Publications by authors named "Glenn M Preminger"

234 Publications

Benchtop Evaluation of Miniature Percutaneous Nephrolithotomy Lithotrites.

J Endourol 2022 Jul 29. Epub 2022 Jul 29.

Duke University Medical Center, Surgery, Urology, DUMC 3167, Durham, North Carolina, United States, 27710;

Introduction: Percutaneous nephrolithotomy (PCNL) is the preferred treatment for kidney stones >2cm. While PCNL has traditionally been performed using 24-30Fr access sheaths, there is a trend toward smaller sheaths and scopes to perform mini-PCNL (mPCNL). We performed benchtop assessment of multiple mPCNL lithotrites.

Methods: One 1cm3, hard Begostone phantom was placed in a cylinder with four 5.5mm cylindrical openings to simulate the size of a 16.5Fr mPCNL sheath. Lithotripsy was performed with the 1.5mm and 1.9mm Trilogy, 1.83mm ShockPulse, or a 200m Holmium:YAG laser. Suction was used for the mechanical lithotrites. The Trilogy probes were set at 50% impact, 6Hz, 80% ultrasound and 10% suction. The ShockPulse was used at high-power setting with low suction. The 1.9mm Trilogy probe was used with a 15Fr mini-nephroscope. The 1.83mm ShockPulse, 1.5mm Trilogy and laser fiber were used with a 12Fr mini-nephroscope. The 120 W holmium laser was set at 0.5J/70Hz Moses-Distance. Ten independent runs were performed with modality. Time to complete stone clearance was recorded and mass stone clearance rates were calculated.

Results: The Trilogy 1.9mm showed superior stone clearance rate (11.69 ± 3.68 mg/s) vs the SP 1.83mm (6.29 ± 1.37 mg/s, p=0.003), the laser fiber (4.73 ± 0.61 mg/s, p<0.0005), and the Trilogy 1.5mm (6.84± 1.21 mg/s). The 200m laser fiber was inferior to all mechanical lithotrites. There was no difference between the 1.5mm Trilogy and the 1.83mm ShockPulse (p=0.772). This translates to 3.9, 4.8 and 8.1 minutes less treatment time vs the 1.5mm Trilogy, SP, and laser, respectively, for a spherical 1.5cm diameter calcium oxalate monohydrate stone.

Conclusion: Among these four commonly used mPCNL lithotripters, the Trilogy 1.9 mm demonstrated superior stone clearance rates in this benchtop model versus the Ho:YAG laser, 1.83mm SP, and Trilogy 1.5mm. Future clinical testing is warranted to evaluate the optimal lithotrite for mPCNL.
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http://dx.doi.org/10.1089/end.2022.0052DOI Listing
July 2022

International Alliance of Urolithiasis guideline on retrograde intrarenal surgery.

BJU Int 2022 Jun 22. Epub 2022 Jun 22.

Department of Urology, Medical School, Biruni University, Istanbul, Turkey.

Objectives: To set out the second in a series of guidelines on the treatment of urolithiasis by the International Alliance of Urolithiasis that concerns retrograde intrarenal surgery (RIRS), with the aim of providing a clinical framework for urologists performing RIRS.

Materials And Methods: After a comprehensive search of RIRS-related literature published between 1 January 1964 and 1 October 2021 from the PubMed database, systematic review and assessment were performed to inform a series of recommendations, which were graded using modified GRADE methodology. Additionally, quality of evidence was classified using a modification of the Oxford Centre for Evidence-Based Medicine Levels of Evidence system. Finally, related comments were provided.

Results: A total of 36 recommendations were developed and graded that covered the following topics: indications and contraindications; preoperative imaging; preoperative ureteric stenting; preoperative medications; peri-operative antibiotics; management of antithrombotic therapy; anaesthesia; patient positioning; equipment; lithotripsy; exit strategy; and complications.

Conclusion: The series of recommendations regarding RIRS, along with the related commentary and supporting documentation, offered here should help provide safe and effective performance of RIRS.
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http://dx.doi.org/10.1111/bju.15836DOI Listing
June 2022

Elucidating the Mechanism of Stone Dusting Requires a Fresh and Rigorous Approach in the New Era of Laser Lithotripsy.

J Endourol 2022 05;36(5):686-687

Division of Urology, Duke University Medical Center, Durham, North Carolina, USA.

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http://dx.doi.org/10.1089/end.2022.0174DOI Listing
May 2022

Initial Safety and Feasibility of Steerable Ureteroscopic Renal Evacuation: A Novel Approach for the Treatment of Urolithiasis.

J Endourol 2022 Jul 19. Epub 2022 Jul 19.

Division of Urologic Surgery, Duke University, Durham, North Carolina, USA.

There is a need to reliably render urolithiasis patients completely stone free with minimal morbidity. We report on the initial safety and feasibility with steerable ureteroscopic renal evacuation (SURE) in a prospective study using basket extraction as a comparison. A pilot randomized controlled study was conducted comparing SURE with basket extraction postlaser lithotripsy. SURE is performed using the CVAC™ Aspiration System, a steerable catheter (with introducer). The safety and feasibility of steering CVAC throughout the collecting system under fluoroscopy and aspirating stone fragments as it was designed to do were evaluated. Fluoroscopy time, change in hemoglobin, adverse events through 30 days, total and proportion of stone volume removed at 1 day, intraoperative stone removal rate, and stone-free rate (SFR) at 30 days through CT were compared. Seventeen patients were treated ( = 9 SURE,  = 8 Basket). Baseline demographics and stone parameters were not significantly different between groups. One adverse event occurred in each group (self-limiting ileus for SURE and urinary tract infection for Basket). No mucosal injury and no contrast extravasation were observed in either group. The CVAC catheter was steered throughout the collecting system and aspirated fragments. There was no significant difference in fluoroscopy time, procedure time, change in hemoglobin, or stone removal rate between groups. SURE removed more and a greater proportion of stone volume at day 1 baskets (202 mm 91 mm,  < 0.01 and 84% 56%,  = 0.022). SURE achieved 100% SFR at 30 days 75% for baskets, although this difference was not statistically significant ( = 0.20). This initial study suggests SURE is safe, feasible, and may be more effective in stone removal postlaser lithotripsy compared to basketing. More development is needed, and larger clinical studies are underway.
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http://dx.doi.org/10.1089/end.2021.0759DOI Listing
July 2022

European Association of Urology Section of Urolithiasis and International Alliance of Urolithiasis Joint Consensus on Retrograde Intrarenal Surgery for the Management of Renal Stones.

Eur Urol Focus 2021 Nov 23. Epub 2021 Nov 23.

Department of Urology, West China Hospital of Sichuan University, Chengdu, China.

Background: Retrograde intrarenal surgery (RIRS) has become the preferred treatment modality for nephrolithiasis. However, because of ongoing uncertainties regarding the optimal perioperative management, operative technique, and postoperative follow-up, as well as a lack of standardization for outcome reporting, consensus is needed to achieve more uniform clinical practice worldwide.

Objective: To develop recommendations for RIRS on the basis of existing data and expert consensus.

Design, Setting, And Participants: A protocol-driven, three-phase study was conducted by the European Association of Urology Section of Urolithiasis (EULIS) and the International Alliance of Urolithiasis (IAU). The process included: (1) a nonsystematic review of the literature to define domains for discussion; (2) a two-round modified Delphi survey involving experts in this field; and (3) an additional group meeting and third-round survey involving 64 senior representative members to formulate the final conclusions.

Outcome Measurements And Statistical Analysis: The results from each previous round were returned to the participants for re-evaluation of their decisions during the next round. The agreement threshold was set at 70%.

Results And Limitations: The panel included 209 participants who developed 29 consensus statements on the following topics of interest: (1) perioperative infection management; (2) perioperative antithrombotic therapy; (3) fundamentals of the operative technique; and (4) standardized outcome reporting. Although this consensus can be considered as a useful reference for more clinically oriented daily practice, we also acknowledge that a higher level of evidence from further clinical trials is needed.

Conclusions: The consensus statements aim to guide and standardize clinical practice and research on RIRS and to recommend standardized outcome reporting.

Patient Summary: An international consensus on the best practice for minimally invasive surgery for kidney stones was organized and developed by two international societies. It is anticipated that this consensus will provide further guidance to urologists and may help to improve clinical outcomes for patients.
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http://dx.doi.org/10.1016/j.euf.2021.10.011DOI Listing
November 2021

Cavitation Plays a Vital Role in Stone Dusting During Short Pulse Holmium:YAG Laser Lithotripsy.

J Endourol 2022 05 29;36(5):674-683. Epub 2022 Apr 29.

Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina, USA.

To investigate the mechanism of stone dusting in Holmium (Ho): YAG laser lithotripsy (LL). Cylindrical BegoStone samples (6 × 6 mm, H × D) were treated in water using a clinical Ho:YAG laser lithotripter in dusting mode (0.2-0.4 J with 70-78 μs in pulse duration, 20 Hz) at various fiber tip to stone standoff distances (SD = 0, 0.5, and 1 mm). Stone damage craters were quantified by optical coherence tomography and bubble dynamics were captured by high-speed video imaging. To differentiate the contribution of cavitation thermal ablation to stone damage, three additional experiments were performed. First, presoaked wet stones were treated in air to assess stone damage without cavitation. Second, the laser fiber was advanced at various offset distances (OSD = 0.25, 1, 2, 3, and 10 mm) from the tip of a flexible ureteroscope to alter the dynamics of bubble collapse. Third, stones were treated with parallel fiber to minimize photothermal damage while isolating the contribution of cavitation to stone damage. Treatment in water resulted in 2.5- to 90-fold increase in stone damage compared with those produced in air where thermal ablation dominates. With the fiber tip placed at OSD = 0.25 mm, the collapse of the bubble was distracted away from the stone surface by the ureteroscope tip, leading to significantly reduced stone damage compared with treatment without the scope or with scope at large OSD of 3-10 mm. The average crater volume produced by parallel fiber orientation at 0.2 J after 100 pulses, where cavitation is the dominant mechanism of stone damage, was comparable with those produced by using perpendicular fiber orientation within SD = 0.25-1 mm. Cavitation plays a dominant role over photothermal ablation in stone dusting during short pulse Ho:YAG LL when 10 or more pulses are delivered to the same location.
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http://dx.doi.org/10.1089/end.2021.0526DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9145256PMC
May 2022

Comparison of Different Pulse Modulation Modes for Holmium:Yttrium-Aluminum-Garnet Laser Lithotripsy Ablation in a Benchtop Model.

J Endourol 2022 01 29;36(1):29-37. Epub 2021 Oct 29.

Division of Urologic Surgery, Duke University Medical Center, Durham, North Carolina, USA.

Manipulation of Holmium:Yttrium-Aluminum-Garnet laser parameters such as pulse energy (PE), frequency, and duration can impact laser lithotripsy ablation efficiency. In 2017, Lumenis introduced Moses™ Technology, which uses pulse modulation to enhance the delivery of energy from fiber to stone as well as to minimize stone retropulsion. Since the introduction of Moses Technology, other companies have brought additional pulse modulation concepts to market. The purpose of this study is to compare the pulse characteristics and stone ablation efficiency of Lumenis Moses Technology with Quanta's Vapor Tunnel™. Submerged BegoStone phantoms were systematically ablated using either the Lumenis Moses Pulse 120H or the Quanta Litho 100 clinical laser system. Two PEs (0.4 and 1 J), three fiber-stone standoff distances (SDs) (0.5, 1, 2 mm), and all available pulse duration and modulation modes for each laser were tested in combination. Fiber speed was adjusted to scan across the stone surface at either 1 or 10 pulses/mm to form single pulse craters or an ablation trough, respectively. Volumes of single craters and 1 mm trough segments were imaged and quantified using optical coherence tomography. Ablation volumes decreased with decreasing PE and increasing SD. Statistically significant variability was seen between pulse types (PT) at every tested parameter set. Among pulse modulation modes, Moses Distance (MD) was superior at 0.5 mm in all testing and at 2 mm in trough testing. Vapor Tunnel (VT) was superior in 2 mm single crater testing. All modulated pulses performed similarly at 1 mm. In this benchtop model of laser lithotripsy, stone ablation was significantly impacted by PT. MD demonstrated superior or noninferior stone ablation at most tested parameters. VT maintained its efficacy the best as SD increased. Future work should focus on the mechanistic differences of these modes relative to other traditional laser pulse modes.
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http://dx.doi.org/10.1089/end.2021.0113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8785761PMC
January 2022

Evolution of Single-Use Urologic Endoscopy: Benchtop and Initial Clinical Assessment of a New Single-Use Flexible Cystoscope.

J Endourol 2022 01;36(1):13-21

Division of Urology, Duke University Hospital, Durham, North Carolina, USA.

Office cystoscopy is one of the most frequently performed procedures by a urologist. However, single-use cystoscopes remain quite undeveloped. Ambu has developed single-use broncoscopes, rhinolaryngoscopes, and duodenoscopes. Recently, they released a single-use cystoscope. In this study, we performed a benchtop and an initial clinical assessment of the Ambu aScope™ (4) Cysto (aS4C) single-use cystoscope. Ten new, never-used aS4C single-use cystoscopes were assessed for optical performance, maximal tip flexion, and irrigation flow rate with empty working channel, 365 μm laser fiber, 0.035 in hydrophilic-tipped wire, 1.9F nitinol basket, and a 1.8 mm flexible stent grasper. All cystoscopes were then fully flexed 25 times in each direction, and maximal flexion angles were remeasured with and without instruments. Optical resolution, distortion, and depth of field were measured and compared with our reusable digital flexible cystoscopes. Assessment of clinical use was performed for inpatient bedside procedures using a Likert feedback survey and the NASA Task Load Index. Maximal upward flexion exceeded 200° and 160° for all working instruments in upward and downward flexion. Downward flexion demonstrated different flexion between instrument groups in pre- and postcycling ( < 0.001). There was no clinical difference between the pre- and postcycling flexion. Flow rate decreased with increasing working instrument size ( < 0.001). The Olympus HD cystoscope resolution was superior at 3 and 5 mm distance, but not at other distances. The Ambu scope was superior to the Olympus SD scope at all distances except 3 mm. The aS4C had higher Likert scale survey scores for clinical use. The new Ambu single-use cystoscope demonstrates good flexion across instruments and comparable optics with reusable cystoscopes. In addition, initial inpatient bedside use of the aS4C and Monitor system compares favorably with the Olympus reusable cystoscope. Further testing in clinical scenarios such as hematuria, urothelial carcinoma, and operative endoscopy is warranted.
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http://dx.doi.org/10.1089/end.2021.0219DOI Listing
January 2022

Case of the Month from Duke University Medical Centre: a complete renal staghorn stone.

BJU Int 2021 07;128(1):25-28

Division of Urological Surgery, Duke University Medical Centre, Durham, NC, USA.

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http://dx.doi.org/10.1111/bju.15360DOI Listing
July 2021

The Role of Cavitation in Energy Delivery and Stone Damage During Laser Lithotripsy.

J Endourol 2021 06 18;35(6):860-870. Epub 2021 Mar 18.

Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina, USA.

Although cavitation during laser lithotripsy (LL) contributes to the Moses effect, the impact of cavitation on stone damage is less clear. Using different laser settings, we investigate the role of cavitation bubbles in energy delivery and stone damage. The role of cavitation in laser energy delivery was characterized by using photodetector measurements synced with high-speed imaging for laser pulses of varying durations. BegoStone samples were treated with the laser fiber oriented perpendicularly in contact with the stone in water or in air to assess the impact of cavitation on crater formation. Crater volume and geometry were quantified by using optical coherence tomography. Further, the role of cavitation in stone damage was elucidated by treatment in water with the fiber oriented parallel to the stone surface and by photoelastic imaging. Longer pulse durations resulted in higher energy delivery but smaller craters. Stones treated in water resulted in greater volume, wider yet shallower craters compared with those treated in air. Stones treated with the parallel fiber showed crater formation after 15 pulses, confirmed by high-speed imaging of the bubble collapse with the resultant stress field captured by photoelastic imaging. Despite improved energy delivery, the longer pulse mode produced smaller crater volume, suggesting additional processes secondary to photothermal ablation are involved in stone damage. Our critical observations of the difference in stone damage treated in water in air, combined with the crater formation by parallel fiber, suggest that cavitation is a contributor to stone damage during LL.
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http://dx.doi.org/10.1089/end.2020.0349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8336231PMC
June 2021

Benchtop Assessment of a New Single-Use Flexible Ureteroscope.

J Endourol 2021 06 22;35(6):755-760. Epub 2020 Dec 22.

Division of Urology, Duke University Medical Center, Durham, North Carolina, USA.

Single-use flexible ureteroscopes are an increasingly popular alternative to reusable ureteroscopes. In this study, we performed a benchtop examination of the physical and optical properties of the new Dornier Axis™ (Webling, Germany) single-use ureteroscope. Ten new, never-used Dornier Axis ureteroscopes were assessed for optical performance, maximal tip deflection, and irrigation flow rate with an empty working channel and with insertion of 200 and 365 μm laser fibers, and a 1.9F nitinol basket. All ureteroscopes were then fully deflected 100 times in each direction, and maximal deflection angles were re-measured with and without instruments in the working channel. All measurements were performed in duplicate. optical testing for resolution, image distortion, and depth of field was performed and compared the LithoVue™ (Boston Scientific, Marlborough, MA) single-use ureteroscope. Statistical analyses using paired Wilcoxon rank-sum tests and Kruskal-Wallis multiple-group comparison tests were performed in R. Median maximal deflection angles exceeded 300° in both directions before and after 100 full deflection cycles for all groups except the 365 μm laser fiber group. After 100 deflection cycles, there was no change in the majority of working instruments, except a decrease in upward flexion with an empty channel and 200 μm Moses™ laser fiber, and downward flexion with 200 μm Flexiva™ laser fiber (all <10°). After excluding the 365 μm fiber, there was no difference in multi-group comparison for upward and downward flexion pre- and post-cycling. Median flow rate through an empty channel was 48.0 mL/min, and it decreased significantly with all used instruments ( < 0.001). Compared with the LithoVue, the Axis demonstrated superior resolution at all tested distances and less distortion. The new Dornier Axis single-use ureteroscope demonstrates excellent tip deflection, which remains unchanged after 100 manual flexions in each direction. The Axis also demonstrates superior optical performance compared with the LithoVue in benchtop testing.
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http://dx.doi.org/10.1089/end.2020.0836DOI Listing
June 2021

Implementation and Impact of a Risk-Stratified Prostate Cancer Screening Algorithm as a Clinical Decision Support Tool in a Primary Care Network.

J Gen Intern Med 2021 01 1;36(1):92-99. Epub 2020 Sep 1.

Duke University, Durham, NC, USA.

Background: Implementation methods of risk-stratified cancer screening guidance throughout a health care system remains understudied.

Objective: Conduct a preliminary analysis of the implementation of a risk-stratified prostate cancer screening algorithm in a single health care system.

Design: Comparison of men seen pre-implementation (2/1/2016-2/1/2017) vs. post-implementation (2/2/2017-2/21/2018).

Participants: Men, aged 40-75 years, without a history of prostate cancer, who were seen by a primary care provider.

Interventions: The algorithm was integrated into two components in the electronic health record (EHR): in Health Maintenance as a personalized screening reminder and in tailored messages to providers that accompanied prostate-specific antigen (PSA) results.

Main Measures: Primary outcomes: percent of men who met screening algorithm criteria; percent of men with a PSA result. Logistic repeated measures mixed models were used to test for differences in the proportion of individuals that met screening criteria in the pre- and post-implementation periods with age, race, family history, and PSA level included as covariates.

Key Results: During the pre- and post-implementation periods, 49,053 and 49,980 men, respectively, were seen across 26 clinics (20.6% African American). The proportion of men who met screening algorithm criteria increased from 49.3% (pre-implementation) to 68.0% (post-implementation) (p < 0.001); this increase was observed across all races, age groups, and primary care clinics. Importantly, the percent of men who had a PSA did not change: 55.3% pre-implementation, 55.0% post-implementation. The adjusted odds of meeting algorithm-based screening was 6.5-times higher in the post-implementation period than in the pre-implementation period (95% confidence interval, 5.97 to 7.05).

Conclusions: In this preliminary analysis, following implementation of an EHR-based algorithm, we observed a rapid change in practice with an increase in screening in higher-risk groups balanced with a decrease in screening in low-risk groups. Future efforts will evaluate costs and downstream outcomes of this strategy.
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http://dx.doi.org/10.1007/s11606-020-06124-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7858708PMC
January 2021

Rising occurrence of hypocitraturia and hyperoxaluria associated with increasing prevalence of stone disease in calcium kidney stone formers.

Scand J Urol 2020 Oct 27;54(5):426-430. Epub 2020 Jul 27.

Division of Urology, Duke University Medical Center, Durham, NC, USA.

Objective: To evaluate metabolic risk factors in calcium kidney stone formers from two different decades, comparing changes in metabolic profiles over time.

Methods: A retrospective analysis was performed of calcium kidney stone formers who underwent metabolic evaluation of urolithiasis with 24-hour urine collections at a single institution. There were 309 patients evaluated from 1988 to 1994 (Group A), and 229 patients from 2007 to 2010 (Group B). A comparison between both groups was performed to assess changes in demographics and in metabolic stone profiles.

Results: Comparing Group A to Group B, the percentage of females increased from 43 to 56%, obese patients (BMI ≥ 30) increased from 22 to 35%, and patients ≥ 50 years increased from 29 to 47% (all  < 0.005). A greater percentage of patients had hypocitraturia in the recent cohort (46-60%,  = 0.001), with hypocitraturia significantly more frequent in obese patients ( = 0.005). Hyperoxaluria was also increased in Group B compared to Group A (23-30%  = 0.07), a finding that was significant in males (32-53%,  = 0.001).

Conclusions: Urolithiasis has increased in females, obese, and older patients, consistent with population-based studies. We report a rising incidence of hypocitraturia and hyperoxaluria in the contemporary cohort, particularly in obese patients and in males, respectively. Further studies are needed to better characterize the metabolic changes corresponding to the increase in stone disease.
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http://dx.doi.org/10.1080/21681805.2020.1794955DOI Listing
October 2020

Letter to the Editor-Reply.

Urology 2020 09 23;143:270. Epub 2020 Jun 23.

Division of Urology, Duke University Medical Center, Durham, NC.

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http://dx.doi.org/10.1016/j.urology.2020.06.012DOI Listing
September 2020

The Impact of Alternative Alkalinizing Agents on 24-Hour Urine Parameters.

Urology 2020 08 21;142:55-59. Epub 2020 Apr 21.

Division of Urology, Duke University Medical Center, Durham, NC.

Objectives: To determine if alternative alkalinizing agents lead to similar changes in 24-hour urine pH and citrate compared to potassium citrate (KCIT). Many stone formers cannot tolerate KCIT due to side effects or cost. In these patients, we have prescribed potassium bicarbonate or sodium bicarbonate as alternative alkali (AA), though their efficacy is unclear.

Methods: We performed a retrospective cohort study of adult stone formers seen from 2000 to 2018 with 24-hour urine analyses. Two analyses were performed. The first evaluated the alkalinizing and citraturic effects in patients with baseline low urine pH or hypocitraturia off of any alkalinizing medications, who were subsequently treated with either KCIT or AA. The second analysis compared the pH and citrate in patients changing from KCIT to an AA. Reasons for switching were abstracted by chart review and cost savings percentages were calculated using GoodRx medication prices.

Results: When starting alkali therapy, the median increase in pH from baseline was 0.64 for KCIT and 0.51 for AA (P = .077), and the median increase in citrate from baseline was 231 mg for KCIT and 171 mg for AA (P = .109). When switching alkali therapy, median pH and citrate did not significantly change. Hyperkalemia (24%), GI upset (19%), and cost (17%) were the most common reasons cited for switching to an AA. AA represented a savings of 86%-92% compared to KCIT.

Conclusion: Alternative alkali appear to offer comparable improvements in 24-hour urine parameters and significant cost-savings compared to KCIT.
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http://dx.doi.org/10.1016/j.urology.2020.04.047DOI Listing
August 2020

Metabolic evaluation and medical management of staghorn calculi.

Asian J Urol 2020 Apr 17;7(2):122-129. Epub 2019 Dec 17.

Duke Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center, Durham, NC, USA.

Staghorn renal calculi are large renal calculi that occupy nearly the entirety of the renal collecting system. They may be composed of metabolic or infection stone types. They are often associated with specific metabolic defects. Infection stones are associated with urease-producing bacterial urinary tract infections. The ideal treatment for staghorn calculi is maximal surgical removal. However, some patients are either unwilling or unable to proceed with that modality of treatment, and therefore other management must be used. One such technique is the metabolic evaluation with directed medical management. Based on contemporary evidence that the majority of staghorn stones are metabolic in etiology, and furthermore that even infection stones are usually associated with metabolic abnormalities, metabolic evaluation with directed medical management is recommended for all staghorn stone formers. The scientific basis of this recommendation is reviewed in the present work.
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http://dx.doi.org/10.1016/j.ajur.2019.12.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7096691PMC
April 2020

Evaluation and Medical Management of Patients with Cystine Nephrolithiasis: A Consensus Statement.

J Endourol 2020 11 6;34(11):1103-1110. Epub 2020 Apr 6.

UC San Diego Health, San Diego, California, USA.

Cystinuria is a genetic disorder with both autosomal recessive and incompletely dominant inheritance. The disorder disrupts cystine and other dibasic amino acid transport in proximal tubules of the kidney, resulting in recurrent kidney stone formation. Currently, there are no consensus guidelines on evaluation and management of this disease. This article represents the consensus of the author panel and will provide clinicians with a stepwise framework for evaluation and clinical management of patients with cystinuria based on evidence in the existing literature. A search of MEDLINE/PubMed and Cochrane databases was performed using the following key words: "cystine nephrolithiasis," "cystinuria," "penicillamine, cystine," and "tiopronin, cystine." In total, as of May 2018, these searches yielded 2335 articles, which were then evaluated for their relevance to the topic of evaluation and management of cystinuria. Evidence was evaluated by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Twenty-five articles on the topic of cystinuria or cystine nephrolithiasis were deemed suitable for inclusion in this study. The literature supports a logical evaluation process and step-wise treatment approach beginning with conservative measures: fluid intake and dietary modification. If stone formation recurs, proceed to pharmacotherapeutic options by first alkalinizing the urine and then using cystine-binding thiol drugs. The proposed clinical pathways provide a framework for efficient evaluation and treatment of patients with cystinuria, which should improve overall outcomes of this rare, but highly recurrent, form of nephrolithiasis.
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http://dx.doi.org/10.1089/end.2019.0703DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7869875PMC
November 2020

Assessment of conservative dietary management as a method for normalization of 24-h urine pH in stone formers.

Urolithiasis 2020 Apr 6;48(2):131-136. Epub 2019 May 6.

Division of Urologic Surgery, Duke University Medical Center, Durham, NC, USA.

Low urine pH is a metabolic risk factor for stone formation. While medical therapy is typically prescribed (as urinary alkalinization), patients typically prefer dietary modifications. We aimed to assess capacity to alter urine pH with dietary management alone. We analyzed a retrospective cohort of stone formers seen between 2000 and 2015 with multiple 24-h urine collections (24hUC). Patients ≥ 18 years old with low urine pH (< 6.0) were included; those prescribed alkalinizing agents or thiazides were excluded. Demographic data, 24hUC parameters, and medications were abstracted. 24hUC was utilized to calculate gastrointestinal alkali absorption (GIAA). The primary outcome was urine pH ≥ 6.0 on second 24hUC. Predictors were selected utilizing multivariable logistic regression. The database consisted of 2197 stone formers; 224 of these met inclusion criteria. On second 24hUC, 124 (55.4%) achieved a favorable pH ≥ 6.0. On univariable analysis, a second pH ≥ 6.0 was associated with high initial pH, low initial sulfate, younger age, increase in citrate/GIAA/urine volume, and decrease in ammonium (P < 0.02). On multivariable analysis, high initial pH (OR = 23.64, P < 0.001), high initial GIAA (OR = 1.03, P = 0.001), lower initial sulfate (OR = 0.95, P < 0.001), increase in urine volume (OR = 2.19, P = 0.001), increase in GIAA (OR = 8.6, P < 0.001), increase in citrate (OR = 2.7, P = 0.014), decrease in ammonium (OR = 0.18, P < 0.001), and younger age (OR = 0.97, P = 0.025) were associated with a second pH ≥ 6.0. The analysis demonstrated a corrected AUC of 0.853. These data suggest that certain dietary recommendations (increases in urine volume, citrate, GIAA, and decreased acid load) may normalize urine pH in a select group of patients. This may allow urologists to counsel patients with low urine pH on possibility of success with dietary modification alone.
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http://dx.doi.org/10.1007/s00240-019-01139-9DOI Listing
April 2020

The Rise and Fall of High Temperatures During Ureteroscopic Holmium Laser Lithotripsy.

J Endourol 2019 10 27;33(10):794-799. Epub 2019 May 27.

Division of Urologic Surgery, Duke University Medical Center, Durham, North Carolina.

Temperatures over 43°C-the threshold for cellular injury-may be achieved during ureteroscopic holmium laser lithotripsy. The time to reach and subsequently clear high temperatures at variable laser power settings and irrigation pressures has not been studied. A flexible or semirigid ureteroscope was placed within an 11/13 F ureteral access sheath inserted into a 250-mL saline bag simulating a normal-caliber ureter, renal pelvis reservoir, and antegrade irrigation flow. A thermocouple was placed adjacent to a 365 μm fiber fired for 45 seconds at 0.6 J/6 Hz, 0.8 J/8 Hz, 1 J/10 Hz, 1 J/20 Hz, and 0.2 J/80 Hz. Irrigation pressures of 200, 100, and 0 mm Hg were tested. Mean temperature changes were recorded with 6°C increase as a threshold for injury (as body temperature is 6°C below 43°C). Semirigid scope: At 200 mm Hg no temperature changes >6°C were observed. At 100 mm Hg, changes >6°C occurred with 1 J/20 Hz within 1 second of activation and returned to ≤6°C within 1 second of cessation. At 0 mm Hg, changes >6°C occurred with all settings; within 1 second at power ≥10 W. Temperatures returned to ≤6°C within 5-10 seconds. Flexible scope: At 200 mm Hg, changes >6°C occurred at 1 J/10 Hz (15 seconds), 0.2 J/80 Hz (3 seconds), and 1 J/20 Hz (2 seconds). Temperatures returned within 6°C of baseline within 2 seconds. At 100 mm Hg, changes >6°C occurred in all but 0.6 J/6 Hz. Temperatures returned to ≤6°C in 5-10 seconds. At 0 mm Hg, all settings produced changes >6°C within 3 seconds, except 0.6 J/6 Hz (35 seconds). Temperatures returned to ≤6°C in under 10 seconds. High temperatures were achieved in our model in as little as 1 second at common irrigation pressures and laser settings, particularly with a flexible ureteroscope and power ≥10 W. However, with laser cessation, temperatures quickly returned to a safe level at each irrigation pressure.
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http://dx.doi.org/10.1089/end.2019.0084DOI Listing
October 2019

Editorial Comment.

J Urol 2019 07 7;202(1):170. Epub 2019 Jun 7.

Duke Comprehensive Kidney Stone Center , Durham , North Carolina.

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http://dx.doi.org/10.1097/01.JU.0000558168.69261.3aDOI Listing
July 2019

Avoiding a Lemon: Performance Consistency of Single-Use Ureteroscopes.

J Endourol 2019 02 31;33(2):127-131. Epub 2019 Jan 31.

1 Division of Urologic Surgery, Duke University Medical Center, Durham, North Carolina.

Introduction And Objectives: Single-use flexible ureteroscopes are increasingly popular because of high repair costs of reusable ureteroscopes. As new single-use ureteroscopes enter the market, the consistency of performance of these devices has been questioned. Our objective was to compare two single-use ureteroscopes: the Pusen PU3022a (Zhuhai Pusen) and the LithoVue (Boston Scientific) with emphasis on physical and optical performance consistency.

Methods: Ten LithoVue and 10 Pusen ureteroscopes were evaluated in never-used condition. The following parameters were recorded: maximal tip deflection with an empty working channel, 200 μm laser fiber, and 1.9F basket; image resolution at 10, 20, and 50 mm; and irrigation flow rate; all ureteroscopes were then fully deflected for 200 cycles. Maximum deflection was remeasured. Mean values for each parameter were compared. To examine within-manufacturer consistency, the variance was calculated and an F-test performed to evaluate for equivalence.

Results: Both ureteroscopes provided max deflection over 270°. The Pusen flexed to a greater degree than LithoVue. The Pusen lost more deflection with a laser fiber in the working channel. LithoVue had higher resolution at 10 mm, but the ureteroscopes were similar at 20 and 50 mm. Although the working channel diameter is identical, irrigation flow was higher with the Pusen. However, its working channel was 7 cm shorter than LithoVue. After 200 cycles of deflections, LithoVue had less deflection loss, although one ureteroscope was excluded from analysis because of mechanical failure. Variability was minimal and not significant between manufacturers at all measured parameters.

Conclusions: LithoVue and the newer PU3022a have similar "out-of-the-box" performance characteristics and seem durable. These two single-use flexible ureteroscopes performed consistently regardless of the manufacturer.
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http://dx.doi.org/10.1089/end.2018.0805DOI Listing
February 2019

Defining metabolic activity of nephrolithiasis - Appropriate evaluation and follow-up of stone formers.

Asian J Urol 2018 Oct 26;5(4):235-242. Epub 2018 Jun 26.

Universidade Federal de São Paulo, Nephrology Division, São Paulo, Brazil.

Considering the variation in metabolic evaluation and medical management of kidney stone disease, this consensus review was created to discuss the metabolic activity of nephrolithiasis, define the difference between single and recurrent stone formers, and develop a schema for metabolic and radiologic follow-up. A systematic review of the literature was performed to identify studies of metabolic evaluation and follow-up of patients with nephrolithiasis. Both single and recurrent stone formers share many similarities in metabolic profiles. The study group determined that based on an assessment of risk for stone recurrence and metabolic activity, single and recurrent stone formers should be evaluated comprehensively, including two 24 h urine studies on a random diet. Targeted medication and dietary recommendations are effective for many patients in reducing the risk of stone recurrence. Follow-up of those with stone disease should be obtained depending on the level of metabolic activity of the patient, the risk of chronic kidney disease and the risk of osteoporosis/osteopenia. A standard scheme includes a baseline metabolic profile, a repeat study 3-6 months after initiation of treatment, and then yearly when stable, with abdominal imaging obtained every 1-2 years.
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http://dx.doi.org/10.1016/j.ajur.2018.06.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6197397PMC
October 2018

Dusting Efficiency of the Moses Holmium Laser: An Automated In Vitro Assessment.

J Endourol 2018 12 16;32(12):1131-1135. Epub 2018 Nov 16.

1 Division of Urologic Surgery, Duke University Medical Center , Durham, North Carolina.

Introduction: Moses technology is a novel Holmium:YAG laser system designed to minimize stone retropulsion and improve stone ablation when the laser is not in direct contact with the stone. Our aim was to assess the efficiency of Moses technology relative to short- and long-pulse lithotripsy using an automated in vitro "dusting model" of stone comminution.

Methods: All tests were conducted using a Lumenis Pulse 120H Holmium:YAG laser with a 365 μm Moses D/F/L fiber. "Hard" (15:3) and "soft" (15:6) Begostones mimicking calcium oxalate monohydrate and uric acid stones, respectively, were used. To assess ablation efficiency and fiber tip degradation, a dusting model was employed: the laser was moved by a three-dimensional positioning system in a spiral motion across a flat Begostone surface submerged in water. Ablation efficiency was measured as stone mass loss after 4 kJ of energy delivery. Fiber tip degradation was measured at 1 kJ intervals. Comparative trials with short pulse, long pulse, Moses contact, and Moses distance settings were completed with the laser tip positioned at 0, 1, and 2 mm distances from the stone at energy settings of 0.4 J delivered at 70 Hz.

Results: In our dusting model, stone ablation was significantly greater the closer the laser was to the stone. On hard stones, pulse type did not have a significant impact on ablation at any distance. On soft stones at 0 mm, Moses contact produced the greatest ablation, significantly greater than long pulse (p < 0.05). At 1 mm, Moses distance produced significantly greater ablation than all other settings (p = 0.025) and was as effective as long or short pulse at 0 mm. At 2 mm distance, no pulse type demonstrated significantly different ablation. Fiber tip degradation was minimal and not significant between settings.

Conclusions: Moses technology delivers greater ablation of soft stones when in contact and 1mm from the stone surface.
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http://dx.doi.org/10.1089/end.2018.0660DOI Listing
December 2018

Psychiatric Diagnoses and Other Factors Associated with Emergency Department Return within 30 Days of Ureteroscopy.

J Urol 2019 03;201(3):556-562

Division of Urologic Surgery, Durham, North Carolina.

Purpose: Emergency department visits after ureteroscopy are costly and inconvenient. To better understand those at risk we aimed to identify patient demographic, medical and surgical factors associated with 30-day emergency department presentation following ureteroscopy for urolithiasis with particular attention to those with a history of a psychiatric diagnosis.

Materials And Methods: We retrospectively reviewed 1,576 cases (1,395 adults) who underwent stone related ureteroscopy during 3 years at a total of 2 hospitals. We collected patient demographics, medical history and operative details. The primary outcome was return to the emergency department within 30 days of ureteroscopy. Logistic regression was performed to examine factors associated with emergency department presentation.

Results: Of the patients 613 (43.9%) had a history of psychiatric diagnosis. Of those with ureteroscopy encounters 12.6% returned to the emergency department within 30 days of ureteroscopy, including 58.8% with a history of psychiatric diagnosis. On multivariable analysis variables associated with emergency department return included a history of psychiatric diagnosis (OR 1.57, p = 0.012), uninsured status (OR 2.46, p = 0.001) and a stone only in the kidney (OR 1.76, p = 0.022). Patients who returned to the emergency department had had more emergency department visits in the year prior to surgery (OR 1.40, p <0.001). On univariable analysis older patients and those with longer operative time were more frequently admitted from the emergency department (OR 1.03, p = 0.002 and OR 1.96, p = 0.03. respectively) while uninsured patients were admitted less frequently (OR 0.19, p = 0.013). No difference was noted in admissions between those with a psychiatric diagnosis and all others (60.7% vs 55.8%, p = 0.48).

Conclusions: We identified factors associated with emergency department return after ureteroscopy, including a history of psychiatric diagnosis, uninsured status and emergency department visits in the year before surgery. These patients may benefit from targeted interventions to help avoid unnecessary emergency department visits.
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http://dx.doi.org/10.1016/j.juro.2018.09.062DOI Listing
March 2019

Antibiotic Utilization Before Endourological Surgery for Urolithiasis: Endourological Society Survey Results.

J Endourol 2018 10 21;32(10):978-985. Epub 2018 Sep 21.

1 Department of Urology, Duke University Medical Center , Durham, North Carolina.

Introduction: Ureteroscopy (URS) and percutaneous nephrolithotomy (PCNL) are common procedures performed to treat kidney stones. Despite advances in technology/technique, serious infectious complications can occur. To better understand the preoperative antibiotic administration patterns and adherence to guidelines from the American Urological Association (AUA) and the European Association of Urology (EAU), members of the Endourological Society were sent a clinical vignette-based survey to assess the antibiotic use in a variety of pre-URS and pre-PCNL scenarios.

Methods: Endourological Society members were e-mailed a survey that queried antibiotic therapy duration before uncomplicated URS and PCNL with negative and asymptomatic positive preoperative urine cultures (PUCs). For negative PUC questions, selecting more perioperative antibiotics was considered a "prolonged" course as it extends past the maximum of 24-hour perioperative prophylaxis recommended by both the AUA and EAU.

Results: The response rate was 16.3% for a total of 326 responders. Twenty-one percent to 39% of respondents reported giving prolonged courses of preoperative antibiotics before a URS or PCNL with a negative PUC (p < 0.0001). When presented with a negative PUC, more prolonged antibiotic courses were reported with the following hierarchy: PCNL for 2 cm intrarenal stones (39%) > URS for 12 mm renal pelvis stone (28%) > URS for 7 mm distal ureteral stones (21%) (p < 0.0001). In both negative and positive PUC questions, differences were noted in preoperative antibiotic prescribing patterns among site of practice (United States, Canada, Europe, Asia, South America, and Others), type of practice (academic vs all others), years in practice (<10 or ≥10 years), and surgical volume (URS and PCNL >100 or ≤100 annual cases).

Conclusions: Adherence to guidelines on antibiotic administration before PCNL and URS with a negative PUC varies by scenario and provider. In 21% to 39% of negative PUC cases, reported antibiotic use before a URS or PCNL is not consistent with recommendations from the AUA and EAU. Before a positive PUC URS or PCNL, nearly all surveyed provide preoperative antibiotics; however, the regimen length is variable.
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http://dx.doi.org/10.1089/end.2018.0494DOI Listing
October 2018

Abdominal Radiography With Digital Tomosynthesis: An Alternative to Computed Tomography for Identification of Urinary Calculi?

Urology 2018 10 10;120:56-61. Epub 2018 Jul 10.

Division of Urologic Surgery, Duke University Medical Center, Durham, NC.

Objective: To compare the accuracy of plain abdominal radiography (kidneys, ureter, and bladder [KUB]) with digital tomosynthesis (DT) to noncontrast computed tomography (NCCT), the gold standard imaging modality for urinary stones. Due to radiation and cost concerns, KUB is often used for diagnosis and follow-up of nephrolithiasis. DT, a novel technique that produces high-quality radiographs with less radiation and/or cost than low-dose NCCT, has not been assessed in this situation.

Materials And Methods: Seven fresh tissue cadavers were implanted with stones of known size and/or composition and imaged with KUB, DT, and NCCT. Four blinded readers (2 urologists, 2 radiologists) evaluated KUBs for presence and/or location of calculi. They then re-evaluated with addition of tomograms to assess additional value. After a memory extinction period, readers evaluated NCCT images. Accuracy of detection was determined using nearest-neighbor match with generalized linear mixed modeling.

Results: Total of 59 stones were identified on reference read. Overall, NCCT and DT were both superior to KUB alone (P < .001) while the difference between DT and NCCT was not significant (P = .06). When evaluating uric acid stones, NCCT and DT outperformed KUB (P < .01 and P < .05, respectively) while DT and NCCT were similar (P = .16). Intrarenal stones were better evaluated on DT and NCCT (P < .001 compared to KUB), while DT and NCCT were similar (P = 1.00). Accuracy was lower than anticipated across modalities due to use of the cadaver model.

Conclusion: Our study demonstrates DT is superior to KUB for identification of intrarenal calculi and could replace routine use of KUB or NCCT for detecting renal stones, even those composed of uric acid.
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http://dx.doi.org/10.1016/j.urology.2018.06.041DOI Listing
October 2018

An in vitro evaluation of laser settings and location in the efficiency of the popcorn effect.

Urolithiasis 2019 Aug 15;47(4):377-382. Epub 2018 Jun 15.

Division of Urologic Surgery, Duke University Medical Center, Durham, NC, USA.

To examine different locations and laser settings' effects on the efficiency of the "popcorn" method of laser lithotripsy, which consists of placing the laser in a group of small stones and firing continuously to break them into smaller particles. Pre-fragmented BegoStones were created between 2 and 4 mm to mimic typical popcorning conditions. A 0.5 g collection of fragments was placed into 3D-printed models (a spherical calyx and ellipsoid pelvis model) and a 200-µm laser fiber was positioned above the stones. The laser was fired for 2 min with irrigation, with 5 trials at each setting: 0.2 J/50 Hz, 0.5 J/20 Hz, 0.5 J/40 Hz, 1 J/20 Hz, 0.2 J/80 Hz, 0.5 J/80 Hz. After drying, fragmentation efficiency was determined by calculating the mass of stones reduced to sub-2 mm particles. Statistical analysis was performed with ANOVA and Student's t test. The trials within the calyx model were significantly more efficient compared to the pelvis (0.19 vs 0.15 g, p = 0.01). When comparing laser settings, there was a difference between groups by one-way ANOVA [F(5,54) = 8.503, p = 5.47 × 10]. Post hoc tests showed a power setting of 0.5 J/80 Hz was significantly more efficient than low-power settings 0.2 J/50 Hz and 0.5 J/20 Hz (p < 0.05). Additionally, 0.2 J/50 Hz was significantly less efficient than 0.5 J/40 Hz, 1 J/20 Hz, and 0.2 J/80 Hz. Popcorning is most efficient in smaller spaces; we recommend displacement of stones into a calyx before popcorning. No difference was seen between high-power settings, although 0.5 J/40 Hz and 0.5 J/80 Hz performed best, suggesting that moderate energy popcorning methods with at least 0.5 J per pulse are most efficient.
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http://dx.doi.org/10.1007/s00240-018-1066-6DOI Listing
August 2019

Let's Get to the Point: Comparing Insertion Characteristics and Scope Damage of Flat-Tip and Ball-Tip Holmium Laser Fibers.

J Endourol 2019 01 31;33(1):22-26. Epub 2018 Jul 31.

1 Division of Urology, Duke University Medical Center , Durham, North Carolina.

Introduction: A ball-tip holmium laser fiber (TracTip; Boston Scientific) has been developed to theoretically reduce damaging friction forces generated within a ureteroscope working channel. We compared the insertional forces and damage with a ureteroscope inner lining when inserting standard flat-tip and ball-tip laser fibers.

Materials And Methods: A standard ureteroscope channel liner was placed in a 3D-printed plastic mold. Molds were created at four angles of deflection (30°, 45°, 90°, and 180°) with a 1 cm radius of curvature. New 200 μm ball-tip (TracTip; Boston Scientific) and 200 μm flat-tip (Flexiva; Boston Scientific) laser fibers were advanced through the liner using a stage controller. A strain gauge was used to measure force required for insertion. Each fiber was passed 600 times at each angle of deflection. The ureteroscope liner was changed every 150 passes. Leak testing was performed every 50 passes or when the insertional force increased significantly to assess damage to the liner.

Results: At all deflection angles, the average insertional force was significantly lower with the ball-tip laser fibers compared with flat-tip laser fibers (p < 0.001). All trials with the ball-tip lasers were completed at each angle without any leaks. Two of four trials using flat-tip fibers at 45° deflection caused liner leaks (at 91 and 114 passes). At 90° deflection, all flat-tip trials caused liner leaks on first pass. The 180° trials could not physically be completed with the flat-tip laser fiber. Within the flat- and ball-tip groups, an increasing amount of force was needed to pass the fiber as the degree of deflection increased (p < 0.001).

Conclusions: The ball-tip holmium laser fiber can be safely passed through a deflected ureteroscope without causing liner perforation. The standard flat-tip fiber requires greater insertion force at all angles and can cause the ureteroscope liner to leak if it is deflected 45° or more.
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http://dx.doi.org/10.1089/end.2018.0229DOI Listing
January 2019

Disproportionate Use of Inpatient Care by Older Adults With Kidney Stones.

Urology 2018 Oct 23;120:103-108. Epub 2018 Jun 23.

Duke Clinical Research Institute, Durham, NC; Duke University Medical Center, Department of Surgery, Division of Urology, Durham, NC.

Objective: To describe variation in utilization and costs of inpatient care for patients with kidney stones, examining associations with older age.

Materials And Methods: Using the Nationwide Inpatient Sample we examined inpatient discharges with stone diagnoses from 2007 to 2011. We examined length of stay, hospitalization cost, and postdischarge care utilization using multivariable regression to identify associations between patient/hospital characteristics and resource.

Results: An estimated 1.7 million hospital discharges for stone disease occurred during the study period. Median length of stay was 2.1 days with a median cost of $6300. Hospital use was substantially higher among persons ≥65 years old (older adults) as compared to those aged 18-64 (younger adults): median length of stay was 3.1 days, with 25% staying more than 5.9 days. Older adults were significantly more likely to utilize home health (odds ratio [OR] 3.6) or skilled nursing (OR 5.0) after discharge. Older adults accounted for 1 in 3 hospital discharges, 40% of costs, and half of postdischarge care utilization. They were more likely to be septic during hospitalization (OR 1.8) which doubled costs per episode, but less likely to receive surgery (OR 0.93).

Conclusion: While historically at lower risk for kidney stones compared to younger adults, older adults utilizing inpatient care account for a disproportionate share of the economic burden of disease. Utilization is higher for older adults across multiple dimensions, including hospital costs, length of stay, and postdischarge care. These findings suggest that efforts to understand and mitigate the impact of kidney stones on this vulnerable population are required.
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http://dx.doi.org/10.1016/j.urology.2018.06.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6689223PMC
October 2018

In Vitro Comparison of a Novel Single Probe Dual-Energy Lithotripter to Current Devices.

J Endourol 2018 06 11;32(6):534-540. Epub 2018 May 11.

1 Division of Urology, Duke University Medical Center , Durham, North Carolina.

Purpose: The LithoClast Trilogy is a novel single probe, dual-energy lithotripter with ultrasonic (US) vibration and electromagnetic impact forces. ShockPulse and LithoClast Select are existing lithotripters that also use a combination of US and mechanical impact energies. We compared the efficacy and tip motion of these devices in an in vitro setting.

Materials And Methods: Begostones, in the ratio 15:3, were used in all trials. Test groups were Trilogy, ShockPulse, Select ultrasound (US) only, and Select ultrasound with pneumatic (USP). For clearance testing, a single investigator facile with each lithotripter fragmented 10 stones per device. For drill testing, a hands-free apparatus with a submerged balance was used to apply 1 or 2 lbs of pressure on a stone in contact with the device tip. High-speed photography was used to assess Trilogy and ShockPulse's probe tip motion.

Results: Select-USP was slowest and Trilogy fastest on clearance testing (p < 0.01). On 1 lbs drill testing, Select-US was slowest (p = 0.001). At 2 lbs, ShockPulse was faster than Select US (p = 0.027), but did not significantly outpace Trilogy nor Select-USP. At either weight, there was no significant difference between Trilogy and ShockPulse. During its US function, Trilogy's maximum downward tip displacement was 0.041 mm relative to 0.0025 mm with ShockPulse. Trilogy had 0.25 mm of maximum downward displacement during its impactor function while ShockPulse had 0.01 mm.

Conclusions: Single probe dual-energy devices, such as Trilogy and ShockPulse, represent the next generation of lithotripters. Trilogy more efficiently cleared stone than currently available devices, which could be explained by its larger probe diameter and greater downward tip displacement during both US and impactor functions.
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http://dx.doi.org/10.1089/end.2018.0143DOI Listing
June 2018
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