Thulium and holmium ureterolithotripsy: evaluation of thermal effects on the ureter by measuring the temperature of the irrigation fluid in vitro

Introduction. Urolithiasis refers to one of the most common diseases of the genitourinary system, which the urologist meets in his daily practice. When a stone is located in the ureter, surgical intervention is often required to restore the passage of urine and prevent the development of obstructive pyelonephritis. Currently, the holmium or thule laser ureterolithotripsy is condidered the «gold standard» of surgical treatment of ureteral calculi. The thermal effect on the ureteral wall when using a laser may be one of the reasons for the postoperative ureteral strictures development. The aim of our study is to compare in vitro thermal effects of these types of laser on the ureter wall by eval uating the change in the temperature of the irrigation fluid when they are used. Materials and methods. A tube with a diameter of 5 mm, which imitated the ureter, was placed in an aqueous medium with a temperature of 36°C. A temperature sensor (HI 98509 Checktemp 1) was installed in its lumen, at a 3 mm distance from the laser fiber. The time when the irrigation fluid reaches a temperature of 43°C, as well as its temperature at a pulse duration of 3 seconds at an irrigation rate of 25 and 50 ml/sec in the dusting and fragmentation modes, were recorded. Results and discussion. It was found that when using a thulium laser, regardless of the flow rate of the irrigation fluid, an increase in its temperature to 43°C is achieved for a longer time. Also, a lower temperature of the irrigation fluid with a pulse duration of 3 second is recorded using thulium laser. The obtained data allow us to assume that the use of a thulium laser is accompanied by a lower thermal effect on the ureter wall. Conclusion. In this study, we found that when using a thulium laser (Fiberlase U2) in the fragmentation and sputtering modes, a slower increase in the temperature of the irrigation liquid is observed than when using a holmium laser (Lumenis VersaPulse 100W), regardless of the irrigation speed. At a 3 second pulse, a lower temperature of the irrigation fluid was recorded during the use of the thulium laser.