[Retrograde intrarenal surgery using a 1.94 m superpulsed thulium fiber laser]

INTRODUCTION

surgical treatment of urinary stone disease plays an important role in urological practice. Stone fragmentation can be performed using various lithotripters, from which Holmium fiber laser (Ho: YAG) has currently taken the main place. According to the current literature, a superpulsed thulium fiber laser with a wavelength of 1.94 m and a maximum power output of 40 W showed in vitro higher efficiency compared to Ho: YAG, while having the same safety profile. The use of a thulium fiber laser with a pulse energy of 0.025-6 J and a high repetition rate (up to 1600 Hz) allows to most effectively perform stone dusting during retrograde intrarenal surgery (RIRS).

AIM

to improve the performance of RIRS using the 1.94m superpulsed thulium fiber laser.

MATERIALS AND METHODS

a total of 152 patients with renal stones who were treated during the period from February 2018 to July 2019 were included in the study. The analysis of the laser settings, their effect on retropulsion and visibility when performing RIRS using a superpulsed thulium fiber laser with a wavelength of 1.94 m and a maximum power output of 40 W, a peak power of 500 W, as well as an assessment of the stone-free rate the first postoperative day and 3 months after the procedure was done.

RESULTS

The most frequently used settings were as following: 0.5 J, 30 Hz, 15 W (No. 1), 0.15 J, 200 Hz, 30 W (No. 2), 0.8 J, 31.25 Hz, 25 W (No. 3), 0.8 J, 37.5 Hz, 30 W (No. 4). The statistical analysis of the influence of the settings on the quality of endoscopic imaging and retropulsion was carried out. In addition, the features of each settings were analyzed. The stone-free rate on the first postoperative day was evaluated using low-dose CT.

CONCLUSION

A superpulsed thulium fiber laser with a wavelength of 1.94 m and a maximum power of 500 W has shown high efficiency in clinical practice when performing RIRS, since it allows to have good endoscopic imaging, minimal retropulsion, and to perform stone dusting, which had a positive effect on the stone-free rate. Optimization of the settings of thulium fiber lithotripsy may improve the results of surgical treatment of urinary stone disease.

[Laser in laparoscopic urology]

Nowadays, various laparoscopic instruments for tissue dissection and vessel coagulation are available. However, there are ongoing studies dedicated to "ideal" type of energy suitable for this aim. Laser radiation has been used for many years in medical practice and it is established as reliable and effective method in surgical armamentarium. The ability to provide highly precision and well-controlled action on the tissues, improved hemostasis, easy adaptability to fiber-optic and minimally invasive delivery systems, as well as the possibility of facilitating complex dissection made lasers an important tool for surgeons. The mechanism and methods of laser energy using in urology have been studied since 1980s, but there is still no consensus on the optimal type of laser and its settings during urological surgeries, which determines the importance of further researches dedicated to this promising form of energy.

[Experimental verification of thulium lithotripsy]

AIM

Experimental evaluation of the efficacy and safety of lithotripsy using a new pulsed thulium fiber laser operating at a wavelength of 1.94 microns, peak power of 500 watts (maximum average power of 50 watts) by comparing it with a holmium laser operating at a wavelength of 2.1 microns (average maximum power 100 W and 120 W).

RELEVANCE

The proportion of minimally invasive surgery in the management of urolithiasis, including retrograde intrarenal surgery, is steadily growing. The most appropriate tool for stone destruction is a laser. To date, the gold standard of minimally invasive surgical treatment of nephrolithiasis is holmium laser lithotripsy, which uses a laser on yttrium-aluminum-garnet activated by holmium ions (Ho: YAG) operating at a wavelength of 2.1 m. However, in recent years, lasers on a Tm-activated fiber with a wavelength of 1.94 m have become increasingly popular since the water absorption coefficient for the Tm radiation of a fiber laser is 5.5 times higher than for a Ho: YAG laser and in 2.2 times higher than for the Tm: YAG laser. This difference may translate into greater effectiveness and speed of stone crushing, which in turn leads to shorter operating time.

MATERIALS AND METHODS

This article describes physical foundations of holmium and thulium laser radiation, the mechanisms of stone fragmentation, data from a series of experiments comparing the efficiency and safety of ex-vivo lithotripsy using a holmium solid-state laser with a wavelength of 2.1 m and a thulium fiber laser with a wavelength of 1.94 m.

RESULTS

The study findings suggest that the STA IRE-Polyus thulium fiber laser operating at a wavelength of 1.94 microns and a maximum power of 500 watts has several advantages over the holmium laser in the stone fragmentation in urological practice.

CONCLUSION

The results of the experimental work allow us to conclude that the use of a thulium fiber laser operating at a wavelength of 1.94 m and a maximum peak power of 500 W enables highly effective and safe lithotripsy.

[En-bloc laser resection of the urinary bladder tumor]

Currently, transurethral resection of a bladder tumor (TUR) is the gold standart treatment for non-muscle invasive bladder cancer (NMIBC). Standard TUR for a bladder wall tumor has a high recurrence rate, which is caused mainly by malignant cell implantation during the surgery. Besides, specimens obtained with conventional TUR are insufficient for accurate pathological staging. The non-conformity of the standard TUR with the established oncological principle of dissecting through normal tissue prompted a search for the optimal surgical modality. En-bloc resection of the bladder wall tumor has been proposed as an alternative method for surgical management of NMIBC. This technique involves the resection of bladder tumor through the underlying muscle layer as a single piece thus providing high quality material for subsequent morphological study and reducing the risk of metastasizing by implantation of malignant cells. This paper presents an analysis of relevant research literature published in the last twenty years, describes all currently existing techniques of the bladder tumor resection using a variety of energy sources, including laser.

[Endoscopic removal of papillary tumors of upper urinary tract]

AIM

To assess the results of organ-sparing endoscopic treatment of patients with tumors of the upper urinary tract (UUT).

MATERIALS AND METHODS

Twenty four patients underwent percutaneous and ureteropyeloscopic interventions for tumors of the upper urinary tract and were followed up at the Urology Clinic, I.M. Sechenov First MSMU. Retrograde removal of benign tumors of the renal pelvis and ureter (tumors sized from 5 to 35 mm), percutaneous removal of papillary carcinoma of renal pelvis of a solitary kidney, percutaneous removal of papillary carcinoma of renal pelvis of only one functioning kidney and percutaneous removal of papillary carcinoma of the lower calyx of the L-shaped kidney were performed in 21, 1, 1 and 1 patients, respectively. The patients had stage T1 papillary cancer of the upper urinary tract. There were 7 (29.2%) men and 17 (70.8%) women with mean age 64+/-5 years. Electroresection/vaporization was carried out in 18 patients, and 6 patients were treated using Holmium laser.

RESULTS

None of the endoscopic procedures required conversion to open surgery or a more extended surgical operation. There were no recurrences or impaired UUT urinary flow in patients with benign UUT tumors at different points of follow-up. In 3 cases of malignant UUT tumors no recurrences occurred during 12-20 months follow-up.

CONCLUSION

and discussion. Nephroureterectomy with resection of the urinary bladder is the standard radical treatment of patients with tumors of the UUT. Technological advances in endoscopic and percutaneous surgery for UUT have allowed for organ-sparing procedures in patients with neoplasms of pelvicalyceal system and ureter. The absolute indications for such organ-sparing operations now include solitary kidney or only one functioning kidney and chronic renal failure. Endoscopic resection of the tumor and renal pelvic wall within healthy tissue, including by holmium laser, with tumor stage not exceeding T1 and followed by trans-fistula chemotherapy can be regarded as an effective treatment for patients with tumors of pelvicalyceal system.