EAU 2018: Understanding Non-Contact Laser Lithotripsy for Dusting – The Popcorn Effect: A Video Analysis

Copenhagen, Denmark (UroToday.com) Dr. Aldoukhi from the University of Michigan in Ann Arbor presented data on the results of his in vitro experiment on the mechanism of stone breakdown when using non-contact laser lithotripsy. As an introduction to his talk, Dr. Aldoukhi explained that this mechanism as well as factors affecting fragmentation make up the “popcorn effect” and are not well understood. 

In the experiment a high-speed camera was used to record video as artificial Begostones were pulverized using a laser in a test tube calyceal model. In this model, a 200 um laser fiber positioned 1-2mm away from the stone with irrigation provided was fired at different 20 and 40 watt settings. All videos were recorded and analyzed to determine the effect of different laser settings, calyceal size, flow rate, and heat generation during popcorning.

Following video analysis, he revealed that in this experiment fragmentation during non-contact laser lithotripsy occurs because of stone to fiber interaction not due to stone to stone interactions or collisions. Additionally, 40-watt settings showed superior fragmentation outcomes. Interestingly, the analysis showed that for every 5 pulses, only 1 pulse made contact with the stone. 

Dr. Aldoukhi concluded that smaller calyceal sizes led to better results, efficiency of fragmentation was maximal after 4 minutes, and flow rate had no significant effect on outcomes. Lastly, he stated that setting with high power output generate more hear, so the laser should be activated in short bursts of no more than 5 to 10 seconds

Presented by: Ali Aldoukhi, MD Department of Urology, University of Michigan

Roberts W. 1 , Hall T. 2 , Ghani K. 1
1. University of Michigan, Dept. of Urology, Ann Arbor, United States of America 
2. University of Michigan, Dept. of Biomedical Engineering, Ann Arbor, United States of America

Written by: Renai Yoon, Department of Urology, University of California-Irvine at the 2018 European Association of Urology Meeting EAU18, 16-20 March, 2018 Copenhagen, Denmark