTS

Both kidney stone types sequestered E. coli. Control stones and stones treated with laser only had growth of numerous bacterial colonies, while stones exposed to NPs and laser grew significantly less, or none (p = 0.02).

CONCLUSIONS

The polymer NPs interface with E. coli on artificial and patient-derived kidney stones, and they can impart a bactericidal effect, when stimulated with NIR to generate heat. This technique may possibly be extended to treating infected kidney stones in patients.

Recent advances in percutaneous lithotripsy techniques

PURPOSE OF REVIEW

To describe and critically discuss the most recent evidence regarding the percutaneous nephrolithotomy (PCNL) techniques.

RECENT FINDINGS

Three-dimensional printing and virtual reality are promising tools to improve surgeon experience and operative performance. Totally ultrasound-guided PCNL is feasible and can reduce the radiological risk. Growing evidence highlights the safety and advantages of the use of miniaturized instrumentations, although some related limitations place the mini PCNL (mPCNL) in direct challenge with the retrograde intrarenal surgery. LithoClast Trilogy and ClearPetra system can improve the stone clearance. Thulium laser is a new source of energy with growing expectations and promising in-vitro results.

SUMMARY

Significant advances have recently been recorded in PCNL techniques. Thulium fiber laser, LithoClast Trilogy, new suction devices, and the development of novel technologies for teaching and planning procedures may overcome mPCNL drawbacks. Further studies are needed to confirm the promising preliminary results available on the topic.

Ablation Efficiency of a Novel Thulium Fiber Laser: An In Vitro Study on Laser Setting and Fiber Usage

Introduction: To investigate the ablation efficiency of super-pulse thulium fiber laser (SPTFL) with different laser settings and fiber usage. Materials and Methods: SPTFL machine was attached with different fibers. Artificial stones were fixed in water, whereas laser fiber was driven on a platform for ablation. Pulse energy, frequency, fiber-moving speed, fiber-to-stone distance, and fiber size were adjusted in each trial. The cross-sectional area of craters on the lateral stone surface was measured for comparison of ablation rate, combined with fiber-moving speed. Results: There was a trend that the ablation rate increased as pulse energy or frequency increased. When pulse energy was set as 0.2 J and frequency was increased from 50 to 150 Hz, the cross-sectional area of the crater was enlarged from 0.21 to 0.37 mm² (p < 0.05); when the frequency was set as 100 Hz and pulse energy was increased from 0.1 to 0.3 J, the crater was enlarged from 0.10 to 0.45 mm² (p < 0.05). Furthermore, energy demonstrated greater impact on ablation rate and the crater was enlarged from 0.20 mm² in the 0.1 J × 300 Hz group to 0.44 mm² in the 0.3 J × 100 Hz group (p < 0.05). Then fiber was set at different moving speeds with the same laser setting; the ablation rate of 3 mm/second group was 3.64 times higher than 0.5 mm/second group (p < 0.05). Ablation diminished as fiber-to-stone distance grew. A 200 μm fiber produced thinner and deeper fissure than 272 and 550 μm fibers, and the ablation rate was the highest for the 200 μm fiber. Conclusion: Pulse energy is a more important factor in influencing ablation efficiency compared with frequency. Closer fiber-to-stone distance, faster fiber movement, and smaller fiber size increase ablation efficiency.

Retrograde intrarenal surgery versus percutaneous nephrolithotomy in larger kidney stones. Could SuperPulsed Thulium-fiber laser change the game?

Introduction

The aim of this article was to compare retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotomy (PCNL) efficacy and safety with SuperPulsed Thulium-fiber laser (SP TFL) for stones 20 mm and larger.

Material and methods

Patients with large kidney stones (20 mm and larger) were recruited to undergo PCNL or RIRS with SP TFL lithotripsy. Both groups were comparable in terms of stone size and density, operation time, laser-on time (LOT), stone-free rate, residual fragments and complication rate. Stone retropulsion and visibility were assessed based on the surgeon's feedback using Likert scales.

Results

A total of 14 and 56 patients were included in the RIRS and PCNL groups, respectively. The mean stone density was 833.8 ±298.3 HU in the RIRS group and 882.3 ±408.5 HU in the PCNL group (p = 0.072). The median LOT was 11.7 (10.0-15.5) min for RIRS and 10.0 (6.0-12.1) min for PCNL (p = 0.207). The median total energy for stone ablation was 13.8 (11.8-25.0) kJ for RIRS and 12.0 (7.0-20.1) kJ for PCNL (p = 0.508). The median ablation speed was 3.9 (3.9-5.7) mm³/sec for RIRS and 5.0 (4.6-11.3) mm³/sec for PCNL (p = 0.085). We found a significant correlation between retropulsion and the type of surgery performed: with higher retropulsion in the PCNL (r = 0.298 with p = 0.012). The stone-free rate at 3-months was 85.7% in RIRS and 89.3% in PCNL (p = 0.505).

Conclusions

SP TFL is a safe and effective modality for lithotripsy for both, RIRS and PCNL, achieving minimal retropulsion and good visibility. No discrepancies in procedure duration, complications, or LOT were identified between the different modalities.

Basic and advanced technological evolution of laser lithotripsy over the past decade: An educational review by the European Society of Urotechnology Section of the European Association of Urology

Laser disintegration of urinary stones is a cornerstone of urolithiasis treatment in the modern era. Despite the wide clinical use of stone lasers, basic and advanced technological achievements and developments are difficult to comprehend and interpret by the average urologist. A descriptive analysis of laser production and stone disintegration mechanisms was performed. We focused on physics of modern types of lithotripters, the construction of laser fibers, laser parameters, new modes, settings, and lithotripsy techniques. The main principle of laser emission remains the same since the first emitting laser was produced. Peak power density and short interaction time lead to photothermal effects responsible for stone disintegration. Modern lithotripters such as Holmium: YAG (low/high power, Moses technology) and thulium fiber laser show basic construction differences with the physical properties of the latter being superior, at least in in vitro studies. By adjusting lasing parameters, a wide spectrum of stone ablation from fragmentation to dusting can be achieved. New technology allows for the production of real dust. Knowledge of laser fiber construction and physical properties are useful in marketing and clinical use. Urologists should understand the physical and physiological background of the lasers used in their everyday practice for stone fragmentation.

Outcomes of thulium fibre laser for treatment of urinary tract stones: results of a systematic review

PURPOSE OF REVIEW

Lasers have become a fundamental aspect of stone treatment. Although Holmium:Yttrium-Aluminum-garnet (Ho:YAG) laser is the current gold-standard in endoscopic laser lithotripsy, there is a lot of buzz around the new thulium fibre laser (TFL). We decided to evaluate the latest data to help create an objective and evidence-based opinion about this new technology and associated clinical outcomes.

RECENT FINDINGS

Sixty full-text articles and peer-reviewed abstract presentations were included in the qualitative synthesis of this systematic review performed over the last 2 years. Current super pulsed TFL machines are capable of achieving peak powers of 500W and emit very small pulse energies of 0.025 Joules going up to 6 Joules, and capable of frequency over 2000 Hz. This makes the TFL ablate twice as fast for fragmentation, 4 times as fast for dusting, more stone dust of finer size and less retropulsion compared to the Ho:YAG laser. Because of the smaller laser fibres with the TFL, future miniaturization of instruments is also possible.

SUMMARY

Based on the review, the TFL is a potential game-changer for kidney stone disease and has a promising role in the future. However larger multicentric prospective clinical studies with long-term follow-up are needed to establish the safety and efficacy of the TFL in endourology.

A scoping review of the clinical efficacy and safety of the novel thulium fiber laser: The rising star of laser lithotripsy

INTRODUCTION

The holmium:yttrium-aluminum-garnet (Ho:YAG) laser is the gold standard for intracorporeal lithotripsy. Preclinical reports suggest the thulium laser fibre (TFL) may possess advantages over the Ho:YAG laser, including improved lithotripsy efficacy, enhanced safety, and lower costs. Although the TFL is well-characterized in-vitro, there are no reviews examining TFL lithotripsy in a clinical setting.

METHODS

A review of the literature was conducted using a systematic search of MEDLINE, PubMed, and Embase, yielding a total of 130 manuscripts published up to May 2020. Two independent reviewers selected studies for screening, eligibility, and inclusion into the scoping review. Following the title, abstract, and full-text review, 14 articles were analyzed.

RESULTS

Within these articles, there were 13 prospective cohort studies and one case series. The average sample size was 100 participants. Study followup durations ranged from four weeks to three months. TFL had comparable stone-free rates to Ho:YAG lasers and improved operating time. TFL was subjectively favorable in terms of stone retropulsion, stone fragmentation, endoscopic maneuverability, and endoscopic visibility. TFL appeared clinically safe and did not result in any major complications. Many studies were underpowered and non-peer-reviewed, demonstrating the need for additional research in this field.

CONCLUSIONS

The TFL has the potential to catalyze a paradigm shift in laser lithotripsy. While the objective of this scoping review was to describe the contemporary landscape of the literature, it is important to consider that inferences posed by the studies described herein must be tempered by the low quality of available evidence.

Clinical Comparison of Super Pulse Thulium Fiber Laser and High-Power Holmium Laser for Ureteral Stone Management

Purpose: To evaluate the efficacy of new super pulse thulium fiber laser (SP TFL) and compare it with holmium laser for ureterolithotripsy. Patients and Methods: A total of 174 patients with solitary ureteral calculi were enrolled in 2016 to 2018. Stone sizes ranged between 0.6 and 2.4 cm. The SP TFL FiberLase U2 and 120H Ho:YAG laser with fibers diameters of 400 and 365 μm, respectively, were used. The laser settings were 1 J × 10 Hz = 10 W for both devices. All patients were randomized into two groups. The age, stone size, location, and density were comparable in both groups. The evaluated parameters were operation time, endoscopic view quality, retropulsion grade, stone-free rate, and complication rate. Results: The total operation time and lasering time were longer in the Ho:YAG group (24.7 ± 0.7 minutes vs 32.4 ± 0.7 minutes, p = 0.05), and postoperative stenting was necessary in one vs four cases, respectively. At 30 days of follow-up, no residual stones were observed in the SP TFL group (vs five cases of Ho:YAG). Conclusion: SP TFL technology was associated with excellent efficacy/safety ratio. The SP TFL may be considered as a viable alternative to Ho:YAG laser stone management.

Active Optical Fibers and Components for Fiber Lasers Emitting in the 2-μm Spectral Range

Laser sources emitting in the infrared range at around 2 µm are attracting great interest for a variety of applications like processing of transparent thermoplastic polymers in industry as well as plenty of applications in medicine, spectroscopy, gas sensing, nonlinear frequency conversion to the mid-infrared, to mention a few. Of late, fiber lasers compared to other kinds of lasers benefit from their all-fiber design, leading to a compact, robust, and well thermally manageable device. Particularly, thulium- and holmium-doped fiber lasers are the first choice in fiber lasers emitting light around 2 µm. In this paper, we give an overview of our recent results in the research on thulium- and holmium-doped optical fibers, fiber lasers, and related research topics in the 2-µm spectral range. In particular, we present, to our knowledge, the first results of improvement of pump absorption in double-clad fibers thanks to the fiber twist frozen during drawing. Finally, a brief demonstration of material processing by thulium all-fiber laser operating at 2 µm is presented.

Impact of Laser Fiber Diameter and Irrigation Fluids on Induced Bubble Stream Dynamics with Thulium Fiber Laser: An In Vitro Study

Objectives: The Thulium Fiber Laser (TFL) is studied as an alternative to the holmium:yttrium-aluminium-garnet (Ho:YAG) laser for lithotripsy, with the advantage of an induced bubble stream (IBS). This in vitro study compared the TFL's IBS with 150- and 272 μm-core-diameter laser fiber (CDF) and in four irrigant fluids. Methods: A TFL of 50 W (IPG Photonics^©) and 150 and 272 μm-CDF (Boston Scientific^©) were used, comparing nine energies (in the range from 0.025 to 4 J). An experimental setup consisted of a vertically disposed fiber in a cuvette filled with saline, iodinated contrast agent (IOA), human urine, or deionized water (DW) at ambient temperature. High-speed imaging of three consecutive IBS was performed to determine the influence of energy on their maximum length (ML; μm), width (MW; μm), and duration (MD; μs). Fibers were cleaved with ceramic scissors between each experience. Results: The IBS had higher ML and MW and MD with 150CDF than 272CDF. Maximum pulse rate for 150CDF and 272CDF was 2182 and 2000 Hz, respectively. Every maximum power was higher than the technological limit of TFL (>50 W). At equal energy density, 150CDF was associated with lower dimensions and durations. The IBS had higher maximum dimensions in IOA compared with saline solution (SS). Compared with DW and urine, IBS in IOA were longer beyond 500 mJ. Over 25 mJ, IBS were thinner in DW, urine, and SS. The IBS in DW, urine, and SS had similar maximum dimensions. The IBS's duration was higher in IOA compared with DW, urine, and SS, meaning a lower theoretical maximum pulse rate and power in IOA. Conclusion: Lasering with 150CDF fits with lower pulse energies-higher pulse rates settings than 272CDF, such as fine dusting mode. In IOA, Induced Bubbles Streams present higher dimensions and durations than in other studied fluids, related to its higher viscosity. Safety distance and pulse rate should be increased and decreased, respectively.

In Vitro Evaluation of Stone Fragment Evacuation by Suction

Introduction: Contemporary, flexible stone baskets are unable to extract submillimeter stone fragments at the time of ureteroscopic laser lithotripsy. In this in vitro study, the feasibility of suctioning submillimeter fragments with a standard Luer Lock syringe through the working channel of a flexible ureteroscope was assessed. Materials and Methods: Phantom stones made from industrial plaster were mechanically fragmented into ≤1 and ≤0.5-mm groups. Both stone groups were divided into five preweighed trial samples. Each stone group was then mixed in a beaker filled with normal saline. A standard 10-mL Luer Lock syringe was connected to a fiber-optic ureteroscope with a 1.2-mm working channel. The syringe was then used to suction stone fragments from the beaker. The suctioned stone fragments and the stone fragments remaining in the beaker after removing the overlying solution were separated, centrifuged with supernatant removed, and dried in an incubator set at 33°C for 1 week. Dried weights were recorded. Results: Mean total weights for ≤0.5 and ≤1.0-mm stone groups at baseline were 0.807 and 0.806 g, respectively. The mean percentages of stone fragments suctioned through the ureteroscope for ≤0.5 and ≤1.0-mm groups were 86% and 86%, respectively (p = 0.973). During suctioning, 64% of stones in the ≤0.5-mm group were trapped in either the working channel of the ureteroscope or within the Luer Lock syringe compared with 78% of stones in the ≤1-mm group (p = 0.001) requiring cessation of the procedure to clear the channel. Conclusions: It is feasible to suction submillimeter stone fragments by connecting a Luer Lock syringe to the working channel of a flexible ureteroscope. The limiting factor for removing stone fragments appears to be the small working channel of flexible ureteroscopes as trapping of fragments during suctioning is common and requires time-consuming removal of the endoscope and clearing of the channel.

Thulium fiber laser: The new kid on the block

OBJECTIVE

Laser technology in urology is currently used for both stone lithotripsy and prostate enucleation. Thulium fiber laser (TFL) is a novel laser, with initial studies showing potential benefits over other lasers both in terms of its effectiveness and safety profile.

MATERIAL AND METHODS

In the first part of this review, a descriptive analysis of the theoretical concepts behind TFL was performed. This part focused on the physics and laser parameters as applied to the clinical practice. These were interpreted in the context of other lasers, namely, the Holmium:YAG laser to highlight the theoretical advantages as well as potential pitfalls offered by the TFL. In the second part of the review, a narrative synthesis of in-vitro studies regarding TFL and its modifications is performed assessing stone-related parameters, namely, ablation rate, operative time retropulsion, and safety.

RESULTS

TFL achieved high ablation rates in most studies and performed better than Holmium:YAG laser across a range of different settings and ablation modes when the two lasers were compared. Moreover, its ability to use low pulse energy ensures minimal stone retropulsion with the retropulsion threshold estimated to be 2-4 times higher than that of Holmium:YAG laser. From a safety viewpoint, TFL poses no additional risks than other lasers, although it does potentially lead to slightly higher temperatures in the surrounding tissues during lithotripsy.

CONCLUSION

The unique properties of TFL have made it an attractive alternative to conventional laser techniques currently used in urology. Clinical studies are required before its application can become more widespread.

Thulium fiber laser: ready to dust all urinary stone composition types?

PURPOSE

To evaluate whether stone dust can be obtained from all prevailing stone composition types using the thulium fiber laser (TFL) for lithotripsy. Where applicable, stone dust was further characterized by morpho-constitutional analysis.

METHODS

Human urinary stones were submitted to in vitro lithotripsy using a FiberLase U2 TFL generator with 150 µm silica core fibers (IPG Photonics^®, IPG Medical™, Marlborough, MA, USA). Laser settings were 0.05 J, 320 Hz and 200 μs. A total of 2400 J were delivered to each stone composition type. All evaluated stones had a > 90% degree of purity (calcium oxalate monohydrate, calcium oxalate dihydrate, uric acid, carbapatite, struvite, brushite and cystine). Spontaneously floating stone particles were considered as stone dust and collected for analysis by scanning electron microscopy and Fourier transform infrared spectroscopy.

RESULTS

Stone dust could be retrieved from all evaluated urinary stones after TFL lithotripsy. Most stone dust samples revealed changes in crystalline organization, except for calcium oxalate monohydrate and carbapatite, which conserved their initial characteristics. Mean maximal width of stone dust particles did not exceed 254 µm.

CONCLUSIONS

The TFL is capable to produce stone dust from all prevailing stone types. Morpho-constitutional changes found in stone dust suggest a photothermal interaction of laser energy with the stone matrix during TFL lithotripsy.