Stone Fragmentation Efficiency Research Articles

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 40ml/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 20W (53.87 ± 2.67°C) indicating potential urothelial damage. In our study of laser lithotripsy for proximal ureteral stones, the group treated with 0.3J pulses had several advantages compared to the 0.8J group: Fewer large fragments (> 4mm): 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 ± 78.30s vs. 463.17 ± 75.15s, 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 15W with an irrigation flow rate of 20ml/min is safe. Moreover, a pulse energy of 0.3J appears to be optimal for achieving the best overall stone fragmentation effect.

Comparison of high and low pulse energy dusting protocols using holmium: YAG laser in flexible ureteroscopy for treatment of renal stones

ABSTRACT Objectives The management of renal stones, particularly those less than 2 cm in diameter, has changed with the development of endourological techniques, among which flexible ureteroscopy (FURS) using laser for lithotripsy has become a cornerstone. This study aims to compare the effectiveness of high pulse energy versus low pulse energy laser settings in renal stone dusting by Holmium YAG laser. Patients and Methods This prospective randomized study was conducted between September 2021 and November 2023 to compare the efficacy and safety of high energy versus low-energy pulse settings using a Holmium: YAG laser dusting of renal stones less than 2 cm in diameter. A total of 174 adult patients were included, divided equally into high- and low-pulse energy groups, based on the energy settings of the laser high energy (ranged from 1.2–2.5 Joules and frequency of 8 hz) and low energy (less than 0.5 Joules and frequency ≥ 15 hz) using the dusting ‎technique with non-touch non-stop approach. The study sought to evaluate the impact of these settings on stone fragmentation efficiency, operative time, laser energy consumption, and postoperative outcomes, including stone-free rates and complications. Results The study involved 174 patients who underwent renal stone lithotripsy and showed that using high pulse energy laser dusting settings significantly reduced operative times and more rapid dusting compared to low pulse energy settings, without affecting the stone-free rate. The study observed no significant differences in stone size or location between both groups. Minor postoperative complications were similar between both groups, indicating high pulse energy settings for lithotripsy dusting. Conclusion The efficacy of high pulse energy dusting in enhancing stone removal during surgery, potentially reducing operative time. Further validation through larger-scale studies is needed to solidify these findings. This technique presents a promising solution, particularly in regions with limited resources where acquiring expensive laser equipment is challenging.

Are Newer Extracorporeal Shock Wave Lithotripsy Models Truly Improving Pancreatolithiasis Lithotripsy Performance? A Japanese Single-Center Study Using Endoscopic Adjunctive Treatment.

Many Japanese institutions use electromagnetic extracorporeal shock wave lithotripsy (ESWL) systems for treating pancreatic duct stones. However, there are no reports on direct comparisons between recent electromagnetic lithotripters. This study aimed to verify whether the new electromagnetic lithotripter can improve the efficiency of pancreatic stone fragmentation, and to clarify the role of combined endoscopic treatment on the clearance of pancreatic duct stones. We retrospectively identified 208 patients with pancreatolithiasis who underwent endoscopic adjunctive treatment after pancreatic ESWL at a single Japanese center over a 17-year period. We evaluated the outcome data of this procedure performed with SLX-F2 (last 2 years; group A) and Lithostar/Lithoskop (first 15 years; group B), as well as additional endoscopic treatments for pancreatolithiasis. We also performed logistic regression analysis to detect various factors associated with the procedure. For pancreatic head stones, ESWL disintegration was achieved in 93.7% of group A patients and 69.0% of group B patients (p=0.004), and adjunctive endoscopic treatment removed stones in 96.8% of group A patients and 73.0% of group B patients (p=0.003). Multivariate analysis revealed that lithotripter type (odds ratio, 6.99; 95% confidence interval, 1.56 to 31.33; p<0.01) and main pancreatic duct stricture (odds ratio, 2.87; 95% confidence interval, 1.27 to 6.45; p<0.01) were significant factors for ESWL fragmentation. The SLX F2 showed high performance in fragmenting the pancreatic duct stones. In addition, endoscopic adjunctive treatment improved the overall success rate of the procedure. The improved ESWL lithotripter has many advantages for patients undergoing pancreatic lithotripsy treatment.

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.

"VirtualBasket" ureteroscopic holmium laser lithotripsy: intraoperative and early postoperative outcomes

The "VirtualBasket" technology (Cook Medical, Bloomington, IN, USA) is the result of pulse modulation during holmium laser emission: the laser emits part of the energy to create an initial bubble, and a second pulse is emitted when the vapor bubble is at its maximum expansion, so that it can pass through the previously created vapor channel. The aim of this study was to outline the outcomes of the "VirtualBasket" technology in ureteral and renal stones. 160 Patients were randomly assigned to holmium laser lithotripsy with or without the "VirtualBasket" technology in ureteric or renal cases (40 per 4 groups). All procedures were performed by four experienced urologists. The Quanta System Cyber Ho 100W laser generator with 365 µm fibers was used for all the ureteral cases, whereas 272 µm fibers were used for all the cases in the renal pelvis. Demographic data, stone parameters, perioperative complications and success rates were compared. A statistical analysis was carried out to assess patients' data and outcomes. All the reported P values were obtained with the two-sided exact method at the conventional 5% significance level. The degree of stone retropulsion was graded on a Likert scale from zero (no retropulsion) to 3 (maximum retropulsion). All groups were comparable in terms of age, and preoperative stone size (ureter stone size: 1.2 vs. 1.1 cm; renal pelvis stone size: 1.55 vs. 1.62 cm). Compared to the regular mode, the "VirtualBasket" technology was associated with significantly lower fragmentation time (mean time for ureteral stones: 20.4 vs. 16.1 minutes, P<0.05; mean time for renal stones: 28.7 vs. 19.8 minutes, P<0.05) and total procedural time (mean time for ureteral stones 49 vs. 35.7 minutes; mean time for renal stones 67.1 vs. 52.4 minutes). There were no significant differences in terms of energy delivered to the stones, intraoperative complications and success rate at 1 month. The "VirtualBasket" technology was associated with significantly lower retropulsion. The "VirtualBasket" technology is associated with significantly lower fragmentation and procedural times. The reduced fragmentation time is a result of the significantly lower retropulsion of the stones during laser lithotripsy, which improves stone fragmentation efficiency.

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

You have accessJournal of UrologyStone Disease: Basic Research & Pathophysiology II1 Apr 2018MP24-10 WAVELENGTH AND PULSE SHAPE EFFECTS ON STONE FRAGMENTATION OF LASER LITHOTRIPTERS Andreas Gross, Benedikt Becker, Mark Taratkin, Dmitry Enikeev, Leonid Rapoport, and Christopher Netsch Andreas GrossAndreas Gross More articles by this author , Benedikt BeckerBenedikt Becker More articles by this author , Mark TaratkinMark Taratkin More articles by this author , Dmitry EnikeevDmitry Enikeev More articles by this author , Leonid RapoportLeonid Rapoport More articles by this author , and Christopher NetschChristopher Netsch More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.763AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Pulsed Holmium:YAG lasers are the energy source of choice in the endoscopic management of urolithiasis. Until recently, pulse frequency and pulse energy were the most investigated parameters to improve efficiency of such lasers. Newer research focusses on the influence of pulse width and pulse shape. Aim of our study was to compare the efficiency of stone dusting of pulsed 2.1µm Holmium:YAG lasers and a pulsed 1.94µm Thulium-fiber laser (TFL) using identical pulse energy, pulse frequency, and average power settings. METHODS The lasers systems tested were the Lumenis Versa Pulse Power Suite P 100 (Ho short pulse), the Lumenis Pulse 120H (Ho long pulse) and a commercially not available prototype of a pulsed TFL (Fig.1, A) to C)). The lasers were tested at 0.2 J and 40 Hz (average power of 8-W). Pulse energies and pulse shapes were measured. Subsequently, efficiency of stone ablation (ablation speed) was compared in vitro on human COM, COM-phosphate, and Uric Acid stones for the three lasers. The in vitro experimental setup included a specially designed cuvette with several levels of metallic meshes allowing for precise quantification of size distribution of stone fragments. RESULTS The pulsewidths (range in ms) of all three lasers are shown in Fig. 1 below. The following values of the peak power were derived from the pulse shape and pulse energy measurements: P100: 1650-W, P120: 1040-W, TFL: 660-W. The measured values of stone ablation speed (in dusting mode, i.e. fragments < 1mm) are summarized in Fig.2. CONCLUSIONS The new pulsed TFL shows a clearly defined pulsewidth with a large area under the curve. This in combination with the wavelength superior in terms of water absorption leads to better efficiency of stone fragmentation in dusting mode. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e293-e294 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Andreas Gross More articles by this author Benedikt Becker More articles by this author Mark Taratkin More articles by this author Dmitry Enikeev More articles by this author Leonid Rapoport More articles by this author Christopher Netsch More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

PD53-04 DOUBLE-BLIND PROSPECTIVE RANDOMIZED CLINICAL TRIAL COMPARING REGULAR AND MOSES MODES OF HOLMIUM LASER LITHOTRIPSY: PRELIMINARY RESULTS

You have accessJournal of UrologyStone Disease: Surgical Therapy V1 Apr 2018PD53-04 DOUBLE-BLIND PROSPECTIVE RANDOMIZED CLINICAL TRIAL COMPARING REGULAR AND MOSES MODES OF HOLMIUM LASER LITHOTRIPSY: PRELIMINARY RESULTS Ahmed Ibrahim, Nader Fahmy, Serge Carrier, Mostafa Elhilali, and Sero Andonian Ahmed IbrahimAhmed Ibrahim More articles by this author , Nader FahmyNader Fahmy More articles by this author , Serge CarrierSerge Carrier More articles by this author , Mostafa ElhilaliMostafa Elhilali More articles by this author , and Sero AndonianSero Andonian More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.2500AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Moses Technology has been shown to improve the fragmentation efficiency and reduced stone retropulsion both in in vivo and in vitro studies. However, there are no randomized trials evaluating effectiveness of this new technology during laser lithotripsy. Therefore, the objective was to compare Regular and Moses modes of holmium laser lithotripsy in terms of stone fragmentation efficiency and perioperative complications. METHODS After obtaining ethics approval, a prospective double-blind randomized trial was conducted for patients undergoing holmium laser lithotripsy. Patients were randomly assigned to have holmium laser lithotripsy with either Regular or Moses modes. Both patients and surgeons were blinded to the laser mode. All procedures were performed by four experienced urologists. Lumenis 120W generator with 200 Moses D/F/L fibers were used for all cases. Demographic data, stone parameters, peri-operative complications and success rates were compared. The degree of stone retropulsion was graded on a Likert scale from zero (no retropulsion) to 3 (maximum retropulsion). RESULTS A total of 66 patients were included in the study (33 per each arm). Both groups were comparable in terms of age, and pre-operative stone size (1.7 vs. 1.6 cm, p>0.05). When compared with the Regular mode, Moses Technology was associated with significantly lower fragmentation time (23.4 vs. 17.5 min, p<0.05) and total procedural time (53 vs. 42.1 min, p<0.05). However, there were no significant differences in terms of lasing time (6.5 vs. 7.1 min, p>0.05) and total energy applied to the stones (10.8 vs. 11.5 KJ, p>0.05). When compared between Regular and Moses modes, Moses technology was associated with significantly less retropulsion (mean grade was 1 vs. 0.4, p<0.05). There was no significant difference between both modes in terms of intra-operative complications (12.1 % vs. 3%, p>0.05). Only one case from Moses group had a small ureteral perforation requiring prolonged indwelling ureteral stenting. The success rate at the end of 1 month was comparable between both groups (90.1 vs. 87.9 %, p> 0.05). CONCLUSIONS Moses technology is associated with significantly lower fragmentation and procedural times. The reduced fragmentation time could be explained by the significantly lower reropulsion of the stones during laser lithotripsy; thus improving stone fragmentation efficiency. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e1047 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Ahmed Ibrahim More articles by this author Nader Fahmy More articles by this author Serge Carrier More articles by this author Mostafa Elhilali More articles by this author Sero Andonian More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Comparison of Broad vs Narrow Focal Width Lithotripter Fields

To investigate the impact of lithotripter focal width on stone fragmentation. A modified reflector was used to reduce -6 dB beam size of the HM3 lithotripter, while increasing concomitantly peak pressure. Fragmentation in vitro was assessed with modified and original reflectors using BegoStone phantoms. A membrane holder was used to mimic lithotripsy in vivo, and a matrix holder was used to assess variations of fragmentation power in the focal plane of the lithotripter field. Stone fragmentation in vivo produced by the two reflectors was further compared in a swine model. Stone fragmentation in vitro after 500 (or 2000) shocks was ∼60% (or ∼82%) vs ∼40% (or ∼75%) with original and modified reflector, respectively (p ≤ 0.0016). Fragmentation power with the modified reflector was the highest on the lithotripter axis, but dropped rapidly in the lateral direction and became insignificant at radial distances >6.0 mm. Stone fragmentation with the original reflector was lower along the lithotripter axis, but fragmentation power decayed slowly in lateral direction, with appreciable fragmentation produced at 6.0 mm. Stone fragmentation efficiency in vivo after 500 (or 2000) shocks was ∼70% (or ∼90%) vs ∼45% (or ∼80%) with original and modified reflector, respectively (p ≤ 0.04). A lithotripter field with broad beam size yields superior stone comminution when compared with narrow beam size under comparable effective acoustic pulse energy both in vivo and in vitro. These findings may facilitate future improvements in lithotripter design to maximize comminution efficiency while minimizing tissue injury.

PD30-11 USE OF MOSES PULSE MODULATION TECHNOLOGY TO IMPROVE HOLMIUM LASER LITHOTRIPSY OUTCOMES: A PRECLINICAL STUDY

You have accessJournal of UrologyStone Disease: Surgical Therapy III1 Apr 2017PD30-11 USE OF MOSES PULSE MODULATION TECHNOLOGY TO IMPROVE HOLMIUM LASER LITHOTRIPSY OUTCOMES: A PRECLINICAL STUDY Mostafa Elhilali, Shadie Badaan, Ahmed Ibrahim, and Sero Andonian Mostafa ElhilaliMostafa Elhilali More articles by this author , Shadie BadaanShadie Badaan More articles by this author , Ahmed IbrahimAhmed Ibrahim More articles by this author , and Sero AndonianSero Andonian More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.1376AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Efficient Holmium laser lithotripsy is limited by two main factors: retropulsion and energy transmission in water, which depends on fiber-stone distance. Recently, Lumenis developed the Moses technology, including the Moses D/F/L fibers, using pulse modulation resulting in improved energy transmission through water and reduced retropulsion. The Moses technology modulates the energy pulse that enables emission of a controlled portion of energy to create a bubble, known as the ″Moses effect″, while leaving a portion that travels through the bubble to the stone. The aim was to conduct a preclinical study investigating the effect of the Moses technology on Holmium laser lithotripsy comparing the Moses mode to the Regular mode in terms of lithotripsy efficiency and laser-tissue interaction METHODS Several experiments were performed to explore the advantages of the Moses technology using the Lumenis P120H system and Moses D/F/L fibers. Experiments included: stone fragmentation efficiency at 1 mm distance; effect on retropulsion (reaction to a single pulse) measured by high-speed camera; efficiency of in vitro laser lithotripsy measured by procedural time, and lasing-pause ratios. In addition, a porcine ureteroscopy model was used to assess stone fragmentation and dusting as well as laser-tissue interaction when the laser fiber touched the ureteral wall. RESULTS Stone fragmentation tests showed that the Moses mode resulted in significantly higher ablation volume when compared with Regular mode (160% higher; p=0.001). Stone displacement experiments following a single pulse showed significant reduction in retropulsion when using the Moses mode. The stone movement was reduced by 50 times at 0.8J and 10Hz (p=0.01). The pronounced reduction of retropulsion in the Moses mode was clearly observed during in vitro fragmentation settings (higher energy) and during dusting for smaller stones (low energy, high Hz). There was also significant reduction in procedure time (average 35% reduction for fragmentation and 23% for dusting, p=0.01) and longer lasing duration with shorter pauses indicating reduced need to reposition the fiber due to lack of retropulsion. Histological analysis of the porcine ureter after direct lasing in the Moses mode showed less damage than in the Regular mode. CONCLUSIONS The Moses technology resulted in more efficient laser lithotripsy in addition to significantly reduced stone retropulsion resulting in significantly shorter procedural time and greater margin of safety. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e582 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Mostafa Elhilali More articles by this author Shadie Badaan More articles by this author Ahmed Ibrahim More articles by this author Sero Andonian More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

A Novel Device to Prevent Stone Fragment Migration During Percutaneous Lithotripsy: Results from an In Vitro Kidney Model.

We developed a polyethylene sack (the PercSac) that fits over the shaft of a rigid nephroscope and is deployed into the collecting system to capture a stone and contain fragments during percutaneous nephrolithotomy (PCNL). We previously reported our results using the PercSac in a percutaneous cystolithopaxy model. In this study, we compare the efficiency of stone fragmentation with and without the PercSac in an anatomically correct in vitro PCNL model. The PCNL model consisted of a human collecting system model created on a 3D printer. Ten BegoStones made in spherical molds of 2.0 cm diameter, matched for weight, were fragmented in the model using a 24F rigid nephroscope and an ultrasonic lithotripter, including five with and five without the PercSac. The total times for stone fragmentation and complete stone clearance, gross assessment of the stone-free status, and need for flexible nephroscopy to achieve a stone-free state were recorded. The median time for stone fragmentation was significantly shorter in the PercSac group compared with the control group (217 seconds [IQR = 169-255] vs 340 seconds [IQR = 310-356], [p = 0.028]). Likewise, the total time for complete stone clearance from the kidney was significantly shorter for the PercSac group (293 seconds [IQR = 244-347] vs 376 seconds [IQR = 375-480], [p = 0.047]). In one trial with the PercSac, residual dust remained in the kidney, while in all five trials without the PercSac small residual fragments remained. All trials without the PercSac required flexible nephroscopy with basket extraction to become stone free, while none of the trials with the PercSac required flexible nephroscopy for stone clearance. Ultrasonic lithotripsy using the novel PercSac stone entrapment device is more efficient and efficacious than traditional ultrasonic lithotripsy in an in vitro PCNL model. The advantage may be even more pronounced during clinical PCNL where residual fragments migrate into difficult-to-access calices. Further in vivo testing is underway.

Shifting the Split Reflectors to Enhance Stone Fragmentation of Shock Wave Lithotripsy

Shock wave lithotripsy (SWL) has been used widely in urology for about three decades to treat kidney calculi. Technical development to improve performance (i.e., stone fragmentation efficiency) is continuous. Low-pressure wide-focus lithotripters have already achieved promising results. In this study, the lithotripter field and profile of lithotripter shock waves were changed simultaneously using a cost-effective and convenient design. An intact parabolic reflector was split into four pieces, and each part was moved individually. By shifting the split reflectors, the focused acoustic beams were separated. As a result, the beam width in the focal region could be increased. Both numerical models of wave propagation using a k-wave approach and hydrophone measurements showed similar pressure waveforms at the focus and the distributions along and transverse to the lithotripter axis. The increase of the shifting distance from 0 mm to 7 mm resulted in the increase of −6 dB beam width from 7.1 mm to 13.9 mm and location of tensile peak on axis moving from z = −14 mm to 1 mm. The Lithotripters at 10 kV (intact reflector) and at 12 kV with the split reflectors shifted by 5 mm were compared with each other because of their similar peak positive pressures at the focus (8.07 MPa ± 0.05 MPa vs. 7.90 MPa ± 0.11 MPa, respectively). However, there were significant differences in their positive beam width (8.7 mm vs. 10.2 mm), peak negative pressure (−6.34 MPa ± 0.04 MPa vs. −7.13 MPa ± 0.13 MPa), the maximum tensile stress (7.55 MPa vs. 8.95 MPa) and shear stress (6.1 MPa vs. 7.76 MPa) in a 10-mm diameter spherical stone and bubble collapse time (127.6 μs ± 5.4 μs vs. 212.7 μs ± 8.2 μs). As a result, stone fragmentation efficiency was enhanced about 1.8-fold (57.9% ± 4.6% vs. 32.2% ± 5.6%, p < 0.05) when shifting the split reflectors. These results suggest that this new reflector design could change the characteristics of the lithotripter field and increase stone fragmentation efficiency.

PD18-11 COMPARISON OF AN ELECTRIC PULSE LITHOTRIPTER TO THE HOLMIUM LASER: STONE FRAGMENTATION EFFICIENCY AND IMPACT ON FLEXIBLE URETEROSCOPE DEFLECTION AND FLOW

INTRODUCTION AND OBJECTIVES: A new intracorporeal lithotriptor uses a nanosecond duration electrical discharge through a flexible coaxial probe to endoscopically fragment urinary stones. This device was compared to a holmium laser with regards to stone fragmentation efficiency and their impact on flexible ureteroscope deflection and flow of irrigation. METHODS: Using a custom bench model, stone fragmentation efficiency of the Nano-electric Pulse Lithotriptor (NPL, Lithotech Group, Israel) was evaluated with a begostone (mixture 5:2) confined under 0.9% normal saline atop sequential mesh sieves. Two NPL probe sizes (2.0 and 3.6F) and two holmium laser fibers (200 mm and 365mm) were evaluated using 6mm begostones. Time to first break, time to complete break (all fragments <3mm), and overall fragment sizes were measured. Ureteroscope deflection was tested in 5 new 4th generation flexible ureteroscopes, with an empty channel followed by placement of a 2.0F NPL probe, a 2.4F NPL probe, a 200mm laser fiber, and a 1.9F wire basket. Ureteroscope irrigation flow was measured using normal saline at 100 cm, with an empty channel and then with a 2.0F NEP probe, a 200mm laser fiber, and a 1.9F wire basket. RESULTS: The 2.0F NPL showed improved stone fragmentation efficiency compared to the 200mm laser (86 mg/min vs. 52 mg/min, p 1⁄4 0.014) as did the 3.6F NPL vs. the 365mm laser (173 mg/min vs. 80 mg/min, p1⁄40.05). The NPL created more 1-2 mm fragments, while the laser created more dust (< 1 mm fragments); the difference was more pronounced between the larger NPL and laser probes. In the 5 ureteroscopes tested, ureteroscope deflection was reduced by an average of 3.75 with the 2.0F NPL probe and 22.25 with the 2.4F NLP probe (compared to 5.25 with the laser and 2.75 with the basket). Irrigation flow through the ureteroscope was 36.5 ml/min on average, and was reduced to 18.3 ml/min with the 200mm laser fiber, and to 6.3 ml/min with the 2.0F NEP probe. CONCLUSIONS: The Nano-electric pulse lithotripter produces improved stone fragmentation efficiency as compared to the holmium laser. However the 2.0F and 2.4F NPL probes limit flow and the 2.4F probe limits ureteroscope deflection.

The modern history and evolution of percutaneous nephrolithotomy.

Serendipity, innovative physicians, evolving techniques for renal access, and improvements in equipment and radiology led to the evolution of percutaneous nephrolithotomy (PCNL). We searched urology texts and the literature for sources pertaining to the history and development of PCNL. In 1941, Rupel and Brown performed the first nephroscopy when a rigid cystoscope was passed into the kidney following open surgery. Willard Goodwin, in 1955, while trying to perform a renal arteriogram, placed a needle into the collecting system of a hydronephrotic kidney and performed the first antegrade nephrostogram. He left a tube to drain the kidney, thereby placing the first nephrostomy tube. By 1976, Fernström and Johansson were the first to describe a technique for extracting renal calculi through a percutaneous nephrostomy under radiological control. In 1978, Arthur Smith, would describe the first antegrade stent placement when he introduced a Gibbons stent through a percutaneous nephrostomy in a patient with a reimplanted ureter. Dr. Smith would coin the term "endourology" to describe closed, controlled manipulation of the genitourinary tract. His collaboration with Kurt Amplatz, an interventional radiologist and medical inventor, would lead to numerous innovations that would further advance PCNL. In the 1980s the process of renal access and tract dilation was improved upon and the use of a rigid cystoscope was replaced by offset nephroscopes with a large straight working channel. Radiographic innovations, including improvements in fluoroscopy would further aid in renal access. The development of various lithotripsy devices and the introduction of the holmium laser improved the efficiency of stone fragmentation and clearance. The increased clinical experience and utilization of PCNL would lead to the characterization of stone-free rates and complications for the procedure. Serendipity, innovations in renal access, optics, radiology, and improvements in lithotripsy all contributed to the modern day PCNL.

Suppressing bubble shielding effect in shock wave lithotripsy by low intensity pulsed ultrasound

Extracorporeal shock wave lithotripsy (ESWL) has been used as an effective modality to fragment kidney calculi. Because of the bubble shielding effect in the pre-focal region, the acoustic energy delivered to the focus is reduced. Low pulse repetition frequency (PRF) will be applied to dissolve these bubbles for better stone comminution efficiency. In this study, low intensity pulsed ultrasound (LIPUS) beam was aligned perpendicular to the axis of a shock wave (SW) lithotripter at its focus. The light transmission was used to evaluate the compressive wave and cavitation induced by SWs without or with a combination of LIPUS for continuous sonication. It is found that bubble shielding effect becomes dominated with the SW exposure and has a greater significant effect on cavitation than compressive wave. Using the combined wave scheme, the improvement began at the 5th pulse and gradually increased. Suppression effect on bubble shielding is independent on the trigger delay, but increases with the acoustic intensity and pulse duration of LIPUS. The peak negative and integral area of light transmission signal, which present the compressive wave and cavitation respectively, using our strategy at PRF of 1Hz are comparable to those using SW alone at PRF of 0.1Hz. In addition, high-speed photography confirmed the bubble activities in both free field and close to a stone surface. Bubble motion in response to the acoustic radiation force by LIPUS was found to be the major mechanism of suppressing bubble shielding effect. There is a 2.6-fold increase in stone fragmentation efficiency after 1000 SWs at PRF of 1Hz in combination with LIPUS. In summary, combination of SWs and LIPUS is an effective way of suppressing bubble shielding effect and, subsequently, improving cavitation at the focus for a better outcome.

Optical coupling control: an important step toward better shockwave lithotripsy.

In modern "dry" lithotripters, shockwaves are generated in a membrane-covered water cushion that is then coupled to the patient.To limit energy loss, a coupling agent, usually ultrasound gel, is used in this acoustic interface. During the coupling process, air pockets are inevitably trapped in the coupling area, which subsequently remains invisible to the operator. These air pockets dramatically decrease stone fragmentation efficiency up to 40%. To check for air bubbles in the coupling interface, a video camera was installed in the therapy head of our Dornier Gemini lithotripter: all air bubbles observed in the coupling zone could then be removed under visual control. We evaluated the effect of this optically controlled coupling (OCC) on treatment results (10/1/12-9/30/13) and compared these to the results obtained in a "blind" coupling mode (4/1/11-4/30/12). Optically controlled removal of air bubbles from the coupling area reduced the required number of shockwaves with 25.4% for renal stones and 25.5% for ureteral stones. Energy level was reduced by 23.1% for renal stones and by 22.5% for ureteral stones. For renal stones, total applied energy was thus reduced by 42.9%. Effectiveness quotients were comparable. Optical control with a video camera proved pivotal in the realization of bubble-free coupling. Bubble-free coupling significantly reduced the total energy needed to obtain comparable treatment results. Theoretically, this should also lead to a reduced incidence and severity of shockwave-induced adverse effects. We consider this an important step toward better and safer shockwave lithotripsy and would therefore advocate the standard incorporation of an OCC system in all new lithotripters.

PD37-03 PERCSAC: A NOVEL DEVICE TO PREVENT STONE FRAGMENT MIGRATION DURING PERCUTANEOUS LITHOTRIPSY

You have accessJournal of UrologyStone Disease: New Technology II1 Apr 2014PD37-03 PERCSAC: A NOVEL DEVICE TO PREVENT STONE FRAGMENT MIGRATION DURING PERCUTANEOUS LITHOTRIPSY Jodi Antonelli, Justin Friedlander, Jeffrey Gahan, Heather Beardsley, Margaret Pearle, and Jeffrey Cadeddu Jodi AntonelliJodi Antonelli More articles by this author , Justin FriedlanderJustin Friedlander More articles by this author , Jeffrey GahanJeffrey Gahan More articles by this author , Heather BeardsleyHeather Beardsley More articles by this author , Margaret PearleMargaret Pearle More articles by this author , and Jeffrey CadedduJeffrey Cadeddu More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.2021AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Up to 50% of patients with residual fragments after percutaneous nephrolithotomy (PCNL) experience a stone-related event. We developed a polyethylene sack (the PercSac) that fits over the shaft of a rigid nephroscope and is deployed in the collecting system to capture a stone, thereby containing fragments generated during PCNL and allowing for efficient and complete removal. We compared the efficiency of stone fragmentation and retrieval with and without the PercSac device in an in vitro percutaneous cystolitholapaxy model. METHODS Using a Limbs & Things® bladder model into which a 30F Amplatz working sheath was placed, 20 canine bladder stones matched for weight and volume were fragmented using a 24F rigid nephroscope and an ultrasonic lithotripter with and then without the PercSac. The total time for complete stone fragmentation and a gross assessment of the stone-free status of the bladder were recorded for each stone. RESULTS The mean stone weight and volume for the PercSac group was 2.63 +/- SD 0.95g and 1.68 +/- SD 0.63cm3, respectively. Similarly, the mean stone weight and volume for the group without the PercSac was 2.57 +/- SD 0.89g and 1.78 +/- SD 0.68cm3. The median time for complete stone fragmentation was significantly shorter in the PercSac group compared with the control group [182.0 sec (IQR= 108-221) vs 296.5 sec (IQR= 226-398), p= 0.004]. Likewise, the total time from insertion of the nephroscope into the bladder to completion of stone fragmentation was shorter for the PercSac group but this did not reach statistical significance [254.5 sec (IQR= 173-302) vs 296.5 sec (IQR= 226-398) respectively, p= 0.112]. The stone-free rate for the PercSac group was 100 vs 0% for the control group. CONCLUSIONS Ultrasonic lithotripsy using the PercSac device is more efficient and efficacious than traditional ultrasonic lithotripsy in a bladder model. This advantage may be even more pronounced during clinical PCNL where residual fragments migrate into difficult-to-access calyces. Further in vitro and in vivo testing in both kidney and bladder models is underway. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e946-e947 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Jodi Antonelli More articles by this author Justin Friedlander More articles by this author Jeffrey Gahan More articles by this author Heather Beardsley More articles by this author Margaret Pearle More articles by this author Jeffrey Cadeddu More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Assessment of a Modified Acoustic Lens for Electromagnetic Shock Wave Lithotripters in a Swine Model

The acoustic lens of the Modularis electromagnetic shock wave lithotripter (Siemens, Malvern, Pennsylvania) was modified to produce a pressure waveform and focal zone more closely resembling that of the original HM3 device (Dornier Medtech, Wessling, Germany). We assessed the newly designed acoustic lens in vivo in an animal model. Stone fragmentation and tissue injury produced by the original and modified lenses of the Modularis lithotripter were evaluated in a swine model under equivalent acoustic pulse energy (about 45 mJ) at 1 Hz pulse repetition frequency. Stone fragmentation was determined by the weight percent of stone fragments less than 2 mm. To assess tissue injury, shock wave treated kidneys were perfused, dehydrated, cast in paraffin wax and sectioned. Digital images were captured every 120 μm and processed to determine functional renal volume damage. After 500 shocks, the mean ± SD stone fragmentation efficiency produced by the original and modified lenses was 48% ± 12% and 52% ± 17%, respectively (p = 0.60). However, after 2,000 shocks, the modified lens showed significantly improved stone fragmentation compared to the original lens (mean 86% ± 10% vs 72% ± 12%, p = 0.02). Tissue injury caused by the original and modified lenses was minimal at a mean of 0.57% ± 0.44% and 0.25% ± 0.25%, respectively (p = 0.27). With lens modification the Modularis lithotripter demonstrates significantly improved stone fragmentation with minimal tissue injury at a clinically relevant acoustic pulse energy. This new lens design could potentially be retrofitted to existing lithotripters, improving the effectiveness of electromagnetic lithotripters.

In Vitro Study of the Revised Ultrasound Based Real-Time Tracking of Renal Stones for Shock Wave Lithotripsy: Part 1

Extracorporeal shock wave lithotripsy has been popular since the 1980s. Only 30% to 50% of the shock waves of all conventional lithotripters are focused on stones. We developed an ultrasound based, real-time stone tracking system (version 1) to improve accuracy and treatment efficiency. However, some problems remained. We revised the existing system (version 2) and tested its reliability and performance. We revised the system by adding more algorithms to decrease renal stone misidentification. We verified the advanced system by 2 tests using no tracking and tracking with 13 stone trajectories for versions 1 and 2. We performed the coincidence test to evaluate the accuracy of targeting the stone within the effective focal area and the stone fragmentation efficiency test to clarify the decrease in the number of shocks needed for stone fragmentation. In the coincidence test the mean ± SD results of the nontracking system, and tracking versions 1 and 2 were 68.8% ± 18.8%, 89.9% ± 5.2% and 94.3% ± 4.5%, respectively. Version 2 was statistically significantly better than version 1 (p = 1.5 × 10(-4)). In the stone fragmentation efficiency test the mean results of the nontracking system, and versions 1 and 2 were 49.5% ± 14.2%, 85.1% ± 4.5% and 89.5% ± 4.2%, respectively. Version 2 was statistically significantly better than version 1 (p = 1.9 × 10(-8)). The revised tracking system is better than version 1. It improves treatment efficiency, decreases stone misidentification and can shorten treatment time.

Characteristics of the Secondary Bubble Cluster Produced by an Electrohydraulic Shock Wave Lithotripter

This study investigated the characteristics of the secondary bubble cluster produced by an electrohydraulic lithotripter using high-speed imaging and passive cavitation detection techniques. The results showed that (i) the discrepancy of the collapse time between near a flat rigid boundary and in a free field of the secondary bubble cluster was not as significant as that by the primary one; (ii) the secondary bubble clusters were small but in a high bubble density and nonuniform in distribution, and they did not expand and aggregate significantly near a rigid boundary; and (iii) the corresponding bubble collapse was weaker with few microjet formation and bubble rebound. By applying a strong suction flow near the electrode tip, the production of the secondary shock wave (SW) and induced bubble cluster could be disturbed significantly, but without influence on the primary ones. Consequently, stone fragmentation efficiency was reduced from 41.2 ± 7.1% to 32.2 ± 3.5% after 250 shocks (p < 0.05). Altogether, these observations suggest that the secondary bubble cluster produced by an electrohydraulic lithotripter may contribute to its ability for effective stone fragmentation.

UP-03.100 Anti-Retropulsion Devices Increase Stone Fragmentation Efficiency with Holmium:YAG Laser Lithotripsy

UP-03.100 Anti-Retropulsion Devices Increase Stone Fragmentation Efficiency with Holmium:YAG Laser Lithotripsy