Evaluation of intrarenal pressure stability at different lithotripter suction settings in a porcine kidney model.

PURPOSE: Using the Swiss LithoClast® Trilogy, urinary stones can be fragmented and removed simultaneously by suction at different selectable suction settings. The aim was to evaluate pressure stability at different settings and test stone fragmentation and suction at the optimal settings. METHODS: In an ex vivo porcine kidney model, we recorded intrarenal pressure levels with different suction levels. Storz® Nephroscopes MIP-M and MIP-L and Swiss LithoClast® Trilogy probes were used. RESULTS: Pressure stabilized at 19 cm H2O with the MIP-M at 1 m gravity irrigation with no instrument introduced. After inserting the 1.5 mm probe, the pressure dropped to 5 cm H2O. With a suction setting of 10%, the pressure stabilized at 3 cm H2O and remained stable for the maximum time of 120 s. After increasing the suction to 20, 30, 40, and 50%, we recorded the pressure drop time to 0 after 22, 14, 11, and 8 s. Using the MIP-L, pressure stabilized at 44 cm H2O and decreased to 8 cm H2O after inserting the 3.4 mm probe. With 10% suction, a pressure stabilization was measured at 2 cm H2O and remained stable for 120 s. At suction levels of 20 and 30%, the pressure drop time to 0 was 6 and 5 s. With a 10% suction, removing stones was efficient, and the kidney's filling volume was maintained. CONCLUSIONS: When using the LithoClast® Trilogy, a suction setting of 10% seems to be optimal for the treatment of urinary calculi when applying suction continuously.

Adherence to guidelines in the management of urolithiasis: are there differences among distinct patient care settings?

INTRODUCTION: Urolithiasis is a common diagnosis in urology. New technologies offer a variety of diagnostic and therapy and consequently display a financial burden on healthcare systems. Hence, clinical practice guidelines (CPG) are essential to implement evidence-based medicine and assure a standard of care considering limited resources. To date, there is no evidence of the use and adherence to CPG on urolithiasis. MATERIAL AND METHODS: Therefore, we performed a cross-sectional study to analyze the use of CPG on urolithiasis. Data collection was carried out by a questionnaire given to 400 German urologists. The survey included use and adherence to guidelines, evaluation of the clinical situation, therapy spectrum, and workplace. In total, 150 (37%) questionnaires were received and included in our survey. Statistics were performed by SPSS using Chi-quadrat test/Fisher's exact test. RESULTS: In our study, urologists were office based, hospital affiliated, non-academic, or academic centers in 53%, 32%, 16% and 5%, respectively. In 74% and 70%, urologists adhere to CPG in diagnostic and therapy. Interestingly, workplace and therapy spectrum determines the use of different CPG (p = 0.01; p = 0.022). Academic urologists were more likely to use international CPG of EAU (40%), while outpatient urologists significantly orientated on national CPG (46%). 86% of urologists with high volume of urolithiasis practice interventions in contrast to 53% in low volume (p = 0.001). More than 80% of urologists use short versions and app version of CPG. CONCLUSION: We firstly describe compliance and the use of CPG on urolithiasis. EAU and DGU present the most commonly used CPG. Short version and app version of CPG find frequent clinical utilization.

Comparison of stone elimination capacity and drilling speed of endoscopic clearance lithotripsy devices.

PURPOSE: To investigate the fragmentation capacity, clearance time, and drilling speed of combined ultrasonic with impact dual-energy and single energy ultrasonic lithotripter devices. METHODS: Stone fragmentation and clearance tests were performed under direct view in an underwater layered hemisphere by four different operators using artificial stones (n = 10/operator). Time for complete clearance was measured. Drilling tests were performed using an underwater setup, consisting of a mounting rack for fixing the lithotripter handpiece with the probe in vertical position and in contact with the stone phantom placed on one side of a balance for defined and constant contact application pressure equivalent to 450 g load. Time until complete perforation or in case of no perforation, the penetration depth after 60 s into the stone sample was recorded. Four devices, one single energy device (SED), one dual-energy dual probe (DEDP), two dual-energy single probe (DESP-1, DESP-2), with different parameters were tested. RESULTS: Stone fragmentation and clearance speed were significantly faster for dual-energy device DESP-1 compared to all other devices (p < 0.001). Using DESP-1, the clearance time needed was 26.0 ± 5.0 s followed by DESP-2, SED and DEDP requiring 38.4 ± 5.8 s, 40.1 ± 6.3 s and 46.3 ± 11.6 s, respectively. Regarding the drilling speed, DESP-1 was faster compared to all other devices used (p < 0.05). While the drilling speed of DESP-1 was 0.69 ± 0.19 mm/s, compared to 0.49 ± 0.18 mm/s of DESP-2, 0.47 ± 0.09 mm/s of DEDP, and 0.19 ± 0.03 mm/s of SED. CONCLUSIONS: The dual-energy/single-probe device combining ultrasonic vibrations with electromechanical impact was significantly faster in fragmentation and clearing stone phantoms as well as in drilling speed compared to all other devices.

Does comprehension (sometimes) go wrong for noncanonical sentences?

This article addresses the question of whether the human parsing mechanism (HPM) derives sentence meaning always from representations that are computed algorithmically or whether the HPM sometimes resorts to non-algorithmic strategies that may result in misinterpretations. Misinterpretation effects for noncanonical sentences, such as passives, constitute important evidence in favour of models allowing for nonveridical representations. However, it is unclear whether these effects reflect errors in the mapping of form to meaning, or difficulties specific to the procedure used to test comprehension. We report two experiments combining two different comprehension tasks to address these alternative possibilities. In Experiment 1, participants first judged the plausibility of canonical and noncanonical sentences and then named the agent or patient of the sentence. In Experiment 2, the order of the two tasks was reversed. Both tasks require the correct identification of agent or patient/theme, but differ regarding the complexity of operations required to complete the task successfully. In both experiments, participants made a substantial number of errors with agent/patient naming, even when they had correctly assessed sentence plausibility. We conclude that misinterpretation effects do not indicate parsing errors and therefore cannot serve as evidence for non-algorithmic processing. Our results support models of the HPM that assume algorithmic processing only.

Comparative evaluation of tissue damage induced by ultrasound and impact dual-mode endoscopic lithotripsy versus conventional single-mode ultrasound lithotripsy.

OBJECTIVE: The aim of our study was to perform comparative investigation of the tissue safety of three different endoscopic lithotripter devices including a new single-probe/dual-energy lithotripter in an in vivo animal model. The Swiss LithoClast Trilogy was compared to the Storz Calcuson and the Swiss LithoClast Vario. The safety test simulated the accidental direct contact between lithotripter probes and the urothelium, which can occur when sliding off a stone or drilling through a calculus during lithotripsy. The safety test included a smallest (1.5 mm) and largest (3.3/3.4 mm) probe diameter per device. METHODS: Testing was performed in nine pigs (three animals per device). The bladder tissue was exposed to direct lithotripter probe contact at maximum power for 10 s to produce visible tissue lesions. Acute tissue trauma was evaluated using a simplified scoring model describing the expected bladder wall injuries for histological examination. After 7 days, all animals were killed, necropsied and examined post mortem. For between-group comparisons regarding microscopic histopathologic features, a Chi-square test was used. A p value < 0.05 was considered to be statistically significant. RESULTS: Irrespective of the lithotripter used, no systemic signs of toxicity were observed. Histologically, signs of normal ongoing healing were observed on the bladder mucosa. There were no significant differences in histological findings taking changes of the epithelium (p = 0.360), the leucocyte infiltration (p = 0.123), the vascular congestion (p = 0.929) and the edema (p = 1.0) between the groups into account. CONCLUSIONS: The results of this study demonstrated a comparable safety between all lithotripsy devices.

[Pressure study of two miniaturised amplatz sheaths of 9.5 F and 12 F outer diameter for minimal invasive percutaneous nephrolithotomy (MIP): An ex vivo organ model measurement]. / Druckverhältnisse bei Verwendung miniaturisierter PNL-Schäfte mit 9,5 Ch bzw. 12 Ch Außendurchmesser für die minimalinvasive perkutane Nephrolitholapaxie (MIP): Ex-vivo-Druckstudien.

Over the last decade, several devices for percutaneous nephrolithotomy with smaller diameters have been introduced in order to reduce renal trauma. Recent studies have found comparable stone free rates but also exhibit the same rate of postoperative fever and septicaemia. One possible cause is the influence of irrigation fluid during stone treatment procedures. The purpose of this ex vivo study was to compare two new miniaturised PNL nephroscopy sheaths with an outer sheath diameter of 9.5 F and 12 F to the well-established MIP M Set (17.5 F) by Karl Storz. MATERIAL AND METHODS: The new devices were tested in a perfused organ model of fresh porcine kidneys with different irrigation pressures, applied either by gravitation or the use of a pressure pump (Uromat E.A.S.I. Pump, Karl Storz, Tuttlingen, Germany).In addition, the 9.5 F sheath was examined for active irrigation evacuation, i. e. suction of irrigation fluid through a mono-J-catheter. An urodynamic pressure probe measured intrapelvic pressure levels throughout the procedures. RESULTS: Regardless of the sheath diameters used, the intrapelvic pressure did not exceed 40 cmH2O (30 mmHg) when applying moderate irrigation pressure levels, either by pump or gravitation. The active suction of irrigation fluid from the kidney basin via the mono-J-catheter had no measurable impact on the detected intrarenal pressures. A crucial increase in the intrapelvic pressure was detected only when using the 9.5 F sheath in combination with applying high irrigation pressures. CONCLUSION: The newly designed miniaturised MIP sets maintain the favourable pressure features of the earlier 17.5 MIP sheath. Although the diameter has been reduced to 12F or 9.5 F, the intrapelvic pressures remained below 40 cmH2O when regular irrigation settings by gravitation or pump irrigation were used.

The misinterpretation of noncanonical sentences revisited.

Most current models of sentence comprehension assume that the human parsing mechanism (HPM) algorithmically computes detailed syntactic representations as basis for extracting sentence meaning. These models share the assumption that the representations computed by the HPM accurately reflect the linguistic input. This assumption has been challenged by Ferreira (2003), who showed that comprehenders sometimes misinterpret unambiguous sentences in which subject and object appear in noncanonical order, such as passives or object-clefts. According to Ferreira, these misinterpretations show that parallel to an algorithmic analysis, the HPM performs a heuristic analysis sometimes resulting in interpretations not licensed by the grammar. Our study investigated whether misinterpretation effects indeed reflect an erroneous mapping of form to meaning due to heuristic processing strategies. Using an experimental design closely following Ferreira (2003), Experiment 1 demonstrates that errors with noncanonical sentences show up in German as well, despite the fact that German provides morphological case, which a heuristic strategy should use. Experiment 2 required participants to judge the plausibility of the same sentences. With this task, no evidence for misinterpretation of noncanonical sentences was found. Taken together, our results suggest that misinterpretation errors do not reflect errors in the mapping of form to meaning, but task-specific difficulties that arise when participants retrieve information from the memory representation of a sentence. Consequently, misinterpretation errors do not provide evidence for the claim that the HPM pursues a heuristic analysis in addition to an algorithmic analysis. Our results instead lend support to models of the HPM that assume algorithmic processing only. (PsycINFO Database Record

Evaluating factors that dictate struvite stone composition: A multi-institutional clinical experience from the EDGE Research Consortium.

INTRODUCTION: Struvite stones account for 15% of urinary calculi and are typically associated with urease-producing urinary tract infections and carry significant morbidity. This study aims to characterize struvite stones based on purity of stone composition, bacterial speciation, risk factors, and clinical features. METHODS: Retrospective data was collected from patients diagnosed with infection stones between 2008 and 2012. Stone analysis, perioperative urine cultures, bacterial speciation, and clinical data were collected and analyzed. The purity of struvite stones was determined. Statistical comparisons were made among homogeneous and heterogeneous struvite stones. RESULTS: From the four participating centres, 121 struvite stones were identified. Only 13.2% (16/121) were homogenous struvite. Other components included calcium phosphate (42.1%), calcium oxalate (33.9%), calcium carbonate (27.3%), and uric acid (5.8%). Partial or full staghorn calculi occurred in 23.7% of cases. Urease-producing bacteria were only present in 30% of cases. Proteus, E. coli, and Enterococcus were the most common bacterial isolates from perioperative urine, and percutaneous nephrolithotomy was the most common modality of treatment. Only 40% of patients had a urinalysis that was nitrite-positive, indicating that urinalysis alone is not reliable for diagnosing infection stones. The study's limitation is its retrospective nature; as such, the optimal timing of cultures with respect to stone analysis or treatment was not always possible, urine cultures were often not congruent with stone cultures in the same patient, and our findings of E. coli commonly cultured does not suggest causation. CONCLUSIONS: Struvite stones are most often heterogeneous in composition. Proteus remains a common bacterial isolate; however, E. coli and Enterococcus were also frequently identified. This new data provides evidence that patients with struvite stones can have urinary tract pathogens other than urease-producing bacteria, thus challenging previous conventional dogma.

Transrectal ultrasound guided prostate biopsy in the era of increasing fluoroquinolone resistance: prophylaxis with single-dose ertapenem.

PURPOSE: The aim of the study was to compare single-dose ertapenem (ERT) with the 3-day regime of ciprofloxacin (CIP) for prophylaxis of possible infections following transrectal prostate biopsy. METHODS: Data from a consecutive group of 542 patients from January 2012 to January 2017 were retrospectively analysed. As preinterventional prophylaxis patient group A (179) received 500 mg CIP twice a day for three days, beginning on the day before the biopsy (until June 2013); group B (363) received a single dose of ERT 60 min prior to intervention. The first follow-up examination for all patients was between post-intervention days 2 and 3. The second follow-up examination was between day 15 and 30 following biopsy. Urine was cultured in all cases and any adverse drug reactions (ADRs) related to the antibiotic treatment were noted. We also recorded all clinically relevant morbidities requiring intervention (ischuria, macrohaematuria, symptomatic urinary tract infections and urosepsis), as well as those not requiring active intervention (macrohaematuria, decreased urinary stream, pain, haemospermia). The main study criterion was the symptomatic urinary tract infection rate and ADRs. RESULTS: All 542 biopsied patients could be included in the study and the drop-out rate was zero. There were no significant differences between groups A and B with regards to complications not requiring intervention. There was, however, a significant reduction from 14.5% (group A) to 0.8% (group B) in infectious complications. This showed a significant correlation in favour of ERT (p < 0.001). Furthermore, in the ERT group there was also a distinct and significant reduction (p > 0.001) in the number of patients with bacteriuria (>10e4 cfu per ml urine) without fever (0.5%) compared to the CIP group (12.3%). CONCLUSION: A single-dose of 1 g of intravenous ERT applied 1 h before a scheduled transrectal prostate biopsy is a safe option and provides effective protection against infection-related complications arising from surgery.

The Limited Role of Number of Nested Syntactic Dependencies in Accounting for Processing Cost: Evidence from German Simplex and Complex Verbal Clusters.

This paper presents three acceptability experiments investigating German verb-final clauses in order to explore possible sources of sentence complexity during human parsing. The point of departure was De Vries et al.'s (2011) generalization that sentences with three or more crossed or nested dependencies are too complex for being processed by the human parsing mechanism without difficulties. This generalization is partially based on findings from Bach et al. (1986) concerning the acceptability of complex verb clusters in German and Dutch. The first experiment tests this generalization by comparing two sentence types: (i) sentences with three nested dependencies within a single clause that contains three verbs in a complex verb cluster; (ii) sentences with four nested dependencies distributed across two embedded clauses, one center-embedded within the other, each containing a two-verb cluster. The results show that sentences with four nested dependencies are judged as acceptable as control sentences with only two nested dependencies, whereas sentences with three nested dependencies are judged as only marginally acceptable. This argues against De Vries et al.'s (2011) claim that the human parser can process no more than two nested dependencies. The results are used to refine the Verb-Cluster Complexity Hypothesis of Bader and Schmid (2009a). The second and the third experiment investigate sentences with four nested dependencies in more detail in order to explore alternative sources of sentence complexity: the number of predicted heads to be held in working memory (storage cost in terms of the Dependency Locality Theory [DLT], Gibson, 2000) and the length of the involved dependencies (integration cost in terms of the DLT). Experiment 2 investigates sentences for which storage cost and integration cost make conflicting predictions. The results show that storage cost outweighs integration cost. Experiment 3 shows that increasing integration cost in sentences with two degrees of center embedding leads to decreased acceptability. Taken together, the results argue in favor of a multifactorial account of the limitations on center embedding in natural languages.

Evaluation of the 'Prostate Interdisciplinary Communication and Mapping Algorithm for Biopsy and Pathology' (PIC-MABP).

INTRODUCTION: Experience from interdisciplinary cooperation revealed the need for a prostate mapping scheme to communicate multiparametric MRI (mpMRI) findings between radiologists, urologists, and pathologists, which should be detailed, yet easy to memorize. For this purpose, the 'Prostate interdisciplinary communication and mapping algorithm for biopsy and pathology' (PIC-MABP) was developed. This study evaluated the accuracy of the PIC-MABP system. METHODS: PIC-MABP was tested and validated in findings of 10 randomly selected patients from routine clinical practise with 18 histologically proven cancer lesions. Patients received an mpMRI of the prostate prior to prostatectomy. After surgery the prostates were prepared as whole-mount step sections. Cancer lesions, which were found suspicious on mpMRI, were assigned to the according PIC-MABP sectors by a radiologist. MpMRI slides were masked and sent to seven urologists from different centres, providing only the PIC-MABP location of each lesion. Urologists marked the accordant regions. Then mpMRI slides were unmasked, and the correctness of each mark was evaluated. RESULTS: One hundred and seventeen of the 126 marks (93%) were correctly assigned. Detection rates differed for lesions >0.5 cc compared with lesions <0.5 cc (p < 0.005): 3/7 (43%) marks were correctly assigned in lesions <0.3 cc, 16/21 (76%) in lesions with 0.3-0.5 cc, and 98/98 (100%) in lesions >0.5 cc. Interobserver agreement was good for lesions >0.5 cc and poor for lesions <0.3 cc (Fleiss Kappa 1 vs. 0.0175). CONCLUSION: PIC-MABP seems to be a reliable system to communicate the location of mpMRI findings >0.5 cc between different disciplines and can be a useful guidance for cognitive mpMRI/TRUS fusion biopsy.

An interference account of the missing-VP effect.

Sentences with doubly center-embedded relative clauses in which a verb phrase (VP) is missing are sometimes perceived as grammatical, thus giving rise to an illusion of grammaticality. In this paper, we provide a new account of why missing-VP sentences, which are both complex and ungrammatical, lead to an illusion of grammaticality, the so-called missing-VP effect. We propose that the missing-VP effect in particular, and processing difficulties with multiply center-embedded clauses more generally, are best understood as resulting from interference during cue-based retrieval. When processing a sentence with double center-embedding, a retrieval error due to interference can cause the verb of an embedded clause to be erroneously attached into a higher clause. This can lead to an illusion of grammaticality in the case of missing-VP sentences and to processing complexity in the case of complete sentences with double center-embedding. Evidence for an interference account of the missing-VP effect comes from experiments that have investigated the missing-VP effect in German using a speeded grammaticality judgments procedure. We review this evidence and then present two new experiments that show that the missing-VP effect can be found in German also with less restricting procedures. One experiment was a questionnaire study which required grammaticality judgments from participants without imposing any time constraints. The second experiment used a self-paced reading procedure and did not require any judgments. Both experiments confirm the prior findings of missing-VP effects in German and also show that the missing-VP effect is subject to a primacy effect as known from the memory literature. Based on this evidence, we argue that an account of missing-VP effects in terms of interference during cue-based retrieval is superior to accounts in terms of limited memory resources or in terms of experience with embedded structures.

The vacuum cleaner effect in minimally invasive percutaneous nephrolitholapaxy.

INTRODUCTION: Percutaneous stone removal increasingly plays an important role among the different approaches of interventional stone therapy, particularly since the development of miniaturized instruments is resulting in lower morbidity for the patients. One major drawback of smaller instruments is the increased difficulty of stone retrieval after disintegration due to the reduced tract diameter. This results in longer operation time and the need of additional tools such as disposable retrieval baskets. One of the key factors in the development of minimally invasive percutaneous nephrolitholapaxy (MIP) was the design of an Amplatz sheath which provides a built-in vacuum cleaner effect for stone retrieval. METHODS: A series of flow analyses with the gauges and shapes of the most commonly used nephroscopes and sheaths in percutaneous nephrolitholapaxy was performed by computational fluid dynamics. Flow velocity and direction in front of the nephroscope were computed and visualized by the software. RESULTS: In our study, the vacuum cleaner effect developed exclusively when a round-shaped nephroscope was used (Nagele Miniature Nephroscope System, Karl Storz GmbH & Co. KG) and depended on the relation between nephroscope diameter and inner sheath diameter. The strongest effect was observed with a 12 F nephroscope and an inner sheath diameter of 15 F. It did not develop when an oval- or crescent-shaped nephroscope was used. In front of the distal end of the round-shaped nephroscope, a slipstream develops, induced by the excursive change of width of the fluid flow on the outlet of the flushing canal. This allows the adhesion of a stone fragment in the eddy while the fluid flow is circulating around the stone. CONCLUSION: This study illustrates and explains the vacuum cleaner effect which has been detected in the development of the Nagele Miniature Nephroscope System used in MIP. It combines the reduced morbidity of smaller kidney puncture diameters with the benefit of quick and complete stone removal.

Impact of pulse duration on Ho:YAG laser lithotripsy: treatment aspects on the single-pulse level.

OBJECTIVES: Holmium-YAG (Ho:YAG) laser lithotripsy is a multi-pulse treatment modality with stochastic effects on the fragmentation. In vitro investigation on the single-pulse-induced effects on fiber, repulsion as well as fragmentation was performed to identify potential impacts of different Ho:YAG laser pulse durations. MATERIALS AND METHODS: A Ho:YAG laser system (Swiss LaserClast, EMS S.A., Nyon, Switzerland) with selectable long- or short-pulse mode was tested with regard to fiber burn back, the repulsion capacity using an underwater pendulum setup and single-pulse-induced fragmentation capacity using artificial (BEGO) stones. The laser parameters were chosen in accordance with clinical application modes (laser fiber: 365 and 200 µm; output power: 4, 6 and 10 W in different combinations of energy per pulse and repetition rate). Evaluation parameters were reduction in fiber length, pendulum deviation and topology of the crater. RESULTS: Using the long-pulse mode, the fiber burn back was nearly negligible, while in short-pulse mode, an increased burn back could be observed. The results of the pendulum test showed that the deviation induced by the momentum of short pulses was by factor 1.5-2 higher compared to longer pulses at identical energy per pulse settings. The ablation volumes induced by single pulses either in short-pulse or long-pulse mode did not differ significantly although different crater shapes appeared. CONCLUSION: Reduced stone repulsion and reduced laser fiber burn back with longer laser pulses may result in a more convenient handling during clinical application and thus in an improved clinical outcome of laser lithotripsy.

Flow matters 2: How to improve irrigation flow in small-calibre percutaneous procedures-the purging effect.

INTRODUCTION: Aim of this study was to investigate whether the combination of high-pressure irrigation inflow combined with simultaneous sensor-controlled suction could improve irrigation turnover without leading to high peak intrarenal pressure in small-calibre percutaneous instruments (SCPI). M + M: A MIP XS sheath (9.5 Fr. outer diameter and 8.5 Fr. inner diameter) and a 7.5-Fr. nephroscope (3-Fr. irrigation channel; MIP XS by Nagele, Karl Storz, Tuttlingen, Germany) was inserted into the collecting system of a non-perfused cadaveric porcine kidney, an 8-Fr. mono-J catheter was introduced through the ureter. Irrigation was performed using a pressure-controlled, combined irrigation/suction pump (Uromat E.A.S.I., Karl Storz, Tuttlingen, Germany) in either single-flow or continuous-flow (=combination of irrigation and suction) mode. Intrarenal pressure was measured and irrigation fluid turnover was measured by a cystometry catheter inserted trans-parenchymally into the renal pelvis. Pressure changes were recorded by a urodynamic workstation. RESULTS: Applying pressure-controlled suction, irrigation fluid turnover could be increased by 5 % at an inflow pressure of 75 mmHg (80-84 ml/min) and 15 % at an inflow pressure of 110 mmHg (196-110 ml/min). Suction decreased the intrarenal pressure by 14 % at 75 mmHg (19-14.5 cm H2O) and 28 % at 110 mmHg inflow pressure (37-26.5 cm H2O). CONCLUSION: Although combination of pressure irrigation with sensor-controlled suction increases irrigation flow in SCPI, the intrarenal pressure could be reduced with combined suction via a transurethral mono-J catheter. This irrigation method in percutaneous surgery is called purging effect.

Single fraction radiosurgery for the treatment of renal tumors.

PURPOSE: High dose local stereotactic radiosurgery was performed in select patients to improve local tumor control and overall survival. We report on patients with renal tumors treated with single fraction robotic stereotactic radiosurgery. MATERIALS AND METHODS: A total of 40 patients with a median age of 64 years who had an indication for nephrectomy and subsequent hemodialysis were entered in a prospective case-control study of single fraction stereotactic radiosurgery. Of the patients 11 had transitional cell cancer and 29 had renal cell cancer. Tumor response, renal function, survival and adverse events were estimated every 3 months. Followup was at least 6 months. RESULTS: A total of 45 renal tumors were treated. Median followup was 28.1 months (range 6.0 to 78.3). The local tumor control rate 9 months after stereotactic radiosurgery was 98% (95% CI 89-99). There was a measurable size reduction in 38 lesions, including complete remission in 19. Renal function remained stable. Using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation median creatinine clearance was 76.8 (range 25.3 to 126.3) and 70.3 ml/minute/1.73 m(2) (range 18.6 to 127.3) at baseline and followup, respectively (p = 0.89). Grade I erythrodermia developed in 1 patient, 3 reported grade I fatigue and 2 reported grade I nausea. Nephrectomy was avoided in all cases. CONCLUSIONS: Single fraction stereotactic radiosurgery as an outpatient procedure is a treatment modality with short-term safety and efficacy. It avoids treatment related loss of renal function and hemodialysis in select patients with transitional or renal cell cancer. At short followup oncologic results were similar to those of other ablative techniques for renal tumors. To date functional results have been excellent. Further studies are needed to determine the long-term results and limits of stereotactic radiosurgery in this setting.

Impact of pulse duration on Ho:YAG laser lithotripsy: fragmentation and dusting performance.

OBJECTIVES: In vitro investigations of Ho:YAG laser-induced stone fragmentation were performed to identify potential impacts of different pulse durations on stone fragmentation characteristics. MATERIALS AND METHODS: A Ho:YAG laser system (Swiss LaserClast, EMS S.A., Nyon, Switzerland) with selectable long or short pulse mode was tested with regard to its fragmentation and laser hardware compatibility properties. The pulse duration is depending on the specific laser parameters. Fragmentation tests (hand-held, hands-free, single-pulse-induced crater) on artificial BEGO stones were performed under reproducible experimental conditions (fibre sizes: 365 and 200 µm; laser settings: 10 W through combinations of 0.5, 1, 2 J/pulse and 20, 10, 5 Hz, respectively). RESULTS: Differences in fragmentation rates between the two pulse duration regimes were detected with statistical significance for defined settings. Hand-held and motivated Ho:YAG laser-assisted fragmentation of BEGO stones showed no significant difference between short pulse mode and long pulse mode, neither in fragmentation rates nor in number of fragments and fragment sizes. Similarly, the results of the hands-free fragmentation tests (with and without anti-repulsion device) showed no statistical differences between long pulse and short pulse modes. CONCLUSION: The study showed that fragmentation rates for long and short pulse durations at identical power settings remain at a comparable level. Longer holmium laser pulse duration reduces stone pushback. Therefore, longer laser pulses may result in better clinical outcome of laser lithotripsy and more convenient handling during clinical use without compromising fragmentation effectiveness.

Efficacy and safety of Ho:YAG laser lithotripsy for ureteroscopic removal of proximal and distal ureteral calculi.

BACKGROUND: Laser lithotripsy is an established endourological modality. Ho:YAG laser have broadened the indications for ureteroscopic stone managements to include larger stone sizes throughout the whole upper urinary tract. Aim of current work is to assess efficacy and safety of Ho:YAG laser lithotripsy during retrograde ureteroscopic management of ureteral calculi in different locations. METHODS: 88 patients were treated with ureteroscopic Ho:YAG laser lithotripsy in our institute. Study endpoint was the number of treatments until the patient was stone-free. Patients were classified according to the location of their stones as Group I (distal ureteric stones, 51 patients) and group II (proximal ureteral stones, 37). Group I patients have larger stones as Group II (10.70 mm vs. 8.24 mm, respectively, P = 0.020). RESULTS: Overall stone free rate for both groups was 95.8%. The mean number of procedures for proximal calculi was 1.1 ± 0.1 (1-3) and for distal calculi was 1.0 ± 0.0. The initial treatment was more successful in patients with distal ureteral calculi (100% vs. 82.40%, respectively, P = 0.008). No significant difference in the stone free rate was noticed after the second laser procedure for stones smaller versus larger than 10 mm (100% versus 94.1%, P = 0.13). Overall complication rate was 7.9% (Clavien II und IIIb). Overall and grade-adjusted complication rates were not dependent on the stone location. No laser induced complications were noticed. CONCLUSIONS: The use of the Ho:YAG laser appears to be an adequate tool to disintegrate ureteral calculi independent of primary location. Combination of the semirigid and flexible ureteroscopes as well as the appropriate endourologic tools could likely improve the stone clearance rates for proximal calculi regardless of stone-size.

In vitro comparisons of retropulsion and fragmentation efficacy of 2 cordless, handheld pneumatic and electromechanical lithotripsy devices.

OBJECTIVE: To compare, in vitro, probe velocity/displacement, retropulsion, and fragmentation capacity of the cordless electromechanical (LithoBreaker) (hard vs soft probe guide) and pneumatic (StoneBreaker). MATERIALS AND METHODS: Probe velocities/displacements were measured using high-speed resolution camera (100.000 frames/s). The lithotripsy probes were projected through a 7.5F ureteroscope against a nonfrangible led ball placed in a 15F horizontally mounted silicone tube immersed in water bath as an in vitro ureter model. Retropulsion is considered as displacement distance of led ball. Fragmentation efficiency was quantified as number of shots required to break Bego-stone phantoms (hard [15:3] and soft [15:6], average size 7.5 × 5.5 mm) placed on metal mesh into <3-mm fragments. Mean and standard deviation of repetitive measurements were statistically analyzed. RESULTS: StoneBreaker yielded higher probe velocity (22 ± 1.9 m/s) compared with LithoBreaker with hard (14.2 ± 0.5 m/s) and soft (11.5 ± 0.5 m/s) probe. Maximum probe displacement for StoneBreaker was 1.04 mm vs 0.9 mm and 1.1 mm (hard vs soft LithoBreaker-probe, respectively). Retropulsion using 1-mm probes showed no statistical differences. Using harder 2-mm probe decreased Lithobreaker retropulsion significantly compared with Stonebreaker. The amount of shots (1-mm probe) to fragment soft Bego stones was significantly higher for LithoBreaker with soft (mean 31.5 ± 11.31) and hard (mean 21.5 ± 5.29) probe guide vs StoneBreaker (mean 11.2 ± 2.65). Fragmentation efficiency for hard Bego stones showed similar statistically significant outcome. Comparison of the 2 probe guides showed higher velocity linked to harder-probe that improved LithoBreaker fragmentation performance and reduce propulsion. CONCLUSION: Both examined lithotripters are effective in cracking stone phantoms with relatively low pulse number. They produce comparable retropulsions. Fragmentation improved substantially using LithoBreaker with hard probe guide. More tests are required to assess differences in stone clearance time.