Tissue effects of a newly developed diode pumped pulsed Thulium:YAG laser compared to continuous wave Thulium:YAG and pulsed Holmium:YAG laser

A prospective analysis of thulium laser enucleation in benign prostatic hyperplasia comparing low- and high-power approaches for prostates exceeding 80 g

INTRODUCTION AND OBJECTIVES

To compare the perioperative and functional outcomes of low-power and high-power thulium:YAG VapoEnucleation (ThuVEP) of the prostate for the treatment of large-volume benign prostatic hyperplasia (BPH) (> 80 ml).

PATIENTS AND METHODS

A prospective analysis of 80 patients with symptomatic BPO and prostatic enlargement (more than 80 ml) was conducted. They were divided randomly into two groups (40 patients in each group). One group was treated with low-power ThuVEP, and the other group was treated with high-power ThuVEP. All patients were assessed preoperatively and early postoperatively, and 12-month follow-up data were analyzed. The complications were noted and classified according to the modified Clavien classification system.

RESULTS

The mean age at surgery was 68 (± 6.1) years, and the mean prostate volume was 112 (± 20.1) cc, and there were no differences between the groups (p = 0.457). The mean operative time was 88.4 ± 11.79 min for group A and 93.4 ± 16.34 min for group B, while the mean enucleation time was 59.68 ± 7.24 min for group A and 63.13 ± 10.75 min for group B. There were no significant differences between the groups regarding catheterization time and postoperative stay. The quality of life (QoL), International Prostate Symptom Score (IPSS), maximum urinary flow rate (Qmax), postvoiding residual urine (PVR), and prostate volume improved significantly after treatment and were not significantly different between those treated with the different energies. The incidence of complications was low and did not differ between both the groups.

CONCLUSION

Low-power ThuVEP is feasible, safe, and effective with comparable results with high-power ThuVEP in the treatment of BPO.

Laser Technology Advancements in the Treatment of Benign Prostatic Hypertrophy

PURPOSE OF REVIEW

Lasers have had a significant impact on the treatment of benign prostatic hypertrophy. This article attempts to distill the advancements in laser technology for the treatment of benign prostatic hypertrophy (BPH) into key and understandable points to help make this topic more accessible to urologists.

RECENT FINDINGS

The holmium:yttrium-aluminum-garnet (YAG) laser, one of the most significant lasers in the field of urology, has recently been improved with pulse modulating technology (Moses™ technology). New thulium:YAG technology allows both pulsed and continuous wave modes. The thulium fiber laser is one of the newer lasers to come to market and has been shown to have effective and safe outcomes. GreenLight™ lasers are predominantly used in photovaporization procedures and have also been studied extensively, although less in recent years. The modern urologist is fortunate to have many high-quality lasers and a wide variety of surgical techniques to choose from when treating BPH. Understanding the basic laser principles and applications will help urologists to select the best treatment options for their patients with BPH.

Experts' recommendations in laser use for the treatment of bladder cancer: a comprehensive guide by the European Section of Uro-Technology (ESUT) and Training and Research in Urological Surgery and Technology (TRUST)-Group

PURPOSE

To identify laser settings and limits applied by experts during laser vaporization (vapBT) and laser en-bloc resection of bladder tumors (ERBT) and to identify preventive measures to reduce complications.

METHODS

After a focused literature search to identify relevant questions, we conducted a survey (57 questions) which was sent to laser experts. The expert selection was based on clinical experience and scientific contribution. Participants were asked for used laser types, typical laser settings during specific scenarios, and preventive measures applied during surgery. Settings for a maximum of 2 different lasers for each scenario were possible. Responses and settings were compared among the reported laser types.

RESULTS

Twenty-three of 29 (79.3%) invited experts completed the survey. Thulium fiber laser (TFL) is the most common laser (57%), followed by Holmium:Yttrium-Aluminium-Garnet (Ho:YAG) (48%), continuous wave (cw) Thulium:Yttrium-Aluminium-Garnet (Tm:YAG) (26%), and pulsed Tm:YAG (13%). Experts prefer ERBT (91.3%) to vapBT (8.7%); however, relevant limitations such as tumor size, number, and anatomical tumor location exist. Laser settings were generally comparable; however, we could find significant differences between the laser sources for lateral wall ERBT (p = 0.028) and standard ERBT (p = 0.033), with cwTm:YAG and pulsed Tm:YAG being operated in higher power modes when compared to TFL and Ho:YAG. Experts prefer long pulse modes for Ho:YAG and short pulse modes for TFL lasers.

CONCLUSION

TFL seems to have replaced Ho:YAG and Tm:YAG. Most laser settings do not differ significantly among laser sources. For experts, continuous flow irrigation is the most commonly applied measure to reduce complications.

Advances in lasers for the minimally invasive treatment of upper and lower urinary tract conditions: a systematic review

PURPOSE

Technological advancements in laser lithotripsy are expanding into numerous fields of urology, like ureteroscopy (URS), percutaneous nephrolithotomy (PCNL), and benign and malignant soft-tissue treatments. Since the amount of research regarding lasers in urology has grown exponentially, we present a systematic review of the most recent and relevant advances encompassing all lasers used in urological endoscopic treatment.

METHODS

We performed a literature search using PubMed (May 2023) to obtain information about lasers for urological purposes. We included only recent data from published articles between 2021 and 2023 or articles ahead of print.

RESULTS

Lasers are widely used in lithotripsy for ureteric, renal, and bladder stones, benign prostate surgery, and bladder and upper tract tumor ablation. While the holmium (Ho:YAG) laser is still predominant, there seems to be more emphasis on pulse modulation and newer lasers such as thulium fiber laser (TFL) and pulsed Tm:YAG laser.

CONCLUSION

The use of lasers and related technological innovations have shown increasing versatility, and over time have proven to be invaluable in the management of stone lithotripsy, treatment of benign and malignant prostate diseases, and urothelial tumors. Laser endoscopic treatment is heavily based on technological nuances, and it is essential to know at least the basics of these technologies. Ultimately the choice of laser used depends on its availability, cost, surgeon experience and expertise.

Novel laser therapies and new technologies in the endoscopic management of upper tract urothelial carcinoma: a narrative review

Background and Objective

Upper tract urothelial carcinoma (UTUC) is a rare disease. The gold standard treatment is radical nephroureterectomy (RNU). Endoscopic management of UTUC has emerged as an alternative therapy that aims to preserve kidney function while providing effective oncologic control. Over the years, this has become an increasingly important alternative to RNU for treating UTUC in patients with localized disease. Advancements in lasers and endoscopic technology have continued to expand the applications of endoscopic nephron-sparing treatment. This review aims to provide an overview of the available lasers and ureteroscopic technologies used in treating UTUC with a focus on their clinical applications and outcomes.

Methods

A comprehensive literature review was completed using PubMed to create this narrative mini review. Publications from peer-reviewed journals written in English between 1987 to 2022 were evaluated by the authors for inclusion.

Key Content and Findings

Improvements in ureteroscopic technology have led to improved visualization and tumor detection. Laser ablation using different laser energies including the holmium/yttrium-aluminum-garnet, neodymium/YAG, and thulium/YAG has demonstrated promising oncologic outcomes. However, accurate staging and risk-stratification remain limitations to the role of laser ablation for the treatment of UTUC. This review also highlights appropriate patient selection as a critical component of successful endoscopic management.

Conclusions

The continued evolution of endoscopic management will rely on the development of new technologies to improve risk stratification and oncologic outcomes. Overall, this review provides insights into the available laser therapies and ureteroscopic technologies for the endoscopic management of UTUC.

Experts' recommendations in laser use for the endoscopic treatment of prostate hypertrophy: a comprehensive guide by the European Section of Uro-Technology (ESUT) and Training-Research in Urological Surgery and Technology (T.R.U.S.T.)-Group

PURPOSE

To identify expert laser settings for BPH treatment and evaluate the application of preventive measures to reduce complications.

METHODS

A survey was conducted after narrative literature research to identify relevant questions regarding laser use for BPH treatment (59 questions). Experts were asked for laser settings during specific clinical scenarios. Settings were compared for the reported laser types, and common settings and preventive measures were identified.

RESULTS

Twenty-two experts completed the survey with a mean filling time of 12.9 min. Ho:YAG, Thulium fiber laser (TFL), continuous wave (cw) Tm:YAG, pulsed Tm:YAG and Greenlight™ lasers are used by 73% (16/22), 50% (11/22), 23% (5/22), 13.6% (3/22) and 9.1% (2/22) of experts, respectively. All experts use anatomical enucleation of the prostate (EEP), preferentially in one- or two-lobe technique. Laser settings differ significantly between laser types, with median laser power for apical/main gland EEP of 75/94 W, 60/60 W, 100/100 W, 100/100 W, and 80/80 W for Ho:YAG, TFL, cwTm:YAG, pulsed Tm:YAG and Greenlight™ lasers, respectively (p = 0.02 and p = 0.005). However, power settings within the same laser source are similar. Pulse shapes for main gland EEP significantly differ between lasers with long and pulse shape modified (e.g., Moses, Virtual Basket) modes preferred for Ho:YAG and short pulse modes for TFL (p = 0.031).

CONCLUSION

Ho:YAG lasers no longer seem to be the mainstay of EEP. TFL lasers are generally used in pulsed mode though clinical applicability for quasi-continuous settings has recently been demonstrated. One and two-lobe techniques are beneficial regarding operative time and are used by most experts.

What to expect from the novel pulsed thulium:YAG laser? A systematic review of endourological applications

INTRODUCTION

Several preclinical studies about a novel pulsed-thulium:yttrium-aluminum-garnet (p-Tm:YAG) device have been published, demonstrating its possible clinical relevance.

METHODS

We systematically reviewed the reality and expectations for this new p-Tm:YAG technology. A PubMed, Scopus and Embase search were performed. All relevant studies and data identified in the bibliographic search were selected, categorized, and summarized.

RESULTS

Tm:YAG is a solid state diode-pumped laser that emits at a wavelength of 2013 nm, in the infrared spectrum. Despite being close to the Ho:YAG emission wavelength (2120 nm), Tm:YAG is much closer to the water absorption peak and has higher absorption coefficient in liquid water. At present, there very few evaluations of the commercially available p-Tm:YAG devices. There is a lack of information on how the technical aspects, functionality and pulse mechanism can be maximized for clinical utility. Available preclinical studies suggest that p-Tm:YAG laser may potentially increase the ablated stone weight as compared to Ho:YAG under specific condition and similar laser parameters, showing lower retropulsion as well. Regarding laser safety, a preclinical study observed similar absolute temperature and cumulative equivalent minutes at 43° C as compared to Ho:YAG. Finally, laser-associated soft-tissue damage was assessed at histological level, showing similar extent of alterations due to coagulation and necrosis when compared with the other clinically relevant lasers.

CONCLUSIONS

The p-Tm:YAG appears to be a potential alternative to the Ho:YAG and TFL according to these preliminary laboratory data. Due to its novelty, further studies are needed to broaden our understanding of its functioning and clinical applicability.

Experts' recommendations in laser use for the treatment of upper tract urothelial carcinoma: a comprehensive guide by the European Section of Uro-Technology (ESUT) and Training Research in Urological Surgery and Technology (T.R.U.S.T.) group

PURPOSE

To highlight and compare experts' laser settings during endoscopic laser treatment of upper tract urothelial carcinoma (UTUC), to identify measures to reduce complications, and to propose guidance for endourologists.

METHODS

Following a focused literature search to identify relevant questions, a survey was sent to laser experts. We asked participants for typical settings during specific scenarios (ureteroscopy (URS), retrograde intrarenal surgery (RIRS), and percutaneous treatment). These settings were compared among the reported laser types to find common settings and limits. Additionally, we identified preventive measures commonly applied during surgery.

RESULTS

Twenty experts completed the survey, needing a mean time of 12.7 min. Overall, most common laser type was Holmium-Yttrium-Aluminum-Garnet (Ho:YAG) (70%, 14/20) followed by Thulium fiber laser (TFL) (45%, 9/20), pulsed Thulium-Yttrium-Aluminum-Garnet (Tm:YAG) (3/20, 15%), and continuous wave (cw)Tm:YAG (1/20, 5%). Pulse energy for the treatment of distal ureteral tumors was significantly different with median settings of 0.9 J, 1 J and 0.45 J for Ho:YAG, TFL and pulsed Tm:YAG, respectively (p = 0.048). During URS and RIRS, pulse shapes were significantly different, with Ho:YAG being used in long pulse and TFL in short pulse mode (all p < 0.05). We did not find further disparities.

CONCLUSION

Ho:YAG is used by most experts, while TFL is the most promising alternative. Laser settings largely do not vary significantly. However, further research with novel lasers is necessary to define the optimal approach. With the recent introduction of small caliber and more flexible scopes, minimal-invasive UTUC treatment is further undergoing an extension of applicability in appropriately selected patients.

Learning from the past and present to change the future: Endoscopic management of upper urinary tract urothelial carcinoma

Current guidelines recommend endoscopic management (EM) for patients with low-risk upper urinary tract urothelial carcinoma, as well as those with an imperative indication. However, regardless of the tumor risk, radical nephroureterectomy is still mainly performed worldwide despite the benefits of EM, such as renal function maintenance, no hemodialysis requirement, and treatment cost reduction. This might be explained by the association of EM with a high risk of local recurrence and progression. Furthermore, the need for rigorous patient selection and close surveillance following EM may be relevant. Nevertheless, recent developments in diagnostic modalities, pathological evaluation, surgical devices and techniques, and intracavitary regimens have been reported, which may contribute to improved risk stratification and treatments with superior oncological outcomes. In this review, considering recent advances in endourology and oncology, we propose novel treatment strategies for optimal EM.

Current laser therapy options for endoscopic treatment of upper tract urothelial carcinoma

Endoscopic management via retrograde ureteroscopic laser ablation of upper tract urothelial carcinoma (UTUC) has become the preferred treatment modality for low-risk tumors. The most popular ablative lasers over the past 15-20 years have been the holmium:yttrium-aluminum-garnet (Ho:YAG) and neodymium (Nd:YAG) lasers, but recently the thulium (Th:YAG) laser has emerged as a potential alternative. This review compares the mechanism of action, physiological properties and effects, and oncologic outcomes of Ho:YAG/Nd:YAG lasers versus the Th:YAG laser for UTUC treatment. Potential advantages of the Th:YAG laser over existing technologies are outlined, followed by a discussion of emerging laser technologies in UTUC management.

Tissue thermal effect during lithotripsy and tissue ablation in endourology: a systematic review of experimental studies comparing Holmium and Thulium lasers

PURPOSE

We looked into the Thulium: yttrium-aluminum-garnet (TM:YAG), Thulium Fibre laser (TFL) and Holmium: yttrium-aluminum-garnet (Ho:YAG) thermal laser tissue effect during lithotripsy and tissue ablation.

METHODS

We performed a PubMed, Scopus, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) search.

RESULTS

During lithotripsy, the Ho:YAG generated temperatures from 24 to 68.7 °C at powers < 20 W, the Tm:YAG from 43.7 °C at 30 W to 68 °C at powers < 20 W, and the TFL from 33 to 40.46 °C. During ablation, the Ho:YAG and continuous wave (cw) Tm:YAG tissue incision depths ranged from 0.08 to 2.26 mm, and from 0.28 to 3.22 mm. The Ho:YAG and Tm:YAG vaporization areas ranged from 0.044 to 0.078 mm² and from 0.050 to 0.078 mm³ and their coagulation zones were 0.075 mm² and 0.125 mm³ respectively. Ho:YAG and Tm:YAG laser damage zones ranged from 0.093 to 2.6 mm³ and from 0.207 to 0.98 mm³ respectively. The TFL incision depth ranged from 0.04 to 5.7 mm. The cw and SuperPulsed (SP) vaporization volumes ranged from 8 to 28.2 mm³/s and from 4 to 11 mm³/s. TFL coagulation depth and coagulation zone ranged from zero to 1.1 mm, 2.2 to 5.1 mm³ in SP mode and from 7.7 to 18.1 mm³ in cw mode.

CONCLUSION

During lithotripsy all lasers caused similar temperature changes and had a safe temperature profile at < 40 W. During tissue ablation, Ho:YAG has a deeper incision depth, while cwTm:YAG and cwTFL have broader coagulation and total laser areas.

Effects of water cooling on laser‐induced thermal damage in rat hepatectomy

Purpose

High‐powered lasers are commonly used for tissue resection in surgeries, including liver resection, medically known as hepatectomy; however, such lasers inevitably induce thermal damage that causes postoperative complications. This study aims to explore the effects of water cooling and different laser output modes on laser‐induced thermal damage during hepatectomy.

Methods

To avoid the influence of superposition, a 980‐nm diode laser was used for a single‐point hepatectomy. Eighteen Sprague–Dawley rats were used to explore the effects of water cooling and different laser output modes. A constant energy 10‐J laser was used to cut the liver tissue with a power of 10 W and time of 1 second. The rats were randomly divided into six groups. The first three groups were assigned as test subjects for different laser output modes. Group 1 was operated with a continuous laser output for a duration of 1 second. Groups 2 and 3 were operated with a pulsed laser output for a duration of 1 second and a pulse width of 0.5 and 0.25 seconds, respectively. Groups 4, 5, and 6 were assigned for the water cooling test. Water cooling was performed based on the parameters of the first three groups. Medical saline (0.9% NaCl) was used for water cooling. The main observation indicators were resection efficiency and thermal damage, including the area of the thermal damage zone. Resection efficiency is calculated by dividing the resection area by the total thermal damage area.

Results

In the three water cooling groups, the area of the resection, carbonized, sub‐boiling coagulated, and total thermal damage zones were 0.0677, 0.00, 1.7293, and 2.2982 mm² in Group 4; 0.0465, 0.00, 1.3205, and 1.8414 mm² in Group 5; and 0.0565, 0.00, 1.4301, and 1.9650 mm² in Group 6, respectively. Compared with the first three groups, the water cooling groups exhibited significantly reduced thermal damage areas of in the carbonized, sub‐boiling coagulated, and total thermal damage zones (p < 0.001 for all). In addition, there was no statistical difference in the resection area, vacuolated area, and resection efficiency. Furthermore, there was no statistical difference in the area of each thermal damage zone between the continuous and pulsed output groups. The resection efficiencies were 4.82%, 3.34%, 3.73%, 3.93%, 3.36%, and 3.01% in Groups 1 to 6, respectively. Moreover, there was no statistical difference (p > 0.05) in the resection efficiencies.

Conclusion

Water cooling can reduce the total laser‐induced thermal damage area and prevent tissue carbonization. Therefore, this cooling method can be used as a simple and safe strategy for controlling thermal damage during hepatectomy.