Innovative Small Fragment Removal System Enhances Stone Extraction in Lithotripsy
Overview
A novel Small Fragment Removal System (SFRS) was clinically evaluated for safety and efficacy in removing residual stone fragments during lithotripsy. The system demonstrated the ability to maintain safe intra-renal pressures while effectively extracting over 75% of small stone fragments, potentially reducing post-operative stone-related complications.
Background
Residual stone fragments after urolithiasis surgery pose significant risks for recurrent stone episodes, with intervention rates up to 47% for fragments larger than 4 mm. Traditional methods often leave clinically significant fragments, including dust-sized particles, which can persist and cause disease progression. The SFRS was developed to address this challenge by combining a Syphon Ureteric Access Sheath, a Dual Action Pump, and an Agitator catheter to enhance irrigation, suction, and targeted fragment removal during flexible ureteroscopy and laser lithotripsy.
Data Highlights
The clinical trial was a prospective single-arm Phase 1–2 study assessing safety via intra-renal pressure (IRP) monitoring and efficacy by the proportion of stone fragments removed. The SFRS components included: - Syphon Ureteric Access Sheath (SAUS) to improve irrigant outflow and reduce IRP - Dual Action Pump (DAP) delivering controlled fluid boluses and simultaneous suction - Steerable 6 Fr Agitator catheter to mobilize fragments under fluoroscopic guidance IRP was continuously measured using a 200 μm fibre optic sensor, with irrigation standardized at 140 cm above kidney level. Two trained urologists performed procedures on pre-stented adult patients with proximal ureter or renal stones.
Key Findings
The SFRS maintained intra-renal pressures below the safety threshold of 40 mm Hg during use.
The system effectively removed over 75% of small stone fragments, including dust-sized particles.
The Syphon UAS component enhanced irrigant outflow and reduced intra-renal pressure compared to conventional UAS.
The Dual Action Pump allowed precise fluid boluses and simultaneous suction, facilitating fragment mobilization and extraction.
The steerable Agitator catheter enabled targeted irrigation at calyces to dislodge and aspirate residual fragments.
There was no significant learning curve for surgeons trained on the device, supporting ease of clinical adoption.
Clinical Implications
The SFRS offers a promising adjunct to flexible ureteroscopy and laser lithotripsy by improving removal of residual stone fragments, potentially reducing the risk of recurrent stone events. Maintaining safe intra-renal pressures during irrigation and suction minimizes complications. Incorporation of this system into clinical practice may enhance stone-free rates and patient outcomes without adding procedural complexity.
Conclusion
This first-in-human trial demonstrates that the Small Fragment Removal System is a safe and effective tool for enhancing stone fragment clearance during lithotripsy. Its use may redefine management of residual fragments, challenging the notion of clinically insignificant stone dust.
References
Cochrane Meta-analysis 2023 -- Natural History of Residual Stone Fragments
Commentators on Clinical Significance of Residual Fragments
Kang et al. -- Fate of Stone Dust Particles Post-Lithotripsy
Lazarus et al. -- In Vitro Evaluation of Small Fragment Removal System
