Holmium:YAG lithotripsy yields smaller fragments than lithoclast, pulsed dye laser or electrohydraulic lithotripsy

Simulation of the temperature distribution of kidney stones induced by thulium fiber laser and Ho: YAG laser lithotripsy

Simulation studies on temperature distribution in laser ablation help predict ablation rates, laser settings, and thermal damage. Despite the limited number of reported numerical studies on the temperature distribution of kidney fluid, there is no simulation study for kidney stone temperature distribution. We employ a numerical approach to study the kidney stone temperature distribution and predict ablation rates, which is an important parameter for clinical lithotripsy. The study looked at how the thulium fiber laser and the Ho:YAG laser differ in terms of temperature profile and ablation depth of kidney stones like calcium oxide monohydrate. The ablation depth increased from 152.7 µm to 489.7 µm when the TFL laser (operated at 10 Hz repetition rate and 1 ms pulse width) fluence increased from 764 J/cm2 to 1146 J/cm2. Correspondingly, the depth increased from 21 µm to 68 µm for the Ho: YAG laser operated at 3 Hz and 0.22 ms pulse width. We attribute this to an increase in temperature with laser energy. We further investigated the effect of pulse width on ablation depth by considering three different TFL pulse widths: 0.5 ms, 0.75 ms, and 1 ms. There was a decrease in ablation depths from 402.5 µm to 242.6 µm when the pulse width increased from 0.5 ms to 1 ms. Because of lower water absorption coefficients, the Ho:YAG laser (70 mJ/10 Hz) produced a smaller ablation depth and temperature profile than the thulium fiber laser (70 mJ/10 Hz). Experimental results from the literature validated the simulation. We found that the Ho:YAG laser worked better for ablation when it was set to 0.2 J/100 Hz for the Ho:YAG laser and 0.4 J/50 Hz for the TFL laser, which were clinical laser settings that we found in the literature. This indicates that, in addition to laser absorption by water, the laser parameters also significantly influence temperature distribution and ablation.

Laser Ablation Efficiency, Laser Ablation Speed, and Laser Energy Consumption During Lithotripsy: What Are They and How Are They Defined? A Systematic Review and Proposal for a Standardized Terminology

CONTEXT

Laser performance for lithotripsy is currently reported using units of measurement such as J/mm3, mm3/J, mm3/s, s/mm3, and mm3/min. However, there are no current standardized definitions or terminology for these metrics. This may lead to confusion when assessing and comparing different laser systems.

OBJECTIVE

The primary objective was to summarize outcome values and corresponding terminology from studies on laser lithotripsy performance using stone volume in relation to time or energy. The secondary objective was to propose a standardized terminology for reporting laser performance metrics.

EVIDENCE ACQUISITION

A systematic review of the literature was conducted using the search string ("j*/mm3" OR "mm3/j*" OR "mm3/s*" OR "s*/mm3" OR "mm3/min*" OR "min*/mm3" AND "lithotripsy") on Scopus, Web of Science, Embase, and PubMed databases. Study selection, data extraction, and quality assessment were performed independently by two authors.

EVIDENCE SYNTHESIS

A total of 28 studies were included, covering holmium:yttrium-aluminum-garnet (Ho:YAG), MOSES, and thulium fiber laser (TFL) technologies. Laser energy consumption values reported for the studies ranged from 2.0 - 43.5 J/mm3in vitro and from 2.7 - 47.8 J/mm3in vivo, translating to laser ablation efficiency of 0.023 - 0.500 mm3/J and 0.021 - 0.370 mm3/J, respectively. Laser ablation speeds ranged from 0.3 - 8.5 mm3/s in vivo, translating to lasing time consumption of 0.12 - 3.33 s/mm3. Laser efficacy ranged from 4.35 - 51.7 mm3/min in vivo. There was high heterogeneity for the terminology used to describe laser performance for the same metrics.

CONCLUSIONS

The range of laser performance metric values relating stone volume to energy or time is wide, with corresponding differing terminology. We propose a standardized terminology for future studies on laser lithotripsy, including laser ablation efficiency (mm3/J), laser ablation speed (mm3/s), and laser energy consumption (J/mm3). Laser efficacy (mm3/min) is proposed as a broader term that is based on the total operative time, encompassing the whole technique using the laser.

PATIENT SUMMARY

We reviewed studies to identify the units and terms used for laser performance when treating urinary stones. The review revealed a wide range of differing units, outcomes, and terms. Therefore, we propose a standardized terminology for future studies on laser stone treatment.

The Effect of High- and Low-power Holmium Laser Settings for Transurethral Lithotripsy in the Management of Adults with Ureteral Stone

Since there is insufficient evidence to determine the best treatment of transurethral laser lithotripsy (TLL) in ureteral stones, this study compared the effectiveness and safety of TLL using high-power (HP) (100 W) and low-power (LP) (20 W) laser settings. All patients with maximally sized ureteral stones who were planned for transurethral holmium laser lithotripsy were enrolled in this open study. One of the two laser setting groups-LP or HP-was allocated to each alternate patient. Using IBM SPSS Statistics 24, the treatment groups were compared for operating time, intraoperative and postoperative problems (up to 1 year), and rates of stone-free recovery. Welch tests were employed to compare continuous data, whereas Fisher's exact or Chi-square tests were used to assess categorical variables. At P < 0.05, statistical significance was established. A total of 207 individuals were included and preoperative data were comparable between the two groups. The HP group had a considerably greater ablation rate and a significantly shorter procedure duration (42.61 ± 11.74 min) than the LP group (78.56 ± 25.91 min) ( P = 0.025). The Overactive Bladder Symptom Score and International Prostate Symptom Score were considerably higher in the HP group than in the LP group. Treatment effectiveness was considerably impacted by the location of the ureteral stone, according to univariate and multivariate logistic regression models. A HP laser setting of up to 100 W greatly shortens the duration of the process for treating ureteral stones without raising the risk of problems.

The Saudi urological association guidelines on urolithiasis

Aims

The Saudi Urolithiasis Guidelines are a set of recommendations for diagnosing, evaluating, and treating urolithiasis in the Saudi population. These guidelines are based on the latest evidence and expert consensus to improve patient outcomes and optimize care delivery. They cover the various aspects of urolithiasis, including risk factors, diagnosis, medical and surgical treatments, and prevention strategies. By following these guidelines, health-care professionals can improve care quality for individuals with urolithiasis in Saudi Arabia.

Panel

The Saudi Urolithiasis Guidelines Panel consists of urologists specialized in endourology with expertise in urolithiasis and consultation with a guideline methodologist. All panelists involved in this document have submitted statements disclosing any potential conflicts of interest.

Methods

The Saudi Guidelines on Urolithiasis were developed by relying primarily on established international guidelines to adopt or adapt the most appropriate guidance for the Saudi context. When necessary, the panel modified the phrasing of recommendations from different sources to ensure consistency within the document. To address areas less well covered in existing guidelines, the panel conducted a directed literature search for high quality evidence published in English, including meta analyses, randomized controlled trials, and prospective nonrandomized comparative studies. The panel also searched for locally relevant studies containing information unique to the Saudi Arabian population. The recommendations are formulated with a direction and strength of recommendation based on GRADE terminology and interpretation while relying on existing summaries of evidence from the existing guidelines.

Pulsed Thulium:YAG laser - What is the lithotripsy ablation efficiency for stone dust from human urinary stones? Results from an in vitro PEARLS study

BACKGROUND

The novel pulsed thulium:yttrium-aluminum-garnet (p-Tm:YAG) laser was recently introduced. Current studies present promising p-Tm:YAG ablation efficiency, although all are based on non-human stone models or with unknown stone composition. The present study aimed to evaluate p-Tm:YAG ablation efficiency for stone dust from human urinary stones of known compositions.

METHODS

Calcium oxalate monohydrate (COM) and uric acid (UA) stones were subjected to lithotripsy in vitro using a p-Tm:YAG laser generator (Thulio®, Dornier MedTech GmbH, Germany). 200 J was applied at 0.1 J × 100 Hz, 0.4 J × 25 Hz or 2.0 J × 5 Hz (average 10W). Ablated stone dust mass was calculated from weight difference between pre-lithotripsy stone and post-lithotripsy fragments > 250 µm. Estimated ablated volume was calculated using prior known stone densities (COM: 2.04 mg/mm3, UA: 1.55 mg/mm3).

RESULTS

Mean ablation mass efficiency was 0.04, 0.06, 0.07 mg/J (COM) and 0.04, 0.05, 0.06 mg/J (UA) for each laser setting, respectively. This translated to 0.021, 0.029, 0.034 mm3/J (COM) and 0.026, 0.030, 0.039 mm3/J (UA). Mean energy consumption was 26, 18, 17 J/mg (COM) and 32, 23, 17 J/mg (UA). This translated to 53, 37, 34 J/mm3 (COM) and 50, 36, 26 J/mm3 (UA). There were no statistically significant differences for laser settings or stone types (all p > 0.05).

CONCLUSION

To our knowledge, this is the first study showing ablation efficiency of the p-Tm:YAG laser for stone dust from human urinary stones of known compositions. The p-Tm:YAG seems to ablate COM and UA equally well, with no statistically significant differences between differing laser settings.

Comparing dusting and fragmenting efficiency using the new SuperPulsed thulium fiber laser versus a 120 W Holmium:YAG laser

PURPOSE

Holmium:YAG laser lithotripsy requires high amperage power and has an upper limit of frequency and a minimal fiber size. The technology utilizing thulium-doped fiber offers low pulse energy settings and high pulse frequencies up to 2,400 Hz. We compared the novel SuperPulsed thulium fiber laser (SOLTIVE™; Olympus) to a commercially available 120 W Ho:YAG laser.

MATERIALS AND METHODS

Bench-top testing was conducted with 125 mm³ standardized BegoStones (Bego USA). Time to ablate the stone into particles <1 mm was recorded for efficiency calculations. Finite energy was delivered, and resulting particle sizes were measured to determine fragmentation (0.5 kJ) and dusting (2 kJ) efficiencies. Remaining mass or number of fragments were measured to compare efficacy.

RESULTS

SOLTIVE™ was faster at ablating stones to particles <1 mm (2.23±0.22 mg/s, 0.6 J 30 Hz short pulse) compared to Ho:YAG laser (1.78±0.44 mg/s, 0.8 J 10 Hz short pulse) (p<0.001). Following 0.5 kJ of energy in fragmentation testing, fewer particles >2 mm remained using SOLTIVE™ than Ho:YAG laser (2.10 vs. 7.20 fragments). After delivering 2 kJ, dusting (1.05±0.08 mg/s) was faster using SOLTIVE™ (0.1 J 200 Hz short pulse) than 120 W 0.46±0.09 mg/s (0.3 J 70 Hz Moses) (p=0.005). SOLTIVE™ (0.1 J 200 Hz) produced more dust particles <0.5 mm (40%) compared to 24% produced by the P120 W laser at 0.3 J 70 Hz Moses and 14% at 0.3 J 70 Hz long pulse (p=0.015).

CONCLUSIONS

The efficacy of SOLTIVE™ is superior to the 120 W Ho:YAG laser by producing smaller dust particles and fewer fragments. Further studies are warranted.

New Generation Pulse Modulation in Holmium:YAG Lasers: A Systematic Review of the Literature and Meta-Analysis

(1) Background: New pulse modulation (PM) technologies in Holmium:YAG lasers are available for urinary stone treatment, but little is known about them. We aim to systematically evaluate the published evidence in terms of their lithotripsy performance. (2) Methods: A systematic electronic search was performed (MEDLINE, Scopus, and Cochrane databases). We included all relevant publications, including randomized controlled trials, non-randomized comparative and non-comparative studies, and in-vitro studies investigating Holmium:YAG lithotripsy performance employing any new PM. (3) Results: Initial search yielded 203 studies; 24 studies were included after selection: 15 in-vitro, 9 in-vivo. 10 In-vitro compared Moses with regular PM, 1 compared Quanta’s, 1 Dornier MedTech’s, 2 Moses with super Thulium Fiber Laser, and 1 compared Moses with Quanta PMs. Six out of seven comparative studies found a statistically significant difference in favor of new-generation PM technologies in terms of operative time and five out of six in fragmentation time; two studies evaluated retropulsion, both in favor of new-generation PM. There were no statistically significant differences regarding stone-free rate, lasing and operative time, and complications between Moses and regular PM when data were meta-analyzed. (4) Conclusions: Moses PM seems to have better lithotripsy performance than regular modes in in-vitro studies, but there are still some doubts about its in-vivo results. Little is known about the other PMs. Although some results favor Quanta PMs, further studies are needed.

Urethral Urolithiasis in Male Cattle Treated Using Pneumatic Lithotripsy

One of the most important problems encountered in cattle breeding is urethral urolithiasis. Urolithiasis can be treated using various methods, but they all carry risks. Thus, a continuous search is being carried out for alternatives in this field. This study aimed to treat urethral urolithiasis in male cattle using pneumatic lithotripsy, a minimally invasive method. The urethra and penile tissues of 20 male cattle of different ages and breeds were obtained from slaughterhouse materials and measured before determining the probe diameters and lengths. The study included 9 male cattle (2 Simmental hybrids, 1 Zavot hybrid, 1 Brown, and 5 Simmental), between 4 months and 2 years of age, diagnosed with urethral urolithiasis. A modified lithotripsy apparatus was used for the pneumatic disintegration of urinary stones. The localization of urinary stones in the urethra was determined by palpation and catheterization. After laying the animal in a lateral position, a lithotripsy probe of appropriate length and diameter was advanced from the external urethral orifice to the site of localization. Once the probe came into contact with the stone, a vibration of 125 bar was applied until the stone was broken. The probe was removed, and the urethral channel was washed with 0.1% iodine solution to remove the shredded urethral stones. Uncomplicated recovery was achieved in all treated cases. In conclusion, pneumatic lithotripsy provided successful results in treating urolithiasis and can be used as an alternative surgical method in cattle. Moreover, the low cost is an additional advantage to breeders.

Pediatric Stone Surgery: What Is Hot and What Is Not

PURPOSE OF REVIEW

We aim to highlight recent advances in technology and techniques for surgical management of urinary tract calculi in pediatric patients.

RECENT FINDINGS

Percutaneous nephrolithotomy (PCNL) is classically performed in the prone position. The supine PCNL was first attempted to overcome the shortcomings of difficult airway access, patient and surgeon discomfort. The supine PCNL, and subsequent modifications, has been successfully described in the pediatric population. Classically, PCNL has also been classically concluded with obligate placement of a nephrostomy tube and bladder catheter. Recently, tubeless and totally tubeless PCNL reduces pain and duration of hospitalization with satisfactory surgical outcomes in children. Finally, we describe the use of thulium laser technology, which offers improved efficacy in stone treatment and may supplant the current dominant technologies in coming years. Recent advances in pediatric stone surgery include supine PCNL, miniaturized PCNL instrumentation, tubeless procedures, and thulium laser technology.

Moses 2.0 for High-Power Ureteroscopic Stone Dusting: Clinical Principles for Step-by-Step Video Technique

Introduction: We present our initial experience using the Moses 2.0 system for flexible-ureteroscopy (f-URS) high-frequency renal stone dusting, including a step-by-step video guide of our clinical principles for dusting technique. Materials and Methods: Twelve consecutive patients undergoing f-URS with Moses 2.0 (Lumenis) for a single renal stone by a single surgeon at an ambulatory center were reviewed. Stone-free rates (SFRs) and Clavien grade complications were assessed. Operative steps with illustrative examples are provided in an accompanying video. Results: Mean (range) stone size and lithotripsy time were 10.4 (5.3-17.2) mm and 15.0 (5-26) minutes, respectively. Complete SFR and <2 mm residual fragments were 82% and 18%, respectively. One patient had a Clavien Grade 1 complication. Operative steps reviewed include instrumentation, stone control, laser settings, and stent omission criteria. The preferred laser settings for renal stone dusting were 0.2-0.3 J and 100-120 Hz. Limitation of this early experience study is the small sample size. Larger studies are needed to confirm our initial findings. Conclusions: Early experience of Moses 2.0 for f-URS renal stone dusting demonstrated effective and efficient laser lithotripsy in patients with renal stones <2 cm.

Mechanisms of Pulse Modulated Holmium:YAG Lithotripsy

Introduction: This study aimed at answering three research questions: (1) Under the experimental conditions studied, what is the dominant mechanism of Holmium:YAG lithotripsy with or without pulse modulation? (2) Under what circumstances can laser pulse modulation increase crater volume of stone ablation per joule of emitted radiant energy? (3) Are BegoStone phantoms a suitable model for laser lithotripsy studies? Materials and Methods: The research questions were addressed by ablation experiments with BegoStone phantoms and native stones. Experiments were performed under three stone conditions: dry stones in air, hydrated stones in air, and hydrated stones in water. Single pulses with and without pulse modulation were applied. For each pulse mode, temporal profile, transmission through 1 mm water, and cavitation bubble collapse pressures were measured and compared. For each stone condition and pulse mode, stones were ablated with a fiber separation distance of 1 mm and crater volumes were measured using optical coherence tomography. Results: Pulses with and without pulse modulation had high (>80%) transmission through 1 mm of water. Pulses without pulse modulation generated much higher peak pressures than those with pulse modulation (62.3 vs 11.4 bar). Pulse modulation resulted in similar or larger craters than without pulse modulation. Trends in BegoStone crater volumes differed from trends in native stones. Conclusions: This results of this study suggest that the dominant mechanism is photothermal with possible photoacoustic contributions for some stone compositions. Pulse modulation can increase ablation volume per joule of emitted radiant energy, but the effect may be composition specific. BegoStones showed unique infrared ablation characteristics compared with native stones and are not a suitable model for laser lithotripsy studies.

Minimally invasive percutaneous nephrolithotomy with SuperPulsed Thulium-fiber laser

We aimed to assess the efficacy and safety of minimally invasive percutaneous nephrolithotomy (PCNL) with SuperPulsed Thulium-fiber laser (SP TFL) using different frequency settings. 125 patients with solitary kidney calculi of up to 55 mm in the maximum diameter underwent mini-PCNL with the SP TFL. Stone-free rate, laser-on time, ablation efficacy, energy consumption, ablation speed and complications were all analyzed. Negative low-dose computed tomography scan or asymptomatic patients with stone fragments < 2 mm were the criteria for assessing the stone-free status. In 36 patients (28.8%) low frequency regimens were used (LF: 3-19 Hz-0.5-6 J), in 75 patients (60%) high frequency regimens were chosen (HF: 20-49 Hz-0.2-2 J) and in 14 (11.2%) patients higher frequency (HRF: 50-200 Hz-0.1-0.5 J) regimens were preferred. The mean age was 52 ± 1.8 years. Median stone diameter and median stone volume were larger at low frequency regimens compared to high frequency regimens. Ablation efficacy (J/mm³) was lower at low rather than at high frequency regimens. Ablation speed (mm³/sec) was higher at low compared to high frequency regimens. Surgeons reported minimal and absent retropulsion at higher frequency regimens. The best visibility was observed at high frequency regimens. The overall stone free rate (SFR) at 3 months was 85%. The majority of the postoperative complications were classified between Clavien grades I-II. SP TFL is an effective and safe tool for performing mini-PCNL regardless of the laser settings.

New devices for kidney stone management

PURPOSE OF REVIEW

The purpose of this review is to summarize recent developments in the array of devices which are commonly used by urologists in the surgical management of kidney stones. To accomplish this goal, an extensive review of recent endourology literature, conference abstracts, and publicly available documents from manufacturers and the United States Food and Drug Administration was collected and reviewed.

RECENT FINDINGS

Recent developments in the holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy include the introduction of pulse modulation. This technique delivers the laser energy in an asymmetric manner such that an initial bubble is created (the 'Moses effect') through which the remainder of the energy can then travel through without being absorbed by surrounding water. Even more novel is the thulium fiber laser, which is produced in a fundamentally different way than traditional Ho:YAG lasers and is not yet available for clinical use. Finally, novel mechanical lithotrites which effectively combine ultrasonic energy, ballistic energy, and suction capability appear to be highly effective for stone clearance in recent benchtop and clinical studies.

SUMMARY

With the introduction of both new modifications of time-tested technologies as well as completely novel modalities, the practicing urologist's armamentarium of devices for the surgical management of kidney stones continues to grow. As the popularity of 'mini' procedures continues to grow, the adaptability of these technologies to these procedures will be critical to maintain maximum relevance.

Analysis of the efficacy of holmium laser and pneumatic ballistic in the treatment of impacted ureteral calculi

To explore the safety and effectiveness of ureteroscopic holmium laser lithotripsy (UHLL) and ureteroscopic pneumatic lithotripsy (UPL) in the treatment of impacted ureteral calculi (IUC).Clinical data of 280 patients in our hospital from April 2016 to May 2019 were retrospectively collected and analyzed, including 136 cases of UHLL group and 144 cases of UPL group. The general clinical data, operation time, intraoperative bleeding volume, hospital stay, stone-free rate (SFR), and surgical complications were collected and analyzed in 2 group.Compared with UPL group, the operation time of UHLL group was significantly reduced (27.25 ± 8.39 vs 34.32 ± 10.57, P < .05), but the hospitalization cost was significantly increased (9.25 ± 0.75 vs 8.24 ± 0.51, P < .05). In terms of total SFR, the UHLL group was significantly higher than the UPL group (93.38% vs 83.33%, P = .011). For proximal IUC, compared with the UPL group, the SFR of the UHLL group was significantly increased (88.33% vs 70.31%, P = 0.005). For distal IUC, there was no significant difference in SFR (97.37% vs 93.75%, P = .638) between the UHLL group and UPL group. There were no significant differences in the complications of local mucosal injury, hematuria, febrile urinary tract infection, ureteral perforation, and urinary sepsis in the 2 groups (P > .05). However, the UHLL group was significantly lower in stone residual rate than the UPL group (6.61% vs 16.67%, P = .001).This study found that UHLL and UPL are safe and effective in the treatment of IUC, but UHLL has the advantages of shorter operation time and high SFR in the treatment of IUC.

Effect of ureteral calculus in outpatients receiving semirigid ureteroscope laser lithotripsy

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

Ho:YAG laser versus pneumatic lithotripsy for management of pediatric ureteral stones: a prospective-comparative analysis with adults

BACKGROUND

There are limited number of studies comparing the results of Holmium:YAG laser lithotripsy (LL) and pneumatic lithotripsy (PL) for pediatric ureteral stones.

OBJECTIVES

To perform a comparative analysis of LL and PL in the management of ureteral stones in children and adults.

STUDY DESIGN

Ninety-eight children (56 boys and 42 girls) and 623 adults (360 men and 263 women), who were treated for ureteral stones at our clinic between 2017 and 2019, were the subjects of this study. Patients were grouped according to their age as group 1 (n:98, pediatric [<18 age]) and group 2 (n:623, adult [≥18 age]). The patients were then grouped according to lithotripter type as laser (n:580) and pneumatic (n:141). The effects of lithotripter type, stone size and location, and operative times on success and complication rates were investigated.

RESULTS

In both groups, mean operation time was in favor of PL (14.6 vs 22.8 min, p = 0.042 and 26.4 vs 36.3 min, p = 0.013, respectively). In both groups, overall stone-free rates (SFR) were in favor of LL (86.8% vs 66.7%, p < 0.001, and 83% vs 73.9%, p = 0.005, respectively), but there was no significant difference in overall SFRs between adults and children (78.4% vs 76.7, p = 0.390). Retreatment rates were higher in the pneumatic group in both children and adults (p = 0.026 and p = 0.041, respectively). While there was no significant difference in the overall complication rates between adults and children (53.5% vs 40.6%, p = 0.816), the rate of complications with LL was lower in adults (37.7% vs 69.4%, p < 0.001) (TABLE).

DISCUSSION

This paper is the first to report a comparative analysis of factors affecting URS success in adults and children. SFRs were higher in all ureteral locations for LL. LL, lower ureteral location, and <6 mm ureteral stone were determined as the predictors of success for both pediatric and adult patients. The presence of multiple surgeons with different levels of experience is the main limitation of this study.

CONCLUSION

Both LL and PL are safe in children and adults with similar clinically insignificant complication rates. However, in the short term, LL provides better SFRs in both children and adults, especially in the upper ureteral stones. Surgeons should decide the energy technique to be used in URS according to the characteristics of the stone rather than the patient's age group.

How much energy do we need to ablate 1 mm3 of stone during Ho:YAG laser lithotripsy? An in vitro study

INTRODUCTION

Holmium:yttrium-aluminium-garnet (Ho:YAG) is currently the gold standard for lithotripsy for the treatment of all known urinary stone types. Stone composition and volume are major determinants of the lithotripsy. This in vitro study evaluated the required energy to ablate 1 mm³ of various stone types with different laser settings using Ho:YAG.

METHODS

272 µm core-diameter laser fibers (Boston Scientific^©) were connected to a 30 Watt MH1 Ho:YAG generator (Rocamed®). An experimental setup consisting of immerged human stones of calcium oxalate monohydrate (COM), uric acid (UA) or cystine (Cys) was used with a single pulse lasing emission (0.6/0.8/1 J), in contact mode. Stones were dried out before three-dimensional scanning to measure ablation volume per pulse (AVP) and required energy to treat 1 mm³ (RE).

RESULTS

All settings considered, ablation volumes per pulse (AVP) for COM were significantly lower than those for UA and Cys (p = 0.002 and p = 0.03, respectively), whereas AVP for Cys was significantly lower than those for UA (p = 0.03). The mean REs at 0.6 J pulse energy (PE) for COM, Cys and UA were 34, 8.5 and 3.2 J, respectively The mean REs at 1 J PE for COM, Cys and UA were 14.7, 6.4 and 2 J, respectively. At 0.6 J PE, RE for COM was more than tenfold and fivefold higher than those for UA and Cys, respectively.

CONCLUSION

This in vitro study shows for the first time a volumetric evaluation of Ho:YAG efficiency by the ablation volume per pulse on human stone samples, according to various pulse energies. The REs for COM, UA and Cys should be considered in clinical practice.

Thulium fiber laser: the new player for kidney stone treatment? A comparison with Holmium:YAG laser

PURPOSE

To compare the operating modes of the Holmium:YAG laser and Thulium fiber laser. Additionally, currently available literature on Thulium fiber laser lithotripsy is reviewed.

MATERIALS AND METHODS

Medline, Scopus, Embase, and Web of Science databases were searched for articles relating to the operating modes of Holmium:YAG and Thulium fiber lasers, including systematic review of articles on Thulium fiber laser lithotripsy.

RESULTS

The laser beam emerging from the Holmium:YAG laser involves fundamental architectural design constraints compared to the Thulium fiber laser. These differences translate into multiple potential advantages in favor of the Thulium fiber laser: four-fold higher absorption coefficient in water, smaller operating laser fibers (50-150 µm core diameter), lower energy per pulse (as low as 0.025 J), and higher maximal pulse repetition rate (up to 2000 Hz). Multiple comparative in vitro studies suggest a 1.5-4 times faster stone ablation rate in favor of the Thulium fiber laser.

CONCLUSIONS

The Thulium fiber laser overcomes the main limitations reported with the Holmium:YAG laser relating to lithotripsy, based on preliminary in vitro studies. This innovative laser technology seems particularly advantageous for ureteroscopy and may become an important milestone for kidney stone treatment.

Laser Versus Pneumatic Lithotripsy With Semi-Rigid Ureteroscope; A Comparative Randomized Study

Introduction: Ureteral stones are among the most common disorders in the urologic field. Miniaturization of endoscopic devices in urology and extracorporeal shock wave lithotripsy (ESWL) has revolutionized the management of ureteral stones. The aim of this study was to compare the efficacy and results of laser versus pneumatic lithotripsy (PL) with semi-rigid ureteroscope in a randomized prospective clinical trial in removing stones. Methods: 117 adult patients underwent transurethral lithotripsy (TUL) in a single academic center and by a single surgeon. The patients were randomized in 2 groups: In group 1, 58 patients with ureteral stones underwent ureteroscopy and stone fragmentation was done by Ho: YAG laser lithotripsy (LL) and in group 2, 59 patients underwent PL (Swiss LithoClast) by using the same ureteroscope. Results: Mean age was 41.77 years and 41.1years in group one and 2 respectively (P=0.79), there was no significant difference in male to female ratio and mean stone in both groups. The success rate for stone clearance was 79.31% and 77.96% in group 1 and 2 respectively (P=0.52). No difference between complications was seen in both groups, but the duration of operations was different (significantly lower in group 2). Conclusion: In both techniques, acceptable results were achieved. We have found a significant statistical difference in duration of operation between our results (P=0.001) and similar studies, while this was shorter in the pneumatic group in our study, it was longer in other similar ones. This might be a result of more experience in working with PL in our center.

Ureteroscopic lithotripsy for ureteral stones in children using holmium: yag laser energy: results of a multicentric survey

BACKGROUND

Holmium:YAG (Ho:YAG) laser lithotripsy has broadened the indications for ureteroscopic stone managements in adults, but few evidence are currently available in the pediatric population.

OBJECTIVE

This article aimed to assess the outcome of Ho:YAG laser lithotripsy during retrograde ureteroscopic management of ureteral stones in different locations in children.

STUDY DESIGN

The medical records of 149 patients (71 boys and 78 girls; median age 9.2 years) treated with Ho:YAG laser ureteroscopic lithotripsy in five international pediatric urology units over the last 5 years were retrospectively reviewed. Exclusion criteria included patients with renal calculi and/or with a history of ipsilateral stricture, renal failure, active urinary tract infection, or coagulation disorder.

RESULTS

Stones were treated with dusting technique in all cases. The median stone size was 10.3 mm (range 5-17). Stones were located in the distal ureter in 77 cases (51.7%), in the middle ureter in 23 cases (15.4%), and in the proximal ureter in 49 cases (32.9%). The median operative time was 29.8 min (range 20-95). Intra-operative complications included five bleedings (3.3%) and seven stone retropulsions (4.7%). Overall stone-free rate was 97.3%. Overall postoperative complications rate was 4.0% and included two cases of stent migration (1.3%) (Clavien II) and four residual stone fragments (2.7%) that were successfully treated using the same technique (Clavien IIIb). On multivariate analysis, re-operation rate was significantly dependent on the proximal stone location and presence of residual fragments >2 mm (P = 0.001).

DISCUSSION

This study is one of the largest pediatric series among those published until now. The study series reported a shorter operative time, a higher success rate, and a lower postoperative complications rate compared with previous series. A limitation of this study is that stone-free rates may be somewhat inaccurate using ultrasonography and plain X-ray compared with computed tomography (CT); the study's 97.3% success rate may be overestimated because no CT scan was done postoperatively to check the stone-free rate. Other limitations of this article include its retrospective nature, the multi-institutional participation, and the heterogeneous patient collective.

CONCLUSION

The Ho:YAG laser ureteroscopic lithotripsy seems to be an excellent first-line treatment for children with ureteral stones, independently from primary location and size. However, patients with proximal ureteral stones and residual fragments >2 mm reported a higher risk to require a secondary procedure to become stone-free. Combination of techniques as well as appropriate endourologic tools are key points for the success of the procedure regardless of stones' size and location.

Comparison of Stone Retrieval Basket, Stone Cone and Holmium Laser: Which One Is Better in Retropulsion and Stone-Free Status for Patients with Upper Ureteral Calculi?

Introduction: Transurethral lithotripsy (TUL) is an appropriate treatment for ureteral stones and is usually used for stones in the middle and lower part of the ureter. Different devices such as the Holmium laser, the stone basket, and the stone cone exist to prevent any fragments from retropulsion during TUL. The present study aims to compare the advantages and disadvantages of the Holmium laser, the stone basket, and the stone cone. Methods: A retrospective study was conducted from September 2016 to January 2018 comparing various TUL methods in 88 subjects with proximal ureteral calculi. The study participants were divided into 4 matched groups. The first one included 20 patients undergoing TUL with no device (group 1), the second group included 22 patients undergoing TUL while using the stone retrieval basket, the third group included 18 patients undergoing TUL while utilizing the stone cone and the fourth group included 28 patients undergoing TUL while using the Hol-YAG laser. Results: A residual stone ≥3 mm was recorded in 15.9% of the patients. The stone free rate was seen in 100%, 90.9, 83.3%, and 55% of the Holmium laser group, the retrieval basket group, the stone cone group and the no device group respectively (P=0.001). The lowest rate of surgery complications including ureteral perforation, post-operative fever, and mucosal damage between the 4 groups (P=0.003) and the highest time of surgery (P=0.001) belonged to the laser group. If we want to ignore the laser group, the success rate for lithotripsy was better in both groups with a stone retrieval device compared to the no device group, but no advantage existed between the stone basket and the stone cone. Conclusion: We can safely conclude that lasers significantly help to prevent stone migration during TUL. If we want to ignore the laser group, the success rate for lithotripsy was significantly better in both groups with a stone retrieval device compared to the no device group, but no advantage existed between the stone basket and the stone cone.

Preclinical comparison of superpulse thulium fiber laser and a holmium:YAG laser for lithotripsy

PURPOSE

A superpulse (500 W peak power) thulium fiber laser operating at a 1940 nm wavelength, suitable for lithotripsy, has recently been developed. The goal of this study was to compare stone fragmentation and dusting performance of the prototype superpulse thulium fiber laser with leading commercially available, high-power holmium:YAG lithotripters (wavelength 2100 nm) in a controlled in vitro environment.

METHODS

Two experimental setups were designed for investigating stone ablation rates and retropulsion effects, respectively. In addition, the ablation setup enabled water temperature measurements during stone fragmentation in the laser-stone interaction zone. Human uric acid (UA) and calcium oxalate monohydrate (COM) stones were used for ablation experiments, whereas standard BegoStone phantoms were utilized in retropulsion experiments. The laser settings were matched in terms of pulse energy, pulse repetition rate, and average power.

RESULTS

At equivalent settings, thulium fiber laser ablation rates were higher than those for holmium:YAG laser in both dusting mode (threefold for COM stones and 2.5-fold for UA stones) and fragmentation mode (twofold for UA stones). For single-pulse retropulsion experiments, the threshold for onset of stone retropulsion was two to four times higher for thulium fiber laser. The holmium:YAG laser generated significantly stronger retropulsion effects at equal pulse energies. The water temperature elevation near the laser-illuminated volume did not differ between the two lasers.

CONCLUSIONS

Distinctive features of the thulium fiber laser (optimal wavelength and long pulse duration) resulted in faster stone ablation and lower retropulsion in comparison to the holmium:YAG laser.

Fragments and dust after Holmium laser lithotripsy with or without "Moses technology": How are they different?

Urinary stones can be readily disintegrated by Holmium:YAG laser (Holmium laser lithotripsy), resulting in a mixture of small stone dust particles, which will spontaneously evacuate with urine and larger residual fragments (RF) requiring mechanical retrieval. Differences between fragments and dust have not been well characterized. Also, it remains unknown how the recently introduced "Moses technology" may alter stone disintegration products. Three complementary analytical techniques have been used in this study to offer an in-depth characterization of disintegration products after in vitro Holmium laser lithotripsy: stereoscopic microscopy, scanning electron microscopy and Fourier-transform infrared spectroscopy. Dust was separated from fragments based on its floating ability in saline irrigation. Depending on initial crystalline constituents, stone dust either conserved attributes found in larger RFs or showed changes in crystalline organization. These included conversion of calcium oxalate dihydrate towards calcium oxalate monohydrate, changes in carbapatite spectra towards an amorphous phase, changes of magnesium ammonium phosphate towards a differing amorphous and crystalline phase and the appearance of hydroxyapatite on brushite fragments. Comparatively, "Moses technology" produced more pronounced changes. These findings provide new insights suggesting a photothermal effect occurring in Holmium laser lithotripsy. Figure: Appearance of hydroxyapatite hexagons on stone dust collected after Holmium laser lithotripsy of a brushite stone using "Moses technology."

Predictors of Uric Acid Stones: Mean Stone Density, Stone Heterogeneity Index, and Variation Coefficient of Stone Density by Single-Energy Non-Contrast Computed Tomography and Urinary pH

We analyzed the capacities of pertinent parameters (determined by single-energy non-contrast computed tomography [NCCT]) and urinary pH to predict uric acid stones. We reviewed the medical records of 501 patients whose stones were removed surgically or passed spontaneously between December 2014 and April 2016. Qualifying participants (n = 420) were stratified by the nature of the stone (calcium oxalate, uric acid, or infectious). Based on NCCT, we determined maximal stone length (MSL), mean stone density (MSD), and stone heterogeneity index (SHI) using Hounsfield units (HU) and calculated the variant coefficient of stone density (VCSD = SHI/MSD × 100). Urinary pH was also ascertained. Mean patient age was 55.55 ± 15.46 years. MSD (448.59 ± 173.21 HU), SHI (100.81 ± 77.37 HU), and VCSD (22.58 ± 10.55) proved to be significantly lower in uric acid versus other types of stones, as did urinary pH (5.33 ± 0.56; all p < 0.001). Receiver operating characteristic (ROC) curves depicting predictability of uric acid stones yielded area under ROC curve (AUC) values for MSD, SHI, VCSD, and urinary pH of 0.806 (95% CI: 0.761⁻0.850), 0.893 (95% CI: 0.855⁻0.931), 0.782 (95% CI: 0.726⁻0.839), and 0.797 (95% CI: 0.749⁻0.846), respectively, with corresponding cutpoints of 572.3 HU, 140.4 HU, 25.79, and 6.0. Among these four parameters, SHI was verifiably (DeLong's test) the most effective predictor of uric acid stones (all p < 0.001). Compared with MSD, VCSD, and urinary pH, SHI may better predict uric acid stones, using a cutpoint of 140.4 HU.

Epidemiology, pathophysiology, and management of uric acid urolithiasis: A narrative review

An in-depth comprehension of the epidemiology as well as pathophysiology of uric acid urolithiasis is important for the identification, treatment, and prophylaxis of calculi in these patients. Persistently low urinary pH, hyperuricosuria, and low urinary volume are the most important factors in pathogenesis of uric acid urolithiasis. Other various causes of calculus formation comprises of chronic diarrhea, renal hyperuricosuria, insulin resistance, primary gout, extra purine in the diet, neoplastic syndromes, and congenital hyperuricemia. Non-contrast-enhanced computed tomography is the radiologic modality of choice for early assessment of patients with renal colic. Excluding situations where there is acute obstruction, rising blood chemistry, severe infection, or unresolved pain, the initial management ought to be medical dissolution by oral chemolysis since this method has proved to be effective in most of the cases.

The Efficacy and Safety of Laser Lithotripsy in Pregnancy

Introduction: The aim of our study was to assess the efficacy and safety of laser lithotripsy in pregnant patients. Methods: In this retrospective study, we reviewed the 15 pregnant women who have been treated for ureteral stones with semi-rigid ureteroscope and holmium laser at our center between Januarys 2007and April 2015. Results: The mean age of patients and mean gestational age was 29.3 years old 27.3 weeks respectively. Mean size of stones was 7.84 mm. Twelve patients had renal colic, and hematuria was found in 3 cases. Irritative urinary symptoms such as frequency and urgency detected in 6 ones and 2 patients had fever. The stone of all patients were fragmented by using holmium laser lithotripter. In 5 patients stone residual fragments were removed by grasper while other 10 patients were left to pass fragments spontaneously. No intraoperative and postoperative urological or obstetric complication was seen. Conclusion: Laser lithotripsy is safe and efficacious in pregnant patients who have ureteral stone that does not respond to conservative management.

Mini-percutaneous nephrolithotomy with high-power holmium YAG laser in pediatric patients with staghorn and complex calculi

INTRODUCTION

Shock wave lithotripsy (SWL) is the treatment of choice for most cases of renal lithiasis in children. Some cases, however, are refractory to SWL and may be associated with anatomic and metabolic changes or a large stone burden. In these circumstances, mini-percutaneous nephrolithotomy (mini-PCNL) is an option.

OBJECTIVE

The aim was to assess the safety and efficacy of high-power holmium YAG (Ho:YAG) laser in mini-PCNL for staghorn calculi.

PATIENTS AND METHODS

The clinical records relating to 35 mini-PCNLs (Table) performed between January 2008 and December 2012 in 33 patients (27 boys and 6 girls; mean age 7 years, range 2-18 years) were retrospectively reviewed. Twenty-two (66.7%) of the patients had undergone a previous SWL (28.6% three sessions). The mini-PCNL puncture technique used involved fluoroscopic guidance with the C arm at 0-90° in the supine position. An 18F tract was used. Stone fragmentation was performed with a high-power Ho:YAG laser (Lumenis 100 W).

RESULTS

Ten of the mini-PCNLs (28.6%) were right sided, and 25 were left sided (71.4%). Stones were located in the lower calyceal group in 64% of patients and in the renal pelvis in 50%. The mean stone size was 4.46 cm(2) (range 3-13.20 cm(2)). The number of stones varied between one and 20, and 83.3% were radiopaque. The laser was set at 70 W (range 50-100 W) (3.5 J/pulse with a frequency of 20 pulses/s). The mean surgical time was 150 min. In 78% of patients, complete stone clearance was achieved, and the overall stone-free rate rose to 85% when residual stones were treated with either SWL or retrograde intrarenal surgery. No perioperative complications were seen.

DISCUSSION

There are few reports in the literature concerning the use of a high-power laser for treatment of complex stones and the few that do exist relate to adults have similar results, showing it to be highly effective and safe, with low morbidity. Some limitations of the present study must be acknowledged. It was retrospective and a relatively small number of patients were included. However, randomized prospective studies are required to confirm our findings and conclusions.

CONCLUSION

In the pediatric population, mini-PCNL with high-power Ho:YAG laser is feasible and safe and represents the technique of choice for complex renal stones.

Extractable fragment versus dusting during ureteroscopic laser lithotripsy in children: Prospective randomized study

INTRODUCTION AND OBJECTIVES

Complete eradication of stone fragments is an important goal during stone management in children. The mode of fragmentation employed to clear stones during ureteroscopic laser lithotripsy raises concerns related to operative time, associated morbidity, costs, and especially potential endoscope damage. The purpose of this study was to evaluate the outcomes of fragmentation into extractable pieces and stone dusting during ureteroscopic laser lithotripsy in children.

MATERIAL AND METHODS

One hundred children with ureteral stones undergoing ureteroscopic holmium laser lithotripsy were prospectively randomized into two groups: group I in which stones were fragmented to dust (n = 50), and group II in which lithotripsy resulted in extractable fragments (n = 50). Different Holmium laser settings were applied during ureteroscopic lithotripsy for each group: low power (500 mJ) and high frequency (12-15 Hz) for lithotripsy to dust. High power (1000-1500 mJ) and reduced frequency (8-10 Hz) for lithotripsy to extractable fragments. The fragmentation time, operating time, stone-free rate, and perioperative complications were compared (Figure).

RESULTS

The mean age of the patients was 6.8 (1-12) years and 8.2 (1-15) years, in groups I and II respectively. The mean fragmentation time and operating time were statistically significantly lower in group II (p = 0.008 and 0.0069 respectively). Minor complications occurred in eight cases (5 in group I and 3 in group II) in the form of hematuria and urinary tract infection. No major complications were encountered in either groups.

CONCLUSIONS

Fragmenting stones into extractable pieces has a significantly shorter fragmentation time and operative time than stone dusting, with similar stone-free and complication rates. Ureteroscopic laser lithotripsy treatment resulting in extractable fragments seems to be an effective and time-saving procedure in children.

Holmium: Yttrium Aluminium Garnet Laser Lithotripsy for Symptomatic Kock Pouch Calculi

Kock first described continent ileostomy for fecal diversion in 1969 as an alternative procedure to conventional ileostomy. Later, this procedure was replaced by restorative proctocolectomy with ileal pouch anal anastomosis as the procedure of choice. The main reasons for its virtual abandonment include technical difficulty, high morbidity, and the need for a stoma. To our knowledge, this report is the first published case of successful enterolith destruction and retrieval from a Kock pouch, using a Holmium: yttrium aluminium garnet laser. This outpatient procedure can avoid the morbidity and cost of a laparotomy.

Pneumatic cystolithotripsy versus holmium:yag laser cystolithotripsy in the treatment of pediatric bladder stones: a prospective randomized study

PURPOSE

Holmium:yttrium-aluminum-garnet (Ho:YAG) laser and Pneumatic cystolithotripsy (CL) are the most widely practiced transurethral procedures for treatment of pediatric bladder stones. The aim of our study was to compare the safety and efficacy of Ho:YAG laser CL and pneumatic CL in the treatment of pediatric bladder stones.

METHODS

In this prospective randomized study from January 2012 to April 2015, 25 male children with bladder stones <3 cm were consecutively randomized into two treatment groups: group A (pneumatic CL) consisted of 13 patients and group B (Ho:YAG CL) consisted of 12 patients. Operative time, duration of stay and complications were recorded. Patients were followed up prospectively.

RESULTS

The mean operative time was significantly lower in group B (25.6 vs. 31.6 min) for stones <1.5 cm (p = 0.040). However, for stones between 1.5 and 3 cm in size, the mean operating times were similar in both the groups (49.4 min in Ho:YAG vs. 44.6 min in pneumatic, p = 0.40). There was no difference in complication rates and hospital stay in both the groups. No major complications were seen in both the groups.

CONCLUSIONS

We found that Ho:YAG CL was more effective than pneumatic CL for treating bladder stones smaller than 1.5 cm.

Outpatient Transurethral Cystolithotripsy of Large Bladder Stones by Holmium Laser

INTRODUCTION

To assessment of the efficacy and safety of transurethral cystolithotripsy of large bladder stones by holmium laser in the outpatient setting.

METHODS

In a prospective study, 48 consecutive adult patients with large bladder stones, were enrolled for transurethral cystolithotripsy. Patients older than 18 years, with bladder stones larger than 2 cm were enrolled. Urethral stricture, active urinary infection, and any anesthetic contraindications for operation, were the exclusion criteria. Demographic characteristics of patients, outcomes and complications related to operation and post operation period, were recorded.

RESULTS

Patients mean age was 46 ± 7.3 years. Male to female ratio was 45/3. Mean body mass index of patients was 28.5 ± 3.5. Mean stone size was 3.7 ± 1.6 cm. Mean operation time was 43.5 ± 15.5 minutes. Nearly complete stone clearance (98.5%) was achieved in all patients. Mean hospital stay was 6.5 ± 1.3 hours. No major complications were seen. Mean visual analog pain score (VAS) was 4.2 ± 2.1 and 1.4 ± 0.6, during and 1 hour after operation, respectively. During follow up of 22.4 ± 12.5 months, recurrence of bladder stone was not seen. No case of urethral stricture was detected.

CONCLUSION

Transurethral holmium laser lithotripsy is an effective and safe alternative in selected patients with large bladder stones. This procedure can be easily performed in the outpatient setting.

A Prospective Randomized Trial Comparing Pneumatic Lithotripsy and Holmium Laser for Management of Middle and Distal Ureteral Calculi

PURPOSE

The aim of this study was to compare the efficacy and safety between pneumatic and holmium:yttrium-aluminum-garnet (Ho:YAG) laser in the treatment of patients with ureteral stones located in the middle and distal ureter.

PATIENTS AND METHODS

We conducted a prospective study in recruiting 982 eligible patients from 2009 to 2012. Patients were randomly divided into two groups-the pneumatic lithotripsy (PL) group or the Ho:YAG laser lithotripsy (LL) group. Patient demographics, stone characteristics, intraoperative parameters, and postoperative complications were evaluated and analyzed.

RESULTS

The baseline demographics of patients and stone characteristics were similar in the two groups. The LL group showed significant benefits compared with the PL group in terms of mean operative time (28±9.2 vs 41±12.4 min, P=0.001) and early stone-free rate (80.8% vs 91.3%, P=0.04), but there was no statistically significant difference at the third month (92.6% vs 95.5%, P=0.15). In the LL group, 24 postoperative cases of stricture were seen, whereas only 5 cases occurred in the PL group (P=0.02). The other complications, such as perforation, bleeding, and mucosal injury, were comparable in the two groups. The average postoperative stay was also similar (1.7±2.4 days for PL and 1.5±3.1 days for LL (P=0.62).

CONCLUSION

Both PL and LL are effective in the management of middle and distal impacted stones. Ho:YAG laser has advantages in better efficacy of stone fragmentation and a higher early stone-free rate but seems to have to face the increased risks of postoperative stricture.

Concurrent stone stabilization improves ultrasonic and pneumatic efficacy during cystolithopaxy: an in vitro analysis

OBJECTIVE

To identify whether stabilization of larger bladder stones would improve the efficacy of combination (ultrasonic/pneumatic) lithotripsy in a phantom bladder stone model for percutaneous cystolithopaxy.

MATERIALS AND METHODS

Using 1cm phantom Bego stones, a spherical model bladder was used to simulate percutaneous bladder access. A UroNet (US Endoscopy, USA) was placed alongside a Swiss Lithoclast probe through the working channel of a Storz 26Fr rigid nephroscope. Using a 30Fr working sheath, the stone was captured, and fragmented for 60 seconds. Resulting fragments and irrigation were filtered through a 1mm strainer, and recorded. Five trials were performed with and without the UN. Durability was then assessed by measuring net defects, and residual grasp strength of each instrument. Descriptive statistics (mean, standard deviations) were used to summarize the data, and Student's t-tests (alpha < 0.05) were used to compare trials.

RESULTS

The mean time to stone capture was 12s (8-45s). After fragmentation with UN stabilization, there were significant improvements in the amount of residual stone (22% dry weight reduction vs 8.1% without UN, p < 0.001), number of fragments (17.5 vs 5.0 frag/stone, p=0.0029), and fragment size (3.6mm vs. 7.05 mm, p=0.035). Mesh defects were noted in all nets, ranging from 2-14 mm, though all but one net retained their original grip strength (36.8N).

CONCLUSIONS

Bladder stone stabilization improved fragmentation when used in conjunction with ultrasonic/pneumatic lithotripsy. However, due to limitations in maneuverability and durability of the UN, other tools need to identified for this indication.

Influence of saline on temperature profile of laser lithotripsy activation

PURPOSE

We established an ex vivo model to evaluate the temperature profile of the ureter during laser lithotripsy, the influence of irrigation on temperature, and thermal spread during lithotripsy with the holmium:yttrium-aluminum-garnet (Ho:YAG) laser.

MATERIALS AND METHODS

Two ex vivo models of Ovis aries urinary tract and human calcium oxalate calculi were used. The Open Ureteral Model was opened longitudinally to measure the thermal profile of the urothelium. On the Clinical Model, anterograde ureteroscopy was performed in an intact urinary system. Temperatures were measured on the external portion of the ureter and the urothelium during lithotripsy and intentional perforation. The lithotripsy group (n=20) was divided into irrigated (n=10) and nonirrigated (n=10), which were compared for thermal spread length and values during laser activation. The intentional perforation group (n=10) was evaluated under saline flow. The Ho:YAG laser with a 365 μm laser fiber and power at 10W was used (1J/Pulse at 10 Hz). Infrared Fluke Ti55 Thermal Imager was used for evaluation. Maximum temperature values were recorded and compared.

RESULTS

On the Clinical Model, the external ureteral wall obtained a temperature of 37.4°C±2.5° and 49.5°C±2.3° (P=0.003) and in the Open Ureteral Model, 49.7°C and 112.4°C with and without irrigation, respectively (P<0.05). The thermal spread along the external ureter wall was not statically significant with or without irrigation (P=0.065). During intentional perforation, differences in temperatures were found between groups (opened with and without irrigation): 81.8°±8.8° and 145.0°±15.0°, respectively (P<0.005).

CONCLUSION

There is an increase in the external ureteral temperature during laser activation, but ureteral thermal values decreased when saline flow was applied. Ureter thermal spread showed no difference between irrigated and nonirrigated subgroups. This is the first laser lithotripsy thermography study establishing the framework to evaluate the temperature profile in the future.

Systematic evaluation of a holmium:yttrium-aluminum-garnet laser lithotripsy device with variable pulse peak power and pulse duration

OBJECTIVE

The Holmium:yttrium-aluminum-garnet (Ho:YAG) laser is the standard lithotrite for ureteroscopy. This paper is to evaluate a Ho:YAG laser with a novel effect function in vitro, which allows a real-time variation of pulse duration and pulse peak power.

METHODS

Two types of phantom calculi with four degrees of hardness were made for fragmentation and retropulsion experiments. Fragmentation was analysed at 5 (0.5 J/10 Hz), 10 (1 J/10 Hz), and 20 (2 J/10 Hz) W in non-floating phantom calculi, retropulsion in an ureteral model at 10 (1 J/10 Hz) and 20 (2 J/10 Hz) W using floating phantom calculi. The effect function was set to 25%, 50%, 75%, and 100% of the maximum possible effect function at each power setting. Primary outcomes: fragmentation (mm3), the distance of retropulsion (cm); ≥5 measurements for each trial.

RESULTS

An increase of the effect feature (25% vs. 100%), i.e., an increase of pulse peak power and decrease of pulse duration, improved Ho:YAG laser fragmentation. This effect was remarkable in soft stone composition, while there was a trend for improved fragmentation with an increase of the effect feature in hard stone composition. Retropulsion increased with increasing effect function, independently of stone composition. The major limitations of the study are the use of artificial stones and the in vitro setup.

CONCLUSION

Changes in pulse duration and pulse peak power may lead to improved stone fragmentation, most prominently in soft stones, but also lead to increased retropulsion. This new effect function may enhance Ho:YAG laser fragmentation when maximum power output is limited or retropulsion is excluded.

Invasive management of proximal ureteral calculi during pregnancy

OBJECTIVE

To review our experience with invasive management of proximal ureteral calculi during pregnancy when conservative treatment fails.

METHODS

From February 2006 to September 2012, a total of 87 pregnant women received invasive management for proximal ureteral calculi in our center. Invasive management included the following: double-J stent insertion, percutaneous nephrostomy (PCN), and ureteroscopic lithotripsy (URSL). The medical records of these patients were reviewed retrospectively.

RESULTS

Of the 87 patients, 4 patients received PCN; 19 patients received cystoscopic double-J stent insertion, whereas 2 patients (10.5%) failed in guide wire inserting and switched to ureteroscopic aid; a total of 64 patients received URSL with holmium laser, in which 52 patients (81.2%) had complete fragmentation of calculi; in 9 patients (14.1%), stone fragments retrograde migrated to the renal pelvis; in 3 patients (4.7%), the stone could not be reached because of serious ureteral tortuosity. One patient (1.6%) patient had a threatened abortion, but this problem was resolved immediately using conservative treatment. All patients completed the full term of pregnancy, and no serious obstetric or urologic complications were observed.

CONCLUSION

For pregnant patients with proximal ureteral calculi, double-J stent insertion, PCN, and URSL all are effective and safe options when conservative treatment fails. They should be chosen on the basis of different patient's condition. However, patient's postoperative tolerance was poor for double-J stent insertion and PCN; URSL (especially with holmium laser lithotripsy) is more effective and should be considered as the preferred choice.

Prospective randomized controlled trial comparing laser lithotripsy with pneumatic lithotripsy in miniperc for renal calculi

BACKGROUND AND PURPOSE

The energy source used for stone fragmentation is important in miniperc. In this study, we compared the stone fragmentation characteristics and outcomes of laser lithotripsy and pneumatic lithotripsy in miniperc for renal calculi.

PATIENTS AND METHODS

After Institutional Review Board approval, 60 patients undergoing miniperc for renal calculi of 15 to 30 mm were equally randomized to laser and pneumatic lithotripsy groups. Miniperc was performed using 16.5F Karl Storz miniperc sheath and a 12F nephroscope. Laser lithotripsy was performed using a 550-μm laser fiber and 30 W laser with variable settings according to the need. Pneumatic lithotripsy was performed using the EMS Swiss lithoclast. Patient demographics, stone characteristics, intraoperative parameters, and postoperative outcomes were analyzed.

RESULTS

The baseline patient demographics and stone characteristics were similar in both groups. The total operative time (P = 0.433) and fragmentation time (P=0.101) were similar between the groups. The surgeon assessed that the Likert score (1 to 5) for fragmentation was similar in both groups (2.1 ± 0.8 vs 1.9 ± 0.9, P=0.313). Stone migration was lower with the laser (1.3 ± 0.5 vs 1.7 ± 0.8, P=0.043), and fragment removal was easier with the laser (1.1 ± 0.3 vs 1.7 ± 1.1, P=0.011). The need for fragment retrieval using a basket was significantly more in the pneumatic lithotripsy group (10% vs 37%, P=0.002). The hemoglobin drop, complication rates, auxiliary procedures, postoperative pain, and stone clearance rates were similar between the groups (P>0.2).

CONCLUSION

Both laser lithotripsy and pneumatic lithotripsy are equally safe and efficient stone fragmentation modalities in miniperc. Laser lithotripsy is associated with lower stone migration and easier retrieval of the smaller fragments it produces.

Damage of stone baskets by endourologic lithotripters: a laboratory study of 5 lithotripters and 4 basket types

Background. In some cases, the ureteral stone is simultaneously stabilized by a stone basket when endourologic lithotripsy is performed. This stabilization can be either on purpose or by accident. By accident means that an impaction in the ureter occurs by an extraction of a stone with a basket. A stabilization on purpose means to avoid a retropulsion of the stone into the kidney during lithotripsy. At this part of the operation, stone baskets have been frequently damaged. This severing of wires can lead to ureteral trauma because of hook formation. Material and Methods. In a laboratory setting, the time and the pulse numbers were measured until breaking the wires from four different nitinol stone baskets by using five different lithotripsy devices. The endpoint was gross visibledamage to the wire and loss of electric conduction. Results. The Ho:YAG laser and the ultrasonic device were able to destroy almost all the wires. The ballistic devices and the electrohydraulic device were able to destroy thin wires. Conclusion. The operating surgeon should know the risk of damagefor every lithotripter. The Ho:YAG-laser and the ultrasonic device should be classified as dangerous for the basket wire with all adverse effects to the patient.

Evaluation of a new 240-μm single-use holmium:YAG optical fiber for flexible ureteroscopy

BACKGROUND AND PURPOSE

Numerous holmium:yttrium-aluminum-garnet laser fibers are available for flexible ureteroscopy. Performance and durability of fibers can vary widely among different manufacturers and their product lines with differences within a single product line have been reported. We sought to evaluate a newly developed nontapered, single-use 240-μm fiber, Flexiva™ 200 (Boston Scientific, Natick, MA), during clinical use and in a bench-testing model.

MATERIALS AND METHODS

A total of 100 new fibers were tested after their use in 100 consecutive flexible ureteroscopic lithotripsy procedures by a single surgeon (B.K.). Prospectively recorded clinical parameters were laser pulse energy and frequency settings, total energy delivered and fibers failure. Subsequently, each fiber was bench-tested using an established protocol. Parameters evaluated for were fibers true diameter, flexibility, tip degradation, energy transmission in straight and 180° bend configuration and fibers failure threshold with stress testing.

RESULTS

The mean total energy delivered was 2.20 kJ (range 0-18.24 kJ) and most common laser settings used were 0.8 J at 8 Hz, 0.2 J at 50 Hz, and 1.0 J at 10 Hz, respectively. No fiber fractured during clinical procedures. The true fiber diameter was 450 μm. Fiber tips burnt back an average of 1.664 mm, but were highly variable. With laser setting of 400 mJ at 5 Hz, the mean energy transmitted was 451 and 441 mJ in straight and 180° bend configuration, respectively. Thirteen percent of fibers fractured at the bend radius of 0.5 cm with a positive correlation to the total energy transmitted during clinical use identified.

CONCLUSION

Fiber performance was consistent in terms of energy transmission and resistance to fracture when activated in bent configuration. Fiber failure during stress testing showed significant correlation with the total energy delivered during the clinical procedure. The lack of fiber fracture during clinical use may reduce the risk of flexible endoscope damage due to fiber failure.

Does stone entrapment with ″Uro-Net″ improve Ho:YAG laser lithotripsy efficiency in percutaneous nephrolithotomy and cystolithopaxy?: an in vitro study

PURPOSE

to test the effect of stone entrapment on laser lithotripsy efficiency.

MATERIALS AND METHODS

Spherical stone phantoms were created using the BegoStone® plaster. Lithotripsy of one stone (1.0 g) per test jar was performed with Ho:YAG laser (365 µm fiber; 1 minute/trial). Four laser settings were tested: I-0.8 J,8 Hz; II-0.2J,50 Hz; III-0.5 J,50 Hz; IV-1.5 J,40 Hz. Uro-Net (US Endoscopy) deployment was used in 3/9 trials. Post-treatment, stone fragments were strained though a 1mm sieve; after a 7-day drying period fragments and unfragmented stone were weighed. Uro-Net nylon mesh and wire frame resistance were tested (laser fired for 30s). All nets used were evaluated for functionality and strength (compared to 10 new nets). Student's T test was used to compare the studied parameters; significance was set at p < 0.05.

RESULTS

Laser settings I and II caused less damage to the net overall; the mesh and wire frame had worst injuries with setting IV; setting III had an intermediate outcome; 42% of nets were rendered unusable and excluded from strength analysis. There was no difference in mean strength between used functional nets and non-used devices (8.05 vs. 7.45 lbs, respectively; p = 0.14). Setting IV was the most efficient for lithotripsy (1.9 ± 0.6 mg/s; p < 0.001) with or without net stabilization; setting III was superior to I and II only if a net was not used.

CONCLUSIONS

Laser lithotripsy is not optimized by stone entrapment with a net retrieval device which may be damaged by high energy laser settings.

Comparison of Ho:YAG laser and pneumatic lithotripsy in the treatment of impacted ureteral stones: an analysis of risk factors

The aim was to compare pneumatic and holmium:yttrium-aluminum-garnet laser in the treatment of impacted ureteral stones with different locations and to identify the risk factors for complications. Between March 2005 and November 2012, a total of 230 patients underwent ureteroscopic lithotripsy for impacted stones. Of the patients, 117 had pneumatic and 113 had laser lithotripsy for the fragmentation of the stones. Treatment outcomes based on evidence of being stone free were evaluated. Preoperative, operative, and postoperative follow-up findings were analyzed and compared. There was a difference between the two groups according to overall stone clearance rate (93.8% vs. 80.3%, p = 0.002). There was no statistically significant difference for distal location between the laser and pneumatic groups (96.8% vs. 91.7%, p =0.288). For 10 patients with intrarenally migrated stones who were managed with flexible ureterorenoscopy in the same session, laser lithotripsy was more successful than pneumatic for proximal ureteral stone (94.4% vs. 67.9%, p = 0.007). The overall complication rate was 26.1%. There was no statistically significant difference between the two groups (29% vs. 23%, p = 0.296). Multivariate logistic regression analysis revealed that the proximal location was a statistically significant parameter for the occurrence of complications in both groups (p = 0.001 for PL, p = 0.004 for laser). The pneumatic and holmium:yttrium-aluminum-garnet laser lithotripsy are effective in the treatment of distal impacted stones. Both treatments with semirigid ureteroscopy are acceptable for proximal impacted ureteral stones, but holmium laser lithotripsy has an advantage of use with flexible ureteroscope for intrarenally migrated stone.