Laser Lithotripsy

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Nathaniel M Fried - One of the best experts on this subject based on the ideXlab platform.

  • recent advances in infrared Laser Lithotripsy invited
    Biomedical Optics Express, 2018
    Co-Authors: Nathaniel M Fried
    Abstract:

    The flashlamp-pumped, solid-state, pulsed, mid-infrared, holmium:YAG Laser (λ = 2120 nm) has been the clinical gold standard Laser for Lithotripsy for over the past two decades. However, while the holmium Laser is the dominant Laser technology in ureteroscopy because it efficiently ablates all urinary stone types, this mature Laser technology has several fundamental limitations. Alternative, mid-IR Laser technologies, including a thulium fiber Laser (λ = 1908 and 1940 nm), a thulium:YAG Laser (λ = 2010 nm), and an erbium:YAG Laser (λ = 2940 nm) have also been explored for Lithotripsy. The capabilities and limitations of these mid-IR Lasers are reviewed in the context of the quest for an ideal Laser Lithotripsy system capable of providing both rapid and safe ablation of urinary stones.

  • thulium fiber Laser Lithotripsy in an in vitro ureter model
    Journal of Biomedical Optics, 2014
    Co-Authors: Luke A Hardy, Pierce B Irby, Christopher R Wilson, Nathaniel M Fried
    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.

  • enhanced thulium fiber Laser Lithotripsy using micro pulse train modulation
    Journal of Biomedical Optics, 2012
    Co-Authors: Richard L Blackmon, Nathaniel M Fried, Pierce B Irby
    Abstract:

    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 (P<0.05). 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.

  • holmium yag λ 2 120 nm versus thulium fiber λ 1 908 nm Laser Lithotripsy
    Lasers in Surgery and Medicine, 2010
    Co-Authors: Richard L Blackmon, Nathaniel M Fried, Pierce B Irby
    Abstract:

    Introduction 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. Methods Holmium Laser radiation pulsed at 3 Hz with 70 mJ pulse energy and 220 microseconds 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-millisecond pulse duration was also delivered through a 100-µm fiber for the same sets of 10 stones each. Results 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. Conclusions 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. Lasers Surg. Med. 42:232–236, 2010. © 2010 Wiley-Liss, Inc.

  • erbium yag Laser Lithotripsy using hybrid germanium silica optical fibers
    Journal of Endourology, 2004
    Co-Authors: Yubing Yang, Charles A Chaney, Nathaniel M Fried
    Abstract:

    Background and Purpose: Previous studies have demonstrated that the erbium:YAG Laser is two to three times more efficient for Laser Lithotripsy than the holmium:YAG Laser. However, the lack of a suitable optical fiber delivery system remains a major obstacle to clinical application of Er:YAG Laser Lithotripsy. This paper describes the initial testing of a hybrid germanium oxide/silica optical fiber for potential endoscopic use with the Er:YAG Laser. Materials and Methods: Er:YAG Laser radiation with a wavelength of 2.94 µm, a pulse energy of 10 to 600 mJ, a pulse length of 220 µsec, and pulse-repetition rates of 3 to 10 Hz was focused into either 350- or 425- µm-core hybrid germanium/silica fibers in contact with human uric acid or calcium oxalate monohydrate stones. Results: Average Er:YAG pulse energies of 157 ± 46 mJ (66 J/cm2) (N = 8) were delivered at 10 Hz through the 425-µm hybrid fibers in contact with urinary stones before fiber damage was observed. A maximum pulse energy of 233 mJ (98 J/cm2) was...

James D Watterson - One of the best experts on this subject based on the ideXlab platform.

  • ureteroscopy and holmium yag Laser Lithotripsy an emerging definitive management strategy for symptomatic ureteral calculi in pregnancy
    Biomedical optics, 2003
    Co-Authors: James D Watterson, Andrew R Girvan, Darren T Beiko, Linda Nott, Timothy A Wollin, Hassan Razvi, John D Denstedt
    Abstract:

    Objectives: Symptomatic urolithiasis in pregnancy that does not respond to conservative measures has traditionally been managed with ureteral stent insertion or percutaneous nephrostomy (PCN). Holmium:yttrium-aluminum-garnet (YAG) Laser Lithotripsy using state-of-the-art ureteroscopes represents an emerging strategy for definitive stone management in pregnancy. The purpose of this study was to review the results of holmium Laser Lithotripsy in a cohort of patients who presented with symptomatic urolithiasis in pregnancy. Methods: A retrospective analysis was conducted at 2 tertiary stone centers from January 1996 to August 2001 to identify pregnant patients who were treated with ureteroscopic holmium Laser Lithotripsy for symptomatic urolithiasis or encrusted stents. Eight patients with a total of 10 symptomatic ureteral calculi and 2 encrusted ureteral stents were treated. Mean gestational age at presentation was 22 weeks. Mean stone size was 8.1 mm. Stones were located in the proximal ureter/ureteropelvic junction (UPJ) (3), mid ureter (1), and distal ureter (6). Results: Complete stone fragmentation and/or removal of encrusted ureteral stents were achieved in all patients using the holmium:YAG Laser. The overall procedural success rate was 91%. The overall stone-free rate was 89%. No obstetrical or urological complications were encountered. Conclusions: Ureteroscopy and holmium Laser Lithotripsy can be performed safely in all stages of pregnancy providing definitive management of symptomatic ureteral calculi. The procedure can be done with minimal or no fluoroscopy and avoids the undesirable features of stents or nephrostomy tubes.

  • safety and efficacy of holmium yag Laser Lithotripsy in patients with bleeding diatheses
    Biomedical optics, 2003
    Co-Authors: James D Watterson, Andrew R Girvan, Anthony J Cook, Darren T Beiko, Linda Nott, Brian K Auge, Glenn M Preminger, D John M D Denstedt
    Abstract:

    Purpose: To assess the safety and efficacy of ureteroscopy and holmium:YAG (yttrium-aluminum-garnet) Laser Lithotripsy in the treatment of upper urinary tract calculi in patients with known and uncorrected bleeding diatheses. Materials and Methods: A retrospective chart review from 2 tertiary stone centers was performed to identify patients with known bleeding diatheses who were treated with holmium:YAG Laser Lithotripsy for upper urinary tract calculi. Twenty-five patients with 29 upper urinary tract calculi were treated with ureteroscopic holmium Laser Lithotripsy. Bleeding diatheses identified were coumadin administration for various conditions (17), liver dysfunction (3), thrombocytopenia (4), and von Willebrand's disease (1). Mean international normalized ratio (INR), platelet count and bleeding time were 2.3, 50 x 10 9 /L, and > 16 minutes, for patients receiving coumadin or with liver dysfunction, thrombocytopenia, or von Willebrand's disease, respectively. Results: Overall, the stone-free rate was 96% (27/28) and 29 of 30 procedures were completed successfully without significant complication. One patient who was treated concomitantly with electrohydraulic Lithotripsy (EHL) had a significant retroperitoneal hemorrhage that required blood transfusion. Conclusions: Treatment of upper tract urinary calculi in patients with uncorrected bleeding diatheses can be safely performed using contemporary small caliber ureteroscopes and holmium Laser as the sole modality of Lithotripsy. Ureteroscopic holmium Laser Lithotripsy without preoperative correction of hemostatic parameters limits the risk of thromboembolic complications and costs associated with an extended hospital stay. Avoidance of the use of EHL is crucial in reducing bleeding complications in this cohort of patients.

  • ureteroscopy and holmium yag Laser Lithotripsy an emerging definitive management strategy for symptomatic ureteral calculi in pregnancy
    Urology, 2002
    Co-Authors: James D Watterson, Andrew R Girvan, Darren T Beiko, Linda Nott, Timothy A Wollin, Hassan Razvi, John D Denstedt
    Abstract:

    Abstract Objectives. To review the results of holmium Laser Lithotripsy in a cohort of patients who presented with symptomatic urolithiasis in pregnancy. Symptomatic urolithiasis in pregnancy that does not respond to conservative measures has traditionally been managed with ureteral stent insertion or percutaneous nephrostomy. Holmium:yttrium-aluminum-garnet (YAG) Laser Lithotripsy using state-of-the-art ureteroscopes represents an emerging strategy for definitive stone management in pregnancy. Methods. A retrospective analysis was conducted at two tertiary stone centers from January 1996 to August 2001 to identify pregnant patients who were treated with ureteroscopic holmium Laser Lithotripsy for symptomatic urolithiasis or encrusted stents. Eight patients with a total of 10 symptomatic ureteral calculi and two encrusted ureteral stents were treated. The mean gestational age at presentation was 22 weeks. The mean stone size was 8.1 mm. The stones were located in the proximal ureter/ureteropelvic junction (n = 3), midureter (n = 1), and distal ureter (n = 6). Results. Complete stone fragmentation and/or removal of encrusted ureteral stents were achieved in all patients using the holmium:YAG Laser. The overall procedural success rate was 91%. The overall stone-free rate was 89%. No obstetric or urologic complications were encountered. Conclusions. Ureteroscopy and holmium Laser Lithotripsy can be performed safely in all stages of pregnancy, providing definitive management of symptomatic ureteral calculi. The procedure can be done with minimal or no fluoroscopy and avoids the undesirable features of stents or nephrostomy tubes.

  • safety and efficacy of holmium yag Laser Lithotripsy in patients with bleeding diatheses
    The Journal of Urology, 2002
    Co-Authors: James D Watterson, Andrew R Girvan, Anthony J Cook, Darren T Beiko, Linda Nott, Brian K Auge, Glenn M Preminger, D John M D Denstedt
    Abstract:

    Purpose: We assessed the safety and efficacy of ureteroscopy and holmium:YAG Laser Lithotripsy for treating upper urinary tract calculi in patients with known and uncorrected bleeding diathesis.Materials and Methods: We retrospectively reviewed the charts at 2 tertiary stone centers to identify patients with known bleeding diathesis who were treated with holmium:YAG Laser Lithotripsy for upper urinary tract calculi. A total of 25 patients (29 upper urinary tract calculi) underwent ureteroscopic holmium Laser Lithotripsy. Bleeding diathesis involved warfarin administration for various conditions in 17 patients, liver dysfunction in 3, thrombocytopenia in 4 and von Willebrand’s disease in 1. The mean international normalized ratio, platelet count and bleeding time were 2.3, 50 × 109/l. and greater than 16 minutes in patients on warfarin and in those with liver dysfunction, thrombocytopenia and von Willebrand’s disease, respectively.Results: Overall the stone-free rate was 96% (27 of 28 cases) and 29 of 30 p...

  • holmium yag Laser Lithotripsy for upper urinary tract calculi in 598 patients
    The Journal of Urology, 2002
    Co-Authors: Mario Sofer, James D Watterson, Linda Nott, Timothy A Wollin, Hassan Razvi, John D Denstedt
    Abstract:

    Purpose: We assessed the effectiveness and safety of holmium:YAG Laser Lithotripsy for managing upper urinary tract calculi in a prospective cohort of 598 patients.Materials and Methods: Ureteroscopic holmium:YAG Laser Lithotripsy was performed in 598 patients between 1993 and 1999. Calculi were located in the distal ureter in 39.6% of cases, mid ureter in 18.6%, proximal ureter in 32.4% and kidney in 9.4%. Patients were treated on an outpatient basis with various flexible and semirigid endoscopes. Of the cases 59% were referred as previous treatment failures. Patients were assessed 6 to 12 weeks postoperatively with repeat plain x-ray and ultrasound or excretory urography for late obstructive complications.Results: The overall stone-free rate was 97%. As stratified by location, the stone-free rate was 98% in the distal ureter, 100% in the mid ureter, 97% in the proximal ureter and 84% in the kidney. Fragmentation was incomplete in 6% of cases and secondary intervention was required in 6%. The overall com...

John D Denstedt - One of the best experts on this subject based on the ideXlab platform.

  • ureteroscopy and holmium yag Laser Lithotripsy an emerging definitive management strategy for symptomatic ureteral calculi in pregnancy
    Biomedical optics, 2003
    Co-Authors: James D Watterson, Andrew R Girvan, Darren T Beiko, Linda Nott, Timothy A Wollin, Hassan Razvi, John D Denstedt
    Abstract:

    Objectives: Symptomatic urolithiasis in pregnancy that does not respond to conservative measures has traditionally been managed with ureteral stent insertion or percutaneous nephrostomy (PCN). Holmium:yttrium-aluminum-garnet (YAG) Laser Lithotripsy using state-of-the-art ureteroscopes represents an emerging strategy for definitive stone management in pregnancy. The purpose of this study was to review the results of holmium Laser Lithotripsy in a cohort of patients who presented with symptomatic urolithiasis in pregnancy. Methods: A retrospective analysis was conducted at 2 tertiary stone centers from January 1996 to August 2001 to identify pregnant patients who were treated with ureteroscopic holmium Laser Lithotripsy for symptomatic urolithiasis or encrusted stents. Eight patients with a total of 10 symptomatic ureteral calculi and 2 encrusted ureteral stents were treated. Mean gestational age at presentation was 22 weeks. Mean stone size was 8.1 mm. Stones were located in the proximal ureter/ureteropelvic junction (UPJ) (3), mid ureter (1), and distal ureter (6). Results: Complete stone fragmentation and/or removal of encrusted ureteral stents were achieved in all patients using the holmium:YAG Laser. The overall procedural success rate was 91%. The overall stone-free rate was 89%. No obstetrical or urological complications were encountered. Conclusions: Ureteroscopy and holmium Laser Lithotripsy can be performed safely in all stages of pregnancy providing definitive management of symptomatic ureteral calculi. The procedure can be done with minimal or no fluoroscopy and avoids the undesirable features of stents or nephrostomy tubes.

  • ureteroscopy and holmium yag Laser Lithotripsy an emerging definitive management strategy for symptomatic ureteral calculi in pregnancy
    Urology, 2002
    Co-Authors: James D Watterson, Andrew R Girvan, Darren T Beiko, Linda Nott, Timothy A Wollin, Hassan Razvi, John D Denstedt
    Abstract:

    Abstract Objectives. To review the results of holmium Laser Lithotripsy in a cohort of patients who presented with symptomatic urolithiasis in pregnancy. Symptomatic urolithiasis in pregnancy that does not respond to conservative measures has traditionally been managed with ureteral stent insertion or percutaneous nephrostomy. Holmium:yttrium-aluminum-garnet (YAG) Laser Lithotripsy using state-of-the-art ureteroscopes represents an emerging strategy for definitive stone management in pregnancy. Methods. A retrospective analysis was conducted at two tertiary stone centers from January 1996 to August 2001 to identify pregnant patients who were treated with ureteroscopic holmium Laser Lithotripsy for symptomatic urolithiasis or encrusted stents. Eight patients with a total of 10 symptomatic ureteral calculi and two encrusted ureteral stents were treated. The mean gestational age at presentation was 22 weeks. The mean stone size was 8.1 mm. The stones were located in the proximal ureter/ureteropelvic junction (n = 3), midureter (n = 1), and distal ureter (n = 6). Results. Complete stone fragmentation and/or removal of encrusted ureteral stents were achieved in all patients using the holmium:YAG Laser. The overall procedural success rate was 91%. The overall stone-free rate was 89%. No obstetric or urologic complications were encountered. Conclusions. Ureteroscopy and holmium Laser Lithotripsy can be performed safely in all stages of pregnancy, providing definitive management of symptomatic ureteral calculi. The procedure can be done with minimal or no fluoroscopy and avoids the undesirable features of stents or nephrostomy tubes.

  • holmium yag Laser Lithotripsy for upper urinary tract calculi in 598 patients
    The Journal of Urology, 2002
    Co-Authors: Mario Sofer, James D Watterson, Linda Nott, Timothy A Wollin, Hassan Razvi, John D Denstedt
    Abstract:

    Purpose: We assessed the effectiveness and safety of holmium:YAG Laser Lithotripsy for managing upper urinary tract calculi in a prospective cohort of 598 patients.Materials and Methods: Ureteroscopic holmium:YAG Laser Lithotripsy was performed in 598 patients between 1993 and 1999. Calculi were located in the distal ureter in 39.6% of cases, mid ureter in 18.6%, proximal ureter in 32.4% and kidney in 9.4%. Patients were treated on an outpatient basis with various flexible and semirigid endoscopes. Of the cases 59% were referred as previous treatment failures. Patients were assessed 6 to 12 weeks postoperatively with repeat plain x-ray and ultrasound or excretory urography for late obstructive complications.Results: The overall stone-free rate was 97%. As stratified by location, the stone-free rate was 98% in the distal ureter, 100% in the mid ureter, 97% in the proximal ureter and 84% in the kidney. Fragmentation was incomplete in 6% of cases and secondary intervention was required in 6%. The overall com...

Linda Nott - One of the best experts on this subject based on the ideXlab platform.

  • ureteroscopy and holmium yag Laser Lithotripsy an emerging definitive management strategy for symptomatic ureteral calculi in pregnancy
    Biomedical optics, 2003
    Co-Authors: James D Watterson, Andrew R Girvan, Darren T Beiko, Linda Nott, Timothy A Wollin, Hassan Razvi, John D Denstedt
    Abstract:

    Objectives: Symptomatic urolithiasis in pregnancy that does not respond to conservative measures has traditionally been managed with ureteral stent insertion or percutaneous nephrostomy (PCN). Holmium:yttrium-aluminum-garnet (YAG) Laser Lithotripsy using state-of-the-art ureteroscopes represents an emerging strategy for definitive stone management in pregnancy. The purpose of this study was to review the results of holmium Laser Lithotripsy in a cohort of patients who presented with symptomatic urolithiasis in pregnancy. Methods: A retrospective analysis was conducted at 2 tertiary stone centers from January 1996 to August 2001 to identify pregnant patients who were treated with ureteroscopic holmium Laser Lithotripsy for symptomatic urolithiasis or encrusted stents. Eight patients with a total of 10 symptomatic ureteral calculi and 2 encrusted ureteral stents were treated. Mean gestational age at presentation was 22 weeks. Mean stone size was 8.1 mm. Stones were located in the proximal ureter/ureteropelvic junction (UPJ) (3), mid ureter (1), and distal ureter (6). Results: Complete stone fragmentation and/or removal of encrusted ureteral stents were achieved in all patients using the holmium:YAG Laser. The overall procedural success rate was 91%. The overall stone-free rate was 89%. No obstetrical or urological complications were encountered. Conclusions: Ureteroscopy and holmium Laser Lithotripsy can be performed safely in all stages of pregnancy providing definitive management of symptomatic ureteral calculi. The procedure can be done with minimal or no fluoroscopy and avoids the undesirable features of stents or nephrostomy tubes.

  • safety and efficacy of holmium yag Laser Lithotripsy in patients with bleeding diatheses
    Biomedical optics, 2003
    Co-Authors: James D Watterson, Andrew R Girvan, Anthony J Cook, Darren T Beiko, Linda Nott, Brian K Auge, Glenn M Preminger, D John M D Denstedt
    Abstract:

    Purpose: To assess the safety and efficacy of ureteroscopy and holmium:YAG (yttrium-aluminum-garnet) Laser Lithotripsy in the treatment of upper urinary tract calculi in patients with known and uncorrected bleeding diatheses. Materials and Methods: A retrospective chart review from 2 tertiary stone centers was performed to identify patients with known bleeding diatheses who were treated with holmium:YAG Laser Lithotripsy for upper urinary tract calculi. Twenty-five patients with 29 upper urinary tract calculi were treated with ureteroscopic holmium Laser Lithotripsy. Bleeding diatheses identified were coumadin administration for various conditions (17), liver dysfunction (3), thrombocytopenia (4), and von Willebrand's disease (1). Mean international normalized ratio (INR), platelet count and bleeding time were 2.3, 50 x 10 9 /L, and > 16 minutes, for patients receiving coumadin or with liver dysfunction, thrombocytopenia, or von Willebrand's disease, respectively. Results: Overall, the stone-free rate was 96% (27/28) and 29 of 30 procedures were completed successfully without significant complication. One patient who was treated concomitantly with electrohydraulic Lithotripsy (EHL) had a significant retroperitoneal hemorrhage that required blood transfusion. Conclusions: Treatment of upper tract urinary calculi in patients with uncorrected bleeding diatheses can be safely performed using contemporary small caliber ureteroscopes and holmium Laser as the sole modality of Lithotripsy. Ureteroscopic holmium Laser Lithotripsy without preoperative correction of hemostatic parameters limits the risk of thromboembolic complications and costs associated with an extended hospital stay. Avoidance of the use of EHL is crucial in reducing bleeding complications in this cohort of patients.

  • ureteroscopy and holmium yag Laser Lithotripsy an emerging definitive management strategy for symptomatic ureteral calculi in pregnancy
    Urology, 2002
    Co-Authors: James D Watterson, Andrew R Girvan, Darren T Beiko, Linda Nott, Timothy A Wollin, Hassan Razvi, John D Denstedt
    Abstract:

    Abstract Objectives. To review the results of holmium Laser Lithotripsy in a cohort of patients who presented with symptomatic urolithiasis in pregnancy. Symptomatic urolithiasis in pregnancy that does not respond to conservative measures has traditionally been managed with ureteral stent insertion or percutaneous nephrostomy. Holmium:yttrium-aluminum-garnet (YAG) Laser Lithotripsy using state-of-the-art ureteroscopes represents an emerging strategy for definitive stone management in pregnancy. Methods. A retrospective analysis was conducted at two tertiary stone centers from January 1996 to August 2001 to identify pregnant patients who were treated with ureteroscopic holmium Laser Lithotripsy for symptomatic urolithiasis or encrusted stents. Eight patients with a total of 10 symptomatic ureteral calculi and two encrusted ureteral stents were treated. The mean gestational age at presentation was 22 weeks. The mean stone size was 8.1 mm. The stones were located in the proximal ureter/ureteropelvic junction (n = 3), midureter (n = 1), and distal ureter (n = 6). Results. Complete stone fragmentation and/or removal of encrusted ureteral stents were achieved in all patients using the holmium:YAG Laser. The overall procedural success rate was 91%. The overall stone-free rate was 89%. No obstetric or urologic complications were encountered. Conclusions. Ureteroscopy and holmium Laser Lithotripsy can be performed safely in all stages of pregnancy, providing definitive management of symptomatic ureteral calculi. The procedure can be done with minimal or no fluoroscopy and avoids the undesirable features of stents or nephrostomy tubes.

  • safety and efficacy of holmium yag Laser Lithotripsy in patients with bleeding diatheses
    The Journal of Urology, 2002
    Co-Authors: James D Watterson, Andrew R Girvan, Anthony J Cook, Darren T Beiko, Linda Nott, Brian K Auge, Glenn M Preminger, D John M D Denstedt
    Abstract:

    Purpose: We assessed the safety and efficacy of ureteroscopy and holmium:YAG Laser Lithotripsy for treating upper urinary tract calculi in patients with known and uncorrected bleeding diathesis.Materials and Methods: We retrospectively reviewed the charts at 2 tertiary stone centers to identify patients with known bleeding diathesis who were treated with holmium:YAG Laser Lithotripsy for upper urinary tract calculi. A total of 25 patients (29 upper urinary tract calculi) underwent ureteroscopic holmium Laser Lithotripsy. Bleeding diathesis involved warfarin administration for various conditions in 17 patients, liver dysfunction in 3, thrombocytopenia in 4 and von Willebrand’s disease in 1. The mean international normalized ratio, platelet count and bleeding time were 2.3, 50 × 109/l. and greater than 16 minutes in patients on warfarin and in those with liver dysfunction, thrombocytopenia and von Willebrand’s disease, respectively.Results: Overall the stone-free rate was 96% (27 of 28 cases) and 29 of 30 p...

  • holmium yag Laser Lithotripsy for upper urinary tract calculi in 598 patients
    The Journal of Urology, 2002
    Co-Authors: Mario Sofer, James D Watterson, Linda Nott, Timothy A Wollin, Hassan Razvi, John D Denstedt
    Abstract:

    Purpose: We assessed the effectiveness and safety of holmium:YAG Laser Lithotripsy for managing upper urinary tract calculi in a prospective cohort of 598 patients.Materials and Methods: Ureteroscopic holmium:YAG Laser Lithotripsy was performed in 598 patients between 1993 and 1999. Calculi were located in the distal ureter in 39.6% of cases, mid ureter in 18.6%, proximal ureter in 32.4% and kidney in 9.4%. Patients were treated on an outpatient basis with various flexible and semirigid endoscopes. Of the cases 59% were referred as previous treatment failures. Patients were assessed 6 to 12 weeks postoperatively with repeat plain x-ray and ultrasound or excretory urography for late obstructive complications.Results: The overall stone-free rate was 97%. As stratified by location, the stone-free rate was 98% in the distal ureter, 100% in the mid ureter, 97% in the proximal ureter and 84% in the kidney. Fragmentation was incomplete in 6% of cases and secondary intervention was required in 6%. The overall com...

Khurshid R Ghani - One of the best experts on this subject based on the ideXlab platform.

  • impact of pulse mode on dusting effect for holmium Laser Lithotripsy in vitro evaluation with calcium oxalate monohydrate stones
    Urology, 2021
    Co-Authors: Nikta Rezakahn Khajeh, William W Roberts, Timothy L Hall, Kristian M Black, Stephanie Daignaultnewton, Khurshid R Ghani
    Abstract:

    OBJECTIVE To assess the distribution of stone fragments ( 2 mm) after in vitro dusting Laser Lithotripsy with varying pulse modes using canine calcium oxalate monohydrate (COM) stones. Recent work demonstrates that fragments <0.25 mm are ideal for dusting, and we hypothesized advanced pulse modes might improve this outcome. METHODS A 3D-printed bulb was used as a calyceal model containing a single COM stone. A 230-core fiber (Lumenis) was passed through a ureteroscope (LithoVue, Boston Scientific). Contact Laser Lithotripsy by a single operator was performed with dusting settings (0.5J x 30Hz; Moses Pulse120H) to deliver 1kJ of energy for each trial. Short pulse (SP), long pulse (LP), Moses Distance (MD) and Moses Contact (MC) modes were tested with five trials for each parameter. Primary outcome was mass of fragments <0.25, <0.5, <1, and <2 mm. Laser fiber tip degradation was measured using a digital caliper. RESULTS Mass of stone fragments <0.25 mm varied from 34.6% to 43.0% depending on the pulse mode, with no statistically significant differences between modes. MC (98.5%) produced a greater mass of fragments <2 mm compared to LP (86.1%; p=0.046) but not SP (92.0%). Significantly less fiber tip burnback occurred with MC (0.29 mm) and MD (0.28 mm), compared to SP (0.83 mm; p<0.0005). CONCLUSION Regardless of pulse mode, greater than one-third of the mass of COM stone was reduced to fragments <0.25 mm following contact Laser Lithotripsy. MC produced a greater mass of fragments <2 mm compared to LP and demonstrated less fiber tip burnback compared to SP.

  • pulse modulation with moses technology improves popcorn Laser Lithotripsy
    World Journal of Urology, 2021
    Co-Authors: Kristian M Black, Joel M H Teichman, Ali H Aldoukhi, William W Roberts, Timothy L Hall, Sami E Majdalany, Khurshid R Ghani
    Abstract:

    Moses™ technology has been developed to improve holmium Laser fragmentation at 1–2 mm distance from the stone. Because popcorn Lithotripsy is a non-contact technique, we compared short pulse (SP) and Moses distance (MD) modes in an in vitro model. BegoStones were fragmented using a 120 W Ho:YAG Laser (P120 Moses) and a 230 μm core fiber introduced through a ureteroscope. 20 W (1 J × 20 Hz; 0.5 J × 40 Hz) and 40 W (1 J × 40 Hz; 0.5 J × 80 Hz) settings (total energy 4.8 kJ) were tested using SP and MD modes. We assessed fragment size distribution and mass lost in fluid (initial mass–final dry mass of all sievable fragments). High-speed video analysis of fragmentation strike rate and vapor bubble characteristics was conducted for 1 J × 20 Hz and 0.5 J × 80 Hz. Laser strike rate (number of strikes divided by frequency) was categorized as: (1) direct—a visual plume of dust ejected from stone while in contact with fiber tip; (2) indirect—a visual plume of dust ejected with distance between stone and fiber tip. For 1 J × 20 Hz (20 W), MD resulted in more mass lost in fluid and a lower distribution of fragments ≥ 2 mm compared to SP (p < 0.05). 0.5 J × 80 Hz (40 W) produced no fragments ≥ 2 mm, and there were no significant differences in fragment distribution between MD and SP (p = 0.34). When using MD at 1 J × 20 Hz, 96% of strikes were indirect vs 61% for SP (p = 0.059). In contrast to the single bubble of SP, with MD, there was forward movement of the collapsing second bubble, away from the fiber-tip. For lower frequency and power popcorn settings, pulse modulation results in more fragmentation through true non-contact Laser Lithotripsy.

  • effect of chilled irrigation on caliceal fluid temperature and time to thermal injury threshold during Laser Lithotripsy in vitro model
    Journal of Endourology, 2021
    Co-Authors: Julie J Dau, Khurshid R Ghani, Timothy L Hall, Adam D Maxwell, William W Roberts
    Abstract:

    Introduction: High-power Lasers (100–120 W) have widely expanded the available settings for Laser Lithotripsy and facilitated tailoring of treatment for individual cases. Previous in vitro and in v...

  • effect of chilled irrigation on caliceal fluid temperature and time to thermal injury threshold during Laser Lithotripsy in vitro model
    Journal of Endourology, 2020
    Co-Authors: Julie J Dau, Khurshid R Ghani, Timothy L Hall, Adam D Maxwell, William W Roberts
    Abstract:

    Introduction: High-power Lasers (100-120 W) have widely expanded the available settings for Laser Lithotripsy and facilitated tailoring of treatment for individual cases. Previous in vitro and in vivo studies have demonstrated that a toxic thermal dose to tissue can result from treatment within a renal calix. The objective of this in vitro study was to compare thermal dose and time with tissue injury threshold when using chilled (CH) irrigation and room temperature (RT) irrigation. Materials and Methods: A glass tube attached to a 19 mm diameter bulb simulating a renal calix was placed in a 37°C water bath. A 242 μm Laser fiber was passed through a ureteroscope with its tip in the center of the glass bulb. A wire thermocouple was placed 3 mm proximal to the ureteroscope tip to measure caliceal fluid temperature. RT at 19°C or CH at 1°C irrigation was delivered at 0, 8, 12, 15, or 40 mL/minute. The Laser was activated at 0.5 J × 80 Hz (40 W) for 60 seconds. Thermal dose was calculated using the Sapareto and Dewey t43 methodology with thermal dose = 120 equivalent minutes considered the threshold for thermal tissue injury. Results: At each irrigation rate, CH irrigation produced a lower starting temperature, a lower plateau temperature, and less thermal dose compared with RT irrigation. The threshold of thermal injury was reached after 13 seconds of Laser activation without irrigation. With 12 mL/minute irrigation, the threshold was reached in 46 seconds with RT irrigation but was not reached with CH irrigation. Conclusion: As higher power Laser Lithotripsy techniques become further refined, methods to mitigate and control thermal dose are necessary to enhance efficiency. CH irrigation slows temperature rise, decreases plateau temperature, and lowers thermal dose during high-power Laser Lithotripsy.

  • assessing the role of light absorption in Laser Lithotripsy by isotopic substitution of kidney stone materials
    ACS Biomaterials Science & Engineering, 2020
    Co-Authors: Sorout Shalini, Ali H Aldoukhi, William W Roberts, Khurshid R Ghani, Derek S Frank, Sami E Majdalany, Adam J Matzger
    Abstract:

    Understanding the chemical characteristics of kidney stones and how the stone composition affects their fragmentation is key to improving clinical Laser Lithotripsy. During Laser Lithotripsy, two mechanisms may be responsible for stone fragmentation: a photothermal mechanism and/or microexplosion mechanism. Herein, we carry out an isotopic substitution of crystal H2O with D2O in calcium oxalate monohydrate and struvite stones to alter their optical properties to study the relationship between the absorption of the stones, at the wavelength of the Ho:YAG (2.12 μm) Laser, and the fragmentation behavior. Changing the absorption of the stones at 2.12 μm changes the extent of fragmentation, whereas changing the absorption of the bulk medium has a negligible effect on fragmentation, leading to the conclusion that kidney stone ablation is dominated by a photothermal mechanism.

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