Stone composition independently predicts stone size in 18,029 spontaneously passed stones

PURPOSE To evaluate whether the size of spontaneously passed stones (SPS) may be associated with clinical parameters. METHODS A search for SPS was conducted in our electronic stone database, comprising data on stones analyzed over the last 33 years at our institution. Adults with upper urinary tract stones were included. Cases with stenotic urinary tract disease or past history of anastomotic urinary tract surgery were excluded. Stone size expressed as maximal stone diameter (MSD) and stone volume (SV) was compared between groups by one-way ANOVA. Logistic regression analyses were performed to identify predictors of MSD ≥ 6 mm. RESULTS Overall mean MSD and SV for 18,029 SPS was 4.1 mm and 11.5 mm$^{3}$, respectively, and significantly differed between stone composition groups (p < 0.001). The lowest mean MSD and SV were found for calcium oxalate monohydrate (3.6 mm and 9.0 mm$^{3}$, respectively) and the highest mean MSD and SV were found for struvite (7.9 mm and 61.0 mm$^{3}$, respectively). Stone composition and increasing age were found to be independent predictors of MSD ≥ 6 mm (both p < 0.001). Sex differentiation did not contribute as a predictor of MSD ≥ 6 mm. CONCLUSIONS Stone composition and-to a lesser extent-age serve as independent predictors of size of spontaneously passed stones. Of particular importance, large spontaneously passed stones of ≥ 6 mm may be frequently found in cystine, brushite or struvite stone formers, whereas a minority of all calcium oxalate stones exceed that cutoff. Future studies shall evaluate these parameters as possible predictors of spontaneous stone passage

Comparaison in vitro de l’efficacité statique ou dynamique des lasers Holmium :YAG et thulium fibré pour la lithotritie endocorporelle : impact de la vitesse de déplacement

La vitesse optimale de déplacement (VOD) de la fibre laser pour réaliser la pulvérisation lithiasique est une variable inconnue à ce jour, autant pour le laser thulium fibré (TFL) que pour le laser Holmium :YAG (Ho :YAG). L’objectif était de déterminer in vitro la VOD de la fibre laser lors d’une lithotritie endocorporelle en fonction des paramètres laser avec le TFL et l’Ho :YAG, au moyen des volumes d’ablation (VA).Bourse de Recherche AFU 201

Initial clinical experience with the pulsed solid-state thulium YAG laser from Dornier during RIRS: first 25 cases

Introduction Holmium:yttrium–aluminium–garnet (Ho:YAG) and thulium fiber (TFL) lasers are currently the two laser sources recommended for endocorporeal laser lithotripsy (ELL). Recently, the pulsed-thulium:YAG (Tm:YAG) laser was also proposed for ELL, as an answer to both Ho:YAG and TFL limitations. We aimed to evaluate the efficiency, safety, and laser settings of Tm:YAG laser in ELL during retrograde intrarenal surgery (RIRS). Methods A prospective study of the first 25 patients with ureteral and renal stones who underwent RIRS using the Thulio (pulsed-Tm:YAG, Dornier©, Germany) was performed in a single center. 272 μm laser fibers were used. Stone size, stone density, laser-on time (LOT) and laser settings were recorded. We also assessed the ablation speed (mm 3 /s), Joules/mm 3 and laser power (W) values for each procedure. Postoperative results, such as stone-free rate (SFR) and zero fragments rate (ZFR) were also recorded. Results A total of 25 patients were analyzed (Table 1). The median (IQR) age was 55 (44–72) years old. Median (IQR) stone volume was 2849 (916–9153)mm3 . Median (IQR) stone density was 1000 (600–1174)HU. Median (IQR) pulse energy, pulse rate and total power were 0.6 (0.6–0,8)J, 15(15–20)Hz and 12(9–16)W, respectively. All procedures used “Captive Frag- menting” pulse modulation (Table 2). The median (IQR) J/mm 3 was 14,8 (6–21). The median (IQR) ablation rate was 0,75 (0,46–2)mm 3 /s. One postoperative complications occurred (streinstrasse). SFR and ZFR were 95% and 55%, respectively. Conclusion The pulsed-Tm:YAG laser is a safe and effective laser source for lithotripsy during RIRS, using low pulse energy and low pulse frequency

Analyse in vitro de l’efficacité de la lithotritie laser : quel modèle utiliser ?

L’étude in vitro de la lithotritie laser (LL) utilise des calculs humains (CH) ou synthétiques (CS). Devant l’augmentation de la pulvérisation laser (Dusting), peu d’échantillons humains sont disponibles. Les CS sont donc privilégiés, confectionnés par mélange d’eau et de plâtre, avec la problématique de leur réhydratation lors des LL. L’objectif était de comparer les volumes d’ablation (VA) entre CS homogènes (CSHo) ou hétérogènes(CSHe), et par rapport au poids ablaté (PA).Bourse de Recherche AFU 201

Comparison of Holmium:YAG and Thulium Fiber Lasers on the Risk of Laser Fiber Fracture

Objectives: To compare the risk of laser fiber fracture between Ho:YAG laser and Thulium Fiber Laser (TFL) with different laser fiber diameters, laser settings, and fiber bending radii. METHODS: Lengths of 200, 272, and 365 mu m single use fibers were used with a 30 W Ho:YAG laser and a 50 W Super Pulsed TFL. Laser fibers of 150 mu m length were also tested with the TFL only. Five different increasingly smaller bend radii were tested: 1, 0.9, 0.75, 0.6, and 0.45 cm. A total of 13 different laser settings were tested for the Ho:YAG laser: six fragmentation settings with a short pulse duration, and seven dusting settings with a long pulse duration. A total of 33 different laser settings were tested for the TFL. Three laser settings were common two both lasers: 0.5 J x 12 Hz, 0.8 J x 8 Hz, 2 J x 3 Hz. The laser was activated for 5 min or until fiber fracture. Each measurement was performed ten times. Results: While fiber failures occurred with all fiber diameters with Ho:YAG laser, none were reported with TFL. Identified risk factors of fiber fracture with the Ho:YAG laser were short pulse and high energy for the 365 mu m fibers (p = 0.041), but not for the 200 and 272 mu m fibers (p = 1 and p = 0.43, respectively). High frequency was not a risk factor of fiber fracture. Fiber diameter also seemed to be a risk factor of fracture. The 200 mu m fibers broke more frequently than the 272 and 365 mu m ones (p = 0.039). There was a trend for a higher number of fractures with the 365 mu m fibers compared to the 272 mu m ones, these occurring at a larger bend radius, but this difference was not significant. Conclusion: TFL appears to be a safer laser regarding the risk of fiber fracture than Ho:YAG when used with fibers in a deflected position

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

Introduction: Holmium:yttrium–aluminium–garnet (Ho:YAG) is currently the gold standard for lithotripsy for the treatment of all known urinary stone types. Stone composition and volume are major determinants of the lithotripsy. This in vitro study evaluated the required energy to ablate 1 mm3 of various stone types with different laser settings using Ho:YAG. Methods: 272 µm core-diameter laser fibers (Boston Scientific©) were connected to a 30 Watt MH1 Ho:YAG generator (Rocamed®). An experimental setup consisting of immerged human stones of calcium oxalate monohydrate (COM), uric acid (UA) or cystine (Cys) was used with a single pulse lasing emission (0.6/0.8/1 J), in contact mode. Stones were dried out before three-dimensional scanning to measure ablation volume per pulse (AVP) and required energy to treat 1 mm3 (RE). Results: All settings considered, ablation volumes per pulse (AVP) for COM were significantly lower than those for UA and Cys (p = 0.002 and p = 0.03, respectively), whereas AVP for Cys was significantly lower than those for UA (p = 0.03). The mean REs at 0.6 J pulse energy (PE) for COM, Cys and UA were 34, 8.5 and 3.2 J, respectively The mean REs at 1 J PE for COM, Cys and UA were 14.7, 6.4 and 2 J, respectively. At 0.6 J PE, RE for COM was more than tenfold and fivefold higher than those for UA and Cys, respectively. Conclusion: This in vitro study shows for the first time a volumetric evaluation of Ho:YAG efficiency by the ablation volume per pulse on human stone samples, according to various pulse energies. The REs for COM, UA and Cys should be considered in clinical practice.In vivo imaging was performed at Life Imag-ing Facility of Paris Descartes University (Plateforme Imageries du Vivant), supported by France Life Imaging (grant ANR-11-INBS-0006) and Infrastructures Biologies-Santé

The new Avicenna Roboflex: How does the irrigation system work? Results from an in vitro experiment

Introduction: Since 2012 Elmed has been working on a robot specifically designed for flexible ureteroscopy. After the first version of Avicenna Roboflex, a second version was developed in 2015, with significant changes especially in the irrigation system. We consider mandatory for the endourologist that works with the Avicenna Roboflex be aware of the functioning of the irrigation system. Materials and Methods: We connected a container to the pump’s irrigation system and measured the quantity of saline per second delivered by each speed setting, with/without the flush in five different modalities: pump on its own, pump with ureteroscope, with two laser fibers, with 1.9 Fr basket, and with a Terumo guidewire. Results: The highest mean flow-rates were observed in the 200- micrometer laser fiber, after the pump on its own. Median flowrates for all speed settings were significantly higher for the pump on its own than for the URS in both flushed and nonflushed modes (p = 0.045, p = 0.039 respectively). There was no statistically significant difference in median flow-rates between the guide wire and basket in all of the speed settings (p = 0.932 and p = 0.977). For both laser fibers there was no statistically significant difference between the median flow rate on both nonflush and flush modes. (p = 0.590 & p = 0.590). There was a linear correlation between the speed setting and the increase measured with the flush-option for pump only measurements (r = 0.602, p = 0.038). There was no statistically significant difference between laser fibers and the pump on its own on the increase of flow rate with flush mode. (p = 0.443 for the 272- micrometer fiber and p = 0.219 for the 200-micrometer fiber). Conclusion: The irrigation system of the new Avicenna Roboflex is optimized compared to the previous version. However other more complex studies concerning the live flow/pressure relationship are needed before firm conclusions can be made

Impact of laser fiber tip cleavage on power output for ureteroscopy and stone treatment

Purpose: Holmium:YAG laser is the most used laser for urolithiasis. Generally, we use metallic scissors to cut the fiber tip to restore its effectiveness. Many cleaving methods have been described to avoid fiber damage and to restore its greatest power to the fiber. There is a lack of information regarding which cleaving method should be used and its effect on the fiber. In order to compare these effects, we studied different cleavage methods in terms of power output and its effects on the fiber. Methods: New single-use 272-μm fibers were used with a holmium:YAG laser lithotripter. Five kinds of fiber tips were compared: a new intact fiber, cleaved with ceramic scissors, cleaved with metallic scissors, first cleaved then stripped and first stripped then cleaved. The fibers were used against synthetic stones (BegoStone ® ) similar to calcium oxalate monohydrate, with fragmentation (SP, 5 Hz, 1.5 J) and dusting (LP, 15 Hz, 0.5 J) settings. We measured power output at 0, 1, 5, 10 and 15 min. Results: For fragmentation parameters, there was a statistical difference between the 5 groups at 0 and 1 min of laser use (p < 0.05) and none for time period over 1 min (p = 0.077–0.658). For dusting parameters, there was a statistical difference between the 5 groups at 0 min of laser use (p < 0.05) and none for time period over 0 min (p = 0.064–1). Conclusion: Cleaving the fiber tip may restore its effectiveness to the fiber, but only for a limited time, although it may preserve the scopes from damage

Ho:YAG laser lithotripsy in non-contact mode: optimization of fiber to stone working distance to improve ablation efficiency

Purpose: To evaluate how variable working distances between the laser fiber and the stone influence ablation volume. Methods: A laser fiber was fixed on a robotic arm perpendicular to an artificial stone. A single laser pulse was triggered at different working distances (0–2.0 mm in 0.2 mm increments) between the distal fiber tip and the stone. To achieve a measurable impact, pulse energy was set to 2 and 3 J, with either short or long pulse duration. Ablation volume was calculated with an optical microscope. Experiments were repeated five times for each setting. Results: Highest ablation volume was observed with a long pulse of 3 J at a working distance of 0.4 mm between the laser fiber and the stone surface (p value 0.05). Compared to lithotripsy in contact mode, triggering a single long pulse at 0.4 mm increased ablation volume by 81% (p value = 0.016) at 2 J and by 89% (p value = 0.034) at 3 J. Conclusions: For Ho:YAG laser lithotripsy, ablation volume may be higher in non-contact mode using long pulses, rather than in direct contact to the stone. Findings of the current study support the need of further studies of lithotripsy in non-contact mode

Comparaison des lasers holmium : yag et thulium fibre sur des applications tissulaires

The Holmium: YAG (Ho: YAG) laser is currently the benchmark laser in urology due to its efficiency and versatility: lithotripsy, incision of strictures (endopyelotomy, ureter and urethra), coagulation of tumors of the upper urinary excretory tract, and enucleation of the prostate for benign hyperplasia. However, this laser has several limitations:- Its wavelength of 2140 nm differs from the maximum absorption peak of water in tissue which is 1940 nm,- The laser pulse duration of around 250 microseconds is not optimal for applications requiring cutting or coagulation,- The laser beam produced (of the order of 300 µm) must be focused in optical fibers of small diameter ( 5%) which allows a greater compactness of the laser and a cooling system to air.Thulium fiber laser is not currently marketed in Europe and does not have any evaluations on its effects on tissue or on lithotripsy compared to them of the current reference laser (Ho: YAG laser). Preliminary work has been carried out at the tissue level with a Thulium fiber laser different from that proposed [1]. Likewise, studies evaluating the Ho: YAG laser are rare [2].The objectives of this science thesis will be to compare the pulsed Thulium fibered and Ho: YAG lasers on an ex vivo tissue application:- Material: Thulium fiber laser (IPG, 50W) and Lumenis 120 W- Comparison of the efficiencies on different tissues (urothelial (bladder and ureter) and prostate) by varying the following parameters: laser parameters (pulse duration, energy, frequency), the laser mode used (Ho: YAG standard mode and Thulium fiber in standard mode), diameter of the laser fibers, the distance between the end of the laser fiber and the fabric. The experiments will be repeated 5 times. The effect will be appreciated by a blind histological study of the laser used to study the depth of the laser incision, the area of ​​coagulation produced.- Study the volume of prostate tissue ablation by laser vaporization by varying the following parameters: laser parameters (pulse duration, energy, frequency), the laser mode used (Ho: YAG standard mode, MOSES Technology mode for Ho : YAG and Thilium fiber in standard mode), diameter of the laser fibersClinical applications:- It will be a question of determining the laser parameters that can be recommended according to the type of surgical intervention (coagulation of tumor of the upper urinary excretory tract, prostatic enucleation, stenosis incision) and the desired effectLe laser Holmium : YAG (Ho: YAG) est actuellement le laser de référence en urologie du fait de son efficacité et sa polyvalence : lithotripsie, incision de sténoses (endopyélotomie, uretère et urètre), coagulation des tumeurs de la voie excrétrice urinaire supérieure, et énucléation de la prostate pour hyperplasie bénigne. Cependant, ce laser présente plusieurs limites :-Sa longueur d'onde de 2140 nm diffère du pic d’absorption maximal de l’eau dans les tissus qui est de 1940 nm,-La durée d'impulsion laser de l'ordre de 250 microsecondes n'est pas optimale pour des applications nécessitant une coupe ou une coagulation,-Le faisceau laser produit (de l’ordre de 300 µm) doit être focalisé dans des fibres optiques de petit diamètre (5%) ce qui permet une plus grande compacité du laser et un système de refroidissement à air.De laser Thulium fibré n’est actuellement pas commercialisé en Europe et ne dispose pas d’évaluations sur ses effets tissulaires ou sur la lithotripsie en comparaison à eux du laser de référence actuel (laser Ho:YAG). Des travaux préliminaires ont été réalisés au niveau tissulaire avec un laser Thulium fibré différent de celui proposé [1]. De même, les études évaluant le laser Ho :YAG sont rares [2].Les objectifs de cette thèse de science seront de comparer les lasers pulsés Thulium fibré et Ho:YAG sur une application tissulaire ex vivo :-Matériel : Laser Thulium fibré (IPG, 50W) et Lumenis 120 W-Comparaison des efficacités sur différents tissus (urothélial (vessie et uretère) et prostatique) en faisant varier les paramètres suivants : paramètres lasers (durée d’impulsion, énergie, fréquence), le mode laser utilisé (Ho:YAG mode standard et Thulium fibré en mode standard), diamètre des fibres lasers, la distance entre l’extrémité de la fibre laser et le tissu. Les expériences seront répétées 5 fois. L’effet sera apprécié par une étude histologique en aveugle du laser utilisé afin d’étudier la profondeur de l’incision laser, la zone de coagulation produite.-Etudier le volume d’ablation tissulaire prostatique par vaporisation laser en faisant varier les paramètres suivants : paramètres lasers (durée d’impulsion, énergie, fréquence), le mode laser utilisé (Ho :YAG mode standard, mode MOSES Technology pour l’Ho:YAG et Thilium fibré en mode standard), diamètre des fibres lasersApplications cliniques :-Il s’agira de déterminer les paramètres lasers pouvant être recommandés en fonction du type d’intervention chirurgicale (coagulation de tumeur de la voie excrétrice urinaire supérieure, énucléation prostatique, incision de sténose) et de l’effet recherch