Steady-state versus burst lasing techniques for thulium fiber laser.

OBJECTIVE: To evaluate the stone ablation rate and direct thermal damage from thulium fiber laser (TFL) lithotripsy using continuous (C) and burst (B) lasing techniques on an in vitro ureteral model. METHODS: The TFL Drive (Coloplast, Humlebaek, Denmark) was used in an in vitro saline-submerged ureteral model. Ten participants, including five junior and five experienced urologists, conducted the experimental setup with 7 different settings comparing two lasing techniques: steady-state lasing (0.5 J/10 Hz = 5W for 300 s and 0.5 J/20 Hz = 10W for 150 s) and burst, intermittent 5 s on/off lasing (0.5 J/20 Hz, 0.5 J/30 Hz, 0.5 J/60 Hz, 0.1 J/200 Hz, and 0.05 J/400 Hz) with a target cumulative energy of 1500 J using cubic 125 mm3 phantom BegoStonesTM. Ureteral damage was graded 1-3 based on the severity of burns and holes observed on the surface of the ureteral model. RESULTS: The were no significant differences in stone ablation mass neither between C and B lasing techniques, nor between expertise levels. At C lasing technique had only mild ureteral lesions with no significant differences between expertise levels (p: 0.97) or laser settings (p: 0.71). At B lasing technique, different types of thermal lesions were found with no expertise (p: 0.11) or setting (p: 0.83) differences. However, B laser setting had higher grade direct thermal lesions than C (p: 0.048). CONCLUSION: Regarding efficacy, C and B lasing techniques achieve comparable stone ablation rates. Safety-wise, B lasing mode showed higher grade of direct thermal lesions. These results should be further investigated to verify which of the lasing mode is the safest in vivo. Until then and unless proven otherwise, a C mode with low frequency should be recommended to avoid ureteral wall lesions.

A multicentric non-randomized prospective observational study on the clinical efficiency of thulium fibre laser in large volume stones (> 1000 mm3).

PURPOSE: Our objective was to analyse the clinical efficiency of TFL in large volume stones during retrograde intrarenal surgery. MATERIALS AND METHODS: Patients with large volume renal stones (> 1000 mm3) operated at two different centres, from May 2020 to April 2021, were enrolled in this study. Retrograde intrarenal surgery was performed using 60W Superpulse thulium fibre laser™ (IPG Photonics, Russia). Demographic data, stone parameters, laser time, and total operating time were recorded, and laser efficacy (J/mm3) and ablation speed (mm3/s) were calculated. NCCT KUB was done at 3 months postoperatively to calculate stone-free rate. RESULTS: A total of 76 patients were included and analysed in the study. Mean stone volume was 1753.12 ± 1245.81 (1169.27-2193.25) mm3, mean stone density was 1104.46 ± 313.09 (875.00-1317.00) HU, mean laser time was 537.79 ± 689.89 (21.00-1080.00) sec, mean operating time was 43.38 ± 12.96 (35.00-51.25) min, mean laser efficacy was 20.30 ± 15.5 (8.88-25.57) J/mm3, and mean ablation speed was 1.32 ± 0.7 (0.82-1.64) mm3/sec. A strong positive correlation was found between the stone volume and ablation speed (r = 0.659, p = 0.000), and a moderate negative correlation was found between the stone volume and laser efficacy (J/mm3) (r = - 0.392, p = 0.000). With increasing volume of the stone, J/mm3 decreased significantly and ablation speed increased significantly (p < 0.001). Complications occurred in 21.05% (16/76) patients, most of which were Clavien grades 1-2. Overall SFR is 96.05%. CONCLUSION: Laser efficiency increases at higher stone volumes (> 1000 mm3), as less energy is required to ablate every mm3 of stone.

Results of a long-term performance and follow-up of Endovenous Laser Ablation procedures performed for treating great saphenous vein incompetence.

OBJECTIVE: To assess the value of endovenous laser ablation (EVLA) for treating great saphenous vein (GSV) incompetence. METHODS: We reviewed the overall results of EVLA procedures performed on 554 patients in our clinic between March 2011 and December 2015. Evaluations were made concerning the situations of the great saphenous vein (GSV), the energy used in the treatments, and the results obtained. We also investigated if there was a possibility to detect failure of EVLA treatment at an early stage. RESULTS: From a total of 657 GSVs that were subjected to EVLA treatment, the procedure was found to be successful for 611 GSVs and unsuccessful for 46 GSVs (success rate: 93%). In 38 of the 46 GSVs, a thrombus formation was detected by color Doppler ultrasonography (CDUS) at the postoperative first month (82.6%). CONCLUSION: EVLA is a reliable and successful method utilized for the treatment of GSV incompetence. It is concluded that the detection of a thrombus in the GSV tract during the first postoperative follow-up month is an indicator for revascularization.