Research on Calculus Kinetics (ROCK) Society
ROCK SOCIETY priorities for research as presented on June 2024 to the NIDDK Urology Interagency Coordinating Committee meeting: ROCK SOCIETY – Urololithiasis research needs
Studying Laser Lithotripsy for Surgical Stone Removal
Pei Zhong, PhD and his CAIRIBU FORWARD* Urology P20 Center team at Duke University have developed a comprehensive research agenda to study mechanisms of action of the new thulium fiber laser (TFL), used in surgical ureteroscopic procedures to remove kidney stones, and to assess TFL technology for efficacy, safety, and effectiveness. In advance of finalizing their research strategy, the team surveyed an international group of urologists with experience using TFL. Investigators queried these urologists for their feedback on which TFL settings they prefered for energy, frequency, and power during ureteroscopic stone removal. The survey also queried urologists about thermal effects and retropulsion during laser lithotripsy.
[*FORWARD, FOstering Research With Additional Resources and Development]
DESCRIPTION AND RESULTS OF THE SURVEY BELOW
Endourologist Survey about Thulium Fiber Laser
Pei Zhong, PhD; Junqin Chen; Jodi Antonelli, MD; Robert Medairos, MD; Arpit Mishra, PhD; Charles D. Scales, MD; Glenn M. Preminger, MD; Michael E. Lipkin, MD; Duke University, Durham, North Carolina 27708
BACKGROUND: Thulium fiber laser (TFL) is gaining clinical popularity, challenging the gold standard supremacy of Ho:YAG lasers in ureteroscopy. Compared to Ho:YAG lasers, the TFL operates at a different wavelength with higher optical absorption in water, lower peak power yet longer pulse duration in a broad range of pulse energy and frequency. Currently, the optimal settings of TFL for stone ablation have not been clearly defined, and the potential risk of urinary tract injuries is significant and needs to be better monitored during laser lithotripsy.
OBJECTIVE: We collected clinical feedback to inform the rational design of a comprehensive research program for determining the optimal settings of TFL for treating kidney stones of various compositions. Our research aims to elucidate the distinctly different physical processes in stone ablation and temperature elevation produced by TFL vs. Ho:YAG lasers. We anticipate progressively achieving such goals via a series of bench tests, evaluations in a newly developed artificial kidney model, and final verification in animal (swine) experiments. Altogether, we strive to unravel the intricate laser-fluid-bubble-stone interactions and their interconnections that are not easily observed during clinical laser lithotripsy. Through such a grand effort, we hope to identify the best treatment strategy for achieving the most desirable outcome (i.e., highest stone ablation efficiency, lowest heat injury risk, and shortest procedure time) for urinary stone treatment with TFL technology.
METHODS: A survey was created by investigators to query endourologists about the TFL pre-settings they use for energy, frequency, and power during dusting, pop-dusting, and fragmenting ureteroscopy procedures. Questions about effectiveness and concerns with TFL technology were included. A convenience sample of urologists was assembled from urologist members of the Research on Calculus Kinetics Society, urologists affiliated with the CAIRIBU research community, and urologists from the international urological surgical community with experience using the TFL.
RESULTS: The survey was sent to 147 endourologists. Respondents (n=45) were not asked to identify themselves. Ultimately, data for 19 surveys were complete enough for a preliminary analysis. Urologists’ preferences for TFL energy settings were higher for fragmenting than for dusting or pop-dusting (Figure 1A), whereas neither frequency settings nor power settings differed among the three ureteroscopic techniques (Figure 1B and 1C). The variation range of these settings are summarized (Table 1). Regarding capacity of the TFL for fragmenting, consensus from those who provided answers was that TFL was “limited,” “no better,” or “inferior” to holmium. In contrast, TFL dusting capacity was rated “outstanding” or “excellent” by a majority of urologists (75%; Figure 2A) compared to 45% for pop-dusting. Nearly all urologists said they have observed charring with the TFL and were concerned about it as well as about thermal effects (Figure 2B). Nearly 60% had no concerns at all about retropulsion with TFL. About 33% said retropulsion concerns with TFL were similar to holmium laser (Figure 2C). While 70% of urologists felt comfortable treating all types of stones using TFL, 30% expressed concerns for treating impacted CaP stones in the ureter. Additionally, 80% agreed or strongly agreed that a comprehensive investigation of the optimal TFL settings for stone management is necessary (Figure 3).
CONCLUSIONS: Among a convenience sample of urologists who have used TFL in surgical stone management, most felt that TFL has high potential for dusting and pop-dusting, yet there is a concern for its fragmenting capability, charring, and thermal effects. There was a strong consensus regarding the need for further research about TFL.
