The future of laser technology in kidney stones

Thulium Fiber Laser Versus Holmium:Yttrium Aluminum Garnet for Lithotripsy: A Systematic Review and Meta-analysis

CONTEXT

Thulium fiber laser (TFL) emerged as a competitor of holmium:yttrium aluminum garnet (Ho:YAG) laser for the treatment of urinary stones.

OBJECTIVE

To compare the efficacy between Ho:YAG and TFL for laser lithotripsy of renal and ureteral stones.

EVIDENCE ACQUISITION

A literature search was conducted using PubMed/Medline, Embase, and Web of Science databases to identify reports published until May 2023. The Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed to identify eligible studies. The primary outcome was to compare the stone-free rate (SFR) between Ho:YAG and TFL for laser lithotripsy.

EVIDENCE SYNTHESIS

Eleven studies met our inclusion criteria, and data from 1286 and 880 patients who underwent, respectively, Ho:YAG and TFL laser lithotripsy were reviewed. Most studies included ureteroscopy (URS) and retrograde intrarenal surgeries as procedures, two included percutaneous nephrolithotomy, and one included URS exclusively. Only two studies reported results in pediatric patients. TFL was associated with a higher SFR (odds ratio [OR] 1.84, 95% confidence interval [CI]: 1.06-3.20; p = 0.031) when no residual fragment is considered, but not when SFR refers to the presence of fragments <3 mm (OR 2.48, 95% CI: 0.98-6.29; p = 0.055) or when only Ho:YAG with MOSES is considered (p = 0.068). According to the stones' location, TFL was associated with higher SFRs than Ho:YAG for renal (OR 3.14, 95% CI: 1.69-5.86; p < 0.001) but not for ureteral (p = 0.8) stones. TFL was associated with a lower intraoperative complication rate (OR 0.34, 95% CI: 0.19-0.63; p < 0.001). No difference was found in major (p = 0.4) or overall (p = 0.4) complication rate, operative time (p = 0.051), and laser time (p = 0.9).

CONCLUSIONS

TFL is a promising laser for the treatment of urinary stones with some advantages over Ho:YAG. Further high-quality studies are needed to confirm these findings and optimize the surgical settings.

PATIENT SUMMARY

The use of thulium fiber laser rather than holmium:yttrium aluminum garnet permits to reach a higher stone-free rate in stones located in the kidney rather than in the ureter.

Effect of Ho:YAG laser on kidney tissue with Virtual Basket™ and Bubble Blast™ pulse modulation: an experimental ex vivo study

PURPOSE

There is a lack of studies in the literature on effects of Virtual Basket™ (VB) and Bubble Blast™ (BB) laser pulse modulations of the Ho:YAG laser on tissue. We aimed to compare the effects of standard modulation (SM), VB, and BB pulse modulations of Ho:YAG laser on kidney tissue.

METHODS

An ex vivo experiment was conducted using veal kidneys. The Quanta System Cyber Ho 100W laser generator with a broad setting spectrum at 15-80 W, 10-40 Hz, 1.5-2 J, and medium pulse duration were tested. Incision depth (ID), vaporization area (VA), coagulation area (CA), and total laser area (TLA = VA + CA) were evaluated. Histopathological measurement outcomes were grouped as a low-power group (15, 20, and 30 W) and a high-power group (40, 60, and 80 W) according to the power outputs used.

RESULTS

A total of 108 experiments were performed. In saline and high-power output (40, 60, 80 W), mean VA, TLA, and ID, histopathological measurements were higher in BB pulse modulation than VB and SM pulse modulations (p: 0.03, p: 0.001, and p: 0.003, respectively). In contrast, mean CA and LE measurements were higher in SM than in VB and BB pulse modulations (p < 0.001 and p < 0.001, respectively). There was no statistically significant difference in mean histopathological measurements of VA, CA, TLA, and ID, among SM, VB, and BB pulse modulations in the low-power output group in saline (p > 0.05).

CONCLUSION

VB can allow controlled dissection, as it does not create a large VA during surgical procedures. BB should be used in a controlled manner in soft tissue surgery due to its strong effect on tissues.

Association between novel anthropometric indices and prevalence of kidney stones in US adults

BACKGROUND

Our aim is to evaluate the relationship between prevalence of kidney stones (KS) and novel anthropometric indices (AHIs).

METHODS

Participants who participated in the KS questionnaire was extracted from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2018.A series of covariates were also obtained. The novel AHIs include a body shape index (ABSI) and body roundness index (BRI). Weighted multivariable-adjusted logistic regression was performed to investigate the association of KS with AHIs.

RESULTS

After relative covariates were adjusted, a greater risk of KS for each z score increase in ABSI (OR = 1.13, 95%CI 1.05-1.22), and the risk of KS augmented by 19% for every 1 BRI z score added (OR = 1.19, 95%CI 1.11-1.27). The results from subgroup analysis showed that among adults aged 20-39 (OR = 1.31, 95%CI 1.04-1.65), male (OR = 1.14, 95%CI 1.02-1.28), the risk of KS is higher with the increase of each ABSI z score. Raising each BRI z score in those who were male aged 20-39 and 40-59 resulted in a higher risk of KS (aged 20-39: OR = 1.34, 95%CI 1.06-1.69; aged 40-59: OR = 1.29, 95%CI 1.09-1.53). In female aged 40-59, increasing each BRI z score led to a higher risk of KS (OR = 1.23, 95%CI 1.07-1.41). A linear association of ABSI z score with the risk of KS and a non-linear relationship between BRI z score and the risk of KS were discovered.

CONCLUSION

This study found that the novel AHIs was related to the risk of kidney stones, and can be used as important indicators to evaluate the risk of KS.

Could Testicular Tissue Be a New Arena for the Holmium Laser?

Introduction We aimed to observe the effects of holmium:yttrium-aluminum-garnet (Ho:YAG) laser on testicular tissue. Methods An ex vivo experiment was conducted using calf testicles. A 100 W laser generator with broad-spectrum settings of 10-80 W, 20-40 Hz, and 0.5-2 J, with a medium pulse duration, was tested. The laser effects on testicular tissues with and without the tunica layer were evaluated histopathologically by calculating the incision depth (ID), vaporization area (VA), coagulation area (CA), and total laser area (TLA=VA+CA) of the specimens. Results A total of 48 experiments were conducted. In testicular tissue without a tunica layer, the highest mean ID was determined at 1 J-20 Hz (0.247±0.0208 mm) and with a tunica layer at 2 J-40 Hz (2.673±0.032 mm). In the testicular tissue without a tunica layer, the highest mean VA was determined at 1.5 J-40 Hz (0.029±0.0016 mm2) and in tissue with a tunica at 2 J-40 Hz (6.173±0.114 mm2). The highest mean TLA in tissue without a tunica was detected at 2 J-20 Hz (0.038±0.0008 mm2) and in tissue with a tunica at 2 J-40 Hz (7.292±0.07 mm2). The mean ID, VA, CA, and TLA values of all the power outputs used were found to be statistically significantly higher in the testicular tissue with the tunica layer than in that without it (p<0.001). Conclusion The Ho:YAG laser has different effects on testicular tissue with and without a tunica layer. In testicular tissue without a tunica, the laser's effect was minimal on the surrounding tissue, especially in terms of the ID, VA, and TLA. This minimal effect of the laser can be an advantage in testicular surgery procedures such as testis-sparing surgery (TSS) or testicular sperm extraction (TESE).

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.

Lasers for stone lithotripsy: advantages/disadvantages of each laser source

PURPOSE

The purpose of this article was to make a narrative review of the literature in search of all articles regarding thulium:yttrium-aluminium-garnet (YAG), thulium laser fiber (TFL) and holmium:YAG (Ho:YAG) for lithotripsy from 2020 to 2023. A selection of articles of special interest and best evidence was made in order to give a better perspective on their advantages and disadvantages.

RECENT FINDINGS

New Ho:YAG technologies of as high power, high frequency and pulsed modulations have shown promising results for lithotripsy by reducing retropulsion with good ablation efficiency. High peak power makes it particularly good for percutaneous nephrolithotomy. High intrarenal temperatures and correct setting are still concerning points.TFL has arrived to be one of the main players in flexible ureteroscopy. Being highly efficient and quick, and by producing micro-dusting the laser is quickly heading to become a gold standard. The new pulsed Thulium YAG is the newest laser. For now, only in-vitro studies show promising results with efficient lithotripsy. As the peak power lies between Ho:YAG and TFL it may be able to adequately perform when needing and low power lithotripsy.

SUMMARY

Several new technologies have been developed in the last years for stone lithotripsy. All being efficient and safe if well used. Different advantages and disadvantages of each laser must be taken into consideration to give each laser the proper indication.

Thulium fibre laser vs holmium: yttrium-aluminium-garnet laser lithotripsy for urolithiasis: meta-analysis of clinical studies

OBJECTIVE

To compare and assess the clinical outcomes between thulium fibre laser (TFL) and holmium: yttrium-aluminium-garnet (Ho:YAG) laser endoscopic lithotripsy of urolithiasis through a meta-analysis of comparative clinical studies.

METHODS

A systematic literature search was performed in May 2022, grey literature search in July 2022. Comparative clinical studies were evaluated according to Cochrane recommendations. Assessed outcomes include the stone-free rate (SFR), complication rate, operative time (OT), laser utilisation time (LUT), ablation rate (stone volume/laser time), ablation efficiency (energy use/stone volume), total energy usage, degree of retropulsion, and hospital stay. Risk ratios (RRs) and standardised mean differences (SMDs) were extrapolated. Subgroup analyses, heterogeneity, publication bias, and Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) assessment were performed. International Prospective Register of Systematic Reviews (PROSPERO) registration: CRD42022300788.

RESULTS

A total of 15 studies with 1698 cases were included in this review. The outcome of SFR showed no significant between-group difference (RR 1.09, 95% confidence interval [CI] 0.99-1.20). However, subgroup analysis of TFL vs Ho:YAG with no pulse modulation showed a SFR favouring TFL (RR 1.11, 95% CI 1.01-1.23). The composite postoperative complication rate was comparable between the two intervention groups (RR 0.97, 95% CI 0.66-1.43). OT, LUT and ablation rate were significantly better for TFL than Ho:YAG (SMD -1.19, 95% CI -1.85 to -0.52; SMD -1.67, 95% CI -2.62 to -0.72; SMD 0.59, 95% CI 0.15-1.03; respectively). The degree of retropulsion was significantly lower for TFL than Ho:YAG without pulse modulation (SMD -1.23, 95% CI -1.74 to -0.71). Ablation efficiency, total energy usage, and hospital stay were all comparable. Based on GRADE criteria, the evidence certainty was determined to be very low.

CONCLUSION

Overall, there was no between-group difference for the SFR. However, compared to Ho:YAG with no pulse modulation, TFL rendered a better SFR. Shorter OT and LUT, a lesser degree of retropulsion, and a better ablation rate were noted in favour of the TFL. There was no overall between-group difference for composite postoperative complication rate, ablation efficiency, total energy usage, and hospital stay. Currently, the available clinical evidence was assessed to be of very low certainty.

Astragalus membranaceus Extract Prevents Calcium Oxalate Crystallization and Extends Lifespan in a Drosophila Urolithiasis Model

Approximately 1 in 20 people develops kidney stones at some point in their life. Although the surgical removal of stones is common, the recurrence rate remains high and it is therefore important to prevent the occurrence of kidney stones. We chose Astragalus membranaceus (AM), which is a traditional Chinese medicine, to study the prevention of urolithiasis using a Drosophila model based on our previous screening of traditional Chinese herbs. Wild-type Drosophila melanogaster Canton-S adult fruit flies were used in this study. Ethylene glycol (EG, 0.5%) was added to food as a lithogenic agent. The positive control agent (2% potassium citrate (K-citrate)) was then compared with AM (2, 8, and 16 mg/mL). After 21 days, the fruit flies were sacrificed under carbon dioxide narcotization, and the Malpighian tubules were dissected, removed, and processed for polarized light microscopy examination to observe calcium oxalate (CaOx) crystallization. Then, the ex vivo dissolution of crystals in the Malpighian tubules was compared between K-citrate and AM. Survival analysis of the EG, K-citrate, and AM groups was also performed. Both 2% K-citrate and AM (16 mg/mL) significantly inhibited EG-induced CaOx crystal formation. Mean lifespan was significantly reduced by the administration of EG, and the results were significantly reversed in the AM (8 and 16 mg/mL) groups. However, AM extract did not directly dissolve CaOx crystals in Drosophila Malpighian tubules ex vivo. In conclusion, AM extract decreased the ratio of CaOx crystallization in the Malpighian tubules and significantly ameliorated EG-induced reduction of lifespan. AM prevented CaOx crystal formation in the Drosophila model.