Comparison between the possibilities of holmium and thulium laser in lithotripsy in vitro

Thulium fiber laser cystolithotripsy under local anesthesia: A day care procedure

INTRODUCTION

Bladder stones account for 5% of all urolithiasis. Patients present with LUTS or acute urinary retention. Thus, warranting an early intervention. Minimally invasive approach with laser lithotripsy is the present gold standard to treat bladder stones.

AIMS AND OBJECTIVES

To evaluate the outcomes of TFL (60 W) for bladder stones performed under local anesthesia as a day-care procedure.

MATERIALS AND METHODS

This was a retrospective single-center study conducted after obtaining IRB approval. Study period was between June 2021 and June 2022 were included. All patients were operated under local anesthesia as a day care procedure. The procedure was carried out using an 18 Fr laser sheath and calculus dusted using TFL energy (15-30 W). Parameters including operative time in minutes, complications were recorded. Patients were encouraged oral and normal voiding in the immediate post-op period.

RESULTS

A total of 47 patients with bladder stones presented during this period. Of these, 30 underwent laser lithotripsy (TFL) for bladder calculi. The clinical presentation of patients was LUTS in 28 (93%) and 5 (16%) patients had AUR. The average size of the stone in this series was 15 ± 2.8 mm. The mean duration of laser lithotripsy was 15 ± 5.4 min. Energy to dust the stone was variable with mean LASER energy of 18.23 ± 10 W. All patients tolerated the procedure well and none required conversion to conventional anesthesia. One patient failed to void in the post-op period. 100% clearance rate was documented in all patients.

CONCLUSION

Thulium fiber laser for transurethral cystolithotripsy of bladder stones under local anesthesia is a feasible technique with minimal morbidity and good outcome.

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.

Retrograde intrarenal surgery: laser showdown (Ho:YAG vs thulium fiber laser)

PURPOSE OF REVIEW

Retrograde intrarenal surgery (RIRS) has always been recommended for large stones > 20 mm, using the Ho:YAG laser. The introduction of a new technology in the urological market, the thulium fiber laser (TFL) has revolutionized the endourology world because of its characteristics and significantly shorter laser-on time (LOT) and operative time, without scarifying the champ vision. The aim of this review is to evaluate the most relevant findings of the last 2 years of each laser technology, confronting Ho:YAG vs TFL, analyzing who is more suitable for performing an efficient RIRS.

RECENT FINDINGS

Five full clinical trials using TFL for RIRS were found. Median LOT was between 2.8 and 34 min. All stones were similar in terms of stone volume, >500 mm3, and stone density, > 800 HU. Low complication rate, mostly Clavien-Dindo grade I and II and not related to the laser itself. One clinical trial only analyzed the efficacy of TFL for > 20 mm renal stones.

SUMMARY

Based on this review, TFL performs a more efficient RIRS than the Ho:YAG laser with similar safety.

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.

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.

Advances in laser technology and fibre-optic delivery systems in lithotripsy

The flashlamp-pumped, solid-state holmium:yttrium-aluminium-garnet (YAG) laser has been the laser of choice for use in ureteroscopic lithotripsy for the past 20 years. However, although the holmium laser works well on all stone compositions and is cost-effective, this technology still has several fundamental limitations. Newer laser technologies, including the frequency-doubled, double-pulse YAG (FREDDY), erbium:YAG, femtosecond, and thulium fibre lasers, have all been explored as potential alternatives to the holmium:YAG laser for lithotripsy. Each of these laser technologies is associated with technical advantages and disadvantages, and the search continues for the next generation of laser lithotripsy systems that can provide rapid, safe, and efficient stone ablation. New fibre-optic approaches for safer and more efficient delivery of the laser energy inside the urinary tract include the use of smaller-core fibres and fibres that are tapered, spherical, detachable or hollow steel, or have muzzle brake distal fibre-optic tips. These specialty fibres might provide advantages, including improved flexibility for maximal ureteroscope deflection, reduced cross section for increased saline irrigation rates through the working channel of the ureteroscope, reduced stone retropulsion for improved stone ablation efficiency, and reduced fibre degradation and burnback for longer fibre life.

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

OBJECTIVES

The experimental Thulium fiber laser (TFL) is currently being studied as a potential alternative to the gold standard Holmium:YAG laser for lithotripsy. Recent advances in both Holmium and TFL technology allow operation at similar laser parameters for direct comparison. The use of a "dusting" mode with low pulse energy (0.2-0.4 J) and high pulse rate (50-80 Hz) settings, is gaining popularity in lithotripsy due to the desire to produce smaller residual stone fragments during ablation, capable of being spontaneously passed through the urinary tract.

METHODS

In this study, Holmium and TFL were directly compared for 'dusting' using three laser groups, G1: 0.2 J/50 Hz/10 W; G2: 0.2 J/80 Hz/16 W; and G3: 0.4 J/80 Hz/32 W. Holmium laser pulse durations ranged from 200 to 350 μs, while TFL pulse durations ranged from 500 to 1,000 μs, due to technical limitations for both laser systems. An experimental setup consisting of 1 × 1 cm cuvette with 1 mm sieve was used with continuous laser operation time limited to ≤5 minutes. Calcium oxalate monohydrate stone samples with a sample size of n = 5 were used for each group, with average initial stone mass ranging from 216 to 297 mg among groups.

RESULTS

Holmium laser ablation rates were lower than for TFL at all three settings (G1: 0.3 ± 0.2 vs. 0.8 ± 0.2; G2: 0.6 ± 0.1 vs. 1.0 ± 0.4; G3: 0.7 ± 0.2 vs. 1.3 ± 0.9 mg/s). The TFL also produced a greater percentage by mass of stone dust (fragments <0.5 mm) than Holmium laser. For all three settings combined, one out of 15 (7%) stones treated with Holmium laser were completely fragmented in ≤5 minutes compared to nine out of 15 (60%) stones treated with TFL.

CONCLUSIONS

These preliminary studies demonstrate that the TFL is a promising alternative laser for lithotripsy when operated in dusting mode, producing higher stone ablation rates and smaller stone fragments than the Holmium laser. Clinical studies are warranted. Lasers Surg. Med. 51:522-530, 2019. © 2019 Wiley Periodicals, Inc.

Recent advances in infrared laser lithotripsy [Invited]

The flashlamp-pumped, solid-state, pulsed, mid-infrared, holmium:YAG laser (λ = 2120 nm) has been the clinical gold standard laser for lithotripsy for over the past two decades. However, while the holmium laser is the dominant laser technology in ureteroscopy because it efficiently ablates all urinary stone types, this mature laser technology has several fundamental limitations. Alternative, mid-IR laser technologies, including a thulium fiber laser (λ = 1908 and 1940 nm), a thulium:YAG laser (λ = 2010 nm), and an erbium:YAG laser (λ = 2940 nm) have also been explored for lithotripsy. The capabilities and limitations of these mid-IR lasers are reviewed in the context of the quest for an ideal laser lithotripsy system capable of providing both rapid and safe ablation of urinary stones.

Advances in Lasers for the Treatment of Stones-a Systematic Review

PURPOSE OF REVIEW

Laser lithotripsy is increasingly used worldwide and is a continuously evolving field with new and extensive research being published every year.

RECENT FINDINGS

Variable pulse length Ho:YAG lithotripters allow new lithotripsy parameters to be manipulated, and there is an effort to integrate new technologies into lithotripters. Pulsed thulium lasers seem to be a viable alternative to holmium lasers. The performance of similar laser fibers varies from manufacturer to manufacturer. Special laser fibers and "cleaving only" fiber tip preparation can be beneficial for the lithotripsy procedure. Different laser settings and the surgical technique employed can have significant impact on the success of laser lithotripsy. When safely done, complications of laser lithotripsy are rare and concern the endoscopic nature of procedure, not the technology itself, making laser lithotripsy one of the safest tools in urology. Laser lithotripsy has had several new developments and more insight has been gained in recent years with many more advances expected in the future.