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

Treatment of Urolithiasis with Thulium Fiber Laser in Fragmentation Mode Using Optimized Pulse Sequences

Objectives: The super-pulsed thulium fiber laser (SP TFL) is a new alternative to high-power holmium laser for intracorporeal lithotripsy. The SP TFL has shown advantages in dusting regimes, but benefits in fragmentation regimes are less understood. The second-generation SP TFL introduces an advanced fragmentation pulse (AFP) sequence to maximize SP TFL's efficiency in fragmentation. This study evaluates safety and efficacy of the SP TFL fragmentation mode in ureteroscopy (URS) and mini percutaneous nephrolithotomy (mini-PCNL). Materials and Methods: The study was conducted in two phases. Safety of a new AFP was compared ex vivo to standard SP TFL fragmentation settings by measuring the dimensions of wounds created in porcine kidney after laser exposure for 0.5, 1.0, and 2.0 s. The resulting wounds were evaluated histologically using nitro blue tetrazolium chloride (NBTC) stain. In the clinical phase, the second-generation SP TFL was used to fragment and extract ureteral and renal stones in 40 patients using ureteroscopic and percutaneous approaches. The stone size, volume, density, laser-on-time, and total energy were recorded for each patient. In addition, the chemical composition, ablation rate, and ablation efficiency were assessed for each stone treatment. Results: The ex vivo mucosa damage profiles caused by AFP were similar to those caused by regular pulses. In clinical phase, the median volume and density for ureteral stones were 0.4 cm3 and 1029 Hounsfield units (HU), for renal stones 1.3 cm3 and 1113 HU, respectively. Different stone types were crushed into fragments suitable for extraction. The mean AFP energy was 3 J and the average power for ureteral stones was 10.5 W, whereas for renal stones it was 28.5 J and 31 W, respectively. The overall complication rate was low in both groups. Conclusion: ST PFL with AFP capability facilitates effective fragmentation of ureteral and renal stones of any composition during URS and mini-PCNL with minimal complication rates.

Navigating urolithiasis treatment: assessing the practicality and performance of thulium fiber laser, holmium YAG, and thulium YAG in real-world scenarios

BACKGROUND

The management of urolithiasis has undergone significant advancements with the introduction of pulsed lasers, particularly the holmium:yttrium-aluminum-garnet (Ho:YAG) laser, which is currently considered the gold standard in endourology. However, the Ho:YAG laser has certain limitations, such as the inability to support small laser fibers (150 μm) and the requirement of a heavy water cooling system, making it challenging to transfer between operating rooms. These limitations have led to the emergence of new laser technologies, including the thulium fiber laser (TFL) and the thulium:yttrium-aluminum-garnet laser (Tm:YAG), as potential alternatives to the Ho:YAG laser.

METHODS

In this review, we aimed to evaluate the effectiveness and safety of TFL, Ho:YAG, and Tm:YAG lasers in real-life scenarios by comparing clinical trial data with laboratory findings. A literature review was conducted, and relevant in vitro studies and clinical trials until March 2023 were analyzed.

RESULTS

The findings indicate that TFL has demonstrated high ablation efficiency for stones of any composition, size, and location, superior the capabilities of Ho:YAG lasers. TFL has shown superior dusting and fragmentation abilities, lower retropulsion, and increased patient safety. The laser parameters, such as ablation efficiency, speed, operative time, dust quality, retropulsion, visibility, temperature safety, and stone-free rate, were compared between laboratory studies and clinical outcomes.

CONCLUSION

Although the number of studies on TFL is limited, the available evidence suggests that TFL represents a significant advancement in laser technology for lithotripsy. However, further research is needed to fully explore the implications and limitations of TFL and Tm:YAG lasers.

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

INTRODUCTION

Holmium:yttrium-aluminium-garnet (Ho:YAG) and thulium fiber (TFL) lasers are currently the two laser sources recommended for endocorporeal laser lithotripsy (ELL). Recently, the pulsed-thulium:YAG (Tm:YAG) laser was also proposed for ELL, as an answer to both Ho:YAG and TFL limitations. We aimed to evaluate the efficiency, safety, and laser settings of Tm:YAG laser in ELL during retrograde intrarenal surgery (RIRS).

METHODS

A prospective study of the first 25 patients with ureteral and renal stones who underwent RIRS using the Thulio (pulsed-Tm:YAG, Dornier©, Germany) was performed in a single center. 272 µm laser fibers were used. Stone size, stone density, laser-on time (LOT) and laser settings were recorded. We also assessed the ablation speed (mm3/s), Joules/mm3 and laser power (W) values for each procedure. Postoperative results, such as stone-free rate (SFR) and zero fragments rate (ZFR) were also recorded.

RESULTS

A total of 25 patients were analyzed (Table 1). The median (IQR) age was 55 (44-72) years old. Median (IQR) stone volume was 2849 (916-9153)mm3. Median (IQR) stone density was 1000 (600-1174)HU. Median (IQR) pulse energy, pulse rate and total power were 0.6 (0.6-0,8)J, 15(15-20)Hz and 12(9-16)W, respectively. All procedures used "Captive Fragmenting" pulse modulation (Table 2). The median (IQR) J/mm3 was 14,8 (6-21). The median (IQR) ablation rate was 0,75 (0,46-2)mm3/s. One postoperative complications occurred (streinstrasse). SFR and ZFR were 95% and 55%, respectively.

CONCLUSION

The pulsed-Tm:YAG laser is a safe and effective laser source for lithotripsy during RIRS, using low pulse energy and low pulse frequency.

Retrograde intra renal surgery and safety: pressure and temperature. A systematic review

PURPOSE OF REVIEW

Retrograde intra renal surgery (RIRS) with laser lithotripsy represents the gold-standard to treat renal stones up to 20 mm. Controlling intraoperative parameters such as intrarenal pressure (IRP) and temperature (IRT) is mandatory to avoid complications. This article reviews advances in IRP and IRT over the last 2 years.

RECENT FINDINGS

We conducted a PubMed/Embase search and reviewed publications that include temperature and pressure during RIRS. Thirty-four articles have been published which met the inclusion criteria. Regarding IRP, a consensus has emerged to control IRP during RIRS, in order to avoid (barotraumatic and septic) complications. Several monitoring devices are under evaluation but none of them are clinically approved for RIRS. Ureteral access sheath, low irrigation pressure and occupied working channel help to maintain a low IRP. Robotic systems and suction devices would improve IRP intraoperative management and monitoring. IRT determinants are the irrigation flow and laser settings. Low power settings(<20 W) with minimal irrigation flow (5-10 ml/min) are sufficient to maintain low IRT and allows continuous laser activation.

SUMMARY

Recent evidence suggests that IRP and IRT are closely related. IRP depends on inflow and outflow rates. Continuous monitoring would help to avoid surgical and infectious complications. IRT depends on the laser settings and the irrigation flow.

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.

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.

Initial clinical experience with the thulium fiber laser from Quanta System: First 50 reported cases

OBJECTIVE

To evaluate the new thulium fiber laser (TFL) from Quanta System (Fiber Dust™) in terms of efficiency, safety, and laser settings in laser lithotripsy during retrograde intrarenal surgery (RIRS).

METHODS

A prospective study of the first 50 patients with ureteral and renal stones who underwent RIRS using the new Fiber Dust (TFL from Quanta System, Italy) was performed in a single center. 200 µm and 150 µm laser fibers were used. Stone size, stone density, laser-on time (LOT) and laser settings were recorded. We also assessed the ablation speed (mm³/s), Joules/mm³ and laser power (W) values for each procedure.

RESULTS

A total of 50 patients were analyzed. The median (IQR) age was 54.5 (43-65) years old. Median (IQR) stone volume was 347 (147-1800) mm³ and 1125 (294-4000) mm³ for ureteral and renal stones, respectively. Median (IQR) stone density was 900 (400-1500) HU for ureteral stones and 950 (725-1125) HU for renal stones. Median (IQR) pulse energy was 0.6 (0.5-1) J and 0.6 (0.5-0.9) J for ureteral and renal stones, respectively. Median (IQR) frequency for ureteral stones was 10 (10-20) Hz and for renal stones, 15 (10-20) Hz. All procedures used short pulse. There were no statistically significant differences in pulse energy, frequency, laser power or LOT in both groups. The median (IQR) J/mm³ was 8.7 (4.8-65.2) for ureteral stones vs 14.3 (7.8-24.7) for renal stones. The median (IQR) ablation rate was 0.3 (0.2-1.3) mm³/s for ureteral stones vs 0.7 (0.4-1.2) mm³/s for renal stones. Neither of those results reached the significance threshold. Overall complication rate was low in both groups, and none was related to TFL.

CONCLUSION

According to our results, the new TFL laser is safe and effective for lithotripsy during RIRS, using low pulse energy and low pulse frequency.

LASER-INDUCED OCULAR LESIONS WITH THULIUM FIBER LASER IN ENDOUROLOGY : AN EX VIVO STUDY

INTRODUCTION AND OBJECTIVES

The Thulium Fiber Laser(Tm-F) is currently studied as an alternative to the Holmium:YAG laser(Ho:YAG), the gold-standard for endocorporeal laser lithotripsy. We aimed to evaluate the ex vivo effects of an accidental Tm-F laser exposure on bovine eyes and to test the protective action of different eyeglasses in preventing eye lesions in case of accident.

METHODS

A 50W-TFL-generator(IPG Photonics®, Russia) with a wavelength of 1940nm and 200µm-core-diameter-fibers(CDF) were used. The laser fiber tip was pointed perpendicularly at different distances(0, 1, 3, 5, 8, 10, respectively) to the pupil center of the bovine eye. The Tm-F laser was activated for 1 or 3 seconds at three different settings(0.5J-20Hz, 1J-10Hz, and 2J-10Hz, respectively). The experiment was repeated using laser safety glasses and eyeglasses. After lasering, eye samples were immersed in a 0,5 % fluorescein serum (Faure-Ciba-Geigy®, Switzerland), then rinsed with saline solution. White- and blue-light examinations looked for localized epithelial burns(LEB), extended epithelial burns(EEB), superficial corneal ulcerations(SCU) and deep corneal ulcerations(DCU).

RESULTS

A total of 68 bovine eyes were used. Despite the laser settings, both DCU(contact) and SCU (1cm) developed without eye protection, for 1 and 3 seconds of lasering. At 3cm fiber-eye distance, only burning lesions were observed. Over 5cm, no lesion was found. At contact or 1 cm fiber-eye distance, pulse energy did not change lesion grade, but at 3cm, high pulse energy led to higher grade corneal lesions(0,5J-10Hz:LEB; 1J-10Hz:EEB). Despite the fiber-eye distance, no corneal lesions were reported in the laser safety glasses or eyeglasses groups for 1 second laser exposure.

CONCLUSION

Our study highlights the risk of eye damage caused by Tm-F. Without proper eye protection Tm-F can cause corneal lesions up to 5cm in distance for 1 second of exposure, despite laser settings. Only dedicated protective eyeglasses are effective for long exposures.

Laser Fiber Displacement Velocity during Tm-Fiber and Ho:YAG Laser Lithotripsy: Introducing the Concept of Optimal Displacement Velocity

BACKGROUND

Endocorporeal laser lithotripsy (EL) during flexible ureteroscopy (URS-f) often uses "dusting" settings with "painting" technique. The displacement velocity of the laser fiber (LF) at the stone surface remains unknown and could improve EL's ablation rates. This in vitro study aimed to define the optimal displacement velocity (ODV) for both holmium:yttrium-aluminium-garnet (Ho:YAG) and thulium fiber laser (Tm-Fiber).

METHODS

A 50W-TFL (IRE Polus^®, Moscow, Russia) and a 30W-MH1-Ho:YAG laser (Rocamed^®, Signes, Provence-Alpes-Côte d'Azur, France), were used with 272 µm-Core-Diameter LF (Sureflex, Boston Scientific^©, San Jose, CA, USA), comparing three TFL modes, "fine dusting" (FD: 0.05-0.15 J/100-600 Hz); "dusting" (D: 0.5 J/30-60 Hz); "fragmentation" (Fr: 1 J/15-30 Hz) and two Ho:YAG modes (D: 0.5 J/20 Hz, Fr: 1 J/15 Hz). An experimental setup consisting of immerged cubes of calcium oxalate monohydrate (COM) stone phantoms (Begostone Plus, Bego^©, Lincoln, RI, USA) was used with a 2 s' laser operation time. LF were in contact with the stones, static or with a displacement of 5, 10 or 20 mm. Experiments were repeated four times. Stones were dried and µ-scanned. Ablation volumes (mm³) were measured by 3D-segmentation.

RESULTS

ODV was higher in dusting compared to fragmentation mode during Ho:YAG lithotripsy (10 mm/s vs. 5 mm/s, respectively). With Tm-Fiber, dusting and fragmentation OVDs were similar (5 mm/s). Tm-Fiber ODV was lower than Ho:YAGs in dusting settings (5 mm/s vs. 10 mm/s, respectively). Without LF displacement, ablation volumes were at least two-fold higher with Tm-Fiber compared to Ho:YAG. Despite the LF-DV, we report a 1.5 to 5-fold higher ablation volume with Tm-Fiber compared to Ho:YAG.

CONCLUSIONS

In dusting mode, the ODV^Tm-Fiber is lower compared to ODV^Ho:YAG, translating to a potential easier Tm-Fiber utilization for "painting" dusting technique. The ODV determinants remain unknown. Dynamic ablation volumes are higher to static ones, regardless of the laser source, settings or LF displacement velocity.

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.

Initial clinical experience with the new thulium fiber laser: first 50 cases

OBJECTIVE

To evaluate the efficacy, safety, and laser settings of thulium fiber laser (TFL) in laser lithotripsy during retrograde intrarenal surgery (RIRS) for ureteral and renal stones.

METHODS

A prospective study of the first 50 patients with ureteral and renal stones who underwent RIRS using TFL (SOLTIVE Premium, Olympus, Japan) was performed. 200 and 150 µm laser fibers were used for ureteral and renal stones, respectively. Stone size, stone density, laser-on time (LOT), and laser settings were recorded. We also assessed the ablation speed (mm³/s), laser power (W), and Joules/mm³ values for each lithotripsy.

RESULTS

A total of 50 patients were included in the study with a median (IQR) age of 66 (55.5-74) years old for patients with ureteral stones and 55 (44-61.5) years old for patients with renal stones. Most of the patients had a Charlson comorbidity index score of 0. Median (IQR) stone volume for ureteral stones was 486 (332-1250) mm³ and for renal stones was 1800 (682.8-2760) mm³. Median (IQR) stone density for ureteral and renal stones was 998 (776-1300) HU and 1200 (750-1300) HU, respectively. Median (IQR) pulse energy for ureteral stones was 0.4 (0.2-0.4) J; and for renal stones, 0.3 (0.2-0.6) J. Median pulse frequency, laser power, and laser operative time were higher in the renal stones group. The overall complication rate was low in both groups.

CONCLUSION

TFL is a safe and effective modality for lithotripsy during RIRS with minimal complication rates.