Our study explores the implications of laser lithotripsy, focusing on the heat generated during the procedure and its potential for thermal damage to surrounding tissues. The research introduces a new concept, the "thermal safety distance", which aims to provide insight into proper laser settings based on the distance between the laser fiber tip and healthy tissue, thereby minimizing the risk of thermal injury.
Methodology
We employed an in-vitro experimental setup using a glass pipette to simulate a renal calyx, assessing the temperature changes during laser activation under various conditions. The study considered multiple parameters such as laser power and the presence or absence of irrigation. A thermal camera was used to monitor temperature changes, and the thermal dose was calculated using the Sapareto and Dewey formula, which predicts tissue damage based on cumulative temperature exposure.
Key Findings
- Correlation Between Power and Temperature: The study found a significant positive correlation between the average power of the laser and the highest recorded temperature. At power settings of 10W and above without irrigation, temperatures exceeded the threshold for potential tissue damage (43°C). With irrigation, this threshold was reached at 20W or higher.
- Effect of Irrigation: Irrigation significantly reduced peak temperatures, demonstrating its role in mitigating thermal damage. The maximum reduction was observed at 40W, with an average temperature decrease of 9.4°C.
- Thermal Dose and Safety Distance: The concept of a thermal safety distance was defined as the distance from the laser tip where the thermal dose does not exceed the threshold for tissue damage. The study suggests a maximum safe power setting of 10W in the ureter and 20W in the kidney when irrigation is used.
Our study highlights the importance of balancing laser power settings with thermal safety considerations. The introduction of the thermal safety distance provides a quantitative standard to prevent thermal injury during laser lithotripsy. The findings emphasize the need for careful power management and adequate irrigation to ensure patient safety.
The research also underscores the significance of the thermal dose over mere temperature measurements, advocating for a more comprehensive approach to evaluating thermal risk.
Conclusions
Our experimental data present a strong case for the cautious application of high-power laser settings in endourological procedures. Our study recommends adhering to specific power thresholds to minimize thermal damage risks, with the thermal safety distance serving as a critical parameter in guiding clinical practice. Future research should focus on validating these findings in clinical settings and exploring alternative measurement modalities for in-vivo applications.
Written by: Daniele Robesti,1,2 Eugenio Ventimiglia,1,2,3,4 Etienne Xavier Keller,3,4,5 Christian Corsini,1,2 Andrea Folcia,1,2 Margherita Fantin,1,2 Luigi Candela,6 Edoardo Pozzi,1,2 Alba Sierra,6,3,4 Amelia Pietropaolo,7,3 Bhaskar K. Somani,7 Frederic Panthier,6,4 Felipe Pauchard,8,4 Ioannis Kartalas Goumas,9 Luca Villa,1,2 Francesco Montorsi,1,2 Olivier Traxer,6,4 Andrea Salonia,1,2 Paola Saccomandi10
- Vita-Salute San Raffaele University, Milan, Italy
- Division of Experimental Oncology/Unit of Urology; URI; IRCCS Ospedale San Raffaele, Milan, Italy
- Young Academic Urologists (YAU), Urolithiasis and Endourology Working Party, Arnhem, The Netherlands
- Progressive Endourological Association for Research and Leading Solutions (PEARLS), Paris, France
- Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
- Sorbonne Universite, Lithiase Urinaire, Hôpital Tenon, Paris, Île-de-France, France
- Department of Urology, University Hospital Southampton, Southampton, UK
- Urology Department, Hospital Naval Almirante Nef, Viña del Mar, Av. Alessandri, Viña del Mar, Valparaíso, Chile
- Dept. of Urology, Istituto Clinico Beato Matteo, Vigevano, Italy
- Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy.