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PURPOSE To present our preliminary results and describe a technical modification of mini-PCNL (12Fr) with the insertion of a ureteral access sheath (UAS) to facilitate the procedure. METHODS A prospective study for the time period of January 2020 to January 2021 was conducted including patients with renal stones sized ≤ 25 mm in whom prone mini-PCNL (tract size 12Fr) together with the retrograde insertion of UAS was performed. All patients had been prestented at least 1 week prior to the planned surgery. A single-step tract dilation to 12Fr diameter was performed through a nonpapillary medial puncture. The lithotripsy was achieved using high-power holmium yttrium aluminum garnet laser (Ho:YAG) with the 60 W power setting (40 Hz and 1.5 J). The follow-up investigations were planned at 1-month after the surgery. RESULTS In total, 32 patients with the median age and stone size of 56.5 (IQR = 53-62) years and 20.8 (IQR = 19.3-22.7) mm were included. The median operative and cumulative fluoroscopy time were 34.0 (IQR = 29.9-37.5) and 1.9 (1.8-2.1) min, respectively. The stone-free rate (SFR) at 1-month follow-up was 93.8% (30/32). Only one patient developed a fever and required prolonged antibiotic administration. None of the patients experienced clinically significant bleeding. CONCLUSION Our preliminary results showed that the use of UASs during mini-PCNL procedures is feasible and provides directed evacuation of the stone fragments reaching 93.8% SFR at a 1-month follow-up. Future well-designed studies are necessary to prove our findings.

Purpose The aim of this study was to compare the enucleation performances of four different types of laser devices in an ex-vivo experiment: a novel, pulsed Tm:YAG solid-state laser evaluation model (p-Tm:YAG), chopped thulium fibre laser (TFL), low-power Ho:YAG laser (LP-Ho:YAG), and a high-power Ho:YAG laser (HP-Ho:YAG). Methods Our primary aim was to endoscopically separate the fascial layers of a porcine belly using laser fibres within a time period of 60 s. The size of a “tissue pocket” was assessed numerically. The enucleation characteristics reflecting the surgeon’s experience were evaluated via the NASA Task Load Index (TLX) questionnaire and a questionnaire based on Likert scale. Results HP-Ho:YAG achieved with the available laser settings the largest overall “tissue pocket” (31.5 cm2) followed by p-Tm:YAG (15 cm2), TFL (12 cm2), and LP-Ho:YAG (6 cm2). The coagulation performances of p-Tm:YAG and TFL were rated the best. In the performance evaluation by the Likert questionnaire, HP-Ho:YAG (average score of 4.06) was rated highest, followed by p-Tm:YAG (3.94), TFL (3.38), and LP-Ho:YAG (3.25). The evaluation of the NASA-TLX performance questionnaire revealed average scores for HP-Ho:YAG, LP-Ho:YAG, TFL and p-Tm:YAG of 4.38, 4.09, 3.92 and 3.90, respectively. Conclusion We are the first to compare different laser devices and settings in an ex-vivo study. We found that the surgeons were most satisfied with the HP-Ho:YAG laser device, followed by the p-Tm:YAG. These findings could be highly relevant for future research and for the practical utilisation of laser systems in endourology.

Purpose The objective of this study is to evaluate the laser-tissue effects of laser radiation emitted by a newly developed high frequency pulsed Tm:YAG laser in comparison to the continuous wave Tm:YAG laser and the pulsed Ho:YAG laser. Methods Ex-vivo experiments were performed on freshly slaughtered porcine kidneys in a physiological saline solution. Experiments were performed using two different laser devices in different settings: A Tm:YAG laser was operated in a pulsed mode up to 300 Hz and in a continuous wave (CW) mode. Results were compared with a 100 W standard pulsed Ho:YAG laser system. Comparative tissue experiments were performed at 5 W, 40 W and 80 W. The incision depth and the laser damage zone were measured under a microscope using a calibrated ocular scale. Results Increased laser power resulted in increased incision depth and increased laser damage zone for all investigated lasers in this set-up. The Ho:YAG created the largest combined tissue effect at the 5 W power setting and seems to be the least controllable laser at low power for soft tissue incisions. The CW Tm:YAG did not incise at all at 5 W, but created the largest laser damage zone. For the new pulsed Tm:YAG laser the tissue effect grew evenly with increasing power. Conclusion Among the investigated laser systems in this setting the pulsed Tm:YAG laser shows the most controllable behavior, insofar as both the incision depth and the laser damage zone increase evenly with increasing laser power.

A superpulse (500 W peak power) thulium fiber laser operating at a 1940 nm wavelength, suitable for lithotripsy, has recently been developed. The goal of this study was to compare stone fragmentation and dusting performance of the prototype superpulse thulium fiber laser with leading commercially available, high-power holmium:YAG lithotripters (wavelength 2100 nm) in a controlled in vitro environment. Two experimental setups were designed for investigating stone ablation rates and retropulsion effects, respectively. In addition, the ablation setup enabled water temperature measurements during stone fragmentation in the laser–stone interaction zone. Human uric acid (UA) and calcium oxalate monohydrate (COM) stones were used for ablation experiments, whereas standard BegoStone phantoms were utilized in retropulsion experiments. The laser settings were matched in terms of pulse energy, pulse repetition rate, and average power. At equivalent settings, thulium fiber laser ablation rates were higher than those for holmium:YAG laser in both dusting mode (threefold for COM stones and 2.5-fold for UA stones) and fragmentation mode (twofold for UA stones). For single-pulse retropulsion experiments, the threshold for onset of stone retropulsion was two to four times higher for thulium fiber laser. The holmium:YAG laser generated significantly stronger retropulsion effects at equal pulse energies. The water temperature elevation near the laser-illuminated volume did not differ between the two lasers. Distinctive features of the thulium fiber laser (optimal wavelength and long pulse duration) resulted in faster stone ablation and lower retropulsion in comparison to the holmium:YAG laser.

To evaluate the impact of age, stone size, location, radiolucency, extraction of stone fragments, size of ureteroscope and presence and degree of hydronephrosis on the efficacy and safety of holmium:YAG (Ho:YAG) laser lithotripsy in the ureteroscopic treatment of ureteral stones in children.Between October 2011 and May 2013, a total of 104 patients were managed using semirigid Ho:YAG ureterolithotripsy. Patient age, stone size and site, radiolucency, use of extraction devices, degree of hydronephrosis and size of ureteroscope were compared for operative time, success and complications.In all, 128 URS were done with a mean age of 4.7 years. The mean stones size was 11 mm. Success rate was 81.25 %. Causes of failure were 12.5 % access failure, 1.5 % extravasation and 4.7 % stone migration. Overall complications were 23.4 %. Failure of dilatation and extravasation were detected only in children2 years old. Extravasation was significantly higher in smaller ureters and cases with stone size15 mm. Stone migration was significantly higher in upper ureteric stones.Failure and complications rates in Ho:YAG ureterolithotripsy were significantly affected by younger age (2 years), upper ureteric stones and smaller ureters but were not related to stone radiolucency or degree of hydronephrosis. Larger stones (15 mm) were associated with increased complications. After multivariate analysis, the age of the patients remained significant predictor for failure of dilatation and stone migration, while size of the ureter was the only significant predicting factor for failure.

We prospectively analyzed and compared the effectiveness and complications of pneumatic lithotripter with a holmium:yttrium-aluminum-garnet (Ho:YAG) laser for the ureterorenoscopic management of impacted ureteral stones.From January 2006 to January 2008, we performed retrograde endoscopic treatment in 288 patients with ureteral stones in our clinic. The patients with impacted stones were randomized into two groups according to the lithotripter used to fragment the stone: pneumatic (n = 40) and laser (n = 40). The preoperative, operative, and post-operative follow-up findings were analyzed and compared.The average stone size was similar in both groups (118.8 ± 58.3 mm(2) vs. 110.7 ± 54.4 mm(2)). The calculi were located in the distal ureter in most of the patients in both groups (65% in pneumatic group and 52.5% in laser group). The operation time was significantly diminished in the laser group (P = 0.001). The stone-free rates after a single ureteroscopic procedure were 80 and 97.5% in the pneumatic and laser groups, respectively (P = 0.03). Auxiliary treatments were needed in seven patients in the pneumatic group, while only one patient in the laser group (P = 0.05) needed this treatment. After the additional procedures, a 100% success rate was achieved in both groups. The rate of double J stent insertion was significantly higher in the pneumatic group (P = 0.01). In the pneumatic group, four cases of stone up-migration and one case of post-operative stricture were seen, whereas only one case of stone up-migration was noted in the laser group.Our comparative study has shown that the use of Ho:YAG as an intracorporeal lithotripter during ureteroscopic management of impacted ureteral stones is highly efficient with high success rates, regardless of the stone location.

Foreign bodies of the urinary tract represent a urologic emergency. First-line treatment is endoscopic removal, but this is often impeded by restricted space, especially in the urethra. We postulated that foreign objects could be fragmented by Holmium:YAG laser and investigated its effect on objects of varying composition.In a specially designed stage flushed with physiologic saline, medical and non-medical objects of differing composition and diameter were subjected to fragmentation by Holmium:YAG at powers of 18 and 30 W. In additional thermal experiments, 5,000 J was applied to differing volumes of 0.9% sodium chloride. Experiments were repeated ten times.With one exception (16 Ch silicon catheter) all medical objects were fragmented (latex urinary catheter, ureteral stents, and guidewires). Of non-medical objects (wood, steel, copper, graphite, and nylon) only copper wire was not amenable to laser dissection. These in vitro results were applied in two patients who presented with a pencil (wood and graphite) in the urethra or bladder. After Holmium:YAG laser fragmentation, the pencil could be removed by forceps each.Foreign objects in the urinary tract can be fragmented with a Holmium:YAG laser. When foreign bodies are too big for initial endoscopic extraction, the clinician should consider this technique as a reasonable and atraumatic option to avoid open surgery.

Few Western studies have focused on percutaneous techniques using percutaneous transhepatic choledochoscopy (PTHC) and holmium:yttrium-aluminum-garnet (YAG) laser to ablate biliary calculi in patients unable or unwilling to undergo endoscopic or surgical removal of the calculi. The authors report the efficacy of the holmium:YAG laser in clearing complex biliary calculi using percutaneous access techniques.This study retrospectively reviewed 13 non-Asian patients with complex secondary biliary calculi treated percutaneously using holmium:YAG laser. Percutaneous access was accomplished via left, right, or bilateral hepatic ducts and upsized for passage of a 7-Fr video choledochoscope. Lithotripsy was performed under choledochoscopic vision using a holmium:YAG laser with 200- or 365-microm fibers generating 0.6 to 1.0 joules at 8 to 15 Hz. Patients underwent treatment until stone clearance was confirmed by PTHC. Downsizing and subsequent removal of percutaneous catheters completed the treatment course.Seven men and six women with an average age of 69 years underwent treatment. All the patients had their biliary tract stones cleared successfully. Of the 13 patients, 3 were treated solely as outpatients. The average length of percutaneous access was 108 days. At this writing, one patient still has a catheter in place. The average number of holmium:YAG laser treatments required for stone clearance was 1.6, with no patients requiring more than 3 treatments. Of the 13 patients, 8 underwent a single holmium:YAG laser treatment to clear their calculi. Prior unsuccessful attempts at endoscopic removal of the calculi had been experienced by 7 of the 13 patients. Five patients underwent percutaneous access and subsequent stone removal as their sole therapy for biliary stones. Five patients were cleared of their calculi after percutaneous laser ablation of large stones and percutaneous basket retrieval of the remaining stone fragments. There was one complication of pain requiring admission, and no deaths.The use of PTHC with holmium:YAG laser ablation is safe and efficacious, but requires prolonged biliary access and often multiple procedures to ensure clearance of all calculi.

Introduction: There has been a steady increase in the number of ureteroscopic laser lithotripsy. In addition to its soft tissue applications Holmium:YAG laser has also been found an excellent intracorporeal lithotripter for all kinds of stones. We here present the results of patients treated with Holmium: YAG laser lithotripsy in our clinic. Methods: Between June 1997 and December 2002, 205 patients with a diagnosis of ureteric calculi were treated with ureteroscopy using Holmium:YAG laser as an intracorporeal lithotriptor. The stones were localized in the distal ureter in 158 patients (77), middle and proximal ureter in 47 patients (23). Stones ranged in size from 5 × 5 mm to 20 × 10 mm and the operation time was about 35 minutes (ranged 25–65 minutes). Follow-up evaluations have done at first and third months. Results: The ureteral stone could not be reached in 10 patients (4.8). Stone fragmentation or removal was accomplished in all other patients. Four patients (1.9) had proximal migration of the fragments and later treated with extra corporeal shock wave lithotripsy, and three patients (1.5) had ureteral perforation. They were managed by double J stent placement. Two of the patients had ureteral obstruction on the third month of procedure. One of the patients was treated with open surgery. For the other one, ureteroscopic balloon dilatation was performed and catheterized by double J stent and there wasn’t any complication after the removal of stent. Conclusions: Ureteroscopic Holmium:YAG laser lithotripsy is a safe, technically feasible and efficacious treatment for ureteral stones.

Neurosurgery has long required a method for dissecting brain tissue without damaging principal vessels and adjacent tissue, so as to prevent neurological complications after operation. In this study we constructed a prototype of such a device and used it in an attempt to resect beagle brain cortex.The prototype device consisted of an optical fibre, a Y adaptor, and a nozzle whose internal exit diameter was 100 microm. Cold physiological saline (4 degrees C) was supplied to it at a rate of 40 ml/h. Pulsed liquid jets were ejected from the nozzle by a pulsed Holmium:YAG) (Ho:YAG) laser at an irradiation energy of 300 mJ/pulse. The profile of the liquid jet was observed with a high-speed camera while changing the distance between the optical fibre end and nozzle exit (equivalent to the standoff distance). With this device (3 Hz operation), brain dissection of anaesthetized beagles was attempted while measuring the local temperature of the target. A histological study of the incised parts was also performed.When the standoff distance was 24 mm, the liquid jet was emitted straight from the nozzle at a maximum initial velocity of 50 m/s. The brain parenchyma was cut with this device while preserving vessels larger than 200 microm in diameter and keeping the operative field clear. The local temperature rose to no more than 41 degrees C, below the functional heat damage threshold of brain tissue. Histological findings showed no signs of thermal tissue damage around the dissected margin.The Ho:YAG laser-induced liquid jet dissector can be applied to neurosurgery after incorporating some minor improvements.

The early results of the first 50 primary endonasal laser dacryocystorhinostomies in 49 patients performed with the holmium:YAG laser are presented. Overall, 35 (70%) were successful in relieving symptoms of nasolacrimal obstruction after a mean follow-up period of 4 months. This improved to 79% in the subgroup of patients who underwent intubation of the naso-lacrimal system. These results were similar to the results of a retrospective study of 67 patients undergoing conventional dacryocystorhinostomy in our unit. Conventional surgery was performed under general anaesthesia in all but 1 case and all were treated as inpatients, with a mean hospital stay of 2.3 days, whereas all but 1 of the laser group had their surgery under local anaesthesia and 46 operations (94%) were performed as an outpatient procedure. Surgery was significantly quicker with the endonasal laser technique and 90% of patients questioned found this technique to be entirely acceptable.

A 35-year-old man with left lower ureteric stone underwent ureteroscopic stone removal. Holmium: YAG laser lithotripsy was used to break the stone and to remove a larger fragment a 3 Fr. steel wire stone basket was introduced through the ureteroscope. However, during removal the basket with the stone became impacted in the intramural part of the ureter. All attempts to dislodge the stone and the basket failed. Laser fiber was introduced through the second channel of the ureteroscope bridge and the laser activated at settings of 0.5J and 10Hz. Pulverization of the stone did not free the basket and hence 2 wires of the stuck basket were cut with the laser. This enabled the basket to be freed and easily removed.

Diese Untersuchungen hatten das Ziel, die Gewebereaktion nach Laser-Synovektomie mit einem Holmium:YAG-Laser (Wellenlange: 2,1 μm) an Kaninchen zu untersuchen und mit jener nach konventionell-mechanischer Therapie zu vergleichen. Bei 48 Kaninchen wurde immunologisch eine chronische Synoviitis in einem Kniegelenk induziert. Zwolf Tiere dienten zur Modellkontrolle. Jeweils 12 weitere Tiere wurden einer Scheinoperation, der Laserbehandlung oder der konventionell-mechanischen Abtragung unterzogen. Bei den Lasereingriffen wurden Pulsenergien vin ca. 600 mJ bei einer Pulsdauer vin 1 ms und einer Wiederholrate von 3 Hz appliziert. Nach Laufzeiten vin einem Tag, einer Woche, einem Monat und 3 Monaten wurden jeweils 3 Tiere jeder Gruppe getotet und die Synovialis makroskopisch, licht- und elektronenmikroskopisch untersucht. Unmittelbar nach der Laserbehandlung entstanden Koagulationsnekrosen, Entzundungen und Odeme. Nach einer Woche zeigte sich im Stratum synoviale eine der Modellkontrollgruppe vergleichbare leichte Fibrose und nach einem Monat erschien die Oberflache der Synovialis glatt. Nach der konventionell-mechanischen Abtragung traten Blutungen und Nekrosen auf. Eine vorbestehende Fibrose verstarkte sich in allen Kapselschichten. Nach 3 Monaten erschien die Oberflache der Synovialis plumpzottig. Aufgrund dieser Ergebnisse konnte die Holmiumlaser-Synovektomie eine Alternative zu bestehenden Verfahren bei der operativen Behandlung der rheumatoiden Arthritis darstellen, gleichzeitig ware bei arthroskopischem Einsatz eine Fibrosierung der Gelenkkapsel durch die mechanische Irritation vermeidbar.

Hemangioma of the renal calyx is a rare disease, which is difficult to diagnose and an even greater challenge to treat. We report the use of the new-generation flexible ureteroscope, in the management of a 37-year-old Asian male with a lower pole renal calyx hemangioma, which was previously inaccessible.