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WATTS happening? Evaluation of thermal dose during holmium laser lithotripsy in a high-fidelity anatomic model

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Abstract

Purpose

To evaluate the thermal profiles of the holmium laser at different laser parameters at different locations in an in vitro anatomic pelvicalyceal collecting system (PCS) model. Laser lithotripsy is the cornerstone of treatment for urolithiasis. With the prevalence of high-powered lasers, stone ablation efficiency has become more pronounced. Patient safety remains paramount during surgery. It is well recognized that the heat generated from laser lithotripsy has the potential to cause thermal tissue damage.

Methods

Utilizing high-fidelity, 3D printed hydrogel models of a PCS with a synthetic BegoStone implanted in the renal pelvis, laser lithotripsy was performed with the Moses 2.0 holmium laser. At a standard power (40 W) and irrigation pressure (100 cm H2O), we evaluated operator duty cycle (ODC) variations with different time-on intervals at four different laser settings. Temperature was measured at two separate locations—at the stone and away from the stone.

Results

Temperatures were highest closest to the laser tip with a decrease away from the laser. Fluid temperatures increased with longer laser-on times and higher ODCs. Thermal doses were greater with increased ODCs and the threshold for thermal injury was reached for ODCs of 75% and 100%.

Conclusion

Temperature generation and thermal dose delivered are greatest closer to the tip of the laser fiber and are not dependent on power alone. Significant temperature differences were noted between four laser settings at a standardized power (40 W). Temperatures can be influenced by a variety of factors, such as laser-on time, operator duty cycle, and location in the PCS.

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Data Availability

The data collection has been included as a supplementary file.

Abbreviations

RIRS:

Retrograde intrarenal surgery

Ho: YAG:

Holmium: Yttrium–Aluminum–Garnet

TD43 :

Thermal dose threshold of injury at 43 °C

CEM:

Cumulative equivalent

URS:

Ureteroscopy

PCS:

Pelvicalyceal collecting system

CFD:

Computational fluid dynamics

PVA:

Polyvinyl alcohol

ODC:

Operator duty cycle

DICOM:

Digital imaging and communications in medicine

CAD:

Computer-aided design

UPJ:

Ureteropelvic junction

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Acknowledgements

The authors would like to graciously thank Dr. William Roberts, MD from the University of Michigan for providing his expertise, input, and guidance in our project. The authors are largely based our project on the excellent work his lab has produced. He reviewed our data and provided insight for data evaluation to provide impactful results.

Funding

There was no source of funding for this project.

Author information

Authors and Affiliations

  1. Department of Urology, University of Rochester Medical Center, Rochester, NY, USA

    Christopher Wanderling, Aaron Saxton, Dennis Phan, Karen Doersch, Lauren Shepard, Nathan Schuler, Thomas Osinski, Scott Quarrier & Ahmed Ghazi

  2. Department of Urology, Johns Hopkins University, Baltimore, MD, USA

    Lauren Shepard, Nathan Schuler & Ahmed Ghazi

Authors
  1. Christopher Wanderling
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  2. Aaron Saxton
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  3. Dennis Phan
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  4. Karen Doersch
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  5. Lauren Shepard
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  6. Nathan Schuler
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  7. Thomas Osinski
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  8. Scott Quarrier
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  9. Ahmed Ghazi
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Contributions

CW: project development, data collection, data analysis, and manuscript writing; AS: data collection and data analysis; DP: data analysis and manuscript writing; KD: data analysis and manuscript writing; LS: project development, data collection, and data analysis; NS: project development, data collection, and data analysis; TO: project development and manuscript writing; SQ: project development and data analysis; AG: project development, data collection, and data analysis. All of the listed authors have contributed substantially to the production of this research and manuscript.

Corresponding author

Correspondence to Christopher Wanderling.

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There are no conflicts of interest nor are there any financial or non-financial interests of any author for any author included in the production of this manuscript.

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This research project does not involve any human participants nor animal studies.

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Wanderling, C., Saxton, A., Phan, D. et al. WATTS happening? Evaluation of thermal dose during holmium laser lithotripsy in a high-fidelity anatomic model. World J Urol 42, 157 (2024). https://doi.org/10.1007/s00345-024-04821-9

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  • DOI: https://doi.org/10.1007/s00345-024-04821-9

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