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.

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.

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.

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.

Encrustation of urologic double pigtail catheters-an ex vivo optical coherence tomography (OCT) study.

This study aims to evaluate whether optical coherence tomography (OCT) using both the surface and the endoluminal technique is feasible to investigate the locations and degree of encrustation process in clinically used ureteral stents. After removal from patients, 14 polyurethane JJ stents were investigated. A fresh JJ served as a control. The external surfaces were examined using an endoscopic surface OCT whereas the intraluminal surfaces were investigated by an endoluminal radial OCT device. The focus was on detection of encrustation or crystalline sedimentation. In 12 female and two male patients, the median indwelling time of the ureteral catheter was 100 days (range, 19-217). Using the endoluminal OCT, the size and grade of intraluminal encrustation could be expressed as a percentage relating to the open lumen of the reference stent. The maximum encrustation observed resulted in a remaining unrestricted lumen of 15-35 % compared to the reference. The luminal reduction caused by encrustation was significantly higher at the proximal end of the ureteral stent as compared to its distal part. The extraluminal OCT investigations facilitated the characterization of extraluminal encrustation. OCT techniques were feasible and facilitated the detection of encrustation of double pigtail catheters on both the extra and intra luminal surface. Quantitative expression of the degree of intraluminal encrustation could be achieved, with the most dense and thickened occurrence of intraluminal incrustation in the upper curl of the JJ stent.

Contemporary management of ureteral stones.

CONTEXT: Ureteral calculi represent a common condition that urologists encounter in everyday practice. Several treatment options are available for calculi that do not pass spontaneously or are unlikely to do so. OBJECTIVE: In this nonsystematic review, we summarize the existing data on contemporary management of ureteral stones focusing on medical expulsive therapy (MET) and different treatment modalities. EVIDENCE ACQUISITION: A PubMed search was performed. We reviewed the recent literature on the management of ureteral calculi. Articles were considered between 1997 and 2011. Older studies were included selectively if historically relevant. EVIDENCE SYNTHESIS: For stones that do not pass spontaneously or with MET, shock wave lithotripsy (SWL) and ureteroscopy (URS) are the most common and efficient treatment modalities. Both techniques have obvious advantages and disadvantages as well as different patterns of complications. For select cases or patients, other modalities may be useful. CONCLUSIONS: Ureteral stones of up to 10mm and eligible for observation may be offered MET. For most ureteral calculi that require treatment, advances in SWL and URS allow urologists to take a minimally invasive approach. Other more invasive treatments are reserved for select "nonstandard" cases.

The "all-seeing needle": initial results of an optical puncture system confirming access in percutaneous nephrolithotomy.

BACKGROUND: In percutaneous nephrolithotomy (PNL), the best possible way to access the collecting system is still a matter of debate. There is little possibility of correcting a suboptimal access. OBJECTIVE: To describe our initial experience using a micro-optical system through a specific puncture needle to confirm the quality of the chosen access prior to dilatation of the operating tract. DESIGN, SETTING AND PARTICIPANTS: Micro-optics of 0.9- and 0.6-mm diameter were used. The micro-optic with integrated light lead was inserted through the working sheath of the puncture needle. The modified needle had a 1.6-mm (4.85-Fr) outer diameter. The optical fiber was connected via a zoom ocular and light adapter to a standard endoscopic camera system. For sufficient intraoperative sight, an irrigation system was connected. INTERVENTION: The optical puncture needle was used in 15 patients for renal access prior to standard PNL procedures. MEASUREMENTS: The optical assessment included determination of the distortion, resolution, angle, and field of view. The irrigation flow was assessed in an ex vivo setting, with the puncture stylet or the needle shaft either empty or with a 0.018-in guidewire inserted. RESULTS AND LIMITATIONS: In all cases, visualization of the punctured kidney calyces was successful and the presence of the target calculi could be confirmed prior to guidewire placement and tract dilation. The 0.9-mm optic was found to be significantly superior in all optical parameters in contrast to the 0.6-mm optic. No significant complications were observed. CONCLUSIONS: The optical puncture needle for PNL appears to be most helpful for confirming the optimal percutaneous access to the kidney prior to dilation of the nephrostomy tract, improving the safety of the technique.

Impact of collateral damage to endourologic tools during laser lithotripsy--in vitro comparison of three different clinical laser systems.

BACKGROUND AND PURPOSE: During laser lithotripsy, working instruments are often in close proximity to the distal fiber tip and may be damaged accidentally or even intentionally. The aim of this study was to compare the amount of damage to a standard guidewire and the nitinol wires of endourologic retrieval baskets that were affected by three different clinically available laser systems. MATERIALS AND METHODS: The impact of pulsed laser irradiation on a standard hydrophilic guidewire and a retrieval basket were investigated. One infrared (IR) laser system (holmium:yttrium-aluminum-garnet [Ho:YAG]: λ = 2100 nm) and two laser systems emitting light in the visible (VIS) spectral range (frequency-doubled double-pulse neodymium:YAG [FREDDY]: λ = 532 nm/1064 nm and flashlamp pulsed dye [FLPD]: λ = 598 nm) were used. Experimental parameters were fiber core diameter, laser pulse energy, and distance between the fiber tip and the investigated tool. Damage was evaluated by microscopic investigation and by quantifying the damage size and magnitude by creating laser impact related damage factors. RESULTS: After application of one single laser pulse, IR-laser related maximum damage to guidewires occurred, depending on the pulse energy and the fiber core diameter, either in contact mode or in a distance of maximum 2 mm. Maximum VIS-laser related damage occurred in a distance range of 2 to 3 mm. The nitinol wires of the extraction tools could be destroyed completely by IR laser irradiation at pulse energies E(P) > 1200 mJ, depending on the fiber core diameter used. VIS lasers were solely able to set visible damage to guidewires without any disruption of nitinol wires. CONCLUSIONS: Ho:YAG laser induced damage to endourologic tools is significantly higher compared with the impact of the FREDDY or the FLPD-laser. Because complete disruption of guidewires and stone extraction tools occurred, a safety clearance must be kept between the fiber tip and the endourologic tool during Ho:YAG stone disintegration. If disruption is intended, such as in the case of basket-retrieval problems, it can easily be performed with Ho:YAG irradiation.

Fluorescence-guided laser therapy for penile carcinoma and precancerous lesions: long-term follow-up.

OBJECTIVES AND AIMS: Laser therapy for penile carcinoma is commonly used despite high recurrence rates of up to 48%. The aim of our study was to investigate the long-term recurrence rate of patients treated by fluorescence-guided laser therapy for penile carcinoma and its impact on oncologic outcome. PATIENTS AND METHODS: Between 1999 and 2005, a total of 26 patients with premalignant carcinoma in situ (Tis) (n = 11) or invasive penile carcinoma (n = 15) were treated by fluorescence-guided laser therapy in our center. The mean follow-up was 71.1 months (range 41-104 months). Recurrence rate, time to recurrence, and impact on survival was investigated for Tis patients and penile carcinoma patients separately. RESULTS: No patient died tumor-associated recurrence during follow-up. No local progression of T stage was observed in patients with Tis tumor. In the group with invasive penile cancer, there were 4 (15.4%) local recurrences. However, 3 of them occurred after more than 3 years and, therefore, are more likely to be considered as "de novo" carcinoma. No intra- or perioperative side effects of photodynamic diagnosis (PDD) were observed. CONCLUSIONS: Local recurrence rate of laser therapy can be reduced by fluorescence guidance without impairing cosmetic or functional results. The necessary equipment is available in many centers that perform PDD for urothelial bladder cancer. PDD, therefore, can be considered to be cost-effective and easy to perform. Prospective multi-center studies to directly compare recurrence rates between white light and fluorescence-guided laser therapy for penile carcinoma are required.

Ho:YAG-laser: treatment of vesicourethral strictures after radical prostatectomy.

OBJECTIVE: To review the indication, feasibility and treatment outcome of Ho:YAG laser application for definitive endoscopic treatment of anastomotic stricture formation after radical prostatectomy. EVIDENCE SYNTHESIS: Currently, no universally accepted regime for managing post-prostatectomy anastomotic strictures exists. Cold knife incision is the most commonly utilized invasive technique for the treatment of bladder neck contractures. The Ho:YAG laser with its shallow tissue absorption of <0.5 mm offers favorable cutting properties including low blood loss and less induction of scar tissue formation and could be a valid alternative to endoscopic knife incision. EVIDENCE ACQUISITION: PubMed and Medline were searched for reports on Ho:YAG laser therapy in strictures from 1980 to 2009 with particular focus on the operating techniques using the Ho:YAG laser system. CONCLUSION: Ho:YAG laser endourethrotomy tends to be a safe and at least minimally invasive therapeutic modality for the treatment of bladder neck contractures after radical prostatectomy. No cohort study that evaluates the use of laser for this modality is available in literature. Due to the lack of comparable randomized multicentre trials, the indications for a laser-related endoscopic treatment option has to be defined based on the operators expertise and the patient's individual situation.

Organ-preserving neodymium-yttrium-aluminium-garnet laser therapy for penile carcinoma: a long-term follow-up.

OBJECTIVE: To retrospectively analyse the long-term follow-up of 54 patients treated with organ-preserving laser therapy for penile carcinoma, as such therapy provides excellent cosmetic and functional results, but recurrence rates are high, which might impair the oncological outcome and worsen tumour-related survival. PATIENTS AND METHODS: Between 1979 and 2008, 54 patients with penile carcinoma were treated with the neodymium-doped yttrium-aluminium-garnet (Nd:YAG) laser at our institution; 11 were classified as having carcinoma in situ (Tis), 39 as T1 and four as T2. RESULTS: There was local recurrence in 16 patients (42%); the mean (range) time to local recurrence was 53 (9-132) months. In half the patients the time to local recurrence was >53 months, with the latest recurrence at 132 months after initial therapy of primary tumour. There was no statistically significant difference in recurrence rates with Tis or invasive penile carcinoma. In lymph-node-negative patients at initial presentation, there were no newly developed positive lymph nodes during the follow-up. CONCLUSIONS: Organ-preserving laser therapy showed a relatively high recurrence rate in patients with a long-term follow up, but the oncological outcome and survival were not compromised by local recurrence. Therefore, laser therapy appears to be appropriate for treating premalignant lesions and early stages of penile carcinoma. Patients should be informed about the potential for late recurrence.

Laser therapy for upper urinary tract transitional cell carcinoma: indications and management.

CONTEXT: Ureteroscopically guided laser techniques are commonly used in the treatment of upper urinary tract transitional cell carcinoma (UUTT); however, there is an ongoing debate with regard to indication and management. OBJECTIVE: To review the indication, feasibility, and treatment outcome of laser application for definitive endoscopic treatment of UUTT, focusing on technical aspects of different laser devices and their impact on tissue. EVIDENCE ACQUISITION: PubMed and Medline were searched for reports on laser therapy in UUTT from 1980 to 2008, with particular focus on the technical background of various laser systems. EVIDENCE SYNTHESIS: For decades, nephroureterectomy has been considered the gold standard for treating UUTT. With the intent to preserve functioning renal parenchyma, minimally invasive approaches, initially advocated for patients requiring a nephron-sparing approach (ie, single functioning kidney, renal insufficiency or significant comorbidities), have gained widespread acceptance due to advances in ureteroscopy, percutaneous renal surgery, and laparoscopy. Ureteroscopically guided laser ablation has been used successfully, resulting in recurrence rates ranging from 31% to 65% and disease-free rates of 35% to 86%, depending on stage and grade at diagnosis. CONCLUSIONS: To obtain the highest treatment success, the initial staging and grading of the tumour is crucial. Because low-grade tumours rarely if ever progress in stage or grade, the success rate of ureteroscopic therapy parallels that of endoscopic resection of identical bladder tumours. In the treatment of higher grade, advanced tumours, ureteroscopic therapy is less likely to be curative, and thus, endoscopic manoeuvres can only be palliative. Due to the relatively low prevalence of this tumour and the lack of comparable randomised, multicentre trials, the indications for an endoscopic laser treatment option has to be defined based on the patient's individual situation.