Current use of thulium lasers in endourology and future perspectives / Uso actual del láser de tulio en endourología y perspectivas de futuro

Thulium lasers operate at wavelengths between 1940-2013 nm either in a continuous wave or in a pulsed mode, which enables smooth incisions with fast vaporization or effective laser lithotripsy for urolithiasis. Thulium laser enucleation is a minimally invasive and size-independent treatment for benign prostatic hyperplasia (BPH) with excellent long-term results. Since its introduction, several modifications in the technology and surgical techniques have been proposed such as vaporesection, vaporization and enucleation with regard to BPH treatment. Recent developments in the thulium laser technology include the introduction of a super pulsed thulium fiber laser. This technique delivers the laser energy through an active fiber with an absorption maximum in water at a wavelength of 1940 μm. Preclinical studies showed a significantly higher stone fragmentation rate in different ex vivo models compared to the Ho:YAG laser. Another innovative thulium laser that works, as a hybrid laser has yet not been tested clinically, however, will soon be introduced. With the introduction of both new thulium lasers as novel devices, the armamentarium in the field of endourology for lithotripsy and enucleation increases. We here present different thulium lasers and surgical techniques that are possible to perform with each device including the reasons and advantages of each modification

El láser de tulio opera entre 1940 y 2013 nm en onda continua o pulsada. Esto permite incisiones sencillas y una vaporización rápida o una litotricia láser para el tratamiento de las litiasis urinarias. La enucleación con láser tulio es mínimamente invasiva e independiente del tamaño de la hiperplasia benigna de próstata con excelentes resultados a largo plazo. Desde su introducción, varias modificaciones en la tecnología y en la técnica quirúrgica se han propuesto como la vaporesección, la vaporización y la enucleación. El desarrollo reciente de la tecnología del láser tulio incluye la introducción de una fibra de láser de superpulsación. Esta técnica administra la energía del láser a través de una fibra activa con una absorción máxima a 1940 nm. Estudios preclínicos han demostrado una mejor fragmentación de las litiasis en diferentes modelos ex vivo en comparación con láser Ho:YAG. Otra innovación del laser tulio es que funciona como un láser híbrido, pero aun no se ha testado clínicamente. Con la introducción de nuevas tecnologías en láser, el conjunto de técnicas en endourología y enucleación incrementa. En este resumen presentamos los diferentes lásers tulio y las técnicas quirúrgicas que son posibles de realizar con cada aparato, incluyendo el racional y las ventajas para cada modificación

Effect of ureteral calculus in outpatients receiving semirigid ureteroscope laser lithotripsy.

The surgical outcomes of patients with single ureteral stones who had undergone ureteroscopic Holmium laser lithotripsy as outpatients and compare them with those of patients who had received the same procedure as inpatients. Records were obtained from January 2012 to December 2016 for selected patients who had undergone the above mentioned procedure at our institution. Patients were excluded if their ECOG performance status was ≥2, presented with multiple stones or concomitant renal stones, had histories of cancer or congenital urinary system abnormalities, or had undergone urinary system reconstruction surgery. Patients could decide whether to receive the procedure as an outpatient or inpatient. All surgeries were performed by a single surgeon. Patients preoperative, operative, and postoperative data were recorded. The clinical results, such as urinary tract infection, analgesic requirement, rate of returning to the emergency room, stone clearance, surgical complications, and medical expenditure for the treatment courses were analyzed and compared between the 2 cohorts. In total, 303 patients met the inclusion criteria. Among them, 119 patients decided to receive ureteroscopic laser lithotripsy as outpatients, whereas 184 decided to be inpatients. The outpatient cohort was younger (P < .001), had smaller stone diameters (P < .001), and fewer comorbidity factors (P = .038). Patients with a history of stone manipulation favored receiving the procedure under admission (P < .001). After 1:1 propensity score matching, no significant differences were discovered between the cohorts with regard to operative time, rate of lithotripsy failure, and operative complications. Furthermore, rates of stone clearance, post-op urinary tract infection, analgesic requirement, and returning to the emergency room were comparable between the 2 groups. However, the medical expenditure was significantly lower in the outpatient cohort (P < .001). Our data revealed that outpatient ureteroscopic lithotripsy with a Holmium laser was more economical compared with the inpatient group and achieved favorable outcomes for patients with a single ureteral stone.

New devices for kidney stone management.

PURPOSE OF REVIEW: The purpose of this review is to summarize recent developments in the array of devices which are commonly used by urologists in the surgical management of kidney stones. To accomplish this goal, an extensive review of recent endourology literature, conference abstracts, and publicly available documents from manufacturers and the United States Food and Drug Administration was collected and reviewed. RECENT FINDINGS: Recent developments in the holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy include the introduction of pulse modulation. This technique delivers the laser energy in an asymmetric manner such that an initial bubble is created (the 'Moses effect') through which the remainder of the energy can then travel through without being absorbed by surrounding water. Even more novel is the thulium fiber laser, which is produced in a fundamentally different way than traditional Ho:YAG lasers and is not yet available for clinical use. Finally, novel mechanical lithotrites which effectively combine ultrasonic energy, ballistic energy, and suction capability appear to be highly effective for stone clearance in recent benchtop and clinical studies. SUMMARY: With the introduction of both new modifications of time-tested technologies as well as completely novel modalities, the practicing urologist's armamentarium of devices for the surgical management of kidney stones continues to grow. As the popularity of 'mini' procedures continues to grow, the adaptability of these technologies to these procedures will be critical to maintain maximum relevance.

Lasers for stone treatment: how safe are they?

PURPOSE OF REVIEW: To update laser lithotripsy advances in regard to new laser types and technologies as well as review contemporary laser safety concerns. RECENT FINDINGS: The high prevalence of urolithiasis and the continuing miniaturization of scopes has encouraged the growth of laser lithotripsy technology. The holmium:yttrium-aluminum-garnet (Ho:YAG) laser has been used for over 20 years in endourology and has been extensively studied. Holmium laser power output is affected by a number of factors, including pulse energy, pulse frequency, and pulse width. Several recent experimental studies suggest that the new dual-phase Moses 'pulse modulation' technology, introduced in high-power laser machines, carries a potential to increase stone ablation efficiency and decrease stone retropulsion. A newly introduced thulium fiber laser (TFL) has been adapted to a very small laser fiber size and is able to generate very low pulse energy and very high pulse frequency. Both of these technologies promise to play a larger role in laser lithotripsy in the near future. However, more experimental and clinical studies are needed to expand on these early experimental findings. Even though laser lithotripsy is considered safe, precautions should be taken to avoid harmful or even catastrophic adverse events to the patient or the operating room staff. SUMMARY: The Ho:YAG laser remains the clinical gold standard for laser lithotripsy for over the last two decades. High-power Ho:YAG laser machines with Moses technology have the potential to decrease stone retropulsion and enhance efficiency of laser ablation. The new TFL has a potential to compete with and perhaps even replace the Ho:YAG laser for laser lithotripsy. Safety precautions should be taken into consideration during laser lithotripsy.

Emerging Laser Techniques for the Management of Stones.

Next-generation holmium laser systems provide the user with a range of parameters that can help optimize fragmentation efficiency. Ureteroscopic strategies broadly consist of fragmentation with active retrieval, or dusting, which uses low pulse energy settings to break stones into fine fragments for spontaneous passage. Techniques for dusting include dancing, chipping, and popcorning. The Moses technology is a multipulse mode that may help reduce retropulsion and increase fragmentation. The thulium fiber laser is an emerging laser technology that provides an extensive parameter range for dusting. Future studies are needed to define the role of these technologies and techniques for laser lithotripsy.

How to perform the dusting technique for calcium oxalate stone phantoms during Ho:YAG laser lithotripsy.

BACKGROUND: To determine the most efficacious setting of Holmium:yttrium-aluminum-garnet (Ho:YAG) laser with a maximum power output of 120 W with in vitro phantom-stone dusting technique. METHODS: A laser was used to treat two 4 × 3 × 3 mm3 sized phantom stones in 5 mL syringes with 1 mm-sized holes at the bottom. According to the pulse width (short 500, middle 750, long pulse 1000 µsec), maximal pulse repetition rates from 50 to 80 Hz were tested with pulse energy of 0.2, 0.4, 0.5, and 0.8 J. Six times of the mean dusting times were measured at each setting. Dusting was performed at continuous firing of the laser until the stones become dusts < 1 mm. RESULTS: The mean Hounsfield unit of phantom stones was 1309.0 ± 60.8. The laser with long pulse generally showed shorter dusting times than short or middle pulse width. With increasing the pulse energy to 0.5 J, the dusting time decreased. However, the pulse energy of 0.8 J showed longer dusting times than those of 0.5 J. On the post-hoc analysis, the pulse energy of 0.5 J, long pulse width, and the repetition rates of 70 Hz demonstrated significantly shorter dusting times than other settings. CONCLUSIONS: The results suggest that long pulse width with 0.5 J and 70 Hz would be the most efficacious setting for dusting techniques of plaster stone phantoms simulating calcium oxalate stones using the 120 W Ho:YAG laser.

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.

Trends of 'urolithiasis: interventions, simulation, and laser technology' over the last 16 years (2000-2015) as published in the literature (PubMed): a systematic review from European section of Uro-technology (ESUT).

PURPOSE: To look at the bibliometric publication trends on 'Urolithiasis' and aspects of treatment and training associated with it over a period of 16 years from 2000 to 2015. To this end, we conducted this study to look at the publication trends associated with urolithiasis, including the use of simulation, laser technology, and all types of interventions for it. MATERIALS AND METHODS: We performed a systematic review of the literature using PubMed over the last 16 years, from January 2000 to December 2015 for all published papers on 'Urolithiasis'. While there were no language restrictions, English language articles and all non-English language papers with published English abstracts were also included. Case reports, animal and laboratory studies, and those studies that did not have a published abstract were excluded from our analysis. We also analyzed the data in two time periods, period-1 (2000-2007) and period-2 (2008-2015). RESULTS: During the last 16 years, a total of 5343 papers were published on 'Urolithiasis', including 4787 in English language and 556 in non-English language. This included papers on URS (n = 1200), PCNL (n = 1715), SWL (n = 887), open stone surgery (n = 87), laparoscopic stone surgery (n = 209), pyelolithotomy (n = 35), simulation in Endourology (n = 82), and use of laser for stone surgery (n = 406). When comparing the two time periods, during period 2, the change was +171% (p = 0.007), +279% (p < 0.001), and -17% (p = 0.2) for URS, PCNL, and SWL, respectively. While there was a rise in laparoscopic surgery (+116%), it decreased for open stone surgery (-11%) and pyelolithotomy (-47%). A total of 82 papers have been published on simulation for stone surgery including 48 papers for URS (67% rise in period-2, p = 0.007), and 34 papers for PCNL (480% rise in period-2, p < 0.001). A rising trend for the use of laser was also seen in period 2 (increase of 126%, p < 0.02, from 124 papers to 281 papers). CONCLUSIONS: Published papers on intervention for Urolithiasis have risen over the last 16 years. While there has been a steep rise of URS and minimally invasive PCNL techniques, SWL and open surgery have shown a slight decline over this period. A similar increase has also been seen for the use of simulation and lasers in Endourology.

Temporal Trends and Treatment Outcomes of Flexible Ureteroscopy for Lower Pole Stones in a Tertiary Referral Stone Center.

INTRODUCTION: To evaluate trends in efficacy and safety of flexible ureteroscopy (fURS) for the treatment of lower pole stones (LPS) over a 6-year period and to compare the annual outcomes after one fURS procedure retrospectively. PATIENTS AND METHODS: Four hundred nine patients were treated for pure LPS. An analysis of the annual outcomes regarding patient characteristics, operative parameters, stone-free rates (SFRs), and complication rates (CRs) was performed. The SFR was stratified according to stone size and number of stones per patient. Patient data are expressed as mean±standard deviation. RESULTS: There were no annual differences regarding age, body-mass index, stone size (7.09±4.31 mm), number of stones per patient (1.66±2.86), operative time (52.93±33.58 minutes), use of postoperative stents (59.2%), and the Ho:YAG laser lithotripsy rate (49.4%) during the 6-year period. Total primary SFR (annual range) of 97.6% (88.2%-100%), 89.1% (82.9%-96.3%), 71% (60%-78.6%) for urinary calculi <5 mm (3.43±0.78 mm), 5-9 mm (6.69±1.34 mm), and ≥10 mm (13.09±6.02 mm) could be demonstrated over the 6-year period. The total SFR differed significantly between urinary calculi <5 mm, 5-9 mm, and those ≥10 mm (p<0.0179). The SFR (annual range) decreased from 90% (86.2%-95.4%) in patients with 1 stone to 84.1% (60%-100%) in those with ≥3 stones. Perioperative complications (annual range) occurred in 9.7% (6%-13.6%) of the patients (Clavien I 5.1% [1.2%-8.6%], Clavien II 2% [0%-4.9%], Clavien IIIa 0.9% [0%-3.4%], Clavien IIIb 1.7% [1.2%-4.8%]) without differences in the annual CR. CONCLUSIONS: fURS is a safe and efficacious procedure for the treatment of LPS with high primary SFR and low CR. fURS in larger LPS (≥10 mm) is associated with the risk for staged procedures.

Update on intracorporeal laser lithotripsy.

Nowadays, rigid and flexible ureteroscopy is a precise, minimal invasive surgery that can assess the entire collecting system in order to treat a stone with intracorporeal lithotripsy. The implication of laser technology has revolutionized the intracorporeal lithotripsy. Currently, laser lithotripsy is advancing in two different directions: improvements of the existing Ho:YAG laser platform and the development of novel laser systems. Herein, we review the current literature upon intracorporeal lithotripsy.

Surgical management of stones: new technology.

In recent years, the surgical treatment of kidney stone disease has undergone tremendous advances, many of which were possible only as a result of improvements in surgical technology. Rigid intracorporeal lithotrites, the mainstay of percutaneous nephrolithotomy, are now available as combination ultrasonic and ballistic devices. These combination devices have been reported to clear a stone burden with much greater efficiency than devices that operate by either ultrasonic or ballistic energy alone. The laser is the most commonly used flexible lithotrite; advances in laser lithotripsy have led to improvements in the currently utilized Holmium laser platform, as well as the development of novel laser platforms such as Thulium and Erbium devices. Our understanding of shock wave lithotripsy (SWL) has been improved over recent years as a consequence of basic science investigations. It is now recognized that there are certain maneuvers with SWL that the treating physician can do that will increase the likelihood of a successful outcome while minimizing the likelihood of adverse treatment-related events.

Clinical trials of the surgical management of urolithiasis: current status and future needs.

We reviewed the literature on the surgical treatment of urolithiasis. All prospective, randomized trials on the surgical treatment of stone disease were reviewed. Percutaneous nephrolithotomy (PNL) is superior to shockwave lithotripsy (SWL) or open surgery in the treatment of staghorn calculi. For ureteral stones, ureteroscopy appears to result in a higher stone-free rate and lower need for retreatment compared with SWL but has a higher complication rate and increased hospital stay. For lower pole renal calculi, PNL results in a higher stone-free rate and lower need for retreatment compared with SWL but has a higher complication rate and increased hospital stay. Most areas of surgical stone treatment have been addressed by a randomized controlled trial; however, most trials were of poor quality. Trials tend to focus only on radiologic outcomes. No study to date has been able to show a measurable quality of life benefit to patients, possibly because no condition-specific quality of life instruments have been developed. In addition, economic impact, both direct and indirect, has been rarely characterized. The surgical treatment of kidney stones is poorly researched. Future trials should be performed with adequate funding and patient-focused outcomes.

The future of lasers in urology.

The use of laser applications in urology has undergone significant advances over the past 20 years. Laser technology is now used in a wide variety of procedures, and has become the primary treatment modality or standard of care for many urologic conditions. Despite these advances, a number of challenges still face laser utilization in urologic practice. Recent work has illuminated the potential improvement and further optimization of this field. Improvements in types of lasers, the wavelength of energy used, optical fiber delivery systems, precision of laser application and cost reduction have served to further improve laser technology and extend the potential applications.

Management of lower-pole caliceal stones.

A series of 205 urologists answered questions about their choice of treatment for lower-caliceal stones. The preferred approaches were extracorporeal shockwave lithotripsy (SWL) for stones <1 cm and percutaneous nephrolithotomy (PCNL) for those >2 cm. For stones of 1 to 2 cm, 65% preferred SWL and 30% would advise PCNL. Thus, SWL is recommended for lower-caliceal stones more frequently than is justified by published success rates. Continued efforts need to be made to inform practicing urologists regarding the most appropriate therapy for patients with lower-pole stones >1 cm.

[The change in laser usage in gastroenterology--the status in 1997]. / Wandel der Laseranwendung in der Gastroenterologie--Stand 1997.

Since the establishing of laser technology in gastroenterology there has been a change in the indications for laser therapy and numerous new laser systems have been introduced in basic and clinical research. First the argon laser and later on the Nd:YAG laser were used mainly for bleeding peptic lesions, today emphasis is on palliative desobliteration of advanced esophageal and rectosigmoidal carcinoma. Moreover, in selected cases it is used for curative ablation of early carcinoma and dysplasia. A new field of application is photocoagulation of the "watermelon stomach". Despite of promising ablation results the erbium:YAG and holmium:YAG laser became not yet established in gastroenterology. Also the KTP laser is rarely used e.g. for treatment of telangiectasia. Difficult bile duct stones can be highly effective fragmented intracorporally by means of laser lithotripsy; an automatic stone-tissue discrimination system avoids uncontrolled injury of the bile ducts. The hitherto experimental interstitial laser therapy of primary and secondary liver malignancies shows excellent results, but online monitoring of the expansion of the necrosis is still a problem. Thermal probes, MRT technology and duplex sonography are under current evaluation. Photodynamic therapy (PDT) is now, after numerous pilot studies, investigated with larger numbers of patients. First results show a marked effectiveness in ablation of dysplasia and mucosal carcinoma. The photosensitizer 5-aminolaevulinic acid seems to be particularly effective for ablation of Barrett's mucosa and m-THPC for treatment of local carcinoma. Palliative PDT of bile duct cancer may help to avoid repeated endoprosthetic treatment. The possibilities and limitations of light induced fluorescence diagnostics of severe dysplasia and carcinoma in situ is now being evaluated intensively. This method might in future facilitate the endoscopic diagnosis of dysplasia in Barrett's esophagus and chronic inflammatory bowel disease.