Assessing renal tissue temperature changes and perfusion effects during laser activation in an in vivo porcine model.

INTRODUCTION: High fluid temperatures have been seen in both in vitro and in vivo studies with laser lithotripsy, yet the thermal distribution within the renal parenchyma has not been well characterized. Additionally, the heat-sink effect of vascular perfusion remains uncertain. Our objectives were twofold: first, to measure renal tissue temperatures in response to laser activation in a calyx, and second, to assess the effect of vascular perfusion on renal tissue temperatures. METHODS: Ureteroscopy was performed in three porcine subjects with a prototype ureteroscope containing a temperature sensor at its tip. A needle with four thermocouples was introduced percutaneously into a kidney with ultrasound guidance to allow temperature measurement in the renal medulla and cortex. Three trials of laser activation (40W) for 60 s were conducted with an irrigation rate of 8 ml/min at room temperature in each subject. After euthanasia, three trials were repeated without vascular perfusion in each subject. RESULTS: Substantial temperature elevation was observed in the renal medulla with thermal dose in two of nine trials exceeding threshold for tissue injury. The temperature decay time (t½) of the non-perfused trials was longer than in the perfused trials. The ratio of t½ between them was greater in the cortex than the medulla. CONCLUSION: High-power laser settings (40W) can induce potentially injurious temperatures in the in vivo porcine kidney, particularly in the medullary region adjacent to the collecting system. Additionally, the influence of vascular perfusion in mitigating thermal risk in this susceptible area appears to be limited.

What Is the Optimal Stenting Duration After Ureteroscopy and Stone Intervention? Impact of Dwell Time on Postoperative Emergency Department Visits.

PURPOSE: AUA stone management guidelines recommend stenting duration following ureteroscopy be minimized to reduce morbidity; stents with extraction strings may be used for this purpose. However, an animal study demonstrated that short dwell time results in suboptimal ureteral dilation, and a pilot clinical study showed this increases postprocedure events. Using real-world practice data we examined stent dwell time after ureteroscopy and its association with postoperative emergency department visits. MATERIALS AND METHODS: We used the Michigan Urological Surgery Improvement Collaborative registry to identify ureteroscopy and stenting procedures (2016-2019). Pre-stented cases were excluded. Stenting cohorts with and without strings were analyzed. Using multivariable logistic regression we evaluated the risk of an emergency department visit occurring on the day of, or day after, stent removal based on dwell time and string status. RESULTS: We identified 4,437 procedures; 1,690 (38%) had a string. Median dwell time was lower in patients with a string (5 vs 9 days). Ureteroscopy in younger patients, smaller stones, or renal stone location had a higher frequency of string use. The predicted probability of an emergency department visit was significantly greater in procedures with string, compared to without string, when dwell times were less than 5 days (P < .01) but were not statistically significant after. CONCLUSIONS: Patients who had ureteroscopy and stenting with a string have short dwell times. Patients are at increased risk of a postoperative emergency department visit around the time of stent removal if dwell time is ≤4 days. We recommended stenting duration of at least 5 days in nonpre-stented patients.

Improving the Quality of Upper Urinary Tract Stone Surgery: External Validation of a Statewide Collaborative's Efforts to Reduce Emergency Department Visits After Ureteroscopy.

PURPOSE: The ROCKS (Reducing Operative Complications from Kidney Stones) program in MUSIC (Michigan Urological Surgery Improvement Collaborative) was created to optimize ureteroscopy outcomes. Through data collection, distribution of reports, patient education, and standardization of medication, post-ureteroscopy emergency department visits in Michigan have declined. It is unclear whether this is because of statewide quality efforts or due to national trends. We therefore sought to understand emergency department visit rates in Michigan compared to a national data set. MATERIALS AND METHODS: We compared the MUSIC ROCKS clinical registry in Michigan against a national cohort, Optum's de-identified Clinformatics Data Mart, from 2016-2021 (excluding Michigan). We identified patients who underwent ureteroscopy and the proportion who had a postoperative emergency department visit within 30 days. Emergency department rates were modeled over time, adjusting for age, gender, comorbidity, and ureteral stenting. RESULTS: We identified 24,688 patients in MUSIC ROCKS and 99,340 in the Clinformatics Data Mart database who underwent ureteroscopy. The risk-adjusted emergency department visit rate in MUSIC ROCKS significantly declined over the study period (10.5% in 2016 to 6.9% in 2021, P < 0.001) while the mean emergency department visit rate in the Clinformatics Data Mart cohort was 9.9% and did not change over time (9.6% in 2016 to 10% in 2021). Comparing emergency department visits between the cohorts, the MUSIC ROCKS rate significantly declined relative to the Clinformatics Data Mart (P < 0.001) over the study period. CONCLUSIONS: Postoperative emergency department visit rates in Michigan have declined significantly after ureteroscopy since the establishment of MUSIC ROCKS. This decline outpaced national rates, providing evidence that systematic quality initiatives can improve urological care.

International Alliance of Urolithiasis guideline on retrograde intrarenal surgery.

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.

Change in renal blood flow in response to intrarenal pressure alterations induced by ureteroscopy in an in-vivo porcine model.

INTRODUCTION: High irrigation rates are commonly used during ureteroscopy and can increase intrarenal pressure (IRP) substantially. Concerns have been raised that elevated IRP may diminish renal blood flow (RBF) and perfusion of the kidney. Our objective was to investigate the real-time changes in RBF while increasing IRP during Ureteroscopy (URS) in an in-vivo porcine model. METHODS: Four renal units in two porcine subjects were used in this study, three experimental units and one control. For the experimental units, RBF was measured by placing an ultrasonic flow cuff around the renal artery, while performing ureteroscopy in the same kidney using a prototype ureteroscope with a pressure sensor at its tip. Irrigation was cycled between two rates to achieve targeted IRPs of 30 mmHg and 100 mmHg. A control data set was obtained by placing the ultrasonic flow cuff on the contralateral renal artery while performing ipsilateral URS. RESULTS: At high IRP, RBF was reduced in all three experimental trials by 10-20% but not in the control trial. The percentage change in RBF due to alteration in IRP was internally consistent in each porcine renal unit and independent of slower systemic variation in RBF encountered in both the experimental and control units. CONCLUSION: RBF decreased 10-20% when IRP was increased from 30 to 100 mmHg during ureteroscopy in an in-vivo porcine model. While this reduction in RBF is unlikely to have an appreciable effect on tissue oxygenation, it may impact heat-sink capacity in vulnerable regions of the kidney.

Quantification of outflow resistance for ureteral drainage devices used during ureteroscopy.

PURPOSE: Since renal pelvis pressure is directly related to irrigation flowrate and outflow resistance, knowledge of outflow resistance associated with commonly used drainage devices could help guide the selection of the type and size of ureteral access sheath or catheter for individual ureteroscopic cases. This study aims to quantitatively measure outflow resistance for different drainage devices utilized during ureteroscopy. METHODS: With measured irrigation flowrate and renal pelvis pressure, outflow resistance was calculated using a hydrodynamic formula. After placement of a drainage device into a silicone kidney-ureter model, a disposable ureteroscope with a 9.5-Fr outer diameter was inserted with its tip positioned at the renal pelvis. Irrigation was delivered through the ureteroscope from varying heights above the renal pelvis. Renal pelvis pressure was measured directly from the port of the kidney model using a pressure sensor (Opsens, Canada). Outflow resistance was determined by plotting flowrate versus renal pelvis pressure. All trials were performed in triplicate for each drainage device inserted. RESULTS: Flowrate was linearly dependent on renal pelvis pressure for all drainage devices tested. Outflow resistance values were 0.2, 1.1, 1.4, 3.9, and 6.5 cmH2O/[ml/min] for UAS 13/15 Fr, UAS 11/13 Fr, UAC 6 Fr, UAC 4.8 Fr, and UAC 4.0 Fr, respectively, across the range of commonly used irrigation flowrates. CONCLUSIONS: In this study, outflow resistance of different ureteral drainage devices was quantitatively measured. This knowledge can be useful when selecting which type and size of drainage device to insert to maintain safe renal pelvis pressure during ureteroscopy.

Practice patterns and outcomes of urgent versus elective ureteroscopy in a statewide surgical collaborative.

PURPOSE: Urgent indications for nephrolithiasis treatment include obstruction with intractable pain or renal impairment without untreated infection. Patients and hospitals may benefit from urgent primary ureteroscopy. We aimed to examine variation in urgent ureteroscopy utilization and associated outcomes. METHODS: Using Reducing Operative Complications from Kidney Stones (ROCKS), we identified all ureteroscopy's between 2016 and 2019. Cases were classified by acuity (elective versus urgent). We assessed practice/urologist variation in urgent ureteroscopy performance. We characterized patients demographic, operative and outcomes data, making bivariate comparisons with elective ureteroscopy to understand implications of urgent surgery. We performed multilevel modeling to understand factors associated with unplanned healthcare encounters after urgent ureteroscopy. RESULTS: 12,859 cases were identified from 33 practices and 204 urologists, 10,854 (84.4%) elective and 2005 (15.6%) urgent. Urgent ureteroscopy was performed on younger patients (53 vs 57, p < 0.001), with higher rates of ureteral stones (72.8% vs 56.8%, p < 0.001). Urgent ureteroscopy rates varied widely by practice (2-70%) and urologist (0-98%). Urgent ureteroscopy had higher stenting rates (77.4% vs 72.5%, p < 0.001), stone free rates (66% vs 58.4%, p < 0.001), and postoperative ED visits (11% vs 7.2%, p < 0.001). There were no differences in intraoperative complications or unplanned hospitalizations. Factors predictive of ED visits in urgent ureteroscopy included concomitant ureteral/renal stone location (OR = 1.53, CI = 1.05-2.23, p = 0.035). CONCLUSIONS: In Michigan elective ureteroscopy is performed 5 times more frequently than urgent ureteroscopy with wide variation. Urgent ureteroscopy demonstrated low morbidity. Urgent ureteroscopy produced modestly higher stone free rates with a slightly increased frequency of unscheduled ED visits particularly for ureteral stones.

How I Do It: Ureteroscopy and high-power holmium laser lithotripsy to treat renal stones.

In North America, ureteroscopy has become the most popular treatment modality for upper urinary tract urinary calculi. Herein we describe our technique for the treatment of renal stones with flexible ureteroscopy and high-power holmium laser lithotripsy. We discuss preoperative planning, intraoperative strategies, and laser settings for a high-frequency dusting technique with the goal to provide optimal patient outcomes.

Development of an automated laser drilling algorithm to compare stone ablation patterns from different laser pulse modes.

PURPOSE: To develop a novel automated three-dimensional (3D) laser drilling algorithm to further investigate laser-stone interaction with different laser pulse modes. Comparison of post-ablative lattice architecture combined with mass of stone ablated can provide a more complete understanding of differences between pulse mode. METHODS: A 3D positioner (securing laser fiber) was programmed to create a 5 × 5 grid of drill holes spaced 1 mm apart on 15:5 cylindrical BegoStones. Beginning 0.5 mm above the stone surface, the laser fiber was activated and advanced 2 mm toward and into the stone for all 25 points. Four trials for each pulse mode [short pulse (SP), long pulse (LP), Moses Contact (MC), Moses Distance (MD)] were completed. Outcome measures were assessment of lattice preservation and mass of ablated stone. RESULTS: MC exhibited the greatest lattice preservation and least stone mass ablated (50.5 ± 2.2 mg). SP (69.4 ± 4.3 mg) and MD (70.0 ± 2.6 mg) had the greatest lattice destruction and stone mass ablated. The differences in stone ablated between MC and MD (p = 0.00003), MC and SP (p = 0.0002), and LP and MD (p = 0.004) were statistically significant. CONCLUSIONS: Consistent quantitative and qualitative differences between pulse modes were observed with a novel automated 3D laser drilling algorithm applied to BegoStone. The laser drilling algorithm developed here can be used to further enhance mechanistic understanding of laser-stone interactions and facilitate selection of appropriate laser pulse modes to balance precision and efficiency across the range of laser lithotripsy techniques.

Laser operator duty cycle effect on temperature and thermal dose: in-vitro study.

PURPOSE: High-power laser lithotripsy can elevate temperature within the urinary collecting system and increase risk of thermal injury. Temperature elevation is dependent on power settings and operator duty cycle (ODC)-the percentage of time the laser pedal is depressed. The objective of this study was to quantify temperature and thermal dose resulting from laser activation at different ODC in an in-vitro model. METHODS: Holmium laser energy (1800 J) was delivered at 30 W (0.5 J × 60 Hz) to a fluid filled glass bulb. Room temperature irrigation was applied at 8 ml/min. ODC was evaluated in 10% increments from 50-100%. Bulb fluid temperature was recorded and thermal dose calculated. Time to reach threshold of thermal injury and maximal allowable energy were also determined at each ODC. RESULTS: Upon laser activation, there was an immediate rise in fluid temperature with a "saw-tooth" oscillation superimposed on the curves for 50-90% ODC corresponding to periodic activation of the laser. Higher ODC resulted in greater maximum temperature and thermal dose, with ODC ≥ 70% exceeding threshold. Use of 50% compared to 60% ODC resulted in a tenfold increase in time required to reach threshold of thermal injury and an eightfold increase in maximal allowable energy. CONCLUSIONS: Laser activation at higher ODC produced greater fluid temperature and thermal dose. Time to threshold of thermal injury and maximal allowable energy were dramatically higher for 50% compared to 60% ODC at high-power settings. Proper management of laser ODC can enhance patient safety and optimize stone treatment.

Ureteral Stent Placement following Ureteroscopy Increases Emergency Department Visits in a Statewide Surgical Collaborative.

PURPOSE: Ureteral stents are commonly placed after ureteroscopy. Although studies indicate that stents are associated with patient discomfort, their impact on downstream health services use is unclear. We examined patterns of stent utilization in Michigan and their association with unplanned health care encounters. MATERIALS AND METHODS: We used the Michigan Urological Surgery Improvement Collaborative's Reducing Operative Complications from Kidney Stones (MUSIC ROCKS) clinical registry to identify ureteroscopy cases between 2016 and 2019. Factors associated with stent placement were examined using bivariate and multivariable statistics. Using multivariable logistic regression, we evaluated whether stent placement was associated with emergency department visits and hospitalizations within 30 days. RESULTS: We identified 9,662 ureteroscopies and a stent was placed in 7,025 (73%) of these. Frequency of stent use across the 137 urologists varied (11%-100%, p <0.001) and was not associated with total case volume. Factors associated with stent use included age and stone size. Pre-stented cases and renal stones had a decreased odds of stent placement. On multivariable analysis after adjusting for risk factors, stent placement was associated with a 1.25 higher odds of emergency department visit (OR 1.25, 95% CI 1.01-1.54, p=0.043) but not hospitalization (OR 1.28, 95% CI 0.94-1.76, p=0.12). In a single high volume practice, 0.5% of cases that omitted a stent required urgent stenting postoperatively. CONCLUSIONS: There is substantial variation in the use of stents in Michigan, irrespective of case volume. Stent placement significantly increased the odds of an emergency department visit after surgery. Importantly, stent omission rarely required subsequent urgent stent placement.

Ureteroscopy in Patients Taking Anticoagulant or Antiplatelet Therapy: Practice Patterns and Outcomes in a Surgical Collaborative.

PURPOSE: AUA guidelines recommend ureteroscopy as first line therapy for patients on anticoagulant or antiplatelet therapy and advocate using a ureteral access sheath. We examined practice patterns and unplanned health care use for these patients in Michigan. MATERIALS AND METHODS: Using the Michigan Urological Surgery Improvement Collaborative (MUSIC) clinical registry we identified ureteroscopy cases from 2016 to 2019. We assessed outcomes and adherence to guidelines based on therapy at time of ureteroscopy: 1) anticoagulant: continuous warfarin or novel oral agent therapy; 2) antiplatelet: continuous clopidogrel or aspirin therapy; 3) control: not on anticoagulant/antiplatelet therapy. We fit multivariate models to assess anticoagulant or antiplatelet therapy association with emergency department visits, hospitalization and ureteral access sheath use. RESULTS: In total, 9,982 ureteroscopies were performed across 31 practices with 3.1% and 7.8% on anticoagulant and antiplatelet therapy, respectively. There were practice (0% to 21%) and surgeon (0% to 35%) variations in performing ureteroscopy on patients on anticoagulant/antiplatelet therapy regardless of volume. After adjusting for risk factors, anticoagulant or antiplatelet therapy was not associated with emergency department visits. Hospitalization rates in anticoagulant, antiplatelet and control groups were 4.3%, 5.5% and 3.2%, respectively, and significantly increased with antiplatelet therapy (OR 1.48, 95% CI 1.02-2.14). Practice-level ureteral access sheath use varied (23% to 100%) and was not associated with anticoagulant/antiplatelet therapy. Limitations include inability to risk stratify between type/dosage of anticoagulant/antiplatelet therapy. CONCLUSIONS: We found practice-level and surgeon-level variation in performing ureteroscopy while on anticoagulant/antiplatelet therapy. Ureteroscopy on anticoagulant is safe. However, antiplatelet therapy increases the risk of hospitalization. Despite guideline recommendations, ureteral access sheath use is not associated with anticoagulant/antiplatelet therapy.

Pulse modulation with Moses technology improves popcorn laser lithotripsy.

PURPOSE: Moses™ technology has been developed to improve holmium laser fragmentation at 1-2 mm distance from the stone. Because popcorn lithotripsy is a non-contact technique, we compared short pulse (SP) and Moses distance (MD) modes in an in vitro model. METHODS: BegoStones were fragmented using a 120 W Ho:YAG laser (P120 Moses) and a 230 µm core fiber introduced through a ureteroscope. 20 W (1 J × 20 Hz; 0.5 J × 40 Hz) and 40 W (1 J × 40 Hz; 0.5 J × 80 Hz) settings (total energy 4.8 kJ) were tested using SP and MD modes. We assessed fragment size distribution and mass lost in fluid (initial mass-final dry mass of all sievable fragments). High-speed video analysis of fragmentation strike rate and vapor bubble characteristics was conducted for 1 J × 20 Hz and 0.5 J × 80 Hz. Laser strike rate (number of strikes divided by frequency) was categorized as: (1) direct-a visual plume of dust ejected from stone while in contact with fiber tip; (2) indirect-a visual plume of dust ejected with distance between stone and fiber tip. RESULTS: For 1 J × 20 Hz (20 W), MD resulted in more mass lost in fluid and a lower distribution of fragments ≥ 2 mm compared to SP (p < 0.05). 0.5 J × 80 Hz (40 W) produced no fragments ≥ 2 mm, and there were no significant differences in fragment distribution between MD and SP (p = 0.34). When using MD at 1 J × 20 Hz, 96% of strikes were indirect vs 61% for SP (p = 0.059). In contrast to the single bubble of SP, with MD, there was forward movement of the collapsing second bubble, away from the fiber-tip. CONCLUSIONS: For lower frequency and power popcorn settings, pulse modulation results in more fragmentation through true non-contact laser lithotripsy.

Consultation on kidney stones, Copenhagen 2019: aspects of intracorporeal lithotripsy in flexible ureterorenoscopy.

PURPOSE: To summarize current knowledge on intracorporeal laser lithotripsy in flexible ureterorenoscopy (fURS), regarding basics of laser lithotripsy, technical aspects, stone clearance, lithotripsy strategies, laser technologies, endoscopes, and safety. METHODS: A scoping review approach was applied to search literature in PubMed, EMBASE, and Web of Science. Consensus was reached through discussions at the Consultation on Kidney Stones held in September 2019 in Copenhagen, Denmark. RESULTS AND CONCLUSIONS: Lasers are widely used for lithotripsy during fURS. The Holmium laser is still the predominant technology, and specific settings for dusting and fragmenting have evolved, which has expanded the role of fURS in stone management. Pulse modulation can increase stone ablation efficacy, possibly by minimizing stone retropulsion. Thulium fibre laser was recently introduced, and this technology may improve laser lithotripsy efficiency. Small fibres give better irrigation, accessibility, and efficiency. To achieve optimal results, laser settings should be adjusted for the individual stone. There is no consensus whether the fragmentation and basketing strategy is preferable to the dusting strategy for increasing stone-free rate. On the contrary, different stone scenarios call for different lithotripsy approaches. Furthermore, for large stone burdens, all laser settings and lithotripsy strategies must be applied to achieve optimal results. Technology for removing dust from the kidney should be in focus in future research and development. Safety concerns about fURS laser lithotripsy include high intrarenal pressures and temperatures, and measures to reduce both those aspects must be taken to avoid complications. Technology to control these parameters should be targeted in further studies.

Single-use flexible ureteroscopes: how to choose and what is around the corner?

PURPOSE OF REVIEW: The pace of technology development with single-use endoscopy has led to a range of disposable ureteroscopes. We review the development of single-use scopes, deconstruct the basic design and functional characteristics of available devices, and discuss future directions for next-generation platforms. RECENT FINDINGS: Currently available devices are differentiated on the basis of several core features. The optical, deflection and irrigation characteristics are marginally different with no device clearly superior in every category. Studies comparing single-use ureteroscopes in patients linked to outcomes are limited. The incorporation of next-generation technologies into these platforms include sensors to monitor intrarenal pressure and temperature, suction of fluid and fragments, and computer vision for artificial intelligence. SUMMARY: Each ureteroscope has specific features that may be advantageous in different circumstances. Single-use devices could transform the ureteroscope from a visual conduit to a transformative surgical instrument that improves outcomes and reduces complications.

Precision Stone Surgery: Current Status of Miniaturized Percutaneous Nephrolithotomy.

PURPOSE OF REVIEW: Innovations in lasers and surgical technology have led to a renewed interest in the miniaturization of percutaneous nephrolithotomy (PCNL). We review the different approaches and evidence on the efficacy of mini-PCNL. RECENT FINDINGS: Mini-PCNL encompasses a range of techniques using tract sizes from 4.8 to 22 F to treat renal stones. The most common device uses irrigation to passively extract stones out of the sheath. Super-mini-PCNL incorporates active suction. Ultra- and micro-techniques reduce the tract to smaller diameters. Laser fragmentation is the main lithotripsy modality. Studies demonstrate an association with reduced complications, hospital stay, and increased tubeless rate. Drawbacks include longer operative times while stone-free rates for larger stones may be sub-optimal. Mini-PCNL has advantages of less trauma and the avoidance of nephrostomy tubes. Ambulatory surgery is feasible in select patients. Advances in laser lithotripsy and active suction have the potential to improve stone clearance and treat larger stones.

Burnback: the role of pulse duration and energy on fiber-tip degradation during high-power laser lithotripsy.

High-power holmium lasers have become popular for ureteroscopic laser lithotripsy and dusting. Our aim was to investigate the effect of pulse duration and pulse energy on fiber-tip degradation when using high-power settings for popcorn lithotripsy. BegoStones were fragmented in a glass bulb to simulate renal calyx, using a 120 W Ho:YAG laser. A 242 µm fiber was placed via the ureteroscope 2 mm distance from stones (popcorn model). To assess the effect of pulse duration on fiber-tip degradation, long pulse (LP) and short pulse (SP) settings were compared at settings of 1.0Jx20Hz (20 W), 0.5Jx70Hz (35 W), and 1.0Jx40Hz (40 W). To assess the effect of pulse energy on tip degradation, 40 W SP settings (0.5Jx80Hz, 0.8Jx50Hz, and 1.0Jx40Hz) were tested. Pulse duration was measured using a photodetector and peak power was then calculated using the pulse duration and pulse energy. Experiments were conducted for 4 min. Fiber-tip length was measured before and after using a digital caliper. Fiber-tip degradation was least when using LP for all settings tested (p < 0.01). For 40 W settings, tip degradation was significantly lower when using a pulse energy of 0.5 J compared to 0.8 J or 1.0 J (p < 0.004). LP mode results in less fiber burnback for all power settings tested. Total power is more important than frequency in the development of burnback. However, high-power 40 W settings can be utilized with less burnback if lower pulse energies are used. Understanding these parameters can improve the longevity of the laser fiber and improve procedural efficiency.

Deep learning computer vision algorithm for detecting kidney stone composition.

OBJECTIVES: To assess the recall of a deep learning (DL) method to automatically detect kidney stones composition from digital photographs of stones. MATERIALS AND METHODS: A total of 63 human kidney stones of varied compositions were obtained from a stone laboratory including calcium oxalate monohydrate (COM), uric acid (UA), magnesium ammonium phosphate hexahydrate (MAPH/struvite), calcium hydrogen phosphate dihydrate (CHPD/brushite), and cystine stones. At least two images of the stones, both surface and inner core, were captured on a digital camera for all stones. A deep convolutional neural network (CNN), ResNet-101 (ResNet, Microsoft), was applied as a multi-class classification model, to each image. This model was assessed using leave-one-out cross-validation with the primary outcome being network prediction recall. RESULTS: The composition prediction recall for each composition was as follows: UA 94% (n = 17), COM 90% (n = 21), MAPH/struvite 86% (n = 7), cystine 75% (n = 4), CHPD/brushite 71% (n = 14). The overall weighted recall of the CNNs composition analysis was 85% for the entire cohort. Specificity and precision for each stone type were as follows: UA (97.83%, 94.12%), COM (97.62%, 95%), struvite (91.84%, 71.43%), cystine (98.31%, 75%), and brushite (96.43%, 75%). CONCLUSION: Deep CNNs can be used to identify kidney stone composition from digital photographs with good recall. Future work is needed to see if DL can be used for detecting stone composition during digital endoscopy. This technology may enable integrated endoscopic and laser systems that automatically provide laser settings based on stone composition recognition with the goal to improve surgical efficiency.

Using video review to understand the technical variation of robot-assisted radical prostatectomy in a statewide surgical collaborative.

PURPOSE: Video assessment is an emerging tool for understanding surgical technique. Patient outcomes after robot-assisted radical prostatectomy (RARP) may be linked to technical aspects of the procedure. In an effort to refine surgical approaches and improve outcomes, we sought to understand technical variation for the key steps of RARP in a surgical collaborative. METHODS: The Michigan Urological Surgery Improvement Collaborative (MUSIC) is a statewide quality improvement collaborative with the aim of improving prostate cancer care. MUSIC surgeons were invited to submit representative complete videos of nerve-sparing RARP for blinded analysis. We also analyzed peri-operative outcomes from these surgeons in the registry. RESULTS: Surgical video data from 20 unique surgeons identified many variations in technique and time to complete different steps. Common to all surgeons was a transperitoneal approach and a running urethrovesical anastomosis. Prior to anastomosis, 25% surgeons undertook a posterior reconstruction and 30% employed urethral suspension. 65% surgeons approached the seminal vesicle anteriorly. For control of the dorsal vein complex, suture ligation was used in 60%, and vascular stapler was 15%. The majority (80%) of surgeons employed clips for managing pedicles. In examining patient outcomes for surgeons, peri-operative outcomes were not correlated with surgeon's operative time; however, surgeons with an EBL > 400 ml had significant difference among the five different techniques employed. CONCLUSIONS: Despite the worldwide popularity of RARP, the operation is still far from standardized. Correlating variation in technique with clinical outcomes may help provide objective data to support best practices with the goal to improve patient outcomes.