Tissue thermal effect during lithotripsy and tissue ablation in endourology: a systematic review of experimental studies comparing Holmium and Thulium lasers

Proof-of-concept for a novel nanotechnology-based treatment for urolithiasis

Proof-of-concept of photonic lithotripsy in an in vitro setting and its ability to fragment the most common stone types is demonstrated. Effectiveness of different classes of photonic nanoparticles in fragmenting human stones is assessed. De-identified human stones were collected after institutional approval. Stones of a size range between 2-4 mm were rehydrated in simulated urine for 24 h. Stones were then coated with a solution of nanoparticles prior to activation with either a 785 nm or 1320 nm near-infrared energy source. Photonic lithotripsy achieved greater than 70% success rate in fragmentating calcium oxalate monohydrate stones using carbon-based nanoparticles for both near-infrared wavelengths. For gold-based nanoparticles, there was a similar success rate with the 785 nm wavelength but a significant decrease when using the 1320 nm wavelength energy source. All stones fragmented with the energy source at a distance ≥ 20 mm from the stone's surface. Limitations include the use of mixed-composition stones, a lack of complete stone immersion in liquid during treatment, and smaller stone size. Different classes of nanoparticles when excited with a near-infrared energy source can fragment common stone types in vitro. This technology has the potential to change the way we approach and treat patients with urolithiasis in a clinical setting.

Experts' recommendations in laser use for the treatment of bladder cancer: a comprehensive guide by the European Section of Uro-Technology (ESUT) and Training and Research in Urological Surgery and Technology (TRUST)-Group

PURPOSE

To identify laser settings and limits applied by experts during laser vaporization (vapBT) and laser en-bloc resection of bladder tumors (ERBT) and to identify preventive measures to reduce complications.

METHODS

After a focused literature search to identify relevant questions, we conducted a survey (57 questions) which was sent to laser experts. The expert selection was based on clinical experience and scientific contribution. Participants were asked for used laser types, typical laser settings during specific scenarios, and preventive measures applied during surgery. Settings for a maximum of 2 different lasers for each scenario were possible. Responses and settings were compared among the reported laser types.

RESULTS

Twenty-three of 29 (79.3%) invited experts completed the survey. Thulium fiber laser (TFL) is the most common laser (57%), followed by Holmium:Yttrium-Aluminium-Garnet (Ho:YAG) (48%), continuous wave (cw) Thulium:Yttrium-Aluminium-Garnet (Tm:YAG) (26%), and pulsed Tm:YAG (13%). Experts prefer ERBT (91.3%) to vapBT (8.7%); however, relevant limitations such as tumor size, number, and anatomical tumor location exist. Laser settings were generally comparable; however, we could find significant differences between the laser sources for lateral wall ERBT (p = 0.028) and standard ERBT (p = 0.033), with cwTm:YAG and pulsed Tm:YAG being operated in higher power modes when compared to TFL and Ho:YAG. Experts prefer long pulse modes for Ho:YAG and short pulse modes for TFL lasers.

CONCLUSION

TFL seems to have replaced Ho:YAG and Tm:YAG. Most laser settings do not differ significantly among laser sources. For experts, continuous flow irrigation is the most commonly applied measure to reduce complications.

Thulium fiber laser vs. holmium laser enucleation of the prostate: results of a prospective randomized non-inferiority trial

PURPOSE

Holmium laser enucleation of the prostate (HoLEP) represents the current standard procedure for size-independent surgical therapy of benign prostatic obstruction (BPO). With advent of the novel laser technology thulium fiber laser (TFL), we hypothesized that the functional outcome of TFL enucleation of the prostate (ThuFLEP) is non-inferior compared to HoLEP.

METHODS

From October 2021 to October 2022, 150 patients with BPO were recruited for the prospective randomized trial in accordance with CONSORT. Stratified randomization into the arms ThuFLEP (n = 74) or HoLEP (n = 76) was carried out. The primary endpoint was non-inferior international prostate symptom score (IPSS) and quality of life (QoL) at three months after treatment. Secondary endpoints were rates of complications, peak flow, residual urine and operation times.

RESULTS

Preoperative characteristics showed no significant differences. Overall IPSS and QoL improved from 21 to 8 and 4 to 1.5, respectively, after three months of follow-up. No statistically significant differences between ThuFLEP and HoLEP were observed regarding median postoperative IPSS (8.5 vs. 7, p > 0.9), QoL (1 vs. 2, p = 0.6), residual urine (48 vs. 30ml, p = 0.065) and peak flow (19 vs. 17ml/s, p > 0.9). Similarly, safety profile was comparable with no statistically significant differences regarding rate of major complications (5.3 vs. 5.4%, p = 0.5), laser hemostasis time (3 vs. 2min, p = 0.2), use of additive electric coagulation (74 vs. 87%, p = 0.06) or electric coagulation time (8 vs. 8min, p = 0.4).

CONCLUSIONS

In this prospective, randomized trial ThuFLEP showed non-inferior results compared to HoLEP in terms of functional outcomes measured by IPSS and QoL as primary endpoint.

TRIAL REGISTRATION NUMBER

DRKS00032699 (18.09.2023, retrospectively registered).

Experts' recommendations in laser use for the treatment of urolithiasis: a comprehensive guide by the European Section of Uro-Technology (ESUT) and Training-Research in Urological Surgery and Technology (T.R.U.S.T.)-Group

PURPOSE

To identify laser lithotripsy settings used by experts for specific clinical scenarios and to identify preventive measures to reduce complications.

METHODS

After literature research to identify relevant questions, a survey was conducted and sent to laser experts. Participants were asked for preferred laser settings during specific clinical lithotripsy scenarios. Different settings were compared for the reported laser types, and common settings and preventive measures were identified.

RESULTS

Twenty-six laser experts fully returned the survey. Holmium-yttrium-aluminum-garnet (Ho:YAG) was the primary laser used (88%), followed by thulium fiber laser (TFL) (42%) and pulsed thulium-yttrium-aluminum-garnet (Tm:YAG) (23%). For most scenarios, we could not identify relevant differences among laser settings. However, the laser power was significantly different for middle-ureteral (p = 0.027), pelvic (p = 0.047), and lower pole stone (p = 0.018) lithotripsy. Fragmentation or a combined fragmentation with dusting was more common for Ho:YAG and pulsed Tm:YAG lasers, whereas dusting or a combination of dusting and fragmentation was more common for TFL lasers. Experts prefer long pulse modes for Ho:YAG lasers to short pulse modes for TFL lasers. Thermal injury due to temperature development during lithotripsy is seriously considered by experts, with preventive measures applied routinely.

CONCLUSIONS

Laser settings do not vary significantly between commonly used lasers for lithotripsy. Lithotripsy techniques and settings mainly depend on the generated laser pulse's and generator settings' physical characteristics. Preventive measures such as maximum power limits, intermittent laser activation, and ureteral access sheaths are commonly used by experts to decrease thermal injury-caused complications.

Experts' recommendations in laser use for the endoscopic treatment of prostate hypertrophy: a comprehensive guide by the European Section of Uro-Technology (ESUT) and Training-Research in Urological Surgery and Technology (T.R.U.S.T.)-Group

PURPOSE

To identify expert laser settings for BPH treatment and evaluate the application of preventive measures to reduce complications.

METHODS

A survey was conducted after narrative literature research to identify relevant questions regarding laser use for BPH treatment (59 questions). Experts were asked for laser settings during specific clinical scenarios. Settings were compared for the reported laser types, and common settings and preventive measures were identified.

RESULTS

Twenty-two experts completed the survey with a mean filling time of 12.9 min. Ho:YAG, Thulium fiber laser (TFL), continuous wave (cw) Tm:YAG, pulsed Tm:YAG and Greenlight™ lasers are used by 73% (16/22), 50% (11/22), 23% (5/22), 13.6% (3/22) and 9.1% (2/22) of experts, respectively. All experts use anatomical enucleation of the prostate (EEP), preferentially in one- or two-lobe technique. Laser settings differ significantly between laser types, with median laser power for apical/main gland EEP of 75/94 W, 60/60 W, 100/100 W, 100/100 W, and 80/80 W for Ho:YAG, TFL, cwTm:YAG, pulsed Tm:YAG and Greenlight™ lasers, respectively (p = 0.02 and p = 0.005). However, power settings within the same laser source are similar. Pulse shapes for main gland EEP significantly differ between lasers with long and pulse shape modified (e.g., Moses, Virtual Basket) modes preferred for Ho:YAG and short pulse modes for TFL (p = 0.031).

CONCLUSION

Ho:YAG lasers no longer seem to be the mainstay of EEP. TFL lasers are generally used in pulsed mode though clinical applicability for quasi-continuous settings has recently been demonstrated. One and two-lobe techniques are beneficial regarding operative time and are used by most experts.

Experts' recommendations in laser use for the treatment of upper tract urothelial carcinoma: a comprehensive guide by the European Section of Uro-Technology (ESUT) and Training Research in Urological Surgery and Technology (T.R.U.S.T.) group

PURPOSE

To highlight and compare experts' laser settings during endoscopic laser treatment of upper tract urothelial carcinoma (UTUC), to identify measures to reduce complications, and to propose guidance for endourologists.

METHODS

Following a focused literature search to identify relevant questions, a survey was sent to laser experts. We asked participants for typical settings during specific scenarios (ureteroscopy (URS), retrograde intrarenal surgery (RIRS), and percutaneous treatment). These settings were compared among the reported laser types to find common settings and limits. Additionally, we identified preventive measures commonly applied during surgery.

RESULTS

Twenty experts completed the survey, needing a mean time of 12.7 min. Overall, most common laser type was Holmium-Yttrium-Aluminum-Garnet (Ho:YAG) (70%, 14/20) followed by Thulium fiber laser (TFL) (45%, 9/20), pulsed Thulium-Yttrium-Aluminum-Garnet (Tm:YAG) (3/20, 15%), and continuous wave (cw)Tm:YAG (1/20, 5%). Pulse energy for the treatment of distal ureteral tumors was significantly different with median settings of 0.9 J, 1 J and 0.45 J for Ho:YAG, TFL and pulsed Tm:YAG, respectively (p = 0.048). During URS and RIRS, pulse shapes were significantly different, with Ho:YAG being used in long pulse and TFL in short pulse mode (all p < 0.05). We did not find further disparities.

CONCLUSION

Ho:YAG is used by most experts, while TFL is the most promising alternative. Laser settings largely do not vary significantly. However, further research with novel lasers is necessary to define the optimal approach. With the recent introduction of small caliber and more flexible scopes, minimal-invasive UTUC treatment is further undergoing an extension of applicability in appropriately selected patients.

Low- vs. High-Power Laser for Holmium Laser Enucleation of Prostate

Holmium laser enucleation of the prostate (HoLEP) constitutes an established technique for treating patients with symptomatic bladder outlet obstruction. Most surgeons perform surgeries using high-power (HP) settings. Nevertheless, HP laser machines are costly, require high-power sockets, and may be linked with increased postoperative dysuria. Low-power (LP) lasers could overcome these drawbacks without compromising postoperative outcomes. Nevertheless, there is a paucity of data regarding LP laser settings during HoLEP, as most endourologists are hesitant to apply them in their clinical practice. We aimed to provide an up-to-date narrative looking at the impact of LP settings in HoLEP and comparing LP with HP HoLEP. According to current evidence, intra- and post-operative outcomes as well as complication rates are independent of the laser power level. LP HoLEP is feasible, safe, and effective and may improve postoperative irritative and storage symptoms.