Lasers in clinical urology: state of the art and new horizons

Evaluation of early apical release with bipolar Collins knife versus Thulium-Yag laser enucleation of large-sized prostate. A randomized study

Introduction and objectives

Anatomical endoscopic enucleation of the prostate (AEEP) provides durable management for patients with lower urinary tract symptoms (LUTS) secondary to large-sized prostate over other surgical modalities. We aimed to assess the early outcomes of Collins knife-assisted bipolar enucleation (BipolEP) versus Thulium-Yag enucleation (ThuLEP) in a group of patients with LUTS secondary to a prostate larger than 80 grams.

Methods

We included patients with benign prostatic hyperplasia (BPH) having a prostate volume > 80 grams, international prostate symptom score (IPSS) >7, urine flow (Q-max) <15, and post-void residual (PVR)>150 ml. We excluded those with a history of previous prostatic surgery, stone, or neurogenic bladder. Bipolar enucleation with early apical release was performed using Collins knife at an 80/100-watt setting (Lamidey Noury), while ThuLEP was conducted using 550- micron fiber and 40/15-watt energy (Lisa Laser). Patients were evaluated before then 2 weeks and 3, 6,12 months postoperatively for changes in IPSS, Q- max, PVR, and the incidence of stress incontinence.

Result

One hundred and twenty patients were equally randomized with a mean prostate size of 104 ± 25 gram. The mean IPSS score was 25 ± 6, Qmax 7.6 ± 1.3 mL/S, and PVR 225 ± 39. There was no significant difference regarding enucleation time, morcellation time, and enucleated tissue volume. Irrigation volume and post-operative hemoglobin drop were significantly lower in the bipolar group (p = 0.008, p = 0.0002), respectively. At the third-month follow-up, IPSS, Q-max, and PVR were comparable across both groups, with stress incontinence at 3.3% in the bipolar group versus 1.6% in the thulium group, showing an insignificant difference (p = 0.5)."

Conclusion

Both BipolEP and ThuLEP, with early apical release, provide a safe and effective management of large-size prostate resulting in significant decrease in post-operative stress incontinence incidence during early follow-up. Intraoperative irrigation saline volume, and post-operative hemoglobin drop favored the bipolar group.

Transurethral columnar balloon dilation of the prostate combined with holmium laser incision for bladder neck contracture in day-surgery mode

The study aimed to investigate the clinical effect of transurethral columnar balloon dilation of the prostate combined with holmium laser in the treatment of bladder neck contracture (BNC). This retrospective study included 41 patients with BNC, who had been treated with transurethral columnar balloon dilation and holmium laser in our hospital from June 2020 to June 2022. Admission, operation, and discharge of all the patients were completed in 24 h. The patients' satisfaction, postoperative complications, and chronic pain after operation were followed up. Clinical parameters, such as International Prostate Symptom Score (IPSS), maximum urinary flow rate (Qmax), quality of life (QoL), and post-void residual volume (PVR) in pre-operation, 1 month and 6 months after operation were recorded. All patients underwent the operations successfully. Six patients experienced urge incontinence and one patient experienced recurrence of BNC after 12 months. At 1 month and 6 months after the operation, IPSS, QoL, PVR, and Qmax of the patients were significantly better than those before the operation (P < 0.05). Transurethral columnar balloon dilation of the prostate combined with holmium laser can effectively treat BNC with simple performance and satisfactory clinical effects. It is a minimally invasive treatment that can be conducted by simple day surgery.

Dusting efficacy between the regular setting of holmium laser (Ho:YAG) versus Vapor Tunnel pulse modality for non-complex kidney stones

The new pulse modality Vapor-Tunnel™ (VT) consists of a very long pulse that uses the minimum peak power, causing the energy to pass through a previously created vapor channel or tunnel. The first part of the pulse creates a vapor channel, whereas the remaining energy is discharged immediately after, passing straight through the previously created tunnel. The aim of this study is to compare the dusting efficacy between Ho:YAG laser with long pulse and Ho:YAG laser with VT for non-complex kidney stones. A retrospective comparative study of 236 patients who underwent retrograde intrarenal surgery using Ho:YAG laser (long pulse vs. VT) was performed. Stone size, stone density, laser settings, laser emission time, and total operative time were recorded. We also assessed the lithotripsy efficacy (J/mm3). The stone-free rate was defined as the absence of stone fragments in a non-contrast abdominal computed tomography 4 weeks after the procedure. A total of 118 patients were included in each group. There was no significant difference in age, gender, and body mass index. Median stone volume (737 mm3 vs. 636 mm3) and stone density (788 HU vs. 656 HU) were higher in the VT group. Total energy used (14.5 J vs. 18.2 J), the laser emission time (20 min vs. 26 min), and the total operative time (79.5 min vs. 95 min) were significantly lower in the VT group. The stone-free rate was comparable between both groups (74.5% for VT and 66.1% for the long-pulse group, p = 0.15). When we evaluated the efficacy of laser lithotripsy, a significantly lower difference was obtained in the VT group (median 12.5 J/mm3 vs. median 23.1 J/mm3). The VT pulse modality was associated with decreased laser time and operative time. Additionally, it increased lithotripsy efficacy compared to Ho:YAG long pulse laser, but with a comparable free-stone rate.

A Case of Bouveret's Syndrome Treated With Holmium:Yttrium-Aluminum-Garnet Laser

Bouveret's syndrome is a rare form of gallstone ileus described as a gastric outlet obstruction from a gallstone that travels from the gallbladder to the bowel through a bilioenteric fistula. Despite its rarity, the mortality rate of this condition is high. Endoscopic treatment is preferred over surgery due to the association with lower mortality rate. To date, there are limited data about the application of holmium:yttrium-aluminum-garnet (YAG) laser lithotripsy for fragmentation of gallstones in Bouveret's syndrome. We present the case of a 74-year-old man with multiple cardiac comorbidities who presented with periumbilical pain, decreased appetite, and vomiting. The patient had previously been admitted three months prior with acute cholecystitis, and a cholecystostomy tube was placed. He had leukocytosis and purulent discharge in his cholecystostomy bag. Computed tomography (CT) scan of the abdomen and pelvis showed a change in the position of a previously seen large gallstone from the neck of the gallbladder on the last admission, to the lumen of the duodenal bulb on this admission. This indicated the development of a cholecystoduodenal fistula, with the stone passing through this fistula into the duodenal bulb, causing the complete obstruction. Endoscopic treatment was recommended by the surgery team due to cardiac comorbidities and the significant friability of the tissue requiring laparotomy. Initial endoscopic evaluation showed complete obstruction of the duodenal bulb by a large smooth stone, not allowing passage of a guidewire beyond the stone. Therefore, holmium:YAG laser lithotripsy was used. After two sessions of laser therapy, four days apart, each breaking a pigmented and calcified stone, it eventually passed through the small bowel into the colon, relieving the obstruction. The patient had a favorable outcome and did not require surgery. This case report shows that holmium:YAG laser lithotripsy is capable of delivering favorable outcomes, as seen in a patient with a heavily calcified and pigmented stone, older age, and multiple comorbidities. Holmium:YAG laser could be considered for use with endoscopic equipment for future management of this condition, especially in patients who have medical comorbidities and heavily calcified gallstones.

Retrospective analysis of 1470-/980-nm dual-wavelength laser en bloc resection versus transurethral resection of bladder tumor for primary non-muscle-invasive bladder cancer

To compare the safety and efficacy of en bloc resection of non-muscle-invasive bladder cancer (NMIBC) using a 1470-/980-nm dual-wavelength laser (DwLRBT) compared to the gold standard, transurethral resection (TURBT). The study group included 251 patients with a confirmed diagnosis of NMIBC, 97 in the DwLRBT group and 154 in the TURBT group. Clinical characteristics, complications, and recurrence-free survival were compared between the two groups. There were no differences between the two groups with regard to age, sex, mean tumor size, mean tumor number, tumor location, risk, fever, and reoperation. Compared to TURBT, DwLRBT was associated with a shorter hospitalization time (mean±standard deviation: 5.81±1.48 days vs. 4.96±1.32, respectively, p=0.001), shorter catheterization time (4.98±1.47 vs. 4.20±1.48 days, respectively; p=0.035), and smaller volume of intraoperative bleeding (8.43±6.21 ml vs. 6.15±5.08, respectively; p=0.003). Recurrence-free survival (RFS) was better for DwLRBT than TURBT in the overall cohort (hazard ratio [HR], 0.4323; 95% confidence interval [CI], 0.2852-0.6554; p=0.0004) and for the following subgroups and tumor types: intermediate-risk (HR, 0.2654; 95%CI, 0.1020-0.6904; p=0.0245) and high-risk (HR, 0.4461; 95% CI, 0.2778-0.7162; p=0.0027) groups; and for pedunculate bladder tumors (HR, 0.4158; 95%CI, 0.2401-0.7202; p=0.0063), single bladder tumors (HR, 0.4136; 95%CI, 0.2376-0.7293; p=0.0072), and multiple bladder tumors (HR, 0.2727; 95%CI, 0.1408-0.5282; p=0.0014). DwLRBT is associated with better operative and postoperative outcomes, including, importantly, a longer RFS, compared to TURBT.

Comparative effectiveness of high-power holmium laser lithotripsy for pediatric patients with kidney and ureteral stones

BACKGROUND

The comparative effectiveness of high-power laser technology for kidney stone surgery in pediatric patients is poorly understood. We compared outcomes for the 120 W Holmium:yttrium-aluminum-garnet (Ho:YAG) laser with MOSES technology to 30 W Ho:YAG laser for pediatric patients undergoing ureteroscopy with laser lithotripsy for kidney and ureteral stones.

OBJECTIVE

We evaluated the outcomes of the new MOSES laser technology as compared to low-power Ho:YAG lasers commonly used for kidney stone treatment in the pediatric population.

METHODS

We performed a retrospective cohort study of 131 consecutive patients aged 1-18 years who underwent ureteroscopy and laser lithotripsy for renal and ureteric calculi at a large freestanding children's hospital between 2013 and 2020. The primary outcome was the efficiency quotient, which incorporates stone clearance, auxiliary procedures, and retreatment rates. Outcomes were compared between groups using Chi-square or Fisher's exact tests and multivariable regression. A sensitivity analysis was performed extending the age limit to ≤21 years.

RESULTS

Outcomes are summarized in the table below. Median age of the cohort was 14 years with 53% of patients being female. MOSES laser had a higher efficiency quotient and was associated with a lower odds of post-operative emergency department visits (OR 0.2, 95% CI 0.0-1.0; p = 0.047). Operative time was similar. In the sensitivity analysis of patients ≤21 years, the statistical significance with fewer emergency department visits was lost and the efficiency quotient was lower.

DISCUSSION

Our results show that stone clearance is similar between the 120 W MOSES and 30 W Ho:YAG lasers. However, there are indications that high-power laser lithotripsy is more efficient due to fewer auxiliary procedures and a reduction in retreatment. In addition, higher power lasers were associated with fewer emergency department visits. The benefits appear to be greater among children ≤18 years. These exploratory findings are important for pediatric patients due to the requirement for general anesthesia for each procedure and their associated impact on children and their caregivers.

CONCLUSIONS

High-power laser lithotripsy may be more efficient than lower power laser lithotripsy, which is driven by the fewer auxiliary procedures and reduction in retreatment particularly among youth ≤18 years old.

The evaluation of the usefulness of CO2 laser in microsurgical resection of brain tumors

BACKGROUND

Since its introduction to surgery, the CO2 laser has been used in the treatment of various neurosurgical pathologies as it combines cutting, vaporizing, and coagulating properties in one tool and has a safe penetration depth. In this case series of 29 patients, we present the evaluation of the usefulness of the closed system type - sealed tube surgical CO2 laser in the surgical removal of brain tumors.

METHODS

The Sharplan 40C model SurgiTouch, sealed tube type CO2 laser, was used in the resection of 29 brain tumors; 13 meningiomas, six metastases, nine gliomas, and one acoustic neuroma. The same senior surgeon (BT) assessed and classified the benefit provided by the CO2 laser in the resection of the neoplasms to considerable (Group 1), moderate (Group 2), and poor (Group 3).

RESULTS

Group 1 included 14 patients with 13 meningiomas and one acoustic neuroma, Group 2 included six patients, all of whom had metastases, and Group 3 included nine patients of which six had glioblastoma and three astrocytoma. No complications or technical problems occurred due to the use of the CO2 laser.

CONCLUSION

The CO2 laser is a valuable complementary tool in brain tumor surgery displaying high efficacy and practicality in the resection of neoplasms which are fibrous and have hard consistency. It has high acquisition and maintenance cost and cannot replace the bipolar diathermy. The newest generation of flexible CO2 laser fiber provides more ergonomy and promises new perspectives of its neurosurgical use in the modern era.

Successful management of multiple obstructing renal calculi in a 30-year-old patient with autosomal dominant polycystic kidney disease using Frequency-Doubled Double-Pulse neodymium: Yttrium - Aluminium garnet laser lithotripsy

Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent genetic disorder that results in end-stage renal disease. Although ADPKD patients experience long disease trajectories, factors such as hypertension, proteinuria and renal calculi have been observed to lead to rapid renal function impairment in patients with ADPKD. Furthermore, due to the distorted anatomy that makes access to stone difficult, the management of nephrolithiasis in ADPKD patients is one of the several special situations in which urinary lithiasis presents management challenges. We report the case of a 30-year-old male with ADPKD and renal function impairment as a result of multiple obstructive calculi who was treated in Dialyser Medical Centre, Oshodi, Lagos, with Frequency-Doubled Double-Pulse Neodymium: Yttrium - Aluminium Garnet laser (FREDDY laser) lithotripsy, highlighting the possible advantage of FREDDY laser over other types of laser procedures given the minimal tissue-damaging potential of the laser type.

Comparison of Different Pulse Modulation Modes for Holmium:Yttrium-Aluminum-Garnet Laser Lithotripsy Ablation in a Benchtop Model

Introduction: Manipulation of Holmium:Yttrium-Aluminum-Garnet laser parameters such as pulse energy (PE), frequency, and duration can impact laser lithotripsy ablation efficiency. In 2017, Lumenis introduced Moses™ Technology, which uses pulse modulation to enhance the delivery of energy from fiber to stone as well as to minimize stone retropulsion. Since the introduction of Moses Technology, other companies have brought additional pulse modulation concepts to market. The purpose of this in vitro study is to compare the pulse characteristics and stone ablation efficiency of Lumenis Moses Technology with Quanta's Vapor Tunnel™. Materials and Methods: Submerged BegoStone phantoms were systematically ablated using either the Lumenis Moses Pulse 120H or the Quanta Litho 100 clinical laser system. Two PEs (0.4 and 1 J), three fiber-stone standoff distances (SDs) (0.5, 1, 2 mm), and all available pulse duration and modulation modes for each laser were tested in combination. Fiber speed was adjusted to scan across the stone surface at either 1 or 10 pulses/mm to form single pulse craters or an ablation trough, respectively. Volumes of single craters and 1 mm trough segments were imaged and quantified using optical coherence tomography. Results: Ablation volumes decreased with decreasing PE and increasing SD. Statistically significant variability was seen between pulse types (PT) at every tested parameter set. Among pulse modulation modes, Moses Distance (MD) was superior at 0.5 mm in all testing and at 2 mm in trough testing. Vapor Tunnel (VT) was superior in 2 mm single crater testing. All modulated pulses performed similarly at 1 mm. Conclusions: In this benchtop model of laser lithotripsy, stone ablation was significantly impacted by PT. MD demonstrated superior or noninferior stone ablation at most tested parameters. VT maintained its efficacy the best as SD increased. Future work should focus on the mechanistic differences of these modes relative to other traditional laser pulse modes.

The Trends of Urolithiasis Therapeutic Interventions over the Last 20 Years: A Bibliographic Study

Introduction: The clinical and economic burden of kidney stones is a challenge for the healthcare system. There is a limited bibliometric project exploring the literature trends on 'urolithiasis' and its related management. Methods: A systematic review was conducted to discover the related abstracts regarding each specific issue, investigated year by year from May 2000 to May 2020 (20 years). To make an effective comparison, the statistics resulting from every single study were allocated to two 10-year periods: period 1 (2000 to 2010) and period 2 (2010 to 2020). In this study, we included all English language articles, all non-English articles with English abstracts, and studies in which interventions were used for stone removal, including laser technology. Also, we excluded the studies without a published abstract, an intervention or a laser, animal and in vitro studies, and case reports. Results: These articles are about ureteroscopy (URS) (n=10360, 33.45%), percutaneous nephrolithotomy (PCN) (n =10790, 34.84%) and extra-corporeal shockwave lithotripsy (ESWL) (n=9846, 31.76%). When evaluating the two time periods, there were 9912 studies available in period one, which increased by ×2.12 times (112.71% rise) to 21084 studies in period two (P = 0.001). The increase was 133%, 103.51%, and 70.4% for URS, PCN, and SWL respectively. A total of 855 studies on Laser application via URS were published on PubMed over a 20-year period. There was an increasing trend toward using laser application via URS over the study period. Also, there were 230 articles published in period one, which increased by nearly 2.71 times (rise of 171.73%) to 625 papers in period two (P < 0.001). There was an increasing trend toward using laser application via PCN; 126 papers were published in period one, which increased by nearly 3.05 times (rise of 205.5%) to 385 papers in period two (P = 0.002). Conclusion: The minimal invasive interventions for stone removal, including URS and PCN, increased dramatically in the last decade, and the use of lasers in stone treatment increased significantly in the last decade.

[Lasers in urology : Relevant principles]

A fundamental understanding of the physical properties is necessary for the application of lasers in medicine in order to be able to understand and appreciate the biological effect. The most important parameters are emission mode, wavelength of the laser and power output measured in watts. Pulsed lasers can be used for the treatment of stones and soft tissues, whereby in urology this essentially applies to the prostate gland and to a lesser extent also for the ureter, urethra, bladder and kidneys.

Comparison of Holmium:YAG and Thulium Fiber Lasers on the Risk of Laser Fiber Fracture

Objectives: To compare the risk of laser fiber fracture between Ho:YAG laser and Thulium Fiber Laser (TFL) with different laser fiber diameters, laser settings, and fiber bending radii. METHODS: Lengths of 200, 272, and 365 μm single use fibers were used with a 30 W Ho:YAG laser and a 50 W Super Pulsed TFL. Laser fibers of 150 µm length were also tested with the TFL only. Five different increasingly smaller bend radii were tested: 1, 0.9, 0.75, 0.6, and 0.45 cm. A total of 13 different laser settings were tested for the Ho:YAG laser: six fragmentation settings with a short pulse duration, and seven dusting settings with a long pulse duration. A total of 33 different laser settings were tested for the TFL. Three laser settings were common two both lasers: 0.5 J × 12 Hz, 0.8 J × 8 Hz, 2 J × 3 Hz. The laser was activated for 5 min or until fiber fracture. Each measurement was performed ten times. Results: While fiber failures occurred with all fiber diameters with Ho:YAG laser, none were reported with TFL. Identified risk factors of fiber fracture with the Ho:YAG laser were short pulse and high energy for the 365 µm fibers (p = 0.041), but not for the 200 and 272 µm fibers (p = 1 and p = 0.43, respectively). High frequency was not a risk factor of fiber fracture. Fiber diameter also seemed to be a risk factor of fracture. The 200 µm fibers broke more frequently than the 272 and 365 µm ones (p = 0.039). There was a trend for a higher number of fractures with the 365 µm fibers compared to the 272 µm ones, these occurring at a larger bend radius, but this difference was not significant. Conclusion: TFL appears to be a safer laser regarding the risk of fiber fracture than Ho:YAG when used with fibers in a deflected position.

Chronic Unilateral Hematuria: Compound Papillae Are Likely to Bleed

Objectives: The present study investigated the recent outcomes of chronic unilateral hematuria (CUH), focusing on the detailed distribution of bleeding points based on the anatomical classification of the pelvicaliceal system. Materials and Methods: We evaluated 75 CUH patients treated in the past decade. Bleeding points were recorded separately as five levels of minor calices (Top, Upper, Middle, Lower, and Bottom). Bleeding point detection, immediate success, and recurrence-free rates were assessed. Results: The median age was 47 (range: 13-81) years. Bleeding points were detected in 62 patients (83%), including at the Top calix in 24 patients (32%), the mid-calices (Upper, Middle, and Lower) in 20 patients (27%), and the Bottom calix in 18 patients (24%). As there are typically six total calices in the mid calices, the probability of bleeding per renal papilla was higher in the compound papillae at the Top and Bottom calices than in the simple papilla at the mid calices. The bleeding point detection rate was significantly higher in the 65 patients with confirmed unilateral gross hematuria than in the 10 patients without confirmation (88% vs 50%, p < 0.01). The immediate success rate was 97% (73/75), and only two patients (3%) needed a second ureteroscopy. Ultimately, all patients achieved the disappearance of gross hematuria, including 13 patients (17%) whose bleeding points were not identified by ureteroscopy. The recurrence-free rate was 100% at a median follow-up of 42 (3-139) months. Conclusions: Compound papillae are more likely to bleed than simple papillae. Therefore, we recommend evaluating the Top and Bottom calices carefully during the initial ureteroscopic observations. Since the patients with confirmed gross hematuria from the unilateral orifice had a higher rate of bleeding point detection than those without confirmation, it is important to perform cystoscopy while the bleeding is persistent.

Power controllable gain switched fiber laser at ~ 3 μm and ~ 2.1 μm

Based on a hybrid pumping method consisting of a 1150 nm continuous-wave pump source and a 1950 nm pulsed pump source, we demonstrate a power controllable gain-switched fiber laser in dual wavebands at ~ 3 μm and ~ 2.1 μm. Different pumping schemes for pumping a Ho³⁺-doped ZBLAN fiber are studied. Using only the 1950 nm pulsed pump source, ~ 2.1 μm gain-switched pulses with single and double pulses are obtained separately at different pump powers. This phenomenon indicates that the 1950 nm pulsed pump source acts as a modulator to trigger different states of the ~ 2.1 μm pulses. Moreover, by fixing the 1150 nm pump power at 3.259 W and adjusting the 1950 nm pump power, the output power of the ~ 2.1 μm gain-switched pulsed laser is flexibly controlled while the ~ 3 μm laser power is almost unchanged, inducing the maximum output powers of 167.96 mW and 260.27 mW at 2910.16 nm and 2061.65 nm, respectively. These results suggest that the comparatively low power of the ~ 2.1 μm gain-switched pulsed laser in dual-waveband laser can be efficiently overcome by reasonably controlling the 1950 nm pump power.

Strike Rate: Analysis of Laser Fiber to Stone Distance During Different Modes of Laser Lithotripsy

Introduction: Different techniques of laser lithotripsy (fragmentation, dusting, and popcorning) are commonly used during ureteroscopy. The efficiency of a single laser pulse is dependent on minimizing laser fiber-stone distance, yet it has not been reported how often the laser fiber is in contact with the stone during laser lithotripsy. In this study, we sought to measure laser fiber to stone distance using light reflectance for each technique of laser lithotripsy. Methods: Continuous light from a 660 nm (red) light-emitting diode (LED) was coupled into a 200 μm fiber using a fiber X-coupler. The LED fiber was positioned immediately next to a 242 μm holmium fiber, and both were passed through the working channel of an ureteroscope. One fiber was used to deliver laser energy to the stone, and the other fiber was used to measure distance based on light reflected from the stone back into the fiber. For fragmentation and dusting experiments, a 5 mm BegoStone was placed into a 20 mm three-dimensional printed caliceal model. For popcorn experiments, 10 BegoStones (3 × 3 × 1.5 mm) were placed in an 11 mm caliceal model and the laser fiber positioned 2 mm away from the stone surface. Data were analyzed using a MATLAB software to report fiber to stone distance at each laser pulse. Results: With fragmentation, 52% of laser pulses were delivered when the fiber was within 0.5 mm of the stone compared to 23% and 4% for dusting and popcorning, respectively. Laser pulses delivered when fiber to stone distance was >1 mm (least effective) accounted for 34%, 48%, and >80% of total pulses during fragmentation, dusting, and popcorning, respectively. Conclusion: Current methods of laser lithotripsy that rely on fixed firing rates are inefficient, especially for the popcorn technique. These data highlight areas for improvement by appropriately gating pulse delivery to maximize lithotripsy effect for each pulse fired.

Superpulsed Thulium Fiber Laser for Stone Dusting: In Search of a Perfect Ablation Regimen-A Prospective Single-Center Study

Objective: To compare the efficacy of the standard and higher frequency regimens for superpulsed thulium fiber laser (SP TFL) retrograde intrarenal surgery (RIRS). Materials and Methods: A prospective study of patients with renal calculi of 10-30 mm was performed. For RIRS, we used the SP TFL (NTO IRE-Polus, Russia) and a 9.5F flexible ureteroscope with 270° deflection and 3.6F working channel. Retropulsion and visibility were assessed based on the surgeon's feedback using three-point Likert scales. The stone-free rate was assessed at 3 months with CT. Results: A total of 40 patients were included in the study with a mean age of 56 years, mean stone density of 880 ± 381 HU, mean stone size of 16.5 ± 6.8 mm, and median stone volume of 883 (interquartile range 606-1664) mm³. Both ablation efficacy and speed were higher in the 200-Hz mode (2.7 J/mm³ vs 3.8 J/mm³ and 5.5 mm³/second vs 8.0 mm³/second, respectively); moreover, the higher frequency correlated with increased ablation speed (r = -0.21, p = 0.019). However, both increased energy and frequency did not lead to increase of laser-on time or intraoperative complication rates. Conclusions: SP TFL is able to effectively disintegrate stones during RIRS with minimal complication rates. The use of higher frequency regimens showed higher efficacy and ablation speed and was not associated with increased complication rates.

Safety, feasibility, and quality of holmium laser en-bloc resection of nonmuscle invasive bladder tumors - A single-center experience

Introduction:

Conventional transurethral resection of bladder tumor (cTURBT), despite its piecemeal resection and associated limitations, remains the most widely practiced technique of TURBT. Resecting the tumor in a single piece would avoid most of the drawbacks of cTURBT. Our objective was to assess the feasibility, safety, and quality of Holmium (Ho) laser en-bloc resection (ERBT) for nonmuscle-invasive bladder cancer (NMIBC).

Materials and Methods:

We retrospectively studied 67 patients who underwent Ho laser EBRT for primary NMIBC. Data were collected regarding tumor size, number and location, intraoperative complications, and postoperative course. Patients were grouped as first 20, next 20 (21–40), and last 27 cases to assess how the quality of resection improved with increasing experience.

Results:

The mean tumor size was 28.7 ± 7.9 mm, with 34.3% of the patients having a tumor larger than 3 cm. While 43 patients (64.17%) had a single tumor, the rest had multiple tumors, ranging from 2 to 9 in number. The mean total duration of resection was 38.7 ± 11.6 min. No case required conversion to cTURBT. No patient experienced obturator reflex or bladder perforation. Detrusor muscle was present in 85.07% of the resections. With increasing experience, requirement for bladder irrigation and the incidence of postoperative clot evacuation decreased (P < 0.0001 and P = 0.31, respectively), and the detrusor-positive rate in the specimen increased (P = 0.24). The mean duration of catheterization was 1.76 ± 0.54 days.

Conclusion:

Ho laser ERBT is safe and feasible for complete resection of NMIBCs with no risk of obturator-nerve reflex and a high rate of detrusor-positive specimens.

A quantitative evaluation of the use of medical lasers in German hospitals

The laser has become an integral part of modern medicine, procedures based on this technique have found their way into a multitude of medical disciplines. There is, however, no data available on the detailed quantitative development of laser use in the medical sector. This fact gave rise to the idea of the present study, which analyzed the raw data of the quality report of German hospitals with respect to this subject. Over the 9 years of report, a steady increase in the cumulative number of cases was evident, although not all body regions in which the medical laser is used followed this trend. The CO₂ laser was found to be the most commonly applied laser, even though a large spectrum of different laser types is used. Based on the present study, the importance of the laser for medical purposes can be confirmed.

Diode Laser Vaporization for Benign Prostate Hyperplasia: Outcome After 126 Procedures

Purpose: Photoselective vaporization of the prostate (PVP) with a 940-nm diode laser is an option for treating symptoms caused by benign prostatic hyperplasia (BPH). Here, we present our experience using this technology. Methods: We prospectively evaluated 126 patients with lower urinary tract symptoms (LUTS) secondary to BPH who underwent PVP with a 940-nm diode laser from January 2011 to January 2014. The patients were assessed using the International Prostate Symptom Score (IPSS), quality of life (QoL) score, prostate-specific antigen (PSA) level, maximum urinary flow (Qmax) by uroflowmetry, postvoid residual volume, and prostate volume by ultrasound at baseline and 3, 6, 12, and 24 months after the procedure. Results: The average patient age was 68.8 ± 8.7 years (range 48-90 years), whereas the average preoperative parameters were as follows: IPSS, 26.1 ± 5.2; IPSS-QoL, 4.9 ± 0.8; Qmax, 4.5 ± 3.1 mL/s; prostate volume, 76.5 ± 35.5 mL; and PSA level, 3.9 ± 2.6 ng/mL. The average catheterization time was 24.7 ± 25.5 hours (range 3-120 hours), and the length of hospital stay was 22.4 ± 17.0 hours (range 8-144 hours). The mean follow-up duration was 17.9 months (range 1-36 months). All parameters showed significant improvement after 12 months. After 24 months, the IPSS (8.8 ± 5.4, p < 0.07), IPSS-QoL (1.6 ± 0.9, p < 0.13), Qmax (15.9 ± 7.3 mL/s, p < 0.11), and PSA level (1.2 ± 0.8 ng/mL, p < 0.11) were improved compared with the baseline, but the difference was not significant, probably due to the small number of patients evaluated in this period. No patients required a transfusion. Conclusions: The results suggest that PVP with a 940-nm diode laser is safe, effective, and durable for the treatment of LUTS secondary to BPH. The patients continue to be monitored for evaluation of the long-term results. A prospective randomized study would allow more solid conclusions regarding the technology to be reached.

Polymer-Mineral Composites Mimic Human Kidney Stones in Laser Lithotripsy Experiments

Despite the widespread use of laser lithotripsy to fragment kidney stones in vivo, there is a lack of robust artificial stone models to replicate the behavior of human stones during lithotripsy procedures. This need for accurate stone models is particularly important as novel laser technologies are introduced in the field of lithotripsy. In this work, we present a method to prepare composite materials that replicate the properties of human kidney stones during laser lithotripsy. Their behavior is understood through the lens of near-IR spectroscopy and helps to elucidate the mechanism of laser lithotripsy in kidney stone materials.

[Evaluation of spinal anesthesia in urological outpatient surgery, comparison between two local anesthetics (Chloroprocaine/Bupivacaine)]

INTRODUCTION

Spinal anesthesia in outpatient urology is controversial (longer hospital stay, risk of urinary retention). The main goal was to evaluate outpatient spinal anesthesia and to compare 2 local anesthetics secondarily.

MATERIAL

Monocentric retrospective study including all patients undergoing surgery in urological ambulatory surgery under spinal anesthesia between December 2011 and May 2015, split into two groups according to the local anesthetic used: bupivacaine (BP) and chloroprocaine (CP). Quantitative variables were compared by Student's t-test, qualitative variables by χ² test.

RESULTS

Seventy-one (95%) out of the 75 patients included have been discharged the same day. Discharge was impossible in these cases: patient alone at home (1), bladder clot (1), JJ intolerance (1), delayed micturition (1). The mean duration of the procedure was 27±19min, the SSPI's was 55±31min, the stay's was 360±91min. A total of 45 patients (60%) received BP and 30 (40%) received CP. The mean residence time in SSPI was significantly reduced in the CP group (47±24min vs. 61±34min, P=0.04). One patient experienced urination delay in the BP group with no significant difference. No significant difference for the other criteria studied despite the mean age, which is higher in the CP group (P=0.02).

CONCLUSION

Spinal anesthesia is adapted to ambulatory urology, and does not increase the risk of urinary retention, especially with CP that would decrease the length of stay in SSPI compared to BP.

LEVEL OF EVIDENCE

4.

Laser Fibers for Holmium:YAG Lithotripsy: What Is Important and What Is New

Holmium:YAG laser is currently the dominant lithotripter used during retrograde intrarenal surgery. The laser energy is delivered to the target via flexible optical laser fibers. The performance characteristics of laser fibers vary. The diameter, flexibility, resistance to fracture with bending, and tip configuration are all important factors that contribute to a fiber's overall performance. Understanding these characteristics assists the end user with proper fiber selection for procedures.

High power holmium:YAG versus thulium fiber laser treatment of kidney stones in dusting mode: ablation rate and fragment size studies

OBJECTIVES

The experimental Thulium fiber laser (TFL) is currently being studied as a potential alternative to the gold standard Holmium:YAG laser for lithotripsy. Recent advances in both Holmium and TFL technology allow operation at similar laser parameters for direct comparison. The use of a "dusting" mode with low pulse energy (0.2-0.4 J) and high pulse rate (50-80 Hz) settings, is gaining popularity in lithotripsy due to the desire to produce smaller residual stone fragments during ablation, capable of being spontaneously passed through the urinary tract.

METHODS

In this study, Holmium and TFL were directly compared for 'dusting' using three laser groups, G1: 0.2 J/50 Hz/10 W; G2: 0.2 J/80 Hz/16 W; and G3: 0.4 J/80 Hz/32 W. Holmium laser pulse durations ranged from 200 to 350 μs, while TFL pulse durations ranged from 500 to 1,000 μs, due to technical limitations for both laser systems. An experimental setup consisting of 1 × 1 cm cuvette with 1 mm sieve was used with continuous laser operation time limited to ≤5 minutes. Calcium oxalate monohydrate stone samples with a sample size of n = 5 were used for each group, with average initial stone mass ranging from 216 to 297 mg among groups.

RESULTS

Holmium laser ablation rates were lower than for TFL at all three settings (G1: 0.3 ± 0.2 vs. 0.8 ± 0.2; G2: 0.6 ± 0.1 vs. 1.0 ± 0.4; G3: 0.7 ± 0.2 vs. 1.3 ± 0.9 mg/s). The TFL also produced a greater percentage by mass of stone dust (fragments <0.5 mm) than Holmium laser. For all three settings combined, one out of 15 (7%) stones treated with Holmium laser were completely fragmented in ≤5 minutes compared to nine out of 15 (60%) stones treated with TFL.

CONCLUSIONS

These preliminary studies demonstrate that the TFL is a promising alternative laser for lithotripsy when operated in dusting mode, producing higher stone ablation rates and smaller stone fragments than the Holmium laser. Clinical studies are warranted. Lasers Surg. Med. 51:522-530, 2019. © 2019 Wiley Periodicals, Inc.

Laparoscopic nephroureterectomy with laser endoscopic transuretral disinsertion in lateral decubitus: progressive adaptation to retroperitoneocopic approach

BACKGROUND

The ureteral disinsertion with bladder cuff technique continues to evolve. We present the endoscopic laser transurethral technique combined with a transperitoneal and retroperitoneal laparoscopic approach in lateral decubitus, without patient repositioning, for treating urothelial carcinomas of the upper urinary tract.

MATERIALS AND METHODS

We present 3 laparoscopic nephroureterectomies: 1 transperitoneal and 2 retroperitoneal. Disinsertion was performed in lateral decubitus using a flexible cystoscope and a 365-μm holmium laser fiber. The endoscopic technique was progressively adapted to 3-port and single-port retroperitoneoscopic approaches. Before laparoscopic handling of the kidney, ureter was clamped below the tumour. The endoscopic technique was then started. Both approaches were simultaneously employed.

RESULTS

Nephroureterectomies were achieved performing en bloc endoscopic disinsertion of the bladder cuff and ensuring a closed system comparable to open technique. The second case required reconversion due to technical problems and extension of the surgical time. No relapses were diagnosed during follow-up.

CONCLUSION

Results are comparable to open surgery, technique ensured compliance to oncology principles, enabled disinsertion in lateral decubitus and avoid patient repositioning saving surgical time. The results reflect the benefits of minimally invasive surgery in all cases.

Numerical Response Surfaces of Volume of Ablation and Retropulsion Amplitude by Settings of Ho:YAG Laser Lithotripter

Objectives

Although laser lithotripsy is now the preferred treatment option for urolithiasis due to shorter operation time and a better stone-free rate, the optimal laser settings for URS (ureteroscopic lithotripsy) for less operation time remain unclear. The aim of this study was to look for quantitative responses of calculus ablation and retropulsion by performing operator-independent experiments to determine the best fit versus the pulse energy, pulse width, and the number of pulses.

Methods

A lab-built Ho:YAG laser was used as the laser pulse source, with a pulse energy from 0.2 J up to 3.0 J and a pulse width of 150 μs up to 1000 μs. The retropulsion was monitored using a high-speed camera, and the laser-induced craters were evaluated with a 3-D digital microscope. The best fit to the experimental data is done by a design of experiment software.

Results

The numerical formulas for the response surfaces of ablation speed and retropulsion amplitude are generated.

Conclusions

The longer the pulse, the less the ablation or retropulsion, while the longer pulse makes the ablation decrease faster than the retropulsion. The best quadratic fit of the response surface for the volume of ablation varied nonlinearly with pulse duration and pulse number.

Laser Application in Iran Urology: A Narrative Review

The usage of laser in medicine is not recent, and its history in urology goes back to 40 years ago. For the last 2 decades, common uses of laser have been treatments of subjects with urolithiasis, bladder tumors, benign prostatic enlargement, lesions of the genitalia and urinary tract strictures. To evaluate laser application in urology in Iran, we reviewed all of the Iranian literature on the topic. This study was designed to retrieve all studies on laser application in urology in Iran, regardless of publication status or language, covering years 1990-2017. Twenty-six articles were identified: 12 about urolithiasis, 8 about benign prostatic hyperplasia (BPH), 2 case reports, 1 paper about prostate cancer, 1 on female urethral stricture, 1 review and 1 basic sciences study. We conclude that the use of this technology has not yet found its position in Iran, especially in the field of urology. The main causes for it are the difficult accessibility and disturb of laser devices and its accessories, as well as the lack of adequate knowledge of the medical community about this modality.

Moses technology in a stone simulator

INTRODUCTION

The objective of this study was to compare fragmentation efficiency of the conventional regular mode of holmium laser to the Moses contact mode on a stone simulator.

METHODS

The Lumenis^® Pulse^TM P120 H holmium laser system, together with Moses D/F/L fibers were used to compare regular mode with Moses contact mode in a stone simulator model using flexible ureteroscopy with artificial stones. Efficiency of laser lithotripsy was measured by procedural time. Degree of stone retropulsion was also compared between regular and Moses modes using a Likert scale from 0 (no retropulsion) to 3 (maximum retropulsion).

RESULTS

Using the stone simulator model, a significant reduction in stone retropulsion was noticed when comparing regular mode to the Moses contact mode (mean Grade 2.5 vs. Grade 1; p<0.01). When compared with the regular mode, the Moses contact mode was associated with significantly shorter procedural time during fragmentation (13.9 vs. 9.1 minutes; p≤0.01) and dusting (9.3 vs. 7.1 minutes; p≤0.01). In addition, when compared with the regular mode, the laser pedal was pressed significantly less often with the Moses mode during fragmentation (86 vs. 43 times; p<0.01) and dusting (50 vs. 26 times; p<0.01). Moses contact mode was associated with significantly higher percentage of lasing vs. pausing when compared with the regular mode for both fragmentation (0.8 J/10 Hz) and pulverization (0.4 J/50 Hz) settings (both p<0.05).

CONCLUSIONS

Using the stone simulator setup, Moses technology was associated with more efficient laser lithotripsy (shorter operative time) due to significantly reduced stone retropulsion.

Intracorporeal lithotripsy

Since the introduction of ESWL, PNL and URS during the early 1980s the application rate of ESWL has declined while those of PNL and URS have increased. This is mainly due to the facts that instruments and techniques for Intracorporeal Lithotripsy (IL) have made a continuous progress. This review shows that today an array of options for IL within the entire urinary tract is available to treat stones in a perfect minimal invasive way. At the same time further improvements of IL are already visible.

Biomedical device innovation methodology: applications in biophotonics

The process of medical device innovation involves an iterative method that focuses on designing innovative, device-oriented solutions that address unmet clinical needs. This process has been applied to the field of biophotonics with many notable successes. Device innovation begins with identifying an unmet clinical need and evaluating this need through a variety of lenses, including currently existing solutions for the need, stakeholders who are interested in the need, and the market that will support an innovative solution. Only once the clinical need is understood in detail can the invention process begin. The ideation phase often involves multiple levels of brainstorming and prototyping with the aim of addressing technical and clinical questions early and in a cost-efficient manner. Once potential solutions are found, they are tested against a number of known translational factors, including intellectual property, regulatory, and reimbursement landscapes. Only when the solution matches the clinical need, the next phase of building a "to market" strategy should begin. Most aspects of the innovation process can be conducted relatively quickly and without significant capital expense. This white paper focuses on key points of the medical device innovation method and how the field of biophotonics has been applied within this framework to generate clinical and commercial success.

Analysis of Thermally Denatured Depth in Laser Vaporization for Benign Prostatic Hyperplasia using a Simulation of Light Propagation and Heat Transfer (secondary publication)

Background and Aims: Laser vaporization of the prostate is expected as a less invasive treatment for benign prostatic hyperplasia (BPH), via the photothermal effect. In order to develop safer and more effective laser vaporization of the prostate, it is essential to set optimal irradiation parameters based on quantitative evaluation of temperature distribution and thermally denatured depth in prostate tissue. Method: A simulation model was therefore devised with light propagation and heat transfer calculation, and the vaporized and thermally denatured depths were estimated by the simulation model. Results: The results of the simulation were compared with those of an ex vivo experiment and clinical trial. Based on the accumulated data, the vaporized depth strongly depended on the distance between the optical fiber and the prostate tissue, and it was suggested that contact laser irradiation could vaporize the prostate tissue most effectively. Additionally, it was suggested by analyzing thermally denatured depth comprehensively that laser irradiation at the distance of 3 mm between the optical fiber and the prostate tissue was useful for hemostasis. Conclusions: This study enabled quantitative and reproducible analysis of laser vaporization for BPH and will play a role in clarification of the safety and efficacy of this treatment.

Endoscopic treatment of Bouverets syndrome in an extremely elderly patient with Holmium: YAG laser

Bouveret's syndrome is a rare presentation of duodenal obstruction or gastric outlet obstruction caused by a large gallstone migrating through a cholecystoduodenal or choledochoduodenal fistula. Most patients are elderly and often have underlying comorbidities, complicating surgery. Endoscopic therapy should be used as first-line treatment for these patients who are not good surgical candidates. We report a case of a 98-year-old Chinese female who presented with vomiting for three days. Esophagogastroduodenoscopy and computed tomography confirmed the diagnosis of Bouveret's syndrome. The patient successfully underwent endoscopic lithotripsy with the Holmium: Yttrium- Aluminum-Garnet (Ho: YAG) laser. Ho: YAG laser lithotripsy has been used to treat Bouveret's syndrome in four case reports. It can be recommended in patients with Bouveret's syndrome who are poor candidates for surgery.

SIMILAR CASES PUBLISHED

4.

Evaluation of dusting versus basketing - can new technologies improve stone-free rates?

Over the past two decades, the management of upper-tract urinary stones has dramatically changed towards an increase in the use of ureteroscopic treatment. This change has been driven by technological advances such as the creation of flexible ureteroscopes with reduced calibre (which now have digital, disposable and dual flexion capability) and holmium lasers with increased power. Two basic principles exist when treating stones ureteroscopically: either creating stone dust and small fragments (<1-2 mm) to theoretically enable spontaneous passage of the small particles or stone fragmentation that enables safe extraction of the stone pieces with a basket or grasper in an efficient manner. Each method has unique advantages and disadvantages, but, ultimately, surgeon preference, stone size, composition, location and intrarenal and/or ureteral anatomy determine which technique is used. To date, clinical trials comparing these two techniques are lacking.

Continuous-wave and quasi-continuous wave thulium-doped all-fiber laser: implementation on kidney stone fragmentations

A continuous-wave (CW) as well as quasi-continuous wave (QCW) thulium-doped all-fiber laser at 1.94 μm has been designed for targeting applications in urology. The thulium-doped active fiber with an octagonal-shaped inner cladding is pumped at 793 nm to achieve stable CW laser power of 10 W with 32% lasing efficiency (against launched pump power). The linear variation of laser power with pump offers a scope of further power scaling. A QCW operation with variation of duty cycle from 0.5% to 90%, repetition rate from 0.1 Hz to 1 kHz, and pulse width from 40 μs to 2 s has been presented. Laser power of 9.5 W in CW mode of operation and average power of 5.2 W with energy range of 10.4-104 mJ in QCW mode of operation has been employed to fragment calcium oxalate monohydrate kidney stones (size of 1.5-4 cm) having different colors and composition. Dependence of ablation threshold, ablation rate, and average fragmented particle size on the average power and energy has been studied. One minute of laser exposure results in fragmentation of a stone surface with ablation rate of 8  mg/min having minimum particle size of 6.54 μm with an average size of 20-100 μm ensuring the natural removal of fragmented parts through the urethra.

Comparison of a New High-Frequency Electric Welding System for Intestinal Closure with Hand-Sewn In Vivo Pig Model

BACKGROUND

Various surgical small intestinal anastomosis methods are in current use, but improvements are always desired. Thus, we compared the feasibility, effectiveness, and safety of a new high-frequency electric welding (HFEW) system for sealing the small bowel versus a hand-sewn in vivo pig model.

MATERIALS AND METHODS

The 96 bowel segments of three pigs were randomized to be sutured either by the HFEW-300 PATONMED device (E.O. Paton Electric Welding Institute of the National Academy of Sciences of Ukraine, Kiev, Ukraine) or hand-sewn, and mucosa-to-mucosa fusions were subjected in vivo testing in the pigs. Bursting pressures, suture time, thermal damage, and the temperature of sealed ends were measured.

RESULTS

Segments that had been treated with a hand-sutured ligature or double-sealed with HFEW were compared. Burst pressure was significantly higher in the hand-sutured group than in the HFEW group (136.2 mm Hg versus 75.8 mm Hg, P<.01). All 48 pig small bowels closed by the HFEW-300 generator showed a success rate of 100.0%. The closing time in the HFEW group was significantly shorter (P<.01). The pathological changes of the closed ends were mainly presented as acute thermal- and pressure-induced injuries.

CONCLUSIONS

Outcomes of the current in vivo study suggest that HFEW is an effective and safe method for ligation of the small bowel in pigs.

Wound healing in urology

Wound healing is a dynamic and complex phenomenon of replacing devitalized tissues in the body. Urethral healing takes place in four phases namely inflammation, proliferation, maturation and remodelling, similar to dermal healing. However, the duration of each phase of wound healing in urology is extended for a longer period when compared to that of dermatology. An ideal wound dressing material removes exudate, creates a moist environment, offers protection from foreign substances and promotes tissue regeneration. A single wound dressing material shall not be sufficient to treat all kinds of wounds as each wound is distinct. This review includes the recent attempts to explore the hidden potential of growth factors, stem cells, siRNA, miRNA and drugs for promoting wound healing in urology. The review also discusses the different technologies used in hospitals to treat wounds in urology, which make use of innovative biomaterials synthesised in regenerative medicines like hydrogels, hydrocolloids, foams, films etc., incorporated with growth factors, drug molecules or nanoparticles. These include surgical zippers, laser tissue welding, negative pressure wound therapy, and hyperbaric oxygen treatment.

Impact of pulse duration on Ho:YAG laser lithotripsy: treatment aspects on the single-pulse level

OBJECTIVES

Holmium-YAG (Ho:YAG) laser lithotripsy is a multi-pulse treatment modality with stochastic effects on the fragmentation. In vitro investigation on the single-pulse-induced effects on fiber, repulsion as well as fragmentation was performed to identify potential impacts of different Ho:YAG laser pulse durations.

MATERIALS AND METHODS

A Ho:YAG laser system (Swiss LaserClast, EMS S.A., Nyon, Switzerland) with selectable long- or short-pulse mode was tested with regard to fiber burn back, the repulsion capacity using an underwater pendulum setup and single-pulse-induced fragmentation capacity using artificial (BEGO) stones. The laser parameters were chosen in accordance with clinical application modes (laser fiber: 365 and 200 µm; output power: 4, 6 and 10 W in different combinations of energy per pulse and repetition rate). Evaluation parameters were reduction in fiber length, pendulum deviation and topology of the crater.

RESULTS

Using the long-pulse mode, the fiber burn back was nearly negligible, while in short-pulse mode, an increased burn back could be observed. The results of the pendulum test showed that the deviation induced by the momentum of short pulses was by factor 1.5-2 higher compared to longer pulses at identical energy per pulse settings. The ablation volumes induced by single pulses either in short-pulse or long-pulse mode did not differ significantly although different crater shapes appeared.

CONCLUSION

Reduced stone repulsion and reduced laser fiber burn back with longer laser pulses may result in a more convenient handling during clinical application and thus in an improved clinical outcome of laser lithotripsy.

Impact of pulse duration on Ho:YAG laser lithotripsy: fragmentation and dusting performance

Objectives

In vitro investigations of Ho:YAG laser-induced stone fragmentation were performed to identify potential impacts of different pulse durations on stone fragmentation characteristics.

Materials and methods

A Ho:YAG laser system (Swiss LaserClast, EMS S.A., Nyon, Switzerland) with selectable long or short pulse mode was tested with regard to its fragmentation and laser hardware compatibility properties. The pulse duration is depending on the specific laser parameters. Fragmentation tests (hand-held, hands-free, single-pulse-induced crater) on artificial BEGO stones were performed under reproducible experimental conditions (fibre sizes: 365 and 200 µm; laser settings: 10 W through combinations of 0.5, 1, 2 J/pulse and 20, 10, 5 Hz, respectively).

Results

Differences in fragmentation rates between the two pulse duration regimes were detected with statistical significance for defined settings. Hand-held and motivated Ho:YAG laser-assisted fragmentation of BEGO stones showed no significant difference between short pulse mode and long pulse mode, neither in fragmentation rates nor in number of fragments and fragment sizes. Similarly, the results of the hands-free fragmentation tests (with and without anti-repulsion device) showed no statistical differences between long pulse and short pulse modes.

Conclusion

The study showed that fragmentation rates for long and short pulse durations at identical power settings remain at a comparable level. Longer holmium laser pulse duration reduces stone pushback. Therefore, longer laser pulses may result in better clinical outcome of laser lithotripsy and more convenient handling during clinical use without compromising fragmentation effectiveness.

Optimizing use of the holmium:YAG laser for surgical management of urinary lithiasis

The holmium:yttrium aluminum garnet (Ho:YAG, holmium) laser is an intracorporeal lithotrite that is widely used in the surgical management of urinary lithiasis. The Ho:YAG laser is capable of fragmenting urinary stones of all compositions while maintaining a wide margin of safety. The 2140-nm wavelength of energy is transmitted from the generator to the stone using specialized silica optical fibers. The effectiveness of the laser can be impacted by the type of laser fiber used, the pulse energy and frequency settings, and the composition of the stone. This paper provides an overview of Ho:YAG laser fibers utilized for lithotripsy during ureteroscopy. We will also review current data regarding optimal energy settings and discuss our experience with different fragmentation techniques.

Ex vivo efficacy evaluation of laser vaporization for treatment of benign prostatic hyperplasia using a 300-W high-power laser diode with a wavelength of 980 nm

BACKGROUND AND OBJECTIVE

Laser vaporization of the prostate is considered to be a promising treatment for benign prostatic hyperplasia (BPH), and efficiency of vaporization and hemostasis are both important parameters for such treatment. In this study, we used a high-power laser diode with a wavelength of 980 nm to obtain high vaporization efficiency with good hemostasis. The objective of this study is to evaluate the efficacy of laser vaporization for treatment of BPH in ex vivo experiments using a 300-W high-power laser diode with a wavelength of 980 nm quantitatively.

MATERIALS AND METHODS

An ex vivo experimental setup simulating clinical treatment situation was constructed. Bovine prostate tissue was used as a sample. The power setting was 100, 150, 200, 250, or 300 W, and the irradiation time was 0.5, 1, or 2 s. After laser irradiation, vaporized and coagulated depths were measured.

RESULTS

The vaporized depth increased with the laser power and irradiation time, and the results confirmed that the high-power laser diode could efficiently vaporize the prostate tissue. Coagulated depth increased as the laser power became higher.

CONCLUSIONS

Laser vaporization of prostate tissue using a high-power laser diode with a wavelength of 980 nm represents a promising treatment for BPH; this method exhibits high vaporization efficiency and good hemostasis. However, operators must be aware of the risk of postoperative perforation of the prostatic capsule caused by coagulation of deep regions that cannot be visualized by endoscopic observation.

Pushing the boundaries of ureteroscopy: current status and future perspectives

Substantial advances in ureteroscopy have resulted in the incorporation of this procedure into routine urological practice in many centres worldwide. Subsequently, an abundance of clinical data and technological progression have enabled the development of novel solutions that have increased the efficacy of ureteroscopy, and reduced associated morbidity and costs. In addition the indications for this retrograde approach have been expanded, and pyelocalyceal diverticulum, infundibular stenosis, urolithiasis in pregnant women or in patients with urinary diversions, as well as upper urinary tract tumours can now be managed using this methodology. New endoscopes are continuously developed, with different manufacturers choosing various technical solutions to further increase the efficacy and safety-and sometimes decrease costs-of ureteroscopy, including miniaturization, inclusion of digital optical systems and dual working channels, and the introduction of disposable apparatus. The holmium laser, currently the most-versatile energy source available, enables tissue incision, tumour ablation, and intracorporeal lithotripsy. Modern ancillary instruments are diverse, flexible, and durable, and novel devices used in daily clinical practice can minimize ascendant migration of stone fragments and, therefore, decrease the failure rate of the retrograde ureteroscopic approach. However, the peak of ureteroscopy evolution seems to remain distant, with further improvement of endoscopes and ancillary instruments, and robot-assisted ureteroscopy representing only some of the areas in which future developments are possible.

High-energy pulsed Raman fiber laser for biological tissue coagulation

We demonstrate a high-energy pulsed Raman fiber laser (RFL) with an emission wavelength of 1.44 μm, corresponding to an absorption peak of water. Microsecond pulses with >20 mJ/pulse and >40 W peak power were generated, well above the threshold for tissue coagulation and ablation. Here, we focus on the optical characterization and optimization of high-energy and high-power RFLs excited by an ytterbium fiber laser, comparing three configurations that use different Raman gain fibers, but all of which were prepared with a one-side opened, free-run mode without output mirrors. We show that the free-run configuration can generate sufficiently high energy without requiring a closed cavity design. Experimental RFL characteristics corresponded well with numerical simulations. We discuss the Stokes beam generation process in our system and loss mechanisms mainly associated with fiber Bragg gratings.

Comparison of outpatient versus inpatient transurethral prostate resection for benign prostatic hyperplasia: Comparative, prospective bi-centre study

INTRODUCTION

We compare the symptomatic relief with urodynamic parameter change and operative safety of the outpatient transurethral resection in saline (TURIS-V) technique with inpatient transurethral resection of the prostate (TURP) for the management of benign prostatic hyperplasia (BPH).

METHODS

This prospective cohort comparison study enrolled patients who needed BPH surgery. Between January 2010 and June 2011, outpatient TURIS-V was performed at 1 centre and the results of the treatment were compared with inpatient TURP performed at a separate hospital. Preoperative characteristics, including prostate volume, were similar in both groups. Perioperative data and any treatment complications were recorded. The analysis compared postoperative outcomes, including a 6-month postoperative International Prostate Symptom Score (IPSS), a quality of life (QoL) evaluation and a record of any changes in uroflowmetry findings, between the 2 groups.

RESULTS

In the TURIS-V patient group, 75 patients agreed to be in the study. Of these, 69 ultimately complete the study. In the TURP group, 76 patients agreed and 71 of these completed the study. Both study groups were well-matched for age, IPSS, QoL and uroflowmetry findings. The TURIS-V group experienced both shorter operation times (54.6 vs. 74.8 minutes) and shorter catheterization times (2.2 vs. 4.2 days) when compared to the TURP group. There were comparable improvements in the 6-month postoperative IPSS, QoL, and uroflowmetry findings between the 2 groups. There were also equally low incidence rates of procedural complications.

CONCLUSIONS

Both TURIS-V and TURP relieve lower urinary tract symptoms in a similar way, with great efficacy and safety. Overall, TURIS-V had shorter operative and catheterization times compared to TURP. Notwithstanding the paper's limitations (non- randomized cohort comparison with possible selection or surgeon bias and small heterogeneous sample size), TURIS-V can be performed safely even in an outpatient setting.