Pierce B. Irby

Laparoscopic versus open nephrectomy in 210 consecutive patients: outcomes, cost, and changes in practice patterns.

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 <0.05 was considered significant. Results: Of the patients, 92 underwent open nephrectomy, and 118 were treated laparoscopically (87 hand-assisted laparoscopic nephrectomy, 31 totally laparoscopic). There was one conversion (0.8%). Patient demographics and indications for surgery were equivalent for both groups. Mean operative time for laparoscopic nephrectomy (230 min) was longer than for open (187 min, p = 0.0001). Blood loss (97 ml vs 216 ml, p = 0.0001), length of stay (3.9 days vs 5.9 days, p = 0.0001), perioperative morbidity (14% vs 31%, p = 0.01), and wound complications (6.8% vs 27.1%, p = 0.0001) were all significantly less for laparoscopic nephrectomy. For live donors, time to convalescence was less (12 days vs 33 days, p = 0.02), but hospital charges were more for patients treated laparoscopically (

Comparison of holmium:YAG and thulium fiber laser lithotripsy: ablation thresholds, ablation rates, and retropulsion effects

19,007 vs

Thulium fiber laser lithotripsy using tapered fibers

13,581, p = 0.0001). Conclusions: Laparoscopic nephrectomy results in less blood loss, fewer hospital days, fewer complications, and more rapid recovery than open surgery. We believe that these benefits outweigh the higher hospital charges associated with the laparoscopic approach.

Thulium fiber laser ablation of kidney stones using a 50-μm-core silica optical fiber

The holmium:YAG (Ho:YAG) laser lithotriptor is capable of operating at high pulse energies, but efficient operation is limited to low pulse rates (∼10 Hz) during lithotripsy. On the contrary, the thulium fiber laser (TFL) is limited to low pulse energies, but can operate efficiently at high pulse rates (up to 1000 Hz). This study compares stone ablation threshold, ablation rate, and retropulsion for the two different Ho:YAG and TFL operation modes. The TFL (λ = 1908 nm) was operated with pulse energies of 5 to 35 mJ, 500-μs pulse duration, and pulse rates of 10 to 400 Hz. The Ho:YAG laser (λ = 2120 nm) was operated with pulse energies of 30 to 550 mJ, 350-μs pulse duration, and a pulse rate of 10 Hz. Laser energy was delivered through 200- and 270-μm-core 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 and 20.8 J∕cm(2), respectively. Stone retropulsion with the Ho:YAG laser linearly increased with pulse energy. Retropulsion with TFL was minimal at pulse rates less than 150 Hz, then rapidly increased at higher pulse rates. For minimal stone retropulsion, Ho:YAG operation at pulse energies less than 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 of 100 to 200 mJ and high pulse rates of 100 to 150 Hz may also provide an alternative to the Ho:YAG laser for higher ablation rates, when retropulsion is not a primary concern.

Thulium fiber laser lithotripsy in an in vitro ureter model

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.

Rapid Thulium Fiber Laser Lithotripsy at Pulse Rates up to 500 Hz Using a Stone Basket

Abstract. Our laboratory is currently studying the experimental thulium fiber laser (TFL) as a potential alternative laser lithotripter to the gold standard, clinical Holmium:YAG laser. We have previously demonstrated the efficient coupling of TFL energy into fibers as small as 100-μm-core-diameter without damage to the proximal end. Although smaller fibers have a greater tendency to degrade at the distal tip during lithotripsy, fiber diameters (≤200  μm) have been shown to increase the saline irrigation rates through the working channel of a flexible ureteroscope, to maximize the ureteroscope deflection, and to reduce the stone retropulsion during laser lithotripsy. In this study, a 50-μm-core-diameter, 85-μm-outer-diameter, low-OH silica fiber is characterized for TFL ablation of human calcium oxalate monohydrate urinary stones, ex vivo. The 50-μm-core fiber consumes approximately 30 times less cross-sectional area inside the single working channel of a ureteroscope than the standard 270-μm-core fiber currently used in the clinic. 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. The stone ablation rate measured 70±22  μg/s for 35-mJ-pulse-energy, 500-μs-pulse-duration, and 50-Hz-pulse-rate. Stone retropulsion and fiber burnback averaged 201±336 and 3000±2600  μm, respectively, after 2 min. 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 alternative to conventional Holmium:YAG laser lithotripsy using larger fibers.

Holmium:YAG (λ = 2,120 nm) versus thulium fiber (λ = 1,908 nm) laser lithotripsy

Abstract. 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.

Fiber-optic manipulation of urinary stone phantoms using holmium:YAG and thulium fiber lasers

Our laboratory is currently studying the experimental thulium fiber laser (TFL) for ablation of kidney stones. Previous studies have reported increased stone ablation rates with TFL operation at higher pulse rates; however, stone retropulsion remains an obstacle to 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 stone ablation efficiency. A TFL beam with pulse energy of 35 mJ, pulse duration of 500 μs, and pulse rates of 10-500 Hz was delivered through 100-μm-core, low-OH, silica fibers, in contact mode with human uric acid (UA) and calcium oxalate monohydrate (COM) stones, ex vivo. TFL operation at 500 Hz produced mean UA and COM stone ablation rates up to 4.4 and 1.4 mg/s, respectively. High TFL pulse rates produce increased stone ablation rates that may be suitable for future translation into the clinic.

Enhanced thulium fiber laser lithotripsy using micro-pulse train modulation

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 (µa = 160 cm−1 at λ = 1,908 nm) is significantly higher than for the holmium wavelength (µa = 28 cm−1 at λ = 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.

Hollow steel tips for reducing distal fiber burn-back during thulium fiber laser lithotripsy

Abstract. Fiber-optic attraction of urinary stones during laser lithotripsy may be exploited to manipulate stone fragments inside the urinary tract without mechanical grasping tools, saving the urologist time and space in the ureteroscope working channel. We compare thulium fiber laser (TFL) high pulse rate/low pulse energy operation to conventional holmium:YAG low pulse rate/high pulse energy operation for fiber-optic suctioning of plaster-of-paris (PoP) stone phantoms. A TFL (wavelength of 1908 nm, pulse energy of 35 mJ, pulse duration of 500 μs, and pulse rate of 10 to 350 Hz) and a holmium laser (wavelength of 2120 nm, pulse energy of 35 to 360 mJ, pulse duration of 300 μs, and pulse rate of 20 Hz) were tested using 270-μm-core optical fibers. A peak drag speed of ∼2.5  mm/s was measured for both TFL (35 mJ and 150 to 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. TFL operation at high pulse rates/low pulse energies is preferable to holmium operation at low pulse rates/high pulse energies for rapid and smooth stone pulling. With further development, this novel technique may be useful for manipulating stone fragments in the urinary tract.