Illumination matters Part III: Impact of light obstruction on illuminance from flexible ureteroscopes - a comparative PEARLS analysis

PURPOSE: Artifacts from poor ureteroscopes' light design with shadowing and dark areas in the field of view have been reported. The aim was to quantify effects of light obstruction in a kidney calyx model. METHODS: We evaluated a series of contemporary flexible ureteroscopes including the Storz Flex-Xc and Flex-X2s, Olympus V3 and P7, Pusen 7.5F and 9.2F, as well as OTU Wiscope using an enclosed 3D-printed pink in vitro kidney calyx model submerged in saline, where the field of light was intentionally partially obstructed alternatively at 12, 3, 6, and 9 o'clock. A color spectrometer was used for illuminance measurements at a 45° opening position in the background of the model. RESULTS: Overall and mean background illuminance for each obstructive situation were significantly different between scopes for both 50% and 100% brightness settings (ANOVA p < 0.001). At 50% brightness setting, almost all scopes had their highest and lowest background illuminance with the 6 o'clock and 3 o'clock obstructive situation, respectively. At 100% brightness setting, these became 6 o'clock and 12 o'clock obstructive situations. Considering each obstructive situation individually, the Flex-Xc was consistently the scope with highest background illuminance and the Pusen 7.5F the lowest. Background illuminance for each obstructive situation varied significantly for each scope individually, with the greatest range of variability for Pusen 7.5F and V3. CONCLUSIONS: Illuminance performance of ureteroscopes within an obstructed calyx model differ significantly for various obstructive situations. Urologists should be aware of this to help guide their choice of ureteroscope

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/mm$^{3}$, UA: 1.55 mg/mm$^{3}$). 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 mm$^{3}$/J (COM) and 0.026, 0.030, 0.039 mm$^{3}$/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/mm$^{3}$ (COM) and 50, 36, 26 J/mm$^{3}$ (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

The Relationship between Modern Fad Diets and Kidney Stone Disease: A Systematic Review of Literature

Objectives: Kidney stone disease (KSD) has a strong association with diet metabolic syndrome. This review aims at exploring the lithogenic risk posed by the current most popular diets. Our approach was to search for the effect of each diet type on the major urinary risk factors, to try to draw conclusions regarding the association of a specific diet type and KSD. Methods: This systematic review searched for the available literature exploring the association between the existing popular fad diets and KSD. Articles in English, French and Spanish were included, without restriction of the search period with the final search done in August 2021. Results: Total number of studies and studies for each diet type was as follows: 22 articles for the low carbohydrate diet, 20 articles for high protein diets, 26 articles for vegetarian and vegan diets. There exists a substantial variability in different low carbohydrate and high protein diets, and considerable overlap between modern popular fad diets. High carbohydrate intake might increase urine uric acid, calcium and oxalate levels. High protein diets increase urine calcium and uric acid and lower urine pH and citrate. Consumption of fruits and vegetables increases the urinary volume and urinary citrate. In vegan diets, sufficient daily calcium intake is important to avoid possible secondary hyperoxaluria. Conclusions: Few studies evaluated the direct relationship between modern fad diets and KSD. In general, the reduction of carbohydrate in the diet, and counterbalancing protein rich diets with sufficient intake of fruits and vegetables, seem to play a protective role against KSD formation. Maintaining sufficient calcium intake in vegan and vegetarian diets is important. Additional research is needed to directly evaluate the link between KSD and each diet type

Role of Citrus Fruit Juices in Prevention of Kidney Stone Disease (KSD): A Narrative Review

To explore the relationship between citrus fruit juices (oranges, grapefruits, and lemonades) and kidney stone disease (KSD). Methods: A systematic review was performed using the Medline, EMBASE, and Scopus databases, in concordance with the PRISMA checklist for all English, French, and Spanish language studies regarding the consumption of citrus fruit juices and the relationship to urinary stone disease. The main outcome of interest was the association of citrus fruit juices with KSD. Results: Thirteen articles met the criteria for inclusion in the final review. Three large epidemiological studies found that grapefruit juice was a risk factor for stone formation, while orange juice did not increase the risk for KSD. Ten small prospective clinical studies found that orange, grapefruit, and lemon juices all increased urinary citrate levels. Only orange and grapefruit juices had an alkalinizing effect and while lemon juice has a protective effect by raising urinary citrate levels, it lacked a significant alkalinizing effect on urine pH. Orange juice and grapefruit juices significantly increased urinary oxalate levels, while orange juice also had a high carbohydrate content. Conclusion: While orange juice seems to play a protective role against stone formation, grapefruit was found to raise the risk of KSD in epidemiological studies but had a protective role in smaller clinical studies. Lemon juice had a smaller protective role than orange juice. Larger amounts of, as well as more accurate, data is needed before recommendations can be made and a high carbohydrate content in these juices needs to be taken into consideration

Endoscopic Treatment of Upper Tract Urothelial Carcinoma: Challenging the Definition of the Maximal Lesion Size for Safe Ablation

Introduction: With advances in endoscopic treatment of upper tract urothelial carcinoma (UTUC) lesions, the recommended upper limit of lesion size amenable to laser ablation was set to 2 cm. However, this limit is based on expert opinion only, and debate still exists regarding this definition. Objective: To determine the maximal size of the tissue, for which total endoscopic ablation with laser energy is achievable, from a laser performance perspective. Materials and Methods: Simulating endoscopic surgery conditions, renal tissue blocks from pork kidneys in growing size from 1 cm3 to 3 cm3 were totally ablated with Ho:YAG laser (1 J, 10 Hz). The time to ablation was recorded for each tissue mass. Following the ablation, each sample was inspected microscopically by an expert pathologist to determine the extent to which the tissue was destroyed. Results: Time to ablation ranged from 16.4 min for a 1 cm3 mass, to 69.7 min for a 3 cm3 mass. Histologic evaluation after laser ablation showed that ablation was achieved in all tissue masses, and no &ldquo;unaffected&rdquo; tissue was present, even for lesions with a size of 3 cm3. Conclusions: This study showed that laser ablation can be achieved for tumor lesions up to a size of 3 cm3. The results of this study can contribute to the debate regarding the limits of endoscopic management of UTUC lesions and strengthen the recommended upper limit of 2 cm3 for endoscopic treatment of tumor lesions

Endoscopic Treatment of Upper Tract Urothelial Carcinoma: Challenging the Definition of the Maximal Lesion Size for Safe Ablation

Introduction: With advances in endoscopic treatment of upper tract urothelial carcinoma (UTUC) lesions, the recommended upper limit of lesion size amenable to laser ablation was set to 2 cm. However, this limit is based on expert opinion only, and debate still exists regarding this definition. Objective: To determine the maximal size of the tissue, for which total endoscopic ablation with laser energy is achievable, from a laser performance perspective. Materials and Methods: Simulating endoscopic surgery conditions, renal tissue blocks from pork kidneys in growing size from 1 cm3 to 3 cm3 were totally ablated with Ho:YAG laser (1 J, 10 Hz). The time to ablation was recorded for each tissue mass. Following the ablation, each sample was inspected microscopically by an expert pathologist to determine the extent to which the tissue was destroyed. Results: Time to ablation ranged from 16.4 min for a 1 cm3 mass, to 69.7 min for a 3 cm3 mass. Histologic evaluation after laser ablation showed that ablation was achieved in all tissue masses, and no “unaffected” tissue was present, even for lesions with a size of 3 cm3. Conclusions: This study showed that laser ablation can be achieved for tumor lesions up to a size of 3 cm3. The results of this study can contribute to the debate regarding the limits of endoscopic management of UTUC lesions and strengthen the recommended upper limit of 2 cm3 for endoscopic treatment of tumor lesions

Comparison of intrapelvic pressures during flexible ureteroscopy, mini-percutaneous nephrolithotomy, standard percutaneous nephrolithotomy, and endoscopic combined intrarenal surgery in a kidney model

PURPOSE To compare intrapelvic pressure (IPP) levels achieved during f-URS, mini-PCNL, standard PCNL, and endoscopic combined intrarenal surgery in a kidney model. METHODS A silicone model simulating the complete urinary tract was used for all the experiments. We compared: a 9.5Fr f-URS, a 12Fr mini-nephroscope and a 26Fr nephroscope. The irrigation pressure was set at 40 and 193 cmH$_{2}$O. We compared: f-URS-S ± ureteral access sheath (UAS, 10/12Fr, 11/13Fr, 12/14Fr) ± 273 μm laser fiber, Mini-PCNL with different sizes of operating sheath (15/16Fr, 16.5/17.5Fr, 21/22Fr) ± 365 μm laser fiber, Standard PCNL with an operating sheath of 30Fr ± Lithotripter LithoClast Master 11.4Fr. RESULTS f-URS: IPP values ranged between 1.4 and 46.2 cmH$_{2}$O. Factors reducing IPP were an irrigation pressure at 40 cmH$_{2}$O, an occupied working channel, and the use of a UAS except with the 10/12Fr at 193 cmH$_{2}$O. Mini-PCNL: IPP values ranged between 2.4 and 39.7 cmH$_{2}$O. Factors reducing IPP were irrigation pressure at 40 cmH$_{2}$O, a large operating sheath (> 15/16Fr). The occupation of the working channel did not affect the IPP at 40 cmH$_{2}$O, while it decreased at 193 cmH$_{2}$O. Standard PCNL: IPP values ranged between 1.4 and 7.3 cmH$_{2}$O. Occupancy of the working channel did not affect IPP at 40 cmH$_{2}$O, while it increased at 193 cmH$_{2}$O. CONCLUSION We recorded for the first time IPP values according to different endourological techniques and configurations. IPP never exceed 50 cmH$_{2}$O irrespectively of the assessed technique/setup. The factors reducing IPP were a low irrigation pressure (40 cmH$_{2}$O), the use of a UAS or a working sheath appropriate to the diameter of the endoscope, as well as the occupation of the working channel in the case of f-URS