AUA 2018: Improved Efficiency of Holmium Laser Lithotripsy with Suction Stabilization and Containment of Fragments

San Francisco, CA USA ( Ali H. Aldoukhi, MD, clinical urology fellow from the University of Michigan, Ann Arbor, presented data that evaluated the efficacy of laser lithotripsy of a prototype device that utilizes suction stabilization and stone confinement during in-vitro laser lithotripsy. As an introduction, Dr. Aldoukhi explained because stones and stone fragments retropulse away from the laser’s target zone, a lot of time and energy during ureteroscopy is spent re-localizing, targeting, and extracting residual stone fragments. To address this issue, they developed a novel device that utilized the concept of suction stabilization to hold stone fragments within the laser’s target zone and to extract stone fragments and the concept of containing stone fragments in a conical chamber.

The novel device used was conical in shape with a 1 mm opening at the bottom. Attached was tubing and a pump which provided a suction flow rate of 120 mL/min. The ureteroscope used was a DUR -8 Gyrus ACMI flexible ureteroscope with a Boston Scientific Flexiva 242 μm laser fiber from a Lumenis P120 120W holmium laser. The model in which laser lithotripsy was performed on were three spherical Begostones (3 mm in diameter) contained within the control, a 19 mm diameter vial, or the experimental prototype suction device. Laser settings of 0.8J x 10Hz or 0.5J x 80Hz were used interchangeably for 2 minutes for each trial. A total of 5 trials were performed for both the control and experimental device.

The mean starting stone mass was 82mg. For the control, the mean residual stone mass was 29mg (23-39), 36% of the original mass. For the experimental, the mean residual stone mass was 1mg (0-7), 1% of the original mass. When statistically analyzed, a p-value of <0.001 was found, showing a significant difference in residual mass between the control and experimental. In 6 out of the 10 trials for the experimental group, the stones were completely treated in less than two minutes (58 to 88 seconds).

Dr. Aldoukhi concluded that suction stabilization and confinement of stones and fragments with the novel device improved efficiency of laser lithotripsy. A future direction that he proposes is to test different suction levels and stone sizes to further characterize results, ultimately creating a clinical functional device.

Presented by: Ali Aldoukhi, a postdoctoral research fellow in endourology at the University of Michigan, Ann Arbor, MI

Written by: Cyrus Lin, Department of Urology, the University of California-Irvine at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA