In Vitro Dusting Performance of a New Solid State Thulium Laser Compared to Holmium Laser Lithotripsy

Abstract Background: Holmium laser lithotripsy is the most common technique for the management of ureteral stone. Studies founded that holmium laser firing can produce lethal heating which will cause thermal injury towards ureter. The aim of our current study is to explore factors affecting thermal effect of holmium laser during ureteroscopic lithotripsy.Materials and Methods: An in vitro experimental model is design to simulate the ureteroscopic lithotripsy procedure. Different laser power settings (10w (0.5JX20Hz, 1.0JX10Hz), 20w (1.0JX20Hz, 2.0JX10Hz), 30w (1.5JX20Hz, 3.0JX10Hz)) with various firing time (3s, 5s, 10s) and irrigation flow rates（10ml/min, 15ml/min, 20ml/min and 30ml/min）were employed in the experiment. The temperature around the laser tip was recorded by thermometer.Results: The temperature in the “ureter” rises significantly with the increasing laser power, prolonging firing time and reducing irrigation flow. The highest regional temperature is 78.0℃ at the experimental set-up, and the lowest temperature is 23.5℃. Higher frequency setting produces more heat at the same power. Laser power<=10w, irrigation flow>=30ml/ml and “high-energy with low-frequency” can permit a safe working temperature.Conclusion: We clarify that the thermal effect of holmium laser is related with both laser working parameters and irrigation flow. The proper setting is the key factor to ensure the safety during ureteroscopic holmium laser lithotripsy.

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Thermal effects of holmium laser lithotripsy in an in vitro model

European Urology Open Science ◽

10.1016/s2666-1683(20)33868-4 ◽

2020 ◽

Vol 19 ◽

pp. e1882

Author(s):

K. Ma ◽

X.B Huang ◽

Q.Q Xu ◽

L.L Xiong ◽

Y. Hong ◽

...

Keyword(s):

Thermal Effects ◽

In Vitro Model ◽

Laser Lithotripsy ◽

Holmium Laser ◽

Holmium Laser Lithotripsy ◽

Vitro Model

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Retropulsion force in laser lithotripsy—an in vitro study comparing a Holmium device to a novel pulsed solid-state Thulium laser

World Journal of Urology ◽

10.1007/s00345-021-03668-8 ◽

2021 ◽

Author(s):

Ralf Petzold ◽

Arkadiusz Miernik ◽

Rodrigo Suarez-Ibarrola

Keyword(s):

Solid State ◽

Pulse Energy ◽

Evaluation Model ◽

In Vitro Study ◽

Bath Temperature ◽

Laser Lithotripsy ◽

Thulium Laser ◽

Data Logger ◽

Long Pulse

Abstract Purpose To investigate retropulsion forces generated by two laser lithotripsy devices, a standard Ho:YAG and a new pulsed solid-state Thulium laser device. Materials and methods Two different Dornier laser devices were assessed: a Medilas H Solvo 35 and a pulsed solid-state Thulium laser evaluation model (Dornier MedTech Laser GmbH, Wessling, Germany). We used a 37 °C water bath; temperature was monitored with a thermocouple/data-logger. Representative sets of settings were examined for both devices, including short and long pulse lengths where applicable. For each setting, ten force values were recorded by a low-force precision piezo sensor whereby the laser fibre was either brought into contact with the sensor or placed at a 3 mm distance. Results The mean retropulsion forces resulting from the new Tm:YAG device were significantly lower than those of the Ho:YAG device under all pulse energy and frequency settings, ranging between 0.92 and 19.60 N for Thulium and 8.09–39.67 N for Holmium. The contact setups yielded lower forces than the distance setups. The forces increased with increasing pulse energy settings while shorter pulse lengths led to 12–44% higher retropulsive force in the 2.0 J/5 Hz comparisons. Conclusion The Tm:YAG device not only significantly generated lower retropulsion forces in all comparisons to Holmium at corresponding settings but also offers adjustment options to achieve lower energy pulses and longer pulse durations to produce even lower retropulsion. These advantages are a promising add-on to laser lithotripsy procedures and may be highly relevant for improving laser lithotripsy performance.

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