Fabrication of acoustically and physically validated artificial stones to natural kidney stones under shock waves and laser lithotripsy.

To present an efficient method for fabricating artificial kidney stones with acoustic and physical properties to assess their fragmentation efficiency under shock waves and laser lithotripsy for very hard stones. The mixture ratio of super-hard plaster and water was adjusted to produce artificial kidney stones for comparison with > 95% human genuine calcium oxalate monohydrate (COM) and uric acid (UA) stones. Acoustic and physical properties, such as wave speed, stone hardness, density, compressive strength, and stone-free rates under shock-wave and laser lithotripsy, were assessed. The longitudinal wave speed of artificial stones prepared at a plaster-to-water ratio of 15:3 closely matched that of COM stones. Similarly, the transverse wave speed of artificial stones prepared at a plaster-to-water ratio of 15:3 to 15:5 aligned with that of COM stones. Stone fragmentation using shock-wave of artificial stones with mixed ratios ranging from 15:3 to 15:5 resembled that of COM stones. The Vickers hardness was similar to that of artificial stones produced with a mixing ratio of 15:3, similar to that of COM stones, while that of artificial stones produced with a mixing ratio of 15:5 was similar to that of UA stones. Density-wise, artificial stones with mixing ratios of 15:4 and 15:5 resembled COM stones. Compressive strength test results did not confirm the similarity between natural and artificial stones. The stone fragmentation using laser showed that stones produced with higher moisture content at a mixing ratio of 15:6 were similar to COM stones. This novel method for fabricating artificial kidney stones could be used to provide reliable materials for lithotripsy research.

Temperature profile during endourological laser activation: introducing the thermal safety distance concept.

PURPOSE: To examine temporal-spatial distribution of heat generated upon laser activation in a bench model of renal calyx. To establish reference values for a safety distance between the laser fiber and healthy tissue during laser lithotripsy. METHODS: We developed an in-vitro experimental setup employing a glass pipette and laser activation under various intra-operative parameters, such as power and presence of irrigation. A thermal camera was used to monitor both temporal and spatial temperature changes during uninterrupted 60-second laser activation. We computed the thermal dose according to Sapareto and Dewey's formula at different distances from the laser fiber tip, in order to determine a safety distance. RESULTS: A positive correlation was observed between average power and the highest recorded temperature (Spearman's coefficient 0.94, p < 0.001). Irrigation was found to reduce the highest recorded temperature, with a maximum average reduction of 9.4 °C at 40 W (p = 0.002). A positive correlation existed between average power and safety distance values (Spearman's coefficient 0.86, p = 0.001). A thermal dose indicative of tissue damage was observed at 20 W without irrigation (safety distance 0.93±0.11 mm). While at 40 W, irrigation led to slight reduction in mean safety distance (4.47±0.85 vs. 5.22±0.09 mm, p = 0.08). CONCLUSIONS: Laser settings with an average power greater than 10 W deliver a thermal dose indicative of tissue damage, which increases with higher average power values. According to safety distance values from this study, a maximum of 10 W should be used in the ureter, and a maximum of 20 W should be used in kidney in presence of irrigation.

Comparison of conventional (basketing + dusting) and Moses (pop-dusting) holmium lasers during flexible ureteroscopy in the treatment of renal stones between 2 and 3 cm: a randomized clinical trial.

To investigate the feasibility of conventional (basketing + dusting) and Moses (pop-dusting) holmium lasers during flexible ureteroscopy (FURS) in the treatment of 2-3 cm renal calculi and to compare the efficiency and safety of the two methods, a total of 230 patients with 2-3 cm kidney stones who underwent FURS were randomly divided into the conventional group and the Moses group. The mode of lithotripsy in the conventional group was fragmentation and dusting. The mode of lithotripsy in the Moses group was dusting and pop-dusting. Clinical and perioperative variables and complications were compared between the two cohorts. Multivariate analyses of factors contributing to the stone-free rate (SFR) and operation time were performed. No statistically significant differences were found in the demographics, renal stone-related data, SFR, or complications between the cohorts. The laser energy was higher in the Moses cohort than in the conventional cohort (119.3 ± 15.2 vs. 92.8 ± 15.1 kJ; P < 0.001), and the operation time was shorter in the Moses cohort than in the conventional cohort (99.5 ± 18.9 vs. 105.3 ± 13.7 min; P = 0.009). When there was isolated stone, the operation time was shorter in the Moses cohort than in the conventional cohort (99.6 ± 17.5 vs. 111.4 ± 10.7 min; P < 0.001), while there was no significant difference between the two cohorts when there were multiple stones (99.5 ± 20 vs. 101.2 ± 14 min; P = 0.415). Multivariate analyses found that an increase in stone volume can decrease the SFR and prolong the operation time, and use of a Moses laser can shorten the operation time. Both holmium laser modes during FURS can effectively treat 2-3 cm renal calculi. The Moses mode is recommended as the first choice for the treatment of isolated 2-3 cm renal stones. When treating multiple stones, the efficiency of these two laser modalities is the same. TRIAL REGISTRATION: ChiCTR2200056091.

Monitoring Intrarenal temperature changes during Ho: YAG laser lithotripsy in patients undergoing retrograde intrarenal surgery: a novel pilot study.

Ho: YAG laser lithotripsy is widely used for urinary stone treatment, but concerns persist regarding its thermal effects on renal tissues. This study aimed to monitor intrarenal temperature changes during kidney stone treatment using retrograde intrarenal surgery with Ho: YAG laser. Fifteen patients were enrolled. Various laser power settings (0.8 J/10 Hz, 1.2 J/12 Hz) and irrigation modes (10 cc/min, 15 cc/min, 20 cc/min, gravity irrigation, and manual pump irrigation) were used. A sterile thermal probe was attached to a flexible ureterorenoscope and delivered into the calyceal system via the ureteral access sheath. Temperature changes were recorded with a T-type thermal probe with ± 0.1 °C accuracy. Laser power significantly influenced mean temperature, with a 4.981 °C difference between 14 W and 8 W laser power (p < 0.001). The mean temperature was 2.075 °C higher with gravity irrigation and 2.828 °C lower with manual pump irrigation (p = 0.038 and p = 0.005, respectively). Body mass index, laser power, irrigation model, and operator duty cycle explained 49.5% of mean temperature variability (Adj. R2 = 0.495). Laser power and operator duty cycle positively impacted mean temperature, while body mass index and specific irrigation models affected it negatively. Laser power and irrigation rate are critical for intrarenal temperature during Ho: YAG laser lithotripsy. Optimal settings and irrigation strategies are vital for minimizing thermal injury risk. This study underscores the need for ongoing research to understand and mitigate thermal effects during laser lithotripsy.

Application Analysis of Low-Pressure Perfusion Combined with Occluder in Holmium Laser Lithotripsy for Patients with Middle and Upper Ureteral Calculi.

BACKGROUND: Ureteroscopic holmium laser lithotripsy has become one of the main methods of treating ureteral calculi. However, in the treatment of middle and upper ureteral calculi, ureteroscopy is difficult to operate owing to the high location of calculi. Thus, how to improve the treatment effect and reduce the stone migration has become the focus in clinical settings. On this basis, we evaluated the application effect of low-pressure perfusion combined with occluder in holmium laser lithotripsy for patients with middle and upper ureteral calculi. METHODS: This retrospective study selected 107 patients with middle and upper ureteral calculi who underwent low-pressure perfusion combined with ureteroscopic holmium laser lithotripsy from January 2021 to December 2022. We excluded 7 patients who did not meet the criteria, and ultimately included 100 patients. According to whether the occluder was used during the surgery, 100 patients were divided into groups A (n = 52, occluder) and B (n = 48, without occluder). The stone-migration rate during surgery, stone-clearance rate at 3 months after surgery, perioperative indicators, postoperative complication rate, and postoperative quality of life between the two groups were compared. RESULTS: The stone-migration rate in group A was significantly lower than that in group B, with statistically significant difference (p < 0.05). Both groups had no significant difference in stone-clearance rate at 3 months after surgery (p > 0.05). Group A had a significantly lower index of EuroQol (EQ) Five Dimensions Questionnaire and significantly higher score of EQ-Visual Analogue Scale than group B (all p < 0.001). CONCLUSIONS: Compared with the simple application of low-pressure perfusion, the combined application of low-pressure perfusion and occluder in ureteroscopic holmium laser lithotripsy can effectively reduce the stone migration and improve the postoperative quality of life.

Holmium:yttrium-aluminium-garnet laser with MOSES technology is more efficient than thulium fibre laser in supine mini-percutaneous nephrolithotomy.

OBJECTIVES: To address the paucity of literature comparing outcomes achieved with utilisation of the high-power holmium:yttrium-aluminium-garnet (Ho:YAG) laser with MOSES technology vs those achieved with the thulium fibre laser (TFL) in mini-percutaneous nephrolithotomy (PCNL). METHODS: A retrospective review was performed of patients undergoing supine mini-PCNL between August 2021 and May 2023. Exclusion criteria were urinary diversion, simultaneous utilisation of >1 laser platform, use of any other form of fragmentation, and ureteric stones. The Ho:YAG platform (Lumenis Pulse P120H™ with MOSES technology, 120W; Boston Scientific®) and the TFL (Soltive SuperPulsed Thulium Fibre [SPTF], 60W; Olympus®) were compared. Data on stone-free rate (SFR) were determined by computed tomography performed on the first postoperative day and presented as absence of stone fragments, no fragments larger than 2 mm, or no fragments larger than 4 mm. RESULTS: A total of 100 patients met the inclusion criteria, 51 mini-PCNLs with the Ho:YAG laser and 49 with the SPTF laser. No significant differences in demographics or stone characteristics were detected between the two groups. The Ho:YAG laser utilised less energy and time, resulting in higher ablation efficiency (P < 0.05) and less total operating time (P < 0.05). Overall, there was no difference in SFR in any category between the Ho:YAG group and the SPTF group (no fragments: relative risk [RR] 0.81, 95% confidence interval [CI] 0.59-1.12, P = 0.21; fragments <2 mm: RR 0.86, 95% CI 0.67-1.10, P = 0.23; fragments <4 mm: RR 0.96, 95% CI 0.80-1.15, P = 0.67). CONCLUSIONS: Although we observed an equivalent postoperative SFR, this study supports a shorter operating time and greater intra-operative laser efficiency with the Ho:YAG laser over the SPTF laser in mini-PCNL.

Optimal parameter settings of thulium fiber laser for ureteral stone lithotripsy: a comparative study in two different testing environments.

This study aims to identify optimal parameters for using Thulium fiber lasers (TFL) in ureteral stone lithotripsy to ensure laser safety and maximize efficacy. Our goal is to improve the outcomes of single-use semi-rigid ureteroscopy for treating stones located in the proximal ureter. A clinically relevant thermal testing device was designed to investigate heating effects during TFL stone fragmentation. The device was utilized to identify safe power thresholds for TFL at various irrigation rates. Three other devices were used to assess varying pulse energy effects on stone fragmentation efficiency, dusting, retropulsion, and depth of tissue vaporization. Comparative experiments in fresh porcine renal units were performed to validate the efficacy and safety of optimal TFL parameters for semi-rigid ureteroscopy in proximal ureteral stone procedures. Our study found that the improved device generated a higher thermal effect. Furthermore, the safe power threshold for laser lithotripsy increased as the irrigation rate was raised. At an irrigation rate of 40 ml/min, it is safe to use an average power of less than 30 watts. Although increasing pulse energy has a progressively lower effect on fragmentation and dust removal efficiency, it did lead to a linear increase in stone displacement and tissue vaporization depth. Thermal testing showed 20 W (53.87 ± 2.67 °C) indicating potential urothelial damage. In our study of laser lithotripsy for proximal ureteral stones, the group treated with 0.3 J pulses had several advantages compared to the 0.8 J group: Fewer large fragments (> 4 mm): 0 vs. 1.67 fragments (1-2.25), p = 0.002, a lower number of collateral tissue injuries: 0.50 (0-1.25) vs. 2.67 (2-4), p = 0.011, and lower stone retropulsion grading: 0.83 (0.75-1) vs. 1.67 (1-2), p = 0.046. There was no significant difference in operating time between the groups (443.33 ± 78.30 s vs. 463.17 ± 75.15 s, p = 0.664). These findings suggest that TFL irradiation generates a greater thermal effect compared to non-irradiated stones. Furthermore, the thermal effect during laser lithotripsy is influenced by both power and irrigation flow rate. Our study suggests that using a power below 15 W with an irrigation flow rate of 20 ml/min is safe. Moreover, a pulse energy of 0.3 J appears to be optimal for achieving the best overall stone fragmentation effect.

[Thulium or holmium laser or both: where will the journey take us?] / Thulium oder Holmium-Laser oder beides: wo geht die Reise hin?

The Holmium:YAG laser has been the gold standard for laser lithotripsy over the past three decades and, since the late 1990s, also for prostate enucleation. Pulsed thulium fibre lasers (TFL) demonstrated their efficacy in in-vitro experiments and were introduced to the market a few years ago. Initial clinical results for TFL in lithotripsy and enucleation are very promising. In addition to TFL, a pulsed Thulium:YAG solid-state laser has been introduced, but clinical data for this laser are currently limited. This article aims to review the key technological differences between Ho:YAG lasers and pulsed thulium lasers and compare/discuss the initial clinical results for stone lithotripsy and laser enucleation.In-vitro studies have demonstrated the technical superiority of TFL compared with Ho:YAG lasers. However, as TFL is still a new technology, only limited studies are available to date, and optimal settings for lithotripsy have not been established. For enucleation, the differences of TFL compared with a high-power Ho:YAG laser seem to be clinically irrelevant. Initial studies on pulsed Tm:YAG lasers show good results, but there continues to be a lack of comparative studies.Based on the current literature, pulsed thulium lasers have the potential of being an alternative to Ho:YAG lasers. However, further studies are necessary to determine the optimal laser technology for enucleation and lithotripsy of urinary stones, considering all parameters, including efficacy, safety, and cost.

Cost-effectiveness of anti-retropulsive devices varies according to the locations of proximal ureteral stones: a retrospective cohort study.

BACKGROUND: Anti-retropulsive devices are often used to prevent stone migration in the treatment of proximal ureteral calculi. They are helpful. However, in the meantime, they also add extra expenses. This study was carried out to investigate the best criteria for treating proximal ureteral stones with anti-retropulsive devices. METHODS: Data from all patients who underwent ureteroscopic holmium: YAG laser lithotripsy for solitary upper ureteral stones in 2018 were collected. Patients who encountered stone retropulsion during the process of inserting the ureteroscope were excluded. Patients were divided into either group URS or group URS + ARD depending on whether the anti-retropulsive device was used. Then, the stone-free rate, expenses and other criteria were compared between groups according to stone location. Stone-free was defined as no stones present. RESULTS: For stones located ≤ 30 mm from the ureteropelvic junction (UPJ), the stone-free rates for the URS group were 80% and 80% at one day and one month after the operation, respectively. Those for the URS + ARD group were 71.4% and 78.6% at one day and one month, respectively. For stones located 31-90 mm from the UPJ, the stone-free rates were 84.7% and 84.7% for the URS group and 89.6% and 95.5% for the URS + ARD group at one day and one month, respectively. A statistically significant difference occurred at one month. For stones located > 90 mm from the UPJ, the two groups were both stone free. In the URS + ARD group, expenses were higher. In addition, the mean diameter of residual stones derived from stones located at 31-90 mm from the UPJ was statistically smaller, and 4 of 7 residual stones passed spontaneously within one month, which was obviously more than that in other locations and the URS group. Other outcomes, including operation time and postoperative stay, showed no significant difference between the groups. CONCLUSION: Anti-retropulsive devices are indeed helpful, but they might be cost-effective for stones located solely in the middle part of the upper ureter, not for those too close to or far from the ureteropelvic junction.

New Lasers for Stone Treatment.

Laser technology has been a breakthrough in urology. The new era in endocorporeal laser lithotripsy has recently begun in mid-2020, where promising technologies tested in vitro have reached their approval for clinical use and, in that way, have made it possible to confirm their safety and advantages in the real world, for the patient and for the urologist.

Superpulse thulium fiber laser lithotripsy: an in vitro comparison of 200 µm and 150 µm laser fibers.

PURPOSE: To investigate the thermal effects, stone retropulsion and ablation rate of SuperPulse Thulium-fiber laser (SP TFL) with two different surgical fibers of 200 and 150 µm in diameter. METHODS: SP TFL (NTO IRE-Polus, Fryazino, Russia) performance with 200 and 150 µm fibers (NTO IRE-Polus, Fryazino, Russia) was evaluated. Before each test, the laser fiber was cleaved, and the power measurement was taken to verify the actual laser output power. To compare the laser fibers in well-controlled environments, a number of setups were used to assess retropulsion, ablation efficacy, fiber burnback, energy transmission, and safety. RESULTS: Power measurements performed before each test revealed a 4.7% power drop for a 200 µm fiber SP TFL (14.3 ± 0.5 W) and 7.3% power drop for a 150 µm fiber SP TFL (13.9 ± 0.5 W) versus the nominally indicated power (15.0 W). Retropulsion with the TFL was minimal and comparable between fibers. We found no clinically relevant temperature differences between SP TFL with either 200 or 150 µm fibers. The ablation efficacy tended to be comparable under most parameters. Yet, we did observe a decreased diameter of residual fragments after the ablation with a 150 µm fiber. CONCLUSION: The smaller fiber (150 µm) is not inferior to 200 µm fiber in terms of fiber burnback, retropulsion, safety, and ablation rate. Moreover, it has the potential to decrease the diameter of fragments during lithotripsy, which may facilitate dusting during RIRS.

Development of a nomogram predicting the probability of stone free rate in patients with ureteral stones eligible for semi-rigid primary laser uretero-litothripsy.

PURPOSE: Few tools are available to predict uretero-lithotripsy outcomes in patients with ureteral stones. Aim of our study was to develop a nomogram predicting the probability of stone free rate in patients undergoing semi-rigid uretero-lithotripsy (ULT) for ureteral stones. METHODS: From January 2014 onwards, patients undergoing semi-rigid Ho: YAG laser uretero-lithotripsy for ureteral stones were prospectively enrolled in two centers. Patients were preoperatively evaluated with accurate clinical history, urinalysis and renal function. Non-contrast CT was used to define number, location and length of the stones and eventually the presence of hydronephrosis. A nomogram was generated based on the logistic regression model used to predict ULT success. RESULTS: Overall, 356 patients with mean age of 54 years (IQR 44/65) were enrolled. 285/356 (80%) patients were stone free at 1 month. On multivariate analysis single stone (OR 1.93, 95% CI 1.05-3.53, p = 0.034), stone size (OR 0.92, 95% CI 0.87-0.97, p = 0.005), distal position (OR 2.12, 95% CI 1.29-3.48, p = 0.003) and the absence of hydronephrosis (OR 2.02, 95% CI 1.08-3.78, p = 0.029) were predictors of success and these were used to develop a nomogram. The nomogram based on the model presented good discrimination (area under the curve [AUC]: 0.75), good calibration (Hosmer-Lemeshow test, p > 0.5) and a net benefit in the range of probabilities between 15 and 65%. Internal validation resulted in an AUC of 0.74. CONCLUSIONS: The implementation of our nomogram could better council patients before treatment and could be used to identify patients at risk of failure. External validation is warranted before its clinical implementation.

Efficiency and Clinical Outcomes of Moses Technology with Flexible Ureteroscopic Laser Lithotripsy for Treatment of Renal Calculus.

OBJECTIVE: The aim of the study was to compare the efficiency and clinical outcomes of Moses contact mode (MCM) and regular dusting mode (RDM) during flexible ureteroscopic lithotripsy (FURL) for treatment of renal calculus. METHODS: This retrospective analysis examined 216 patients with renal calculus who underwent FURL with MCM or RDM between March 2015 and January 2020. Stone characteristics, including size, volume, and density, were collected. Laser parameters, including laser type, laser working time, laser pause time, and foot-pedal use, were automatically recorded by the lithotripter work panel. The percentages of laser working time and laser pause time, stone fragmentation efficiency (SFE; volume/laser working time), postoperative complications, including fever and acute renal failure (ARF), stone-free rate (SFR), and the need for auxiliary procedures were determined. RESULTS: There were no significant differences in preoperative demographic and stone characteristics between the MCM group and the RDM group. The MCM group had a shorter laser working time (4.99 ± 1.06 vs. 5.94 ± 0.96 min, p < 0.001) and a greater SFE (137.86 [163.78-114.38] versus 114.94 [132.06-101.34] mm3/min, p < 0.001), which shortened the overall operative time (18.39 ± 5.13 vs. 21.17 ± 6.78 min, p = 0.001). There were no differences in postoperative complications, including fever and ARF, SFR (86.8 vs. 85.3%, p = 0.743), and auxiliary procedures between the 2 groups. CONCLUSIONS: Using Moses laser technology with FURL significantly reduced laser working time and increased SFE, which shortened overall operative time. Urologists should consider this new instrument for the clinical management of renal calculus.

Effects of irrigation fluid temperature during flexible ureteroscopic holmium laser lithotripsy on postoperative fever and shivering: a randomized controlled trial.

BACKGROUND: Flexible ureteroscopic holmium laser lithotripsy is used to treat urinary tract calculi, but postoperative complications include shivering, fever and infection. To investigate the effects of irrigation fluid temperature on postoperative complications. METHODS: This randomized controlled trial included 120 consecutive patients undergoing flexible ureteroscopic holmium laser lithotripsy at the Urology Department, Suining Central Hospital, Sichuan, China between January 2017 and July 2019. Patients were randomized 1:1:1 into three groups (17 °C, 27 °C or 37 °C). Primary outcome was fever incidence (body temperature > 37.5 °C) within 48 h after surgery. Secondary outcomes included shivering incidence during recovery from anesthesia, white blood cell count (WBC), serum procalcitonin (PCT) and incidence of suspected infection (temperature > 38.5 °C and PCT > 0.5 µg/L). RESULTS: There were 108 patients, (17 °C group, n = 36; 27 °C group, n = 35; 37 °C group, n = 37), received flexible ureteroscopic holmium laser lithotripsy and analyzed. Age, gender distribution, body mass index, ASA grade, stone burden, preoperative creatinine, preoperative core temperature and irrigation fluid volume did not differ significantly between groups. 17 °C, 27 °C and 37 °C groups exhibited significant differences in the incidences of postoperative fever (38.9% vs. 17.1% vs. 13.5%) and shivering (22.2% vs. 5.7% vs. 2.7%) (p < 0.05 for all pairwise comparisons). There was no significant difference of WBC, PCT and incidence of suspected infection in 37 °C or 27 °C group compared with 17 °C group. One case each of flash pulmonary edema and bleeding occurred in 37 °C group. CONCLUSION: Warming the irrigation fluid can reduce the incidence of postoperative fever and shivering, but further studies are needed to determine the optimal temperature. Trial registration The trial was registered at the Chinese Clinical Trials Registry and allocated as ChiCTR2000031683. The trial was registered on 07/04/2020 and this was a retrospective registration.