OBJECTIVE: To assess laser-tissue interactions through ablation, coagulation, and carbonisation characteristics in a non-perfused porcine kidney model between three pulsed lasers: holmium (Ho): yttrium-aluminium-garnet (YAG), thulium fiber laser (TFL), and pulsed thulium (p-Tm):YAG.
METHODS: A 150-W Ho:YAG, a 60-W TFL, and a 100-W p-Tm:YAG lasers were compared. The laser settings that can be set identically between the three lasers and be clinically relevant for prostate laser enucleation were identified and used on fresh, unfrozen porcine kidneys. Laser incisions were performed using stripped laser fibers of 365 and 550 μm, set at distances of 0 and 1 mm from the tissue surface at a constant speed of 2 mm/s. Histological analysis evaluated shape, depth, width of the incision, axial coagulation depth, and presence of carbonisation.
RESULTS: Incision depths, widths, and coagulation zones were greater with Ho:YAG and p-Tm:YAG lasers than TFL. Although no carbonisation was found with the Ho:YAG and p-Tm:YAG lasers, it was common with TFL, especially at high frequencies. The shapes of the incisions and coagulation zones were more regular and homogeneous with the p-Tm:YAG laser and TFL than with Ho:YAG laser. Regardless of the laser used, short pulse durations resulted in deeper incisions than long pulse durations. Concerning the distance, we found that to be effective, TFL had to be used in contact with the tissue. Finally, 365-μm fibers resulted in deeper incisions, while 550-μm fibers led to wider incisions and larger coagulation zones.
CONCLUSIONS: Histological analysis revealed greater tissue penetration with the p-Tm:YAG laser compared to the TFL, while remaining less than with Ho:YAG. Its coagulation properties seem interesting insofar as it provides homogeneous coagulation without carbonisation, while incisions remained uniform without tissue laceration. Thus, the p-Tm:YAG laser appears to be an effective alternative to Ho:YAG and TFL lasers in prostate surgery.

Ho: YAG laser lithotripsy is widely used for urinary stone treatment, but concerns persist regarding its thermal effects on renal tissues. This study aimed to monitor intrarenal temperature changes during kidney stone treatment using retrograde intrarenal surgery with Ho: YAG laser. Fifteen patients were enrolled. Various laser power settings (0.8 J/10 Hz, 1.2 J/12 Hz) and irrigation modes (10 cc/min, 15 cc/min, 20 cc/min, gravity irrigation, and manual pump irrigation) were used. A sterile thermal probe was attached to a flexible ureterorenoscope and delivered into the calyceal system via the ureteral access sheath. Temperature changes were recorded with a T-type thermal probe with ± 0.1 °C accuracy. Laser power significantly influenced mean temperature, with a 4.981 °C difference between 14 W and 8 W laser power (p < 0.001). The mean temperature was 2.075 °C higher with gravity irrigation and 2.828 °C lower with manual pump irrigation (p = 0.038 and p = 0.005, respectively). Body mass index, laser power, irrigation model, and operator duty cycle explained 49.5% of mean temperature variability (Adj. R2 = 0.495). Laser power and operator duty cycle positively impacted mean temperature, while body mass index and specific irrigation models affected it negatively. Laser power and irrigation rate are critical for intrarenal temperature during Ho: YAG laser lithotripsy. Optimal settings and irrigation strategies are vital for minimizing thermal injury risk. This study underscores the need for ongoing research to understand and mitigate thermal effects during laser lithotripsy.

UNASSIGNED: To evaluate the efficacy and safety of Holmium: Yttrium-Aluminum-Garnet (Ho:YAG) laser in bladder lithotripsy using high-power settings > 100 W.
UNASSIGNED: A combined experimental and clinical study was conducted. The Quanta Cyber: Ho 150 with a 550 μm Quanta optical fiber was utilized in all set-ups. Ablation rates for soft and hard artificial stones were tested in vitro using 100 W and 20 W power settings. In the experiment, a porcine bladder was used. The optical fiber was inserted through a rigid cystoscope, whilst a K-type thermocouple was inserted in the bladder dome. The tested high-power settings were 152 W, 120 W and 105 W. In every trial, the lasing time was over 60 s. In the clinical study, 35 patients underwent transurethral high-power bladder lithotripsy. Laser settings were set between 100 W and 150 W.
UNASSIGNED: Stone mass (stone weight) was significantly lower after stone ablation independently of the stone type or the laser settings. Significantly higher mass decrease and ablation rate were detected in high-power compared to low-power settings. In the experiment, the highest temperature recorded was 32°C at 152 W. At 120 W and 105 W, the peak temperatures didn\'t reach 30°C. In the clinical study, a stone-free rate of 100% and a mean operative time of 43 ± 18 min were reported. All patients stayed in the hospital for one day except for one who presented minor hematuria. Additional complications did not occur.
UNASSIGNED: Ho:YAG laser lithotripsy > 100 W is an effective, fast and safe modality for the treatment of bladder calculi.

OBJECTIVE: The risk of thermal damage increases with the introduction of high-power lasers during holmium laser lithotripsy. This study aimed to quantitatively evaluate the temperature change of renal calyx in the human body and the 3D printed model during high-power flexible ureteroscopic holmium laser lithotripsy and map out the temperature curve.
METHODS: The temperature was continuously measured by a medical temperature sensor secured to a flexible ureteroscope. Between December 2021 and December 2022, willing patients with kidney stones undergoing flexible ureteroscopic holmium laser lithotripsy were enrolled. High frequency and high-power settings (24 W, 80 Hz/0.3 J and 32 W, 80 Hz/0.4 J) were performed for each patient with room temperature (25 °C) irrigation. In the 3D printed model, we studied more holmium laser settings (24 W, 80 Hz/0.3 J, 32 W, 80 Hz/0.4 J and 40 W, 80 Hz/0.4 J) with warmed (37 °C) and room temperature (25 °C) irrigation.
RESULTS: Twenty-two patients were enrolled in our study. With 30 ml/min or 60 ml/min irrigation, the local temperature of the renal calyx did not reach 43 °C in any patient under 25 °C irrigation after 60 s laser activation. There were similar temperature changes in the 3D printed model with the human body under the irrigation of 25 °C. Under the irrigation of 37 °C, the temperature rise slowed down, but the temperature in the renal calyces was close to or even exceeded the 43 °C at the setting of 32 W, 30 ml/min and 40 W, 30 ml/min after continuing laser activation.
CONCLUSIONS: In the irrigation of 60 ml/min, the temperature in the renal calyces can still be maintained within a safe range after continuous activation of a holmium laser up to 40 W. However, continuous activation of 32 W or higher power holmium laser in the renal calyces for more than 60 s in the limited irrigation of 30 ml/min can cause excessive local temperature, in such situation room temperature perfusion at 25 ℃ may be a relatively safer option.

The goal of this study was to assess the ablation, coagulation, and carbonization characteristics of the holmium:YAG (Ho:YAG) laser and thulium fiber lasers (TFL). The Ho:YAG laser (100 W av.power), the quasi-continuous (QCW) TFL (120 W av.power), and the SuperPulsed (SP) TFL (50 W av.power) were compared on a non-frozen porcine kidney. To control the cutting speed (2 or 5 mm/s), an XY translation stage was used. The Ho:YAG was tested using E = 1.5 J and Pav = 40 W or Pav = 70 W settings. The TFL was tested using E = 1.5 J and Pav = 30 W or Pav = 60 W settings. After ex vivo incision, histological analysis was performed in order to estimate thermal damage. At 40 W, the Ho:YAG displayed a shallower cutting at 2 and 5 mm/s (1.1 ± 0.2 mm and 0.5 ± 0.2 mm, respectively) with virtually zero coagulation. While at 70 W, the minimal coagulation depth measured 0.1 ± 0.1 mm. The incisions demonstrated zero carbonization. Both the QCW and SP TFL did show effective cutting at all speeds (2.1 ± 0.2 mm and 1.3 ± 0.2 mm, respectively, at 30 W) with prominent coagulation (0.6 ± 0.1 mm and 0.4 ± 0.1 mm, respectively, at 70 W) and carbonization. Our study introduced the TFL as a novel efficient alternative for soft tissue surgery to the Ho:YAG laser. The SP TFL offers a Ho:YAG-like incision, while QCW TFL allows for fast, deep, and precise cutting with increased carbonization.

OBJECTIVE: The aim of this study was to compare the thermal effects of Ho:YAG and Tm-fiber lasers during lithotripsy in an in-vitro model via real-time temperature measurement.
METHODS: We compared a Ho:YAG laser (pav up to 100 W, Lumenis, Yokneam, Israel) and a superpulse Tm-fiber laser (SP TFL, pav up to 40 W, NTO IRE-Polus, Fryazino, Russia), both equipped with 200 µm bare-ended fibers. The following settings were used: 0.2 J, 40 Hz (nominal pav 8 W). Power meter FieldMaxII-TO (Coherent, Santa Clara, CA, USA) was used to verify output laser power (pav). Each laser was fired for 60 s in two setups: (1) thermos-insulated (quasi-adiabatic) cuvette; (2) actively irrigated setup with precise flow control (irrigation rates 0, 10, 35 mL/min).
RESULTS: Power measurements performed before the test revealed a 10% power drop in Ho:YAG (up to 7.2 ± 0.1 W) and 6.25% power drop in SP TFL (up to 7.5 ± 0.1). At the second step of our experiment, irrigation reduced the respective temperatures in the same manner for both lasers (e.g., at 35 mL/s SP TFL - 1.9 °C; for Ho:YAG laser - 2.8 °C at 60 s).
CONCLUSIONS: SP TFL and Ho:YAG lasers are not different in terms of volume-averaged temperature increase when the same settings are used in both lasers. Local temperature rises may fluctuate to some degree and differ for the two lasers due to varying jet streaming caused by non-uniform heating of the aqueous medium by laser light.

Introduction: There are two main mechanisms of stone ablation with long-pulsed infrared lasers: photothermal and photomechanical. Which of them is primary in stone destruction is still a matter of discussion. Water holds importance in both mechanisms but plays a major role in the latter. We sought to identify the prevailing mechanism of stone ablation by evaluating the stone mass loss after lithotripsy in different media. Materials and Methods: We tested a holmium:yttrium-aluminum-garnet (Ho:YAG) laser (100 W; Lumenis), a thulium-fiber laser U1 (TFL U1) (120 W; NTO IRE-Polus, Russia), and a SuperPulse thulium-fiber laser U2 (TFL U2) (500 W; NTO IRE-Polus). A single set of laser parameters (15 W = 0.5 J × 30 Hz) was used. Contact lithotripsy was performed in phantoms (BegoStones) in different settings: (a) hydrated phantoms in water, (b) hydrated phantoms in air, (c) dehydrated phantoms in water, and (d) dehydrated phantoms in air. Laser ablation was performed with total energy of 0.3 kJ. Phantom mass loss was defined as the difference between the initial phantom mass and the final phantom mass of the ablated phantoms. Results: All lasers demonstrated effective ablation in hydrated phantoms ablated in water; no visual differences between the lasers were detected. The ablation of dehydrated phantoms in air was also effective with visible vapor during ablation and condensation on the cuvette wall. Dehydrated phantoms in water and in air show minimal to no ablation accompanied with formation of white crust on phantom surface. Among laser types, TFL U2 had the highest phantom mass loss in all groups except for dehydrated phantoms ablated in air. Conclusions: Our results suggest that both photothermal and thermomechanical ablation mechanisms (explosive vaporization) occur in parallel during laser lithotripsy. In Ho:YAG and TFL U2 stone ablation explosive vaporization prevails, whereas in TFL U1 ablation photothermal mechanism appears to predominate.

Introduction: Presently, different holmium: yttrium aluminum garnet (Ho:YAG) laser calibers are used for endoscopic stone treatment, which include 200, 365, 500 and 1000 Mm fibers. Currently, there are not enough studies to compare the performance of these fibers. In this retrospective investigation, we compared the outcome of 200, 365 and 500 Mm fibers of Ho:YAG laser in transurethral lithotripsy of ureteral stone. Methods: From January 2016 to June 2017, 74 subjects with mean age of 35.3 ± 5.6 were randomly allocated to 3 groups according to the caliber of laser, 200, 365 and 500 Mm for transurethral lithotripsy. The main purpose of this investigation was to evaluate mean operation time (MOT), stone free rate (SFR) and complications. Results: MOT and SFR were significantly different in 500 Mm laser caliber (P=0.046, P=0.029, respectively). There was no remarkable difference between the 3 groups in this regard. Conclusion: Based upon our data, the clinical potency of the Ho: YAG laser was great in all 3 fiber calibers. The most important results of this comparison were the significantly higher SFR with increased laser caliber.

The objective of this study was to evaluate the safety and efficacy of flexible ureteroscopy (FURS) and holmium:YAG laser lithotripsy for the treatment of upper urinary tract stones in patients on active oral anticoagulants. The records of 1081 patients who underwent flexible ureteroscopic holmium:YAG (Ho:YAG) laser lithotripsy for upper ureteral and renal calculi from 1999 to 2015 were retrospectively reviewed. A total of 84 patients on continuous oral anticoagulation or antiplatelet therapy (warfarin, aspirin, or clopidogrel) were identified. Of these patients, 40 were on warfarin, 25 on aspirin, 11 on clopidogrel, and 8 on both aspirin and clopidogrel. The drugs were not discontinued. The baseline characteristics, indications for anticoagulation therapy, perioperative data, stone-free rate, and complications were documented. Evaluation of outcomes was assessed at 1-, 3-, and 6-month follow-up postoperatively. Mean stone size was 19.7 ± 9.4 (range 8 to 31 mm). Twenty patients had upper ureteral and 64 patients had intrarenal calculi. Two patients had bilateral renal calculi. Mean operation time was 78.2 ± 23.8 min (range 17 to 144 min). Two procedures (2.3%) in warfarin group were terminated due to persistent bleeding causing visual impairment. No transfusions were required. The mean serum hemoglobin levels did not change significantly (12.9 ± 3.7 to 12.2 ± 3.3 g/dL). No thromboembolic or cardiac adverse events were observed perioperatively. The double-j (DJ) ureteral catheterization time was 29.6 ± 9.3 days (range 14 to 68 days) and the hospital stay was 1.6 ± 0.6 days (range 1 to 4). The stone-free rate was 95.2% (80 patients) at 6 months. Flexible ureteroscopic Ho:YAG laser lithotripsy in patients requiring long-term anticoagulation therapy seems to be a safe and effective procedure and should be considered as a first-line treatment option in such patients for the surgical management of upper urinary tract stones.

OBJECTIVE: Laser modalities and direct metal laser sintering (DMLS) have a potential to enhance micromechanical bonding between dental super- and infrastructures. However, the effect of different manufacturing methods on the metal-ceramic bond strength needs further evaluation. We investigated the effect of surface treatment with Er:YAG, Nd:YAG, and Ho:YAG lasers on the shear bond strength (SBS) of high-fusion dental porcelains (Vita and G-Ceram) to infrastructures prepared with DMLS in vitro settings.
METHODS: Study specimens (n = 128) were randomly divided into study subsets (n = 8), considering treatment types applied on the surface of infrastructures, including sandblasting and selected laser modalities; infrastructure types as direct laser sintered (DLS) and Ni-Cr based; and superstructure porcelains as Vita and G-Ceram. The SBS test was performed to assess the effectiveness of surface modifications that were also examined with a stereo microscope.
RESULTS: Considering laser procedure types, the highest SBS values were obtained by Er:YAG laser, followed by, with a decreasing efficiency, Ho:YAG laser and sandblasting procedures, and Nd:YAG laser procedure (p < 0.05). Nd:YAG laser decreases the bonding of Vita and G-Ceram in all the infrastructures compared with sandblasting. Considering porcelains, the highest SBS values were obtained by Vita (p < 0.05). Considering infrastructures, the highest SBS values were obtained by DMLS procedure (p < 0.05). The laser procedures caused surface irregularities as revealed by the stereo microscopic examination.
CONCLUSIONS: In current experimental settings, Er:YAG laser applied to DLS infrastructure veneered with Vita porcelain increases bonding strength more distinctly, and Nd:YAG laser applied to Ni-Cr-based infrastructure veneered with G-Ceram porcelain alters bonding strength unfavorably.