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Background: Initially slow to gain widespread acceptance within the urological community, laparoscopic nephrectomy is now becoming the standard of care in many centers. Our institution has seen a dramatic transformation in practice patterns and patient outcomes in the 2 years following the introduction of laparoscopic nephrectomy. We compare the experience with laparoscopic and open nephrectomy within a single medical center. Methods: Data were collected for all patients undergoing elective nephrectomy (live donor, radical, simple, partial, and nephroureterectomy) between August 1998 and September 2002. Data were analyzed by Wilcoxon rank sum, chi-square, and Fisher’s exact test. A p-value

The experimental thulium fiber laser (TFL) is being explored as an alternative to the current clinical gold standard Holmium:YAG laser for lithotripsy. The near single-mode TFL beam allows coupling of higher power into smaller optical fibers than the multimode Holmium laser beam profile, without proximal fiber tip degradation. A smaller fiber is desirable because it provides more space in the ureteroscope working channel for increased saline irrigation rates and allows maximum ureteroscope deflection. However, distal fiber tip burnback increases as fiber diameter decreases. Previous studies utilizing hollow steel sheaths around recessed distal fiber tips reduced fiber burnback but increased stone retropulsion. A “fiber muzzle brake” was tested for reducing both fiber burnback and stone retropulsion by manipulating vapor bubble expansion. TFL lithotripsy studies were performed at 1908 nm, 35 mJ, 500 ?? ? s , and 300 Hz using a 100 - ? m -core fiber. The optimal stainless steel muzzle brake tip tested consisted of a 1-cm-long, 560 - ? m -outer-diameter, 360 - ? m -inner-diameter tube with a 275 - ? m -diameter through hole located 250 ?? ? m from the distal end. The fiber tip was recessed a distance of 500 ?? ? m . Stone phantom retropulsion, fiber tip burnback, and calcium oxalate stone ablation studies were performed ex vivo. Small stones with a mass of 40 ± 4 ?? mg and 4-mm-diameter were ablated over a 1.5-mm sieve in 25 ± 4 ?? s

Using a validated in vitro ureter model for laser lithotripsy, the performance of an experimental thulium fiber laser (TFL) was studied and compared to the clinical gold standard holmium:YAG laser. The holmium laser (λ = 2120 nm) was operated with standard parameters of 600 mJ, 350 μs, 6 Hz, and 270-μm-core optical fiber. The TFL (λ=1908 nm) was operated with 35 mJ, 500 μs, 150 to 500 Hz, and a 100-μm-core fiber. Urinary stones (60% calcium oxalate monohydrate/40% calcium phosphate) of uniform mass and diameter (4 to 5 mm) were laser ablated with fibers through a flexible video-ureteroscope under saline irrigation with flow rates of 22.7 and 13.7 ml/ min for the TFL and holmium laser, respectively. The temperature 3 mm from the tube's center and 1 mm above the mesh sieve was measured by a thermocouple and recorded throughout each experiment for both lasers. Total laser and operation times were recorded once all stone fragments passed through a 1.5-mm sieve. The holmium laser time measured 167±41 s (n=12). TFL times measured 111±49, 39±11, and 23±4 s, for pulse rates of 150, 300, and 500 Hz, respectively (n=12 each). Mean peak saline irrigation temperatures reached 24±1°C for holmium, and 33±3°C, 33±7°C, and 39±6°C, for TFL at pulse rates of 150, 300, and 500 Hz, respectively. To avoid thermal buildup and provide a sufficient safety margin, TFL lithotripsy should be performed with pulse rates below 500 Hz and/or increased saline irrigation rates. The TFL rapidly fragmented kidney stones due in part to its high pulse rate, high power density, high average power, and observation of reduced stone retropulsion and may provide a clinical alternative to the conventional holmium laser for lithotripsy.

Our laboratory is currently studying the Thulium fiber laser (TFL) as a potential alternative laser lithotripter to the standard clinical Holmium:YAG laser. We have previously demonstrated efficient coupling of TFL energy into fibers as small as 100-μm-core-diameter without damage to the proximal end. Although smaller fibers have greater tendency to degrade at the distal tip during lithotripsy, fiber diameters (≤ 200 μm) have been shown to increase saline irrigation rates through the working channel of a flexible ureteroscope, maximize ureteroscope deflection, and reduce stone retropulsion during laser lithotripsy. In this study, a 50-μm-core-diameter, 85-μm-outer-diameter fiber is characterized for TFL ablation of human calcium oxalate monohydrate urinary stones, ex vivo . The stone ablation rate was measured to be 70 ± 22 μg/s for 35-mJ-pulse-energy, 500-μs-pulse-duration, and 50-Hz-pulse-rate. The ureteroscope working channel flow rate including the 50-μm fiber decreased by only 10% with no impairment of ureteroscope deflection. The fiber delivered up to 15.4 ± 5.9 W under extreme bending (5-mm-radius) conditions. Stone retropulsion and fiber burn-back averaged 201 ± 336 and 3000 ± 2600 μm, respectively, after 2 minutes. With further development, Thulium fiber laser lithotripsy using ultra-small, 50-μm-core fibers may introduce new integration and miniaturization possibilities and potentially provide an alternatiμe to conventional Holmium:YAG laser lithotripsy using larger fibers.

The Thulium fiber laser (TFL) is being explored as an alternative laser lithotripter to the Holmium:YAG laser. The TFL's superior near-single mode beam profile enables higher power transmission through smaller fibers with reduced proximal fiber tip damage. Recent studies have also reported that attaching hollow steel tubing to the distal fiber tip decreases fiber degradation and burn-back without compromising stone ablation rates. However, significant stone retropulsion was observed, which increased with pulse rate. In this study, the hollow steel tip fiber design was integrated with a stone basket to minimize stone retropulsion during ablation. A device was constructed consisting of a 100-μm-core, 140-μm-OD silica fiber outfitted with 5-mm-long stainless steel tubing at the distal tip, and integrated with a 1.3-Fr (0.433-mm-OD) disposable nitinol wire basket, to form an overall 1.9-Fr (0.633-mm- OD) integrated device. This compact design may provide several potential advantages including increased flexibility, higher saline irrigation rates through the ureteroscope working channel, and reduced fiber tip degradation compared to separate fiber and stone basket manipulation. TFL pulse energy of 31.5 mJ with 500 μs pulse duration and pulse rate of 500 Hz was delivered through the integrated fiber/basket device in contact with human uric acid stones, ex vivo. TFL stone ablation rates measured 1.5 ± 0.2 mg/s, comparable to 1.7 ± 0.3 mg/s (P > 0.05) using standard bare fiber tips separately with a stone basket. With further development, this device may be useful for minimizing stone retropulsion, thus enabling more efficient TFL lithotripsy at higher pulse rates.

The Holmium:YAG laser (λ = 2120 nm) is currently the preferred laser for fragmenting kidney stones in the clinic. However, this laser has some limitations, including operation at low pulse rates and a multimode spatial beam profile which prohibits its use with smaller, more flexible optical fibers. Our laboratory is studying the Thulium fiber laser (λ = 1908 nm) as an alternative lithotripter. The TFL has several advantages, including lower stone ablation thresholds, use with smaller and more flexible fibers, and operation at arbitrary pulse lengths and pulse rates. Previous studies have reported increased stone ablation rates with TFL operation at higher pulse rates, however, stone retropulsion remains an obstacle to even more efficient stone ablation. This study explores TFL operation at high pulse rates in combination with a stone stabilization device (e.g. stone basket) for improved efficiency. A TFL beam with pulse energy of 35 mJ, pulse duration of 500-μs, and pulse rates of 10-500 Hz was coupled into 100-μm-core, low-OH, silica fibers, in contact mode with uric acid and calcium oxalate monohydrate stones, ex vivo. TFL operation at 500 Hz produced UA and COM stone ablation rates up to 5.0 mg/s and 1.3 mg/s, respectively. High TFL pulse rates produced increased stone ablation rates sufficient for use in the clinic.

The yeast scaffold protein Pan1 contains two EH domains at its N-terminus, a predicted coiled-coil central region, and a C-terminal proline-rich domain. Pan1 is also predicted to contain regions of intrinsic disorder, characteristic of proteins that have many binding partners. In vitro biochemical data suggest that Pan1 exists as a dimer, and we have identified amino acids 705 to 848 as critical for this homotypic interaction. Tryptophan fluorescence was used to further characterize Pan1 conformational states. Pan1 contains four endogenous tryptophans, each in a distinct region of the protein: Trp(312) and Trp(642) are each in an EH domain, Trp(957) is in the central region, and Trp(1280) is a critical residue in the Arp2/3 activation domain. To examine the local environment of each of these tryptophans, three of the four tryptophans were mutagenized to phenylalanine to create four proteins, each with only one tryptophan residue. When quenched with acrylamide, these single tryptophan mutants appeared to undergo collisional quenching exclusively and were moderately accessible to the acrylamide molecule. Quenching with iodide or cesium, however, revealed different Stern-Volmer constants due to unique electrostatic environments of the tryptophan residues. Time-resolved fluorescence anisotropy data confirmed structural and disorder predictions of Pan1. Further experimentation to fully develop a model of Pan1 conformational dynamics will assist in a deeper understanding of the mechanisms of endocytosis.

The use of thulium fiber laser (TFL) as a potential alternative laser lithotripter to the clinical holmium:YAG laser is being studied. The TFL’s Gaussian spatial beam profile provides efficient coupling of higher laser power into smaller core fibers without proximal fiber tip degradation. Smaller fiber diameters are more desirable, because they free up space in the single working channel of the ureteroscope for increased saline irrigation rates and allow maximum ureteroscope deflection. However, distal fiber tip degradation and “burn-back” increase as fiber diameter decreases due to both excessive temperatures and mechanical stress experienced during stone ablation. To eliminate fiber tip burn-back, the distal tip of a 150-μm core silica fiber was glued inside 1-cm-long steel tubing with fiber tip recessed 100, 250, 500, 1000, or 2000 μm inside the steel tubing to create the hollow-tip fiber. TFL pulse energy of 34 mJ with 500-μs pulse duration and 150-Hz pulse rate was delivered through the hollow-tip fibers in contact with human calcium oxalate monohydrate urinary stones during ex vivo studies. Significant fiber tip burn-back and degradation was observed for bare 150-μm core-diameter fibers. However, hollow steel tip fibers experienced minimal fiber burn-back without compromising stone ablation rates. A simple, robust, compact, and inexpensive hollow fiber tip design was characterized for minimizing distal fiber burn-back during the TFL lithotripsy. Although an increase in stone retropulsion was observed, potential integration of the hollow fiber tip into a stone basket may provide rapid stone vaporization, while minimizing retropulsion.

Fiber optic attraction of urinary stones during laser lithotripsy has been previously observed, and this phenomenon may potentially be exploited to pull stones inside the urinary tract without mechanical grasping tools, thus saving the urologist valuable time and space in the ureteroscope’s single working channel. In this study, Thulium fiber laser (TFL) high-pulse-rate/low-pulse-energy operation and Holmium:YAG low-pulse-rate/high-pulse-energy operation are compared for fiber optic “suctioning” of Plaster-of-Paris stone phantoms. A TFL with wavelength of 1908 nm, pulse energy of 35 mJ, pulse duration of 500 μs, and pulse rate of 10-350 Hz, and Holmium laser with wavelength of 2120 nm, pulse energy of 35-360 mJ, pulse duration of 300 μs, and pulse rate of 20 Hz were tested using 270-μm-core fibers. A peak “pull” speed of ~ 2.5 mm/s was measured for both TFL (35 mJ and 150-250 Hz) and Holmium laser (210 mJ and 20 Hz). Particle image velocimetry and thermal imaging were used to track water flow for all parameters. Fiber optic suctioning of urinary stone phantoms is feasible for both lasers. However, TFL operation at high-pulse-rates/low-pulse-energies provides faster, smoother stone pulling than Holmium operation at low-pulserates/ high-pulse-energies. After further study, this method may be used to manipulate urinary stones in the clinic.

Purpose: We studied the effect of second generation lithotripsy on renal function.Materials and Methods: We evaluated 42 patients with unilateral renal calculi by nuclear renography, serum creatinine levels, renal ultrasonography and plain radiographs.Results: There was no significant change in glomerular filtration rate at 1 or 3 months. Split function of the treated kidneys was lower at 1 month (mean 47.2 percent, p = 0.01) and 3 months (47.3 percent, p = 0.01) than before treatment (49.1 percent). A greater than 5 percent decrease in split function of the treated kidney occurred at 1 month in 6 patients (16.2 percent) and at 3 months in 3. Of the patients 23 (62.2 percent) were stone-free and 11 had residual fragments less than 4 mm., with a 19 percent retreatment rate for an overall success rate of 91.9 percent.Conclusions: Newer generation lithotriptors may limit renal damage while permitting satisfactory treatment of renal calculi.

The thulium fiber laser (TFL) is being studied as an alternative to the standard holmium:YAG laser for lithotripsy. The TFL beam originates within an 18-μm-core thulium-doped silica fiber, and its near single mode, Gaussian beam profile enables transmission of higher laser power through smaller (e.g., 50- to 150-μm core) fibers than possible during holmium laser lithotripsy. This study examines whether the more uniform TFL beam profile also reduces proximal fiber tip damage compared with the holmium laser multimodal beam. Light and confocal microscopy images were taken of the proximal surface of each fiber to inspect for possible laser-induced damage. A TFL beam at a wavelength of 1908 nm was coupled into 105-μm-core silica fibers, with 35-mJ energy, and 500-μs pulse duration, and 100,000 pulses were delivered at each pulse rate setting of 50, 100, 200, 300, and 400 Hz. For comparison, single use, 270-μm-core fibers were collected after clinical holmium laser lithotripsy procedures performed with standard settings (600 mJ, 350 μs, 6 Hz). Total laser energy, number of laser pulses, and laser irradiation time were recorded, and fibers were rated for damage. For TFL studies, output pulse energy and average power were stable, and no proximal fiber damage was observed at settings up to 35 mJ, 400 Hz, and 14 W average power (n=5). In contrast, confocal microscopy images of fiber tips after holmium lithotripsy showed proximal fiber tip degradation, indicated by small ablation craters on the scale of several micrometers in all fibers (n=20). In summary, the proximal fiber tip of a 105-μm-core fiber transmitted up to 14 W of TFL power without degradation, compared to degradation of 270-μm-core fibers after transmission of 3.6 W of holmium laser power. The smaller and more uniform TFL beam profile may improve fiber lifetime, and potentially translate into lower costs for the surgical disposables as well.

The thulium fiber laser (TFL) is currently being studied as an alternative to the conventional holmium:YAG (Ho:YAG) laser for lithotripsy. The diode-pumped TFL may be electronically modulated to operate with variable parameters (e.g., pulse rate, pulse duration, and duty cycle) for studying the influence of pulse train mode on stone ablation rates. The TFL under study was operated at 1908 nm, 35-mJ pulse energy, and 500-μs pulse duration, in a train of 5 micro-pulses, with macro-pulse rates of 10 Hz, compared with conventional TFL operation at 10 to 50 Hz. TFL energy was delivered through 100-μm-core fibers in contact with human uric acid (UA) and calcium oxalate monohydrate (COM) stones. Mass removal rates, optical coherence tomography, and light microscopy were used to analyze the ablation craters. Stone retropulsion and fiber tip degradation studies also were conducted for these laser parameters. TFL operation in micro-pulse train (MPT) mode resulted in a factor of two increase in the ablation rate of 414 ± 94 μg/s and 122 ± 24 μg/s for the UA and COM stones, respectively, compared to 182 ± 69 μg/s and 60 ± 14 μg/s with standard pulse trains delivered at 50 Hz (P0.05). Stone retropulsion remained minimal (2 mm after 1200 pulses) for both pulse modes. Fiber burnback was significant for both pulse modes and was higher for COM stones than UA stones. TFL operation in MPT mode results in increased stone ablation rates which, with further optimization, may approach levels comparable to Ho:YAG laser lithotripsy in the clinic.

The Thulium Fiber Laser (TFL) is being studied as an alternative to the Holmium:YAG (Ho:YAG) laser for lithotripsy. The diode-pumped TFL may be electronically modulated to operate with variable parameters for studying the influence of pulse train mode on stone ablation rates. In this study, the TFL was operated at 1908 nm, 35-mJ pulse energy, and 500-μs pulse duration, in a train of 5 micro-pulses, with macro-pulse rates of 10 Hz, compared with TFL operation at 10-50 Hz. TFL energy was delivered through 100-μm-core fibers in contact with human uric acid (UA) and calcium oxalate monohydrate (COM) stones. Mass removal rates, optical coherence tomography, and light microscopy were used to analyze ablation craters. Stone retropulsion and fiber tip degradation was also studied for these laser parameters. TFL operation in micro-pulse train (MPT) mode resulted in a two-fold increase in the ablation rate of 414 ± 94 μg/s and 122 ± 24 μg/s for the UA and COM stones, respectively, compared to 182 ± 69 μg/s and 60 ± 14 μg/s with standard pulse trains delivered at 50 Hz (P < 0.05). Stone retropulsion remained minimal for both pulse modes. Fiber burnback was significant for both pulse modes and was higher for COM stones than UA stones. TFL operation in MPT mode results in increased stone ablation rates which, with further optimization, may approach rates comparable to Ho:YAG laser lithotripsy in the clinic.

Fibroepithelial polyps are the most common benign tumor of the ureter. Most of the literature regarding their cause ascribes it to chronic infection. These publications, however, show that the majority of such cases never were associated with a documented urinary tract infection. Fibroepithelial polyps appear with equal frequency in male and female subjects and are found in all age groups including children, in contrast to what would have been expected with an infectious cause. Four histologically confirmed cases of fibroepithelial polyps were associated with chronic inflammation of the upper urinary tract related to the presence of calculi and/or Double J ureteral stents. All patients were managed successfully by endoscopic means, preserving renal function. Fibroepithelial ureteral polyps may be associated with urolithiasis, which serves as a source of chronic inflammation. A review of the literature is presented and supports these observations.

We present five patients with urinary matrix calculi, which, in contrast to the normally brittle calcigerous calculi, are soft, pliable, and amorphous. Common clinical features include a history of calcigerous stone disease, renal surgery, urinary obstruction or stasis, and chronic infection with Proteus species or coliforms. The diagnosis is usually made at surgery, but certain preoperative radiographic findings may be suggestive. Matrix calculi are radiolucent on plain abdominal films, although their appearance on nonenhanced CT scans is similar to that of calcigerous calculi despite their small mineral content. Extracorporeal shockwave lithotripsy is ineffective; open or percutaneous techniques are necessary. Histologic inspection reveals laminar concentric rings of organized matrix with an orderly, layered deposition of minerals. Histochemical investigation can provide insight into the possible sequence of events in normal calculogenesis. The successful management of urinary matrix calculi depends on a high index of suspicion and a thorough knowledge of their clinicopathologic features.

The clinical solid-state Holmium:YAG laser lithotripter (λ=2120 nm) is capable of operating at high pulse energies, but its efficient operation is limited to low pulse rates during lithotripsy. The diode-pumped experimental Thulium Fiber Laser (λ=1908 nm) is limited to low pulse energies, but can operate at high pulse rates. This review compares stone ablation threshold, ablation rate, and retropulsion effects for Ho:YAG and TFL. Laser lithotripsy complications also include optical fiber bending failure resulting in endoscope damage and low irrigation rates leading to poor visibility. Both problems are related to fiber diameter and limited by Ho:YAG laser multimode spatial beam profile. This study exploits TFL spatial beam profile for higher power transmission through smaller fibers. A short taper is also studied for expanding TFL beam at the distal tip of a small-core fiber. Stone mass loss, stone crater depths, fiber transmission losses, fiber burn-back, irrigation rates, and deflection through a flexible ureteroscope were measured for tapered fiber and compared with conventional fibers. The stone ablation threshold for TFL was four times lower than for Ho:YAG. Stone retropulsion with Ho:YAG increased linearly with pulse energy. Retropulsion with TFL was minimal at pulse rates < 150 Hz, then rapidly increased at higher pulse rates. TFL beam profile provides higher laser power through smaller fibers than Ho:YAG laser, potentially reducing fiber failure and endoscope damage and allowing greater irrigation rates for improved visibility and safety. Use of a short tapered distal fiber tip also allows expansion of the laser beam, resulting in decreased fiber tip damage compared to conventional fibers, without compromising fiber bending, stone ablation efficiency, or irrigation rates.

The Holmium:YAG (Ho:YAG) laser lithotriptor is capable of operating at high pulse energies, but its efficient operation is limited to relatively low pulse rates (~10 Hz) during lithotripsy. On the contrary, the Thulium Fiber Laser (TFL) is limited to low pulse energies, but can operate at very high pulse rates (up to 1000 Hz). This study compares stone ablation threshold, ablation rate, and retropulsion effects for different Ho:YAG and TFL operation modes. The TFL (λ=1908 nm) was operated with pulse energies of 5-35 mJ, 500-μs pulse duration, and pulse rates of 10-400 Hz. The Ho:YAG laser (λ=2120 nm) was operated with pulse energies of 30-550 mJ, 350-μs pulse duration, and pulse rate of 10 Hz. Laser energy was delivered through small-core (200-270-μm) optical fibers in contact mode with human calcium oxalate monohydrate (COM) stones for ablation studies and plaster-of-Paris stone phantoms for retropulsion studies. The COM stone ablation threshold for Ho:YAG and TFL measured 82.6 J/cm 2 and 20.8 J/cm 2 , respectively. Stone retropulsion with Ho:YAG laser increased linearly with pulse energy. Retropulsion with TFL was minimal at pulse rates < 150 Hz, then rapidly increased at higher pulse rates. For minimal stone retropulsion, Ho:YAG operation at pulse energies < 175 mJ at 10 Hz, and TFL operation at 35 mJ at 100 Hz is recommended, with both lasers producing comparable ablation rates. Further development of a TFL operating with both high pulse energies (e.g. 100-200 mJ) and high pulse rates (100-150 Hz) may also provide higher ablation rates, when retropulsion is not the primary concern.

Six studies providing information on 2,704 patients were included into a retrospective analysis. The incidence of spontaneous passage relating both stone size and location was determined from these collated studies. The rate of spontaneous passage for stones smaller than 4 mm was 38% compared to 1.2% for those larger than 6 mm, irrespective of their position in the ureter at the time of presentation. Calculi discovered in the distal third of the ureter had a spontaneous passage rate of 45%, compared with the mid third of 22%, and the proximal third of 12%. Two thirds of all stones which passed did so within 4 weeks after the onset of symptoms. These data from the literature were compared to the treatment modalities applied for the last 100 consecutive patients treated with the diagnosis of ureteral stone at UCSF. 42% of the stones were found in the proximal, 13% in the mid and 45% in the distal third of the ureter. Treatment modalities included ureteroscopic stone extraction (36), ESWL (31) and watchful waiting for stone passage (30). Oral litholysis was performed in 2 cases and percutaneous removal of a proximal stone in 1. No calculus larger than 6 mm passed spontaneously. The passage rate from the proximal ureter was 18%, from the mid ureter 15%, and 38% from the distal ureter disregarding the size of the stones. The rate of complications reached 20% when symptoms exceeded 4 weeks in duration compared to 7% in patients with symptoms lasting less than 4 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

The holmium:YAG laser is currently the most common laser lithotripter. However, recent experimental studies have demonstrated that the thulium fiber laser is also capable of vaporizing urinary stones. The high-temperature water absorption coefficient for the thulium wavelength (mu(a) = 160 cm(-1) at lambda = 1,908 nm) is significantly higher than for the holmium wavelength (mu(a) = 28 cm(-1) at lambda = 2,120 nm). We hypothesize that this should translate into more efficient laser lithotripsy using the thulium fiber laser. This study directly compares stone vaporization rates for holmium and thulium fiber lasers.Holmium laser radiation pulsed at 3 Hz with 70 mJ pulse energy and 220 microseconds pulse duration was delivered through a 100-microm-core silica fiber to human uric acid (UA) and calcium oxalate monohydrate (COM) stones, ex vivo (n = 10 each). Thulium fiber laser radiation pulsed at 10 Hz with 70 mJ pulse energy and 1-millisecond pulse duration was also delivered through a 100-microm fiber for the same sets of 10 stones each.For the same number of pulses and total energy (126 J) delivered to each stone, the mass loss averaged 2.4+/-0.6 mg (UA) and 0.7+/-0.2 mg (COM) for the holmium laser and 12.6+/-2.5 mg (UA) and 6.8+/-1.7 (COM) for the thulium fiber laser.UA and COM stone vaporization rates for the thulium fiber laser averaged 5-10 times higher than for the holmium laser at 70 mJ pulse energies. With further development, the thulium fiber laser may represent an alternative to the conventional holmium laser for more efficient laser lithotripsy.

The Holmium:YAG laser is currently the most common laser lithotripter. However, recent experimental studies have demonstrated that the Thulium fiber laser is also capable of vaporizing urinary stones. The high-temperature water absorption coefficient for the Thulium wavelength (μ a = 160 cm -1 at λ = 1908 nm) is significantly greater than for the Holmium wavelength (μ a = 28 cm -1 at λ = 2120 nm). We hypothesize that this should translate into more efficient laser lithotripsy using the Thulium fiber laser. This study directly compares stone vaporization rates for Holmium and Thulium fiber lasers. Holmium laser radiation pulsed at 3 Hz with 70 mJ pulse energy and 220 μs pulse duration was delivered through a 100-μm-core silica fiber to human uric acid (UA) and calcium oxalate monohydrate (COM) stones, ex vivo (n = 10 each). Thulium fiber laser radiation pulsed at 10 Hz with 70 mJ pulse energy and 1 ms pulse duration was also delivered through a 100-μm fiber for the same sets of 10 stones. For same number of pulses and total energy (126 J) delivered to each stone, mass loss averaged 2.4 ± 0.6 mg (UA) and 0.7 ± 0.2 mg (COM) for Holmium laser and 12.6 ± 2.5 mg (UA) and 6.8 ± 1.7 (COM) for Thulium fiber laser. UA and COM stone vaporization rates for Thulium fiber laser averaged 5-10 times higher than for Holmium laser at 70 mJ pulse energies. With further development, the Thulium fiber laser may represent an alternative to the conventional Holmium laser for more efficient laser lithotripsy.

The Thulium fiber laser has recently been tested as a potential alternative to the Holmium:YAG laser for lithotripsy. This study explores use of a short taper for expanding the Thulium fiber laser beam at the distal tip of a small-core fiber. Thulium fiber laser radiation with a wavelength of 1908 nm, 10 Hz pulse rate, 70 mJ pulse energy, and 1-ms pulse duration was delivered through a 2-m-length fiber with 150-μm-input-end, 300-μm-output-end, and 5-mmlength taper, in contact with human uric acid (UA) and calcium oxalate monohydrate (COM) stones, ex vivo (n=10 each). Stone mass loss, stone crater depths, fiber transmission losses, fiber burn-back, irrigation rates, and deflection through a flexible ureteroscope were measured for the above tapered fiber and compared with conventional fibers. After delivery of 1800 pulses through the tapered fiber, mass loss measured 12.7 ± 2.6 mg for UA and 7.2 ± 0.8 mg COM stones, comparable to conventional 100-μm-core fibers (12.6 ± 2.5 mg for UA and 6.8 ± 1.7 mg for COM stones). No transmission losses or burn-back occurred for the tapered fiber after 36,000 pulses, while a conventional 150-μm fiber experienced significant tip degradation after only 1800 pulses. High irrigation rates were measured with the tapered fiber inserted through the working port of an ureteroscope, without hindering ureteroscope deflection, mimicking that of conventional 150 im fibers. The short tapered distal fiber tip allows expansion of the laser beam, resulting in decreased fiber tip damage compared to conventional small-core fibers, without compromising fiber bending, stone vaporization efficiency, or irrigation rates.

The Thulium fiber laser has recently been tested as a potential alternative to the Holmium:YAG laser for lithotripsy. This study explores use of a short taper for expanding the Thulium fiber laser beam at the distal tip of a small-core fiber.Thulium fiber laser radiation with a wavelength of 1,908 nm, 10 Hz pulse rate, 70 mJ pulse energy, and 1-millisecond pulse duration was delivered through a 2-m-length fiber with 150-microm-core-input-end, 300-microm-core-output-end, and 5-mm-length taper, in contact with human uric acid (UA) and calcium oxalate monohydrate (COM) stones, ex vivo (n = 10 each). Stone mass loss, stone crater depths, fiber transmission losses, fiber burn-back, irrigation rates, and deflection through a flexible ureteroscope were measured for the tapered fiber and compared with conventional fibers.After delivery of 1,800 pulses through the tapered fiber, mass loss measured 12.7+/-2.6 mg for UA and 7.2+/-0.8 mg COM stones, comparable to conventional 100-microm-core fibers (12.6+/-2.5 mg for UA and 6.8+/-1.7 mg for COM stones). No transmission losses or burn-back occurred for the tapered fiber after 36,000 pulses, while a conventional 150-microm fiber experienced significant tip degradation after only 1,800 pulses. High irrigation rates were measured with the tapered fiber inserted through the working port of a flexible ureteroscope without hindering its deflection, mimicking that of a conventional 150 microm fiber.The short tapered distal fiber tip allows expansion of the laser beam, resulting in decreased fiber tip damage compared to conventional small-core fibers, without compromising fiber bending, stone vaporization efficiency, or irrigation rates.

We examined the effects of ileocystoplasty on renal function and bone mineral content in 160 juvenile male Wistar-Furth rats with and without renal insufficiency induced by 5/6 nephrectomy. At intervals up to 20 weeks blood, bone and kidney samples were obtained with the animals under anesthesia and then they were sacrificed. Serum parameters of renal function and calcium metabolism were measured. Samples of bone were analyzed for calcium, magnesium and phosphorus content. At 20 weeks after 5/6 nephrectomy renal function was decreased by approximately half. The decrease in renal function and the changes in renal histology were identical in animals with and without ileocystoplasty. Bone mineral content in the animals with renal insufficiency with or without ileocystoplasty was not different from sham operated animals or from animals with an ileocystoplasty and normal renal function. These studies demonstrate that ileocystoplasty per se does not hasten the progression to renal failure or produce bone demineralization in rats having moderate renal insufficiency.

Objectives To study, in a prospective fashion, acute traumatic effects on the gastrointestinal tract of patients treated by extracorporeal shock wave lithotripsy (ESWL). Methods Stool samples from each of 54 patients were tested before and after ESWL for conversion to hemoccult positive. A minimum of one negative pre-ESWL stool guaiac test was required for inclusion into the study. A minimum of two stool guaiac tests were done after ESWL to verify negativity. Patients who converted to a positive hemoccult test after ESWL were then evaluated by colonoscopy for the source of bleeding. Results Fifty patients completed the study. A single patient (2.0%) converted to a positive post-ESWL hemoccult test and was evaluated with colonoscopy. This patient was found to have two benign adenomatous polyps in the sigmoid and descending colon after treatment for a left renal pelvis calculus. An additional patient with a slightly positive post-ESWL conversion refused further evaluation. The overall post-ESWL conversion rate to guaiac positive, therefore, was less than 4% (2 of 51 patients). Conclusions There is no evidence of significant trauma or detectable bleeding in the normal gastrointestinal tract caused by ESWL as measured by postprocedure stool guaiac testing. Guaiac testing of the stool after ESWL may unmask pre-existing gastrointestinal disease. Therefore a positive guaiac test after ESWL warrants further evaluation. This study reaffirms that ESWL is a safe, minimally invasive technique for the treatment of urolithiasis, without significant adverse side effects on the gastrointestinal tract