MP24-10 WAVELENGTH AND PULSE SHAPE EFFECTS ON STONE FRAGMENTATION OF LASER LITHOTRIPTERS

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.

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.

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.

Ho: YaG laser lithotripsy: recent innovations

PURPOSE OF REVIEW

The aim of this study was to summarize the recent innovations of the holmium laser with special respect to lithotripsy. Therefore, we reviewed and discussed the most recent and pivotal publications on this topic.

RECENT FINDINGS

The current literature underlines Holmium:yttrium-aluminium-garnet (Ho:YAG) lithotripsy as a well tolerated and efficient method to treat urinary calculi. Because of modifiable adjustments of pulse energy, pulse frequency, and pulse length, especially with newer generations of holmium lasers, urologists can accurately choose between the 'fragmentation' and 'dusting' technique with its alterations. Recently, the 'Moses mode' as a new feature incorporated in the Lumenis Pulse P120H holmium laser showed less retropulsion with higher rates of stone ablation because of an improved energy transmission from the laser fiber towards the targeted calculus in in-vitro studies.

SUMMARY

Based on technological developments, Ho:YAG laser lithotripsy has become more efficient in reducing retropulsion and increasing stone ablation volume. However, despite its widespread use as a lithotripter, a newly developed thulium fiber laser, which has already shown promising results in experimental studies, could become an alternative in future practice.

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.